JP2000104550A - Direct injection type spark ignition engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the combustion properties of stratified combustion and uniform combustion and to improve the properties of exhaust nature. SOLUTION: It is set that front collision occurs between cylinder fluid A and injection fuel F during stratified combustion, and since a pair of rise walls 11 to suppress diffusion of fuel in a lateral direction of an injection axis of fuel are formed on the crown surface of a piston 2, vaporization of fuel, the promotion of the generation of air-fuel mixture, and suppression of diffusion of air-fuel mixture are performed to effect excellent stratified combustion. In a way that, during uniform combustion, injection fuel F is diffused over the whole of a cylinder with the fuel flowing over the cylinder fluid A, uniform air-fuel mixture is formed through the pulverization of fuel and the promotion of vaporization and excellent uniform combustion is carried out. Further, since a cavity combustion chamber is eliminated, the adhesion of fuel to a piston crown surface is suppressed and the improvement of an exhaust shape is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a direct injection type spark ignition engine.

[0002]

2. Description of the Related Art Some in-cylinder injection spark ignition engines include, for example, Japanese Patent Application Laid-Open No. 8-35429.
As shown in Japanese Unexamined Patent Application Publication No. 6-81651, the swirl flows from substantially below the intake valve to the piston crown surface, as shown in Japanese Unexamined Patent Publication No. 6-81651. There has been known a configuration in which a reverse tumble flow is provided, which is reversed at a piston crown surface and becomes a vertical flow toward a spark plug in a central portion of a combustion chamber.

[0003] In any of these, a cavity combustion chamber is recessed in a piston crown surface, and fuel is injected to a spark plug by performing fuel injection in a state where the swirl or reverse tumble flow is preserved by the cavity combustion chamber in a compression stroke. The fuel is transported to form stratified combustion by forming a relatively rich air-fuel mixture only around the spark plug. In order to perform the stratified combustion satisfactorily, the fuel injected in the compression stroke is transported to the spark plug. It is important that they do not diffuse widely into the combustion chamber in between.

For this reason, the above-mentioned cavity combustion chamber is formed as large and deep as possible by offsetting substantially half of the piston crown surface on the intake valve arrangement side, while the fuel injection valve is injected in the compression stroke during stratified combustion. The nozzle direction is set so that almost all of the fuel spray is contained in the cavity combustion chamber.

[0005]

However, in such a conventional direct injection type internal combustion engine, as described above, the largest and deepest cavity combustion chamber is unevenly distributed on one side of the piston crown surface. Therefore, the piston balance with respect to the cylinder center axis is poor, and especially when the engine is cold, the difference in the coefficient of thermal expansion between the cylinder and the piston becomes remarkable, so that the piston can easily swing, causing abnormal noise and uneven wear. The likelihood increases.

Further, since the cavity combustion chamber on the piston crown surface is formed as large and deep as possible, fuel easily adheres to the wall surface of the cavity combustion chamber, and smoke and unburned HC
Not only deteriorates exhaust properties as a cause of
There is a possibility that a decrease in output due to a decrease in combustion efficiency may occur.

Particularly, during stratified charge combustion, the nozzle direction of the fuel injection valve is set so that almost the entire amount of fuel spray is contained in the cavity combustion chamber, so that most of the injected fuel collides with the wall surface of the cavity combustion chamber. As a result, the fuel adheres in the form of a liquid film, so that the aforementioned smoke and unburned HC are remarkably generated, and the attached fuel may be deposited as a deposit.

Therefore, the present invention can improve the fuel consumption rate and the exhaust properties under low load by performing good combustion in both stratified combustion and homogeneous combustion, can improve the output under high load, and improve the engine output. To provide an in-cylinder injection type spark ignition engine that can also enhance the durability of the engine.

[0009]

According to the first aspect of the present invention, there is provided an in-cylinder injection type spark having a fuel injection valve for directly injecting fuel into a combustion chamber and providing in-cylinder flow to intake air. In the ignition engine, the fuel injection valve is mounted so that the injection axis of the injected fuel substantially collides with the main flow direction of the in-cylinder flow during fuel injection during stratified charge combustion. A pair of upright walls is provided to prevent the fuel spray injected from the fuel cell from diffusing in the left-right direction with respect to the fuel injection axis.

