JP2003013737A - Cylinder-injection-of-fuel-type spark ignition internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder-injection-of-fuel-type spark ignition internal combustion engine capable of remarkably improving the output performance and the fuel cost performance by homogeneously distributing an air-fuel mixture in a combustion chamber (forming homogeneous air-fuel mixture), and sufficiently exercising a merit of the homogeneous combustion, when the homogeneous air-fuel mixture is formed by directly injecting the fuel into a cylinder during an intake stroke. SOLUTION: This cylinder-injection-of-fuel-type spark ignition internal combustion engine 10 is provided with a first inclined plane 32 and a second inclined plane 34 on a top of piston 18. The first inclined plane 32 has a rising gradient of a predetermined angle toward the fuel injecting direction, and the second inclined plane 34 has a rising gradient of a predetermined angle. The fuel atomization injected during the intake stroke is uniformly divided and diffused to the injecting direction and a side opposite to the injecting direction, whereby the air-fuel mixture can be homogeneously distributed in a combustion chamber 16, and the homogeneous combustion can be achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-cylinder injection spark ignition internal combustion engine in which fuel is directly injected into a combustion chamber of a cylinder to form an air-fuel mixture which is ignited and burned by an ignition plug.

[0002]

2. Description of the Related Art A cylinder injection type spark ignition internal combustion engine (so-called direct injection gasoline engine) is known in which fuel is directly injected into a cylinder (combustion chamber) and ignited and burned by spark ignition.

In an existing in-cylinder injection type spark ignition internal combustion engine of this type, when a rich air-fuel mixture is formed in the vicinity of the spark plug and a lean air-fuel mixture is formed around it, the average air-fuel ratio of the whole is considerably low. However, it is possible to ignite, low load range (partial load)
In order to improve the fuel consumption of the fuel cell, there is a fuel cell configured to perform so-called stratified combustion. Moreover, it is generally based on the concept of utilizing the wall shape of the combustion chamber for stratified combustion, that is, for forming the stratified mixture. In other words, by injecting fuel spray toward the cavity provided on the top surface of the piston and devising the shape of the cavity wall, the direction of spray movement can be changed and fuel can be retained in the cavity to form a stratified mixture. This is a configuration to be formed (as one example, Japanese Patent Laid-Open No. 9-158736).

In this type of in-cylinder injection spark ignition internal combustion engine, fuel injection is performed in the compression stroke in the low load region (partial load) to achieve the above-mentioned stratified combustion to improve fuel efficiency, while at the time of high load, In order to utilize the air sucked into the cylinder as effectively as possible, fuel injection is performed in the intake stroke to form a homogeneous air-fuel mixture and homogeneous combustion is performed to improve the output.

By the way, it is said that the in-cylinder injection type spark ignition internal combustion engine has advantages even in the homogeneous combustion as described above. That is, by injecting fuel during the intake stroke in which air is flowing into the cylinder, it is possible to cool the intake air by the generation of steam, which improves knock resistance and increases the compression ratio. It becomes possible and the fuel economy performance may be improved. Further, the intake cooling may improve the filling efficiency and the output performance.

However, in the conventional cylinder injection type spark ignition internal combustion engine, although there is a great merit in performing the stratified combustion and the homogeneous combustion as described above, compared with the so-called port injection type spark ignition internal combustion engine, a mixture mixture is formed. Since it is inferior in terms of homogenization, there is a reality that the above-mentioned great merit is not fully exerted. That is, FIG. 17 (A)
Through a cylinder injection type spark ignition internal combustion engine 1 shown in FIG.
Piston 10 to form a stratified mixture, such as
Since the cavity 104 provided on the top surface of 2 traps the spray Z, the homogenization of the air-fuel mixture is hindered, and the combustion chamber 1
A rich mixture R and a lean mixture S were simultaneously formed in 06, which deteriorated combustion, offsetting the above merit, and lowering the output performance and fuel efficiency.

Therefore, in-cylinder injection sparks using a piston having a substantially flat top surface shape are not used for forming the stratified mixture (not to be a factor, that is, the cavity is removed) without using the cavity wall provided on the piston top surface. Ignition internal combustion engines are considered. In this type of cylinder injection type spark ignition internal combustion engine, fuel is injected during the intake stroke in all load ranges to form a homogeneous mixture and perform homogeneous combustion. It aims to improve output performance and fuel efficiency compared to spark ignition internal combustion engines.