According to a second aspect of the present invention, the main flow of the in-cylinder flow described in the first aspect and the injected fuel injected between the pair of upright walls are located almost immediately above a position near a frontal collision. A spark plug is provided.

According to the third aspect of the present invention,
The surface between the pair of upright walls of the piston crown surface described in (1) is a recess formed by excavating the reference surface of the piston crown surface.

According to the fourth aspect of the invention. A recess provided between a pair of upright walls of the piston crown surface according to claim 3 is formed in a V-shaped cross section in a length direction between the upright walls.

According to a fifth aspect of the present invention, the concave portion provided between the pair of standing walls of the piston crown surface according to the third aspect is formed as a concave curved surface having an arc-shaped cross section in the length direction between the standing walls. It is characterized by.

According to the sixth aspect of the present invention, the first to fifth aspects are provided.
The pair of upright walls described in the above has a narrow portion between the upright walls in the substantially central portion of the length, and was formed into a curved surface so that the interval between the upright walls gradually increased from the narrow portion to both ends in the lengthwise direction of the upright wall. It is characterized by.

In the invention of claim 7, claims 1 to 6
The outer portions of the pair of standing walls described in (1) are formed as protrusions protruding from the reference surface of the piston crown surface.

In the invention of claim 8, claims 1 to 7
Is characterized in that the pair of upright walls has a top portion at a substantially central portion of the length thereof, and is formed in a side mountain shape in which the height of the upright wall gradually decreases from the top portion to both ends of the upright wall.

According to the ninth aspect of the present invention, the first to eighth aspects are provided.
The in-cylinder injection spark ignition engine described in (1) is characterized in that an in-cylinder flow enhancing means is provided in the intake system.

[0018]

According to the first aspect of the present invention, during stratified charge combustion, the fuel spray injected from the fuel injection valve during the compression stroke with respect to the main flow direction of the in-cylinder flow formed in the combustion chamber during the intake stroke. The head-on collision maximizes the relative speed between the fuel spray and the in-cylinder flow, atomizes the fuel and maximizes the use of fluid friction, thereby promoting the vaporization of the fuel spray and the formation of a combustible mixture. The pair of standing walls suppress the diffusion of the fuel spray in the left-right direction, so that a local combustible mixture is formed, and the combustible mixture is formed by the rise of the piston and the in-cylinder flow. It can be reliably transported to the surroundings to perform stratified combustion.

As a result, the formation of the combustible air-fuel mixture and the transport of the combustible air-fuel mixture around the ignition plug can be performed satisfactorily without providing a large and deep cavity combustion chamber on the piston crown surface. In addition, it is possible to reduce smoke and unburned HC due to the adhesion of fuel to the wall surface of the cavity combustion chamber, and to suppress deposit accumulation on the piston crown surface, as well as to stabilize stratified combustion, and
Improvements in fuel consumption rate and exhaust properties can be realized.

On the other hand, during homogeneous combustion, fuel is injected from the fuel injection valve in the intake stroke, and in this case, the injected fuel is diffused throughout the cylinder along with the main flow of the in-cylinder flow, thereby causing in-cylinder mixing. The homogenization of the gas is improved, and the preservation of the in-cylinder flow is improved by the presence of the pair of upright walls, so that the atomization of the fuel and the vaporization and the formation of a combustible mixture are promoted, and the fuel is almost uniformly spread in the combustion chamber. The homogeneous combustion can be favorably performed. Therefore, in this case as well, the reduction of smoke and unburned HC and the accumulation of deposits can be suppressed, and the improvement of combustion efficiency and output can be realized.

In addition, since the preservability of the in-cylinder flow during the fuel injection stroke during the above-mentioned injection is improved, the vaporization of the fuel is promoted, so that the fuel inhales a large amount of latent heat of vaporization of the intake air to cool the air. In addition, the actual charging efficiency is improved, and the output of the engine can be further improved.

Further, since there is no cavity combustion chamber deviated to one side of the piston crown surface, the piston balance is improved and the possibility of generating abnormal noise and uneven wear is low.
The durability and reliability of the engine can be further improved.

According to the invention described in claim 2, according to claim 1
In addition to the effect of the invention, the spark plug is provided at a position almost directly above the position where the main flow of in-cylinder flow during stratified combustion and the injected fuel injected between the pair of upright walls of the piston crown face near the frontal collision. Therefore, when the combustible mixture is transported around the spark plug, diffusion to the surroundings is suppressed as much as possible, so that transportability can be improved, and the stratification degree of the mixture can be maintained high, thereby performing more stable stratified combustion. be able to.

According to the third aspect of the present invention, in addition to the effects of the first and second aspects, the surface between the pair of upright walls of the piston crown is dug with respect to the reference plane of the piston crown. Since it is formed as a concave portion, the vertical distance between the tip of the fuel injection valve and the piston crown surface can be sufficiently secured during stratified combustion, thereby further reducing the amount of fuel adhering to the piston crown surface. It is possible to further improve the fuel consumption rate and exhaust characteristics of the engine.

According to the invention described in claim 4, according to claim 3,
In addition to the effects of the invention, the recess provided between the pair of upright walls of the piston crown surface is formed in a V-shaped cross section in the length direction between the upright walls, so that the injected fuel and the in-cylinder flow during stratified combustion are reduced. The height dimension between the upper surface of the vertical wall and the piston crown surface at the central portion in the longitudinal direction between the vertical walls that collide with each other can be sufficiently secured, and the effect of suppressing the diffusion of fuel spray in the left-right direction can be enhanced. .

Further, the surface area of the piston crown can be made as small as possible for the formation of the concave portion, so that heat loss from the combustion chamber to the piston crown can be reduced, and the engine heat efficiency can be improved.

According to the invention set forth in claim 5, according to claim 3,
In addition to the effect of the invention, the concave portion provided between the pair of standing walls of the piston crown surface is formed as a concave curved surface having an arc-shaped cross section in the length direction between the standing walls, so that the injected fuel and the in-cylinder during stratified combustion. The height dimension between the top wall of the vertical wall and the piston crown surface at the central part in the longitudinal direction between the vertical walls where the flow collides with the front can be sufficiently secured to enhance the effect of suppressing the diffusion of fuel spray in the left-right direction. Can be.

When the in-cylinder flow is a vertical swirling flow (tumble flow), the tumble flow can be smoothly passed between the pair of upright walls, so that the preservation of the tumble flow is improved, and the injected fuel is improved. Of fuel due to head-on collision with
The mixture formation is further promoted, the transportability of the mixture around the spark plug is further improved, and the stratified combustion can be performed stably under a wide range of operating conditions, further improving the fuel consumption rate of the engine. can do.

According to the invention of claim 6, according to claim 1,
In addition to the effects of the inventions of (1) to (5), a fuel spray injected at a wide spray angle from a fuel injection valve during stratified combustion has a narrow portion at the center in the longitudinal direction between the pair of upright walls. In addition, the fuel spray can be focused at the narrow center part while suppressing the diffusion in the left-right direction from between the standing walls, and the in-cylinder flow is narrowed at the narrow part to form a high-velocity part locally Therefore, the effect of promoting the vaporization of the fuel and the formation of the air-fuel mixture due to the frontal collision with the injected fuel is further enhanced, and the transportability of the air-fuel mixture around the spark plug can be further improved.

According to the seventh aspect of the present invention, the first aspect is provided.
In addition to the effects of the present invention, the outer portions of the pair of upright walls are formed as protrusions protruding from the reference surface of the piston crown surface, so that the increase in the volume of the combustion chamber is suppressed and the engine compression ratio is reduced. By increasing the value, it is possible to improve the engine output and the thermal efficiency.

Further, since the shape of the piston crown surface is simplified, the moldability is good and the cost can be reduced.

[0032] According to the invention of claim 8, according to claim 1 of the present invention.
In addition to the effects of the present invention, the pair of upright walls is formed in a side mountain shape, so that the overall upward protrusion of the upright walls is reduced, and the injected fuel and the in-cylinder flow collide with each other during stratified combustion. The height dimension between the piston crown and the upper edge of the vertical wall at the center in the longitudinal direction between the rising walls can be sufficiently increased to improve the effect of suppressing the fuel spray from diffusing in the left and right direction and the piston crown surface area The heat loss can be reduced by suppressing the increase of the heat loss.