However, the in-cylinder injection type spark ignition internal combustion engine using a piston having a substantially flat top surface shape still has the following drawbacks. That is, in FIG.
The intake valve 20 of the cylinder head 202, as in the in-cylinder injection type spark ignition internal combustion engine 200 shown in FIGS.
The fuel spray Z injected from the fuel injection valve 206, which is biased toward the four side, collides obliquely with the top surface of the piston 208, and most of the fuel spray Z is on the side in the injection proceeding direction (generally, the exhaust valve 210). On the side of the intake valve 20).
The fuel spray Z existing on the side (4) is reduced. Therefore, although the air-fuel mixture can be uniformly distributed to the inside of the combustion chamber 212 (form a homogeneous air-fuel mixture) by injecting the fuel during the intake stroke, the cavity 104 is provided on the top surface as described above. Although the homogenization of the air-fuel mixture (formation of a homogenous air-fuel mixture) is improved as compared with the case where the piston 102 is used, it is not sufficient and the combustion chamber 212 still has a rich air-fuel mixture R and an excessive air-fuel mixture. A thin mixture S is formed at the same time. Therefore, the merits of performing the homogeneous combustion described above are still offset, and the output performance and the fuel efficiency performance deteriorate.

As described above, in the cylinder injection type spark ignition internal combustion engine in which fuel is directly injected into the cylinder during the intake stroke by the fuel injection valve arranged on the intake valve side of the cylinder head, the mixture is homogenized. There was a problem that (formation of a homogeneous mixture) was insufficient.

[0010]

In view of the above facts, the present invention distributes the air-fuel mixture homogeneously in the combustion chamber when forming a homogenous air-fuel mixture by directly injecting fuel into the cylinder during the intake stroke. It is an object of the present invention to obtain a cylinder injection type spark ignition internal combustion engine in which the advantages of performing homogeneous combustion (forming a homogeneous mixture) and performing homogeneous combustion are sufficiently exerted, and the output performance and the fuel efficiency performance are significantly improved.

[0011]

According to a first aspect of the present invention, there is provided a cylinder injection type spark ignition internal combustion engine which sucks air from an intake pipe, and injects fuel into a cylinder by an injection valve installed at a position distant from the center of the cylinder. Direct injection to form a mixture,
In a cylinder injection type spark ignition internal combustion engine that ignites and burns the air-fuel mixture by means of a spark plug installed substantially in the center of the cylinder, the injection valve is formed on a piston top surface facing the injection valve and is substantially flat and A first inclined surface having an ascending slope of a predetermined angle θa toward the advancing direction of fuel injection, and a piston top surface formed continuously with the lower end edge of the first inclined surface. A second inclined surface having a rising slope of a predetermined angle θb in the direction opposite to the surface.

In the cylinder injection type spark ignition internal combustion engine according to the first aspect, air is sucked from the intake pipe during the intake stroke, and the fuel is directly injected into the cylinder (combustion chamber) by the injection valve to form the air-fuel mixture. It is formed and the mixture is ignited and burned by the spark plug.

Here, in forming the air-fuel mixture by directly injecting fuel into the cylinder during the intake stroke, the injected fuel spray collides with the first inclined surface and is shunted to the surroundings in sequence, While diffusing to the upper end side of the slope of the first inclined surface, shunt diffusion is also performed along the second inclined surface continuous with the lower end edge of the first inclined surface. In this case, the first inclined surface is
A predetermined angle θ toward the direction of fuel injection by the injection valve
Since the ascending slope is a, a part of the fuel spray that collides with the first inclined surface returns to the direction of the second inclined surface (that is, the opposite side to the advancing direction of the fuel injection by the injection valve), and The shunt diffusion also occurs along the inclined surface of 2. As a result, the fuel spray is divided and diffused evenly in the direction of the injection and the opposite side of the injection, and the air-fuel mixture can be homogeneously distributed in the combustion chamber (a homogeneous air-fuel mixture can be formed). Combustion can be performed.

Therefore, in the cylinder injection type spark ignition internal combustion engine according to the first aspect of the present invention, the advantages of homogeneously distributing the air-fuel mixture in the combustion chamber (forming a homogenous air-fuel mixture) and performing homogeneous combustion are sufficiently exhibited. Thus, the output performance and the fuel efficiency performance can be significantly improved.

A cylinder injection type spark ignition internal combustion engine according to a second aspect of the present invention is the cylinder injection type spark ignition internal combustion engine according to the first aspect, wherein a lower surface of a cylinder head having a spray axis φ for fuel injection by the injection valve is used. When the angle with respect to is θs,
“0 ≦ θa ≦ (90 ° −θs)”, and “0 ≦ θb ≦ 9
It is characterized in that the step height h of the lower end edge of the first inclined surface with respect to the piston top surface is set to 15 mm or less.

Here, the collision angle of the spray axis of the fuel injection by the injection valve with respect to the first inclined surface is θi, and the flow rate of the spray in the advancing direction of the injection is Q1. (Q2 / Q1) = if the collision angle θi is 90 °
It becomes 1, and the spray is divided evenly. That is, the ratio of Q2 decreases as the collision angle θi decreases. Here, the spray axis φ of the fuel injection by the injection valve
The angle θs with respect to the lower surface of the cylinder head is practically set within 60 ° in order to prevent the spray from adhering to the inner surface of the cylinder wall on the injection valve side. That is, it is effective to keep the angle θs appropriate and prevent the spray from adhering to the inner surface of the cylinder wall on the injection valve side, while making the collision angle θi close to 90 °.

In this respect, in the cylinder injection type spark ignition internal combustion engine according to the second aspect, the collision angle θi can be increased while maintaining the angle θs appropriately, and (Q2 / Q1) can be brought close to 1. it can. As a result, the spray splits evenly, and the air-fuel mixture can be uniformly distributed (form a homogeneous air-fuel mixture) in the combustion chamber.

Furthermore, if the step difference on the piston top surface due to the first inclined surface and the second inclined surface becomes excessively large, the cooling loss due to the increase of the piston surface area increases, but the cylinder injection type according to claim 2 In a spark ignition internal combustion engine,
Since the step h of the lower end edge of the first inclined surface with respect to the piston top surface is set to 15 mm or less, it is possible to preferably form the homogeneous air-fuel mixture while suppressing disadvantages such as cooling loss due to the increase of the piston surface area.

The cylinder injection type spark ignition internal combustion engine of the invention according to claim 3 sucks air from the intake pipe and directly injects fuel into the cylinder by an injection valve installed at a position apart from the center of the cylinder to mix the fuel. In an in-cylinder injection spark ignition internal combustion engine that forms air and ignites and burns the air-fuel mixture by means of an ignition plug installed substantially in the center of the cylinder, the top surface of the piston is formed into a substantially flat surface, and It is characterized in that it is provided with a projecting portion which is formed so as to project on the piston top surface so as to face the direction of progress of fuel injection and which receives a part of the spray and diverts it.

In the cylinder injection type spark ignition internal combustion engine according to the third aspect, air is sucked from the intake pipe during the intake stroke, and the fuel is directly injected into the cylinder (combustion chamber) by the injection valve to form the air-fuel mixture. It is formed and the mixture is ignited and burned by the spark plug.

Here, in forming the air-fuel mixture by directly injecting the fuel into the cylinder during the intake stroke, the injected fuel spray collides with the piston top surface (substantially flat surface) and then a part thereof. Is diffused along the piston top surface (substantially flat surface) in the direction of fuel injection by the injection valve, and another part collides with a protrusion formed on the piston top surface and is dammed, The flow splits and diffuses while returning to the side opposite to the direction of fuel injection by the injection valve. As a result, the fuel spray is divided and diffused evenly in the direction of the injection and the opposite side of the injection, and the air-fuel mixture can be homogeneously distributed in the combustion chamber (a homogeneous air-fuel mixture can be formed). Combustion can be performed.

Therefore, in the cylinder injection type spark ignition internal combustion engine according to the third aspect of the present invention, the advantages of homogeneously distributing the air-fuel mixture in the combustion chamber (forming a homogenous air-fuel mixture) and performing homogeneous combustion are sufficiently exhibited. Thus, the output performance and the fuel efficiency performance can be significantly improved.