[0033] According to the ninth aspect of the present invention, the first aspect is provided.
In addition to the effects of the present invention, the in-cylinder flow enhancement means is provided in the intake system, so that even during low-speed stratified combustion with a low piston moving speed, vaporization is promoted by frontal collision with injected fuel, and the spark plug is improved. It is possible to obtain an in-cylinder flow having sufficient strength for transporting the air-fuel mixture to the surroundings, and to perform stable stratified combustion under a wider range of operating conditions.

[0034]

Embodiments of the present invention will be described below in detail with reference to the drawings.

1 to 3, reference numeral 1 denotes a cylinder block, 2 denotes a piston, 3 denotes a cylinder head, and 4 denotes a combustion chamber formed by the cylinder block 1, the piston 2, and the cylinder head 3.

The cylinder head 3 is provided with two intake valves 5 and two exhaust valves 6 arranged opposite to the intake valves 5, and takes in air from one intake port 7 and exhausts it from the other exhaust port 8. It has a cross flow port structure.

The cylinder head 3 is provided with an ignition plug 9 substantially at the center of the combustion chamber 4, and at the side of the combustion chamber in the vicinity of the intake valve 5, specifically, at two sides of the combustion chamber 4. A fuel injection valve 10 is provided at a position near the opening between the intake ports 7, 7, and fuel is directly injected from the fuel injection valve 10 into the combustion chamber 4.

As shown by an arrow A in FIG. 1, the intake ports 7 pass through the lower side of the spark plug 9 and the piston 2 from the exhaust valve arrangement side as shown by the arrow A in FIG.
And a reverse tumble flow toward the upper spark plug 9 to form a forward tumble flow.

In the fuel injection valve 10, the fuel injected at the latter stage of the compression stroke during the stratified charge combustion is inverted at the crown of the piston 2 as shown by the arrow F in FIG. The jet axis of the forward tumble flow A is mounted at an angle pointing toward the inversion portion of the forward tumble flow A so that the main flow of the forward tumble flow A can collide head-on.

On the other hand, a pair of standing walls 11, 11 are provided on the crown surface of the piston 2 at appropriate intervals in a direction parallel to the injection axis of the fuel injection valve 10 in plan view, and are stratified by the standing walls 11, 11. The fuel injected at the time of combustion can be prevented from diffusing in the left-right direction with respect to the injection axis.

In this embodiment, the upright walls 11, 11 are provided at substantially the center of their length, that is, at the time of stratified combustion, the injected fuel F
And the forward tumble flow A have a top in the center of the crown surface of the piston 2 where the frontal collision occurs, and the height of the standing wall gradually decreases from the top to both ends of the standing wall so as to match the reference surface S of the piston crown. It is formed in.

The intake port 7 is provided near the intake valve 5 as an in-cylinder flow strengthening means to cut off a substantially lower half of the intake port 7 during stratified charge combustion and to take in air from a substantially upper half of the intake port 7. In addition, a partial shutoff valve 12 for enhancing the forward tumble flow A is provided.

According to the structure of the above embodiment, during the stratified charge combustion, the forward tumble flow A formed in the combustion chamber 4 during the intake stroke.
On the other hand, fuel is injected from the fuel injection valve 10 toward the space between the upright walls 11 at the center of the crown of the piston 2 in the latter half of the compression stroke, so that the injected fuel (fuel spray) F is forward tumbled. , The relative velocity between the fuel spray F and the forward tumble flow A is maximized, and the fuel is atomized and the fluid friction can be maximized, so that the fuel spray F is vaporized and the combustible mixture is formed. Promoted.

Moreover, the pair of upright walls 11 and 11
Since fuel is injected in between, the vertical walls 11 and 11 suppress the diffusion of the fuel spray F in the left-right direction to form a local combustible mixture, and the rise of the piston 2 and the forward tumble flow A This combustible air-fuel mixture can be reliably transported around the ignition plug 9 above the central portion of the combustion chamber 4 to perform stratified combustion.