A cylinder injection type spark ignition internal combustion engine according to a fourth aspect of the present invention is the cylinder injection type spark ignition internal combustion engine according to the third aspect, wherein the protrusion height h of the protrusion is set to 15 mm or less. It is characterized by that.

Here, if the projection formed on the top surface of the piston is excessively large, the cooling loss due to the increase of the piston surface area increases, but in the cylinder injection type spark ignition internal combustion engine according to claim 4, The protrusion height h of the protrusion is 15 m
Since it is set to m or less, it is possible to preferably form a homogeneous mixture while suppressing disadvantages such as cooling loss due to the increase in the piston surface area.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] FIG.
1C shows the configuration of the main part of a direct injection spark ignition internal combustion engine 10 according to the first embodiment of the present invention.

In this cylinder injection type spark ignition internal combustion engine 10, the cylinder block 12 and the cylinder head 14 constitute a combustion chamber 16, and the combustion chamber 16 is further provided.
A piston 18 is housed inside. This piston 1
Reference numeral 8 is connected to the crankshaft via a connecting rod (not shown). Further, the combustion chamber 16 includes an intake port 22 and an exhaust port 24 formed in the cylinder head 14.
Are in communication. The intake port 22 is provided with an intake valve 26, and the exhaust port 24 is provided with an exhaust valve 28. Further, a spark plug 30 is attached to a central portion of the cylinder head 14 (between the intake port 22 and the exhaust port 24).

A fuel injection valve 20 is provided on the cylinder head 14. The fuel injection valve 20 is arranged at a position (side of the intake port 22) away from the center of the cylinder block 12 (combustion chamber 16) and can directly inject fuel into the combustion chamber 16.

Further, here, FIG. 2 (A) and FIG. 2 (B)
As shown in FIG. 1, the piston 18 housed in the combustion chamber 16
A first inclined surface 32 and a second inclined surface 34 are formed on the top surface of the. The first inclined surface 32 is formed by the fuel injection valve 20.
Is provided so as to face the fuel injection valve 2 and is substantially flat.
Toward the direction of fuel injection by 0 (in other words,
There is a rising slope of a predetermined angle θa toward the intake port 22 side.

On the other hand, the second inclined surface 34 is formed on the top surface of the piston 18 continuously with the lower end edge of the first inclined surface 32, and is in the opposite direction to the first inclined surface 32 (that is, the fuel). The rising gradient is a predetermined angle θb toward the injection valve 20).

Further, the lower end edges (continuous connection portions) of the first inclined surface 32 and the second inclined surface 34 are formed linearly (acutely in cross section) without being curved. Has become.

Here, as schematically shown in FIG. 3, when the angle of the spray axis φ of the fuel injection by the fuel injection valve 20 with respect to the lower surface of the cylinder head 14 is θs, “0 ≦ θ
"a≤ (90 ° -θs)" and "0≤θb≤90 °". Further, the step h of the lower end edge of the first inclined surface 32 with respect to the top surface of the piston 18 is set to 15 mm or less.

Next, the operation of the first embodiment will be described.

In-cylinder injection type spark ignition internal combustion engine 1 having the above structure
At 0, during the intake stroke, air is taken in from the intake port 22 and the fuel is injected by the fuel injection valve 20 into the combustion chamber 16
The air-fuel mixture is formed by being directly injected into the (cylinder block 12), and the air-fuel mixture is ignited and burned by the spark plug 30.

Here, in forming the air-fuel mixture by directly injecting the fuel into the combustion chamber 16 during the intake stroke, the injected fuel spray collides with the first inclined surface 32 and is sequentially divided into the surrounding area. Sink (shown in FIG. 1 (A)), first inclined surface 3
2 is diffused toward the upper end side of the inclined surface (that is, the side of the exhaust valve 28), and is also branched and diffused along the second inclined surface 34 continuous with the lower end edge of the first inclined surface 32.

In this case, the first inclined surface 32 has a predetermined angle .theta. Toward the advancing direction of the fuel injection by the fuel injection valve 20.
Since the ascending slope is a, a part of the fuel spray that collides with the first inclined surface 32 is directed in the direction of the second inclined surface 34 (that is, the side opposite to the advancing direction of fuel injection by the fuel injection valve 20). While returning, shunt diffusion also occurs along the second inclined surface 34. As a result, the fuel spray is divided and diffused evenly in the direction in which the fuel is advancing and on the side opposite thereto (the state shown in FIG. 1B), and the air-fuel mixture is uniformly distributed in the combustion chamber 16 (homogeneous). A mixture can be formed) and homogeneous combustion can be performed (the state shown in FIG. 1C).

Here, as shown in FIG. 4 (A), the collision angle of the spray axis φ of the fuel injection by the fuel injection valve 20 with the flat plate X is θi, and the flow rate of the spray in the injection proceeding direction is Q1. And the flow rate Q2 of the spray that returns in the opposite direction and is divided, (Q
A diagram showing the change of 2 / Q1) is shown in FIG. 4 (B). As is clear from FIG. 4B, when the collision angle θi is 90 °, (Q2 / Q1) = 1, and the spray is evenly divided, but as the collision angle θi becomes smaller. The ratio of Q2 decreases. In this respect, in the conventional in-cylinder injection spark ignition internal combustion engine configured to use a piston having a substantially flat top surface to inject fuel from a fuel injection valve that is biasedly arranged on the intake valve side, FIG. As shown in A), the angle θs of the spray axis φ of the fuel injection by the fuel injection valve with respect to the lower surface of the cylinder head is equal to the collision angle θi. If this angle θs is increased (Q2 / Q1) approaches 1, it is possible to distribute the air-fuel mixture homogeneously in the combustion chamber (form a homogenous air-fuel mixture).
If s is made too large, the spray adheres to the inner surface of the cylinder wall on the fuel injection valve side, making it impossible to form an appropriate mixture. Therefore, the angle θs is often set within about 60 °. Therefore, as can be seen in FIG.
/ Q1) is about 0.3 or less. That is, the collision angle θi is set to 90 ° while the angle θs is properly maintained so that the spray does not adhere to the inner surface of the cylinder wall on the fuel injection valve side.
It turns out that it is effective to bring it closer to.

In this respect, in the direct injection spark ignition internal combustion engine 10 according to the first embodiment, when the angle of the spray axis φ of the fuel injection by the fuel injection valve 20 with respect to the lower surface of the cylinder head 14 is θs. , “0 ≦ θa ≦ (90 ° −θ
s) ”and“ 0 ≦ θb ≦ 90 ° ”, and the step h of the lower end edge of the first inclined surface 32 with respect to the top surface of the piston 18 is set to 15 mm or less.

Therefore, in the cylinder injection type spark ignition internal combustion engine 10, the collision angle θ is maintained while the angle θs is properly maintained.
i can be increased and (Q2 / Q1) can be brought closer to 1. As a result, the spray is evenly divided, and the air-fuel mixture can be uniformly distributed (form a homogeneous air-fuel mixture) in the combustion chamber 16.

Furthermore, the step h on the top surface of the piston 18 by the first inclined surface 32 and the second inclined surface 34 is
If it becomes excessively large, the cooling loss due to the increase in the surface area of the piston 18 increases, but the cylinder injection type spark ignition internal combustion engine 10
Since the step h is set to 15 mm or less, it is possible to preferably form a homogeneous air-fuel mixture while suppressing disadvantages such as cooling loss due to an increase in the surface area of the piston 18.

As a result, in the in-cylinder injection type spark ignition internal combustion engine 10, the air-fuel mixture can be homogeneously distributed in the combustion chamber 16 (form a homogenous air-fuel mixture) to perform homogeneous combustion, and intake air by fuel vaporization is obtained. The advantages of increasing the compression ratio and improving the volumetric efficiency based on the cooling effect can be fully exerted, and the output performance and fuel efficiency performance can be greatly improved.