As a result, the formation of a combustible air-fuel mixture can be achieved without providing a large and deep cavity combustion chamber on the piston crown surface for preserving the in-cylinder flow during stratified combustion and transporting the injected fuel around the ignition plug. And the transport of the combustible air-fuel mixture around the ignition plug 9, so that smoke and unburned HC caused by fuel adhesion to the wall surface of the cavity combustion chamber can be reduced, and the piston crown can be reduced. Not only can deposits on the surface be suppressed, but also stratified combustion can be stabilized, and improvements in fuel consumption rate and exhaust properties can be realized.

In this embodiment, in particular, in the present embodiment, the pair of upright walls 11, 11 of the piston crown surface are formed in a mountain-like shape on the side, so that the overall upward protrusion of the upright walls 11, 11 is reduced as much as possible, and then the stratification is performed. The height dimension between the upper edges of the vertical walls 11, 11 at the longitudinal center portion between the vertical walls 11, 11 where the injected fuel F and the forward tumble flow A collide with each other during combustion can be sufficiently secured. Further, the effect of suppressing the diffusion of the fuel spray in the left-right direction can be improved, and the heat loss can be reduced by suppressing the increase of the piston crown surface area, and the output can be improved.

In addition, the ignition plug 9 is provided at the center of the combustion chamber, which is almost immediately above a part of the injected fuel F and the forward tumble flow A heading up and facing upward during stratified combustion.
When the combustible air-fuel mixture is transported around the ignition plug 9, diffusion to the surroundings is suppressed as much as possible, so that transportability can be improved, and the stratification of the air-fuel mixture can be kept high, so that more stable stratified combustion can be performed. .

Also, a partial shut-off valve 12 is provided in the intake port 7 as in-cylinder flow strengthening means during stratified combustion so as to strengthen the forward tumble flow A. Even during combustion, the injected fuel F
And forward tumbling flow A, the vaporization can be promoted by the frontal collision, and the mixture transport property around the ignition plug 9 can be improved, and stable stratified combustion can be performed under a wide range of operating conditions.

On the other hand, during homogeneous combustion, fuel is injected from the fuel injection valve 10 during the intake stroke, and in this case, the injected fuel F rides on the main flow of the forward tumble flow A and is diffused throughout the cylinder. The homogenization of the air-fuel mixture in the cylinder is improved, and the preservability of the forward tumble flow A is improved by the presence of the pair of upright walls 11, 11 on the piston crown surface. It is promoted to spread the combustion chamber 4 almost uniformly, so that homogeneous combustion can be favorably performed. Therefore, also in this case, reduction of smoke and unburned HC and suppression of deposit accumulation can be performed. Output direction can be realized.

In addition, since the preservability of the forward tumble flow A is improved during the above-described fuel intake stroke injection, the vaporization of the fuel is promoted, so that the fuel intensifies the latent heat of vaporization of the intake air to cool the air. Therefore, the actual charging efficiency is improved, and the engine output can be further improved.

On the other hand, apart from the effect of the combustibility of stratified combustion and homogeneous combustion, there is no cavity combustion chamber which is deviated to one side on the piston crown surface, so that the piston balance is improved. Therefore, the possibility of generating abnormal noise and uneven wear is low, and the durability and reliability of the engine can be further improved.

FIG. 4 shows the structure of the piston crown in the second embodiment of the present invention. In this embodiment, a pair of upright walls 1 of the piston crown in the first embodiment is shown.
The surface between 1 and 11 is formed as a flat concave portion 13 dug out with respect to the reference surface S of the piston crown surface.

Therefore, according to this embodiment, in addition to the effect of the first embodiment, the vertical distance between the tip of the fuel injection valve 10 and the piston crown surface during stratified combustion is sufficiently secured due to the presence of the recess 13. It is possible to further reduce the amount of the injected fuel F adhering to the piston crown surface,
The fuel consumption rate and exhaust characteristics of the engine can be further improved, and the preservability of the forward tumble flow A can be enhanced.

The third embodiment shown in FIG.
Is formed to have a V-shaped cross section in the length direction between the upright walls 11, 11. According to the configuration of the third embodiment, in addition to the effect of the second embodiment, the injection fuel F and the The height between the upper edges of the standing walls 11, 11 at the center in the longitudinal direction between the standing walls 11, 11 where the tumble flow A collides head-on, and the height dimension between the piston crown surface can be sufficiently taken, and the lateral direction of the fuel spray can be obtained. The effect of suppressing diffusion to the surface can be enhanced.