Here, in FIGS. 5 to 11, the first inclined surface 32 and the second inclined surface 32 formed on the top surface of the piston 18 are used.
An example of another specific shape of the inclined surface 34 of FIG. First inclined surface 52 shown in FIGS. 5 (A) and 5 (B)
And the second inclined surface 54, the first inclined surface 52 and the second inclined surface 54
The lower end edge (continuous connection portion) of the inclined surface 54 is curved with a predetermined curvature (so-called rounded shape). First inclined surface 56 shown in FIGS. 6A and 6B.
In the second inclined surface 58, the upper end portion of the first inclined surface 56 is formed higher than the upper end portion of the second inclined surface 58. First inclined surface 60 shown in FIGS. 7 (A) and 7 (B)
In the second inclined surface 62, the upper end portion of the first inclined surface 60 is formed lower than the upper end portion of the second inclined surface 62. First inclined surface 64 shown in FIGS. 8 (A) and 8 (B)
And the second inclined surface 66, the first inclined surface 64 and the second inclined surface 66.
The inclined surface 66 is formed with a width dimension narrower than the width of the piston 18 (with a relatively large number of general plane portions left on the top surface of the piston 18). First inclined surface 68 shown in FIGS. 9 (A) and 9 (B)
Also, the second inclined surface 70 is formed such that the width dimension thereof gradually increases (becomes wider) from the second inclined surface 70 to the first inclined surface 68 in a plan view. ing. The first inclined surface 72 and the second inclined surface 74 shown in FIGS.
The edge in the width direction is formed to extend in an arc shape from the inclined surface 74 to the first inclined surface 72. The first inclined surface 76 and the second inclined surface 78 shown in FIGS. 11A to 11C have the first inclined surface 76 in plan view.
Of the inclined surface 76 and the peripheral surface of the second inclined surface 78 are curved (so-called rounded) (piston 1
8 is a structure in which it is connected to the general flat surface portion of the top surface in a rounded shape). [Second Embodiment] FIGS. 12 (A) to 12 (C) show the structure of the main part of a cylinder injection type spark ignition internal combustion engine 90 according to a second embodiment of the present invention. There is. In addition,
Components that are basically the same as those of the cylinder injection type spark ignition internal combustion engine 10 according to the first embodiment described above are given the same reference numerals as in the first embodiment of the previous term, and description thereof is omitted. .

In this cylinder injection type spark ignition internal combustion engine 90, the top surface of the piston 18 is formed into a substantially flat surface.
Further, on the top surface of the piston 18, a pair of protrusions 92
Are formed to project. The protrusion 92 is provided on the fuel injection valve 20.
Is formed so as to project toward the peripheral edge portion of the top surface of the piston 18 so as to face the direction of fuel injection by the above, and a part of the spray can be received and the flow can be divided.

In this case, the projection height h of the projection 92 is
Is set to 15 mm or less. Also, the protrusion 92
The standing surface (wall surface facing the advancing direction of fuel injection) of may be formed perpendicular to the top surface of the piston 18,
Alternatively, it may be slightly inclined (overhang) to the fuel injection valve 20 side. Further, it is preferable that the boundary between the protrusion 92 and the general flat surface portion of the top surface of the piston 18 is formed to be curved with a predetermined curvature (so-called rounded shape), but the boundary portion is not curved and is a straight line. It may be configured to have a shape (a sharp angle in a sectional view).

In-cylinder injection type spark ignition internal combustion engine 9 having the above structure
At 0, during the intake stroke, air is taken in from the intake port 22 and the fuel is injected by the fuel injection valve 20 into the combustion chamber 16
The mixture is directly injected into the mixture to form an air-fuel mixture, and the spark plug 30
The mixture is ignited by and burned.

Here, in forming the air-fuel mixture by directly injecting the fuel into the combustion chamber 16 during the intake stroke, the injected fuel spray collides with the top surface (generally flat general surface) of the piston 18. After (FIG. 12 (A) and FIG. 13 (A)
(A state shown in the figure), a part of which diffuses in the traveling direction of the fuel injection by the fuel injection valve 20 along the top surface (generally flat general surface) of the piston 18, and the other part projects to the top surface of the piston 18. The pair of projecting portions 92 thus formed collide and are dammed (state shown in FIG. 12B and FIG. 13B), and diverge and diffuse while returning to the side opposite to the direction of fuel injection by the fuel injection valve 20. . As a result, the fuel spray is divided and diffused evenly in the direction in which the fuel is advancing and on the opposite side, and the air-fuel mixture can be uniformly distributed in the combustion chamber 16 (a homogeneous air-fuel mixture can be formed). (Fig. 1
2 (C) and FIG. 13 (C) illustrated state).

Furthermore, the protrusion height h of the protrusion 92 is
If it becomes excessively large, the cooling loss due to the increase in the surface area of the piston 18 increases, but the cylinder injection type spark ignition internal combustion engine 90
Then, since the protrusion height h is set to 15 mm or less,
It is possible to preferably form a homogeneous air-fuel mixture while suppressing disadvantages such as cooling loss due to an increase in the surface area of the piston 18.