Further, the surface area of the piston crown surface can be reduced as much as possible for the formation of the concave portion, and the heat loss from the inside of the combustion chamber 4 to the piston crown surface can be reduced, so that the engine heat efficiency can be improved.

In any of the fourth to seventh embodiments shown in FIGS. 6 to 11, the concave portion 13 is formed as a concave curved surface having an arc-shaped cross section in the length direction between the upright walls 11, 11.
According to the configurations of the sixth to sixth embodiments, in addition to the effects of the second embodiment, the vertical wall at the central portion in the longitudinal direction between the vertical walls 11, 11 where the injected fuel F and the forward tumble flow A collide head-on during stratified combustion. The height dimension between the upper edge of the piston 11 and the piston crown surface can be made sufficiently large, and the effect of suppressing the diffusion of the fuel spray in the left-right direction can be enhanced.

Further, since the forward tumble flow A can be smoothly passed between the standing walls 11 and 11, the preservability of the forward tumble flow A is further improved, and the forward fuel T and the forward tumble flow A are caused by a frontal collision. The vaporization of the fuel and the formation of the air-fuel mixture are further promoted, the transportability of the air-fuel mixture around the ignition plug 9 is further improved, and the stratified combustion can be stably performed under a wider range of operating conditions.

Here, in the fifth embodiment shown in FIGS. 7 and 8, the sixth embodiment shown in FIGS. 9 and 10, and the seventh embodiment shown in FIG. A narrow portion N is provided between the standing walls 11 at substantially the center of the vertical wall, and the standing wall 1 extends from the narrow portion N to both ends in the longitudinal direction of the standing wall.
It is formed in a curved surface so that the interval between 1 and 11 gradually widens. Therefore, in these embodiments, in addition to the effects described above,
Even in the case of fuel spray injected at a wide spray angle from the fuel injection valve 10 at the time of stratified combustion, the fuel spray F is focused at the narrow portion N at the center while suppressing diffusion in the left-right direction from between the vertical walls 11. And the forward tumble flow A is contracted at the narrow portion N to locally form a high flow velocity portion. Therefore, the fuel vaporization due to the frontal collision between the injected fuel F and the forward tumble flow A, The effect of promoting the mixture formation is further enhanced, and the transportability of the mixture around the spark plug 9 can be further improved.

In the embodiment shown in FIGS. 9, 10, and 11, the outer portions of the vertical walls 11 and 11 are connected to the reference surface S of the piston crown surface.
Therefore, apart from the above-described effects, it is possible to suppress the increase in the volume of the combustion chamber and increase the engine compression ratio to improve the engine output and the thermal efficiency. Since the shape of the piston crown surface is simplified, the moldability is good and the cost can be reduced.

FIGS. 12 and 13 show an eighth embodiment in which the present invention is applied to a swirl concept engine.

In this embodiment, two intake ports 7, 7
One of the intake ports 7 is provided with a swirl control valve 15 that closes during stratified charge combustion, and during stratified charge combustion, the intake ratio from the other intake port 7 is increased to allow in-cylinder flow as indicated by an arrow As in FIG. The swirl of the left turn as shown by is formed.

A pair of upright walls 11, 11 are provided on one side of the crown surface of the piston 2 at an appropriate interval substantially in parallel with the swirl flow As at an appropriate interval, and the fuel provided on the side where the intake valve is disposed is provided. The injection valve 10 is arranged such that the axis of the injected fuel F
The swirl flow As is mounted at an angle that allows a frontal collision with the swirl flow As between the positions 1 and 11.

The spark plug 9 is provided at a central portion in the longitudinal direction between the upright walls 11 and 11 at a position almost directly above a portion where the injected fuel F and the swirl flow As collide head-on.

Therefore, even in the case of such an engine of the swirl concept, substantially the same effects as those of the first embodiment shown in FIGS.

Also in the case of the eighth embodiment, the surface between the standing walls 11 and 11 of the piston crown surface may be formed into a concave shape in the length direction to enhance the fuel adhesion suppressing effect and the fuel diffusion suppressing effect. Needless to say, the intake port 7 may be provided with a swirl reinforcing means.