As a result, in the cylinder injection type spark ignition internal combustion engine 90, the air-fuel mixture can be homogeneously distributed in the combustion chamber 16 (forms a homogenous air-fuel mixture), and homogeneous combustion can be performed. The advantages of increasing the compression ratio and improving the volumetric efficiency based on the cooling effect can be fully exerted, and the output performance and fuel efficiency performance can be greatly improved.

In the above-described second embodiment, the pair of protrusions 92 is formed on the peripheral portion of the top surface of the piston 18, but the shape, number, and formation location of the protrusions 92 are different. It is not limited to.

For example, as shown in FIGS. 14A to 14C, a single protrusion 94 may be provided at one location near the center of the top surface of the piston 18. In addition, FIG.
As shown in FIGS. 15A to 15C, the pair of protrusions 96
Is provided on the peripheral portion of the top surface of the piston 18, and the pair of protrusions 96 has a boundary wall with the top surface (generally flat surface) of the piston 18 along the direction in which the spray spreads (plan view). It may be formed so as to spread in the same direction as. Further, as shown in FIGS. 16 (A) to 16 (C), a pair of protrusions 98 are provided on the peripheral portion of the top surface of the piston 18, and further, the peripheral portion of the top surface of the piston 18 is formed to be raised. The boundary between the 18-top surface and the generally flat general surface may be curved (so-called rounded).

[0050]

As described above, in the cylinder injection type spark ignition internal combustion engine according to the present invention, when the homogeneous mixture is formed by directly injecting the fuel into the cylinder during the intake stroke, the mixture is formed in the combustion chamber. Are uniformly distributed (form a homogeneous mixture), and the advantages of homogeneous combustion are fully exerted, resulting in an excellent effect that the output performance and fuel efficiency performance are significantly improved.

[Brief description of drawings]

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

FIG. 2 shows a configuration of a first inclined surface and a second inclined surface provided on a piston of a cylinder injection type spark ignition internal combustion engine according to a first embodiment of the present invention, and (A) is a schematic diagram. 3B is a vertical cross-sectional view, and FIG.

FIG. 3 is a schematic diagram showing a correspondence relationship between a first inclined surface provided on a piston of a cylinder injection type spark ignition internal combustion engine according to a first embodiment of the present invention and a fuel injection angle by a fuel injection valve. It is a block diagram.

FIG. 4A is a schematic configuration diagram corresponding to FIG. 3 showing the collision angle and the spray flow rate of the fuel injection from the fuel injection valve with respect to the flat plate, and FIG. 4B shows the change of the spray flow rate ratio with respect to the collision angle. It is the represented diagram.

FIG. 5 shows another example of the first inclined surface and the second inclined surface provided on the piston of the direct injection spark ignition internal combustion engine according to the first embodiment of the present invention, (A) Is a schematic vertical sectional view, and (B) is a plan view.

FIG. 6 shows another example of the first inclined surface and the second inclined surface provided on the piston of the direct injection spark ignition internal combustion engine according to the first embodiment of the present invention, (A) Is a schematic vertical sectional view, and (B) is a plan view.

FIG. 7 shows another example of the first inclined surface and the second inclined surface provided on the piston of the direct injection spark ignition internal combustion engine according to the first embodiment of the present invention, (A) Is a schematic vertical sectional view, and (B) is a plan view.

FIG. 8 shows another example of the first inclined surface and the second inclined surface provided on the piston of the cylinder injection type spark ignition internal combustion engine according to the first embodiment of the present invention, (A) Is a schematic vertical sectional view, and (B) is a plan view.

FIG. 9 shows another example of the first inclined surface and the second inclined surface provided on the piston of the cylinder injection type spark ignition internal combustion engine according to the first embodiment of the present invention, (A) Is a schematic vertical sectional view, and (B) is a plan view.

FIG. 10 shows another example of the first inclined surface and the second inclined surface provided on the piston of the cylinder injection type spark ignition internal combustion engine according to the first embodiment of the present invention, (A) Is a schematic vertical sectional view, and (B) is a plan view.

FIG. 11 shows another example of the first inclined surface and the second inclined surface provided on the piston of the direct injection spark ignition internal combustion engine according to the first embodiment of the present invention, (A) Is a schematic vertical sectional view, (B) is a plan view, and (C) is (B).
It is sectional drawing along the CC line of FIG.

FIG. 12 is a schematic sectional view showing a configuration of a main part of a cylinder injection type spark ignition internal combustion engine according to a second embodiment of the present invention.

FIG. 13 is a schematic plan view showing a diffusion state of injected fuel spray in a cylinder injection type spark ignition internal combustion engine according to a second embodiment of the present invention in a piston plan view.

FIG. 14 shows another example of the protrusion provided on the piston of the cylinder injection type spark ignition internal combustion engine according to the second embodiment of the present invention, and (A) is a schematic vertical sectional view. , (B) are plan views, and (C) is a schematic perspective view.

FIG. 15 shows another example of the protrusion provided on the piston of the cylinder injection type spark ignition internal combustion engine according to the second embodiment of the present invention, and (A) is a schematic vertical sectional view. , (B) are plan views, and (C) is a schematic perspective view.

FIG. 16 shows another example of the protrusion provided on the piston of the cylinder injection type spark ignition internal combustion engine according to the second embodiment of the present invention, and (A) is a schematic vertical sectional view. , (B) are plan views, and (C) is a schematic perspective view.

FIG. 17 is a schematic cross-sectional view showing a configuration of a main part of a conventional cylinder injection type spark ignition internal combustion engine in which a cavity is provided on a top surface of a piston and a diffusion state of injected fuel spray.

FIG. 18 is a schematic cross-sectional view showing a structure of a main part of a conventional cylinder injection type spark ignition internal combustion engine using a piston having a flat top surface shape and a diffusion state of injected fuel spray.

[Explanation of symbols]

10 In-cylinder injection type spark ignition internal combustion engine 16 Combustion chamber 20 Fuel injection valve 22 Intake port 24 exhaust port 26 Intake valve 28 Exhaust valve 30 spark plug 32 First inclined surface 34 Second inclined surface 90 In-cylinder injection spark ignition internal combustion engine 92 Projection

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshihiro Nomura             Aichi Prefecture Nagachite Town Aichi District             Local 1 Toyota Central Research Institute Co., Ltd. F term (reference) 3G023 AA01 AA02 AA07 AB03 AC05                       AD02 AD09 AD14 AG01 AG02                 3G066 AA02 AB02 AD12 BA16 BA17                       CC34 CC48 CD30

Claims (4)

[Claims] 1. A spark plug installed in substantially the center of the cylinder by inhaling air from an intake pipe and directly injecting fuel into the cylinder by an injection valve installed at a position distant from the center of the cylinder to form an air-fuel mixture. An in-cylinder injection spark ignition internal combustion engine that ignites and burns the air-fuel mixture by means of a piston top surface that faces the injection valve, is substantially flat, and has a predetermined direction in the direction of fuel injection by the injection valve. A first inclined surface having an ascending slope of an angle θa and a piston top surface formed continuously with a lower end edge of the first inclined surface, and having a predetermined angle θb in a direction opposite to the first inclined surface. A cylinder-injection spark ignition internal combustion engine, comprising: a second inclined surface having a rising slope of 2. A spray axis φ of fuel injection by the injection valve
When the angle with respect to the bottom surface of the cylinder head is θs,
“0 ≦ θa ≦ (90 ° −θs)”, and “0 ≦ θb ≦ 9
The internal combustion engine spark ignition internal combustion engine according to claim 1, wherein the step height h of the lower end edge of the first inclined surface with respect to the piston top surface is set to 15 mm or less. organ. 3. An ignition plug installed in substantially the center of the cylinder by inhaling air from an intake pipe and directly injecting fuel into the cylinder by an injection valve installed at a position away from the center of the cylinder to form an air-fuel mixture. In a cylinder injection type spark ignition internal combustion engine that ignites and burns the air-fuel mixture by means of a piston top surface is formed to be a substantially flat surface, and the piston top surface is formed so as to face the direction of fuel injection by the injection valve. An in-cylinder injection spark ignition internal combustion engine, characterized in that it is provided with a projection formed to receive a part of the spray and divert it. 4. The in-cylinder injection spark ignition internal combustion engine according to claim 3, wherein the protrusion height h of the protrusion is set to 15 mm or less.