[Brief description of the drawings]

FIG. 1 is a sectional explanatory view schematically showing a configuration of a first embodiment of the present invention.

FIG. 2 is a schematic plan explanatory view of the embodiment.

FIG. 3 is a schematic perspective view of a piston according to the embodiment.

FIG. 4 is a schematic perspective view of a piston according to a second embodiment of the present invention.

FIG. 5 is a schematic perspective view of a piston according to a third embodiment of the present invention.

FIG. 6 is a schematic perspective view of a piston according to a fourth embodiment of the present invention.

FIG. 7 is a schematic plan explanatory view of a fifth embodiment of the present invention.

FIG. 8 is a schematic perspective view of a piston in the embodiment.

FIG. 9 is a schematic plan explanatory view of a sixth embodiment of the present invention.

FIG. 10 is a schematic perspective view of a piston in the embodiment.

FIG. 11 is a schematic perspective view of a piston according to a seventh embodiment of the present invention.

FIG. 12 is a schematic plan explanatory view of an eighth embodiment of the present invention.

FIG. 13 is a schematic perspective view of a piston in the same embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Piston 3 Cylinder head 4 Combustion chamber 5 Intake valve 6 Exhaust valve 7 Intake port 8 Exhaust port 9 Ignition plug 10 Fuel injection valve 11 Upright wall 12 In-cylinder flow enhancement means 13 Recess 14 Projection A, As In-cylinder flow F Injected fuel S Piston reference surface N Narrow part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F02F 3/26 F02F 3/26 A (72) Inventor Tohru Noda 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor In-house F term (reference) 3G023 AA02 AA04 AA15 AB03 AC05 AD03 AD07 AD09 AG01 3G301 HA01 HA04 HA16 HA17 JA01 JA02 JA24 JA26 LA05 MA19

Claims (9)

[Claims] 1. An in-cylinder injection spark ignition engine having a fuel injection valve for directly injecting fuel into a combustion chamber and imparting an in-cylinder flow to intake air, wherein the fuel injection valve comprises:
At the time of fuel injection during stratified charge combustion, the fuel injection axis is mounted so that the injection axis of the injected fuel substantially collides with the main flow direction of the in-cylinder flow, and the fuel spray injected from the fuel injection valve onto the piston crown surface is aligned with the fuel injection axis. An in-cylinder injection type spark ignition engine characterized by having a pair of upright walls for suppressing diffusion in the left-right direction with respect to the engine. 2. The ignition plug according to claim 1, wherein the spark plug is disposed substantially immediately above a position near a position where the main flow of the in-cylinder flow and the fuel injected toward the space between the pair of upright walls collide head-on. 2. The in-cylinder injection spark ignition engine according to claim 1. 3. The in-cylinder injection type spark according to claim 1, wherein the surface between the pair of upright walls of the piston crown is a recess dug out with respect to the reference surface of the piston crown. Ignition engine. 4. The in-cylinder injection spark ignition according to claim 3, wherein a recess provided between the pair of standing walls of the piston crown surface is formed in a V-shaped cross section in a length direction between the standing walls. organ. 5. The in-cylinder injection type according to claim 3, wherein the concave portion provided between the pair of standing walls of the piston crown surface is formed as a concave curved surface having an arc-shaped cross section in the length direction between the standing walls. Spark ignition engine. 6. A pair of upright walls has a narrow portion between the upright walls in a substantially central portion of the length thereof, and is formed into a curved surface so that the distance between the upright walls gradually increases from the narrow portion to both ends in the lengthwise direction of the upright wall. The in-cylinder injection type spark ignition engine according to any one of claims 1 to 5, wherein: 7. The in-cylinder injection type according to claim 1, wherein each of the outer portions of the pair of upright walls is formed as a protrusion protruding from a reference surface of the piston crown. Spark ignition engine. 8. A pair of upright walls, each of which has a top portion at a substantially central portion of its length, and has a side mountain shape in which the height of the upright wall gradually decreases from the top portion to both ends of the upright wall. 8. The in-cylinder injection spark ignition engine according to 7. 9. The in-cylinder injection spark ignition engine according to claim 1, wherein an in-cylinder flow enhancement means is provided in the intake system.