JPH10141065A - Direct in-cylinder injection type spark ignition engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion chamber structure suitable for a direct in-cylinder injection type spark ignition engine. SOLUTION: In a direct in-cylinder injection type spark ignition engine, a slope 12 inclined such that fuel is guided to the vicinity of an ignition plug 4 through tumbling is formed at the crown part 10 of a piston 1 and a protrusion part 15 protruding from the crown part 10 of the piston 1 and guiding squish in a manner that the squish is spaced away from an ignition plug 4 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an intake system in a direct cylinder injection type spark ignition engine.

[0002]

2. Description of the Related Art In order to stratify an air-fuel mixture that collects fuel near an ignition plug, an injector (fuel injection valve) faces a cylinder and direct fuel is injected into the cylinder. There is an injection spark ignition engine.

[0003] As a conventional direct in-cylinder injection spark ignition engine, for example, there is one shown in Figs. 12 and 13 (see Japanese Patent Laid-Open No. 6-207542).

[0004] To explain this, the injector 6
Faces the cylinder 5 from the center of the ceiling wall 20 of the combustion chamber,
Fuel is injected toward a cavity 11 that is recessed in a crown 10 of the piston 1.

[0005] An intake port (not shown) is formed upright along the cylinder 5. The intake air that has flowed into the cylinder 5 from the upright intake port descends along the cylinder 5 and then generates a reverse tumble swirling along the piston crown 10.

The protrusion 1 protruding from the crown 10 of the piston 1
5 are formed, and the ridgeline 19 of the projection 15 extends in the same direction as a crankshaft (not shown). The cavity 11 is formed so as to eliminate the ridge 39 of the projection 15.

[0007] A slope 12 is formed in the cavity 11 and slopes toward the spark plug 4. The fuel spray swirling with the reverse tumble on the cavity 11 rises along the slope 12 toward the spark plug 4. As a result, the rich mixture is collected in the vicinity of the ignition plug 4.

[0008]

However, in such a conventional direct in-cylinder injection spark ignition engine, when the piston 1 reaches near the top dead center, the outer peripheral portion of the piston crown 10 and the combustion chamber A squish toward the center of the combustion chamber 3 is generated in the air compressed between the ceiling walls 20 as indicated by an arrow in the figure, and the squish causes the rich mixture collected near the spark plug 4 to be ignited. The mixture is blown off before being mixed, and stratification of the air-fuel mixture cannot be achieved.

The present invention has been made in view of the above problems, and has as its object to provide a combustion chamber structure suitable for a direct cylinder injection type spark ignition engine.

[0010]

According to a first aspect of the present invention, there is provided a direct in-cylinder injection spark ignition engine, comprising: an intake port for introducing intake air into a cylinder; an injector for injecting fuel into the cylinder; In a direct in-cylinder injection type spark ignition engine having an ignition plug for igniting air and an exhaust port for discharging exhaust from inside the cylinder, a tumble generating means for generating a tumble in intake air flowing into the cylinder from an intake port, A slope is formed in the crown of the piston so that fuel is guided to the vicinity of the spark plug by tumble, and squish is generated toward the center of the combustion chamber in the air compressed between the crown of the piston and the ceiling wall of the combustion chamber. A squish generating means for forming a convex portion that protrudes from the crown of the piston and guides the squish away from the spark plug.

According to a second aspect of the present invention, in the direct in-cylinder injection spark ignition engine according to the first aspect of the present invention, a plane including a center line of the cylinder and orthogonal to a rotation center axis of the crankshaft is defined by a cylinder center plane C. The combustion chamber is formed symmetrically with respect to the cylinder center plane C, and the ridge line of the projection is disposed on the cylinder center plane C.

According to a third aspect of the present invention, there is provided a direct in-cylinder injection spark ignition engine according to the first aspect of the present invention, wherein a plane including the center line of the cylinder and orthogonal to a rotation center axis of the crankshaft is a cylinder center plane C. The combustion chamber is formed symmetrically with respect to the cylinder center plane C, and the apex of the projection is arranged on the cylinder center plane C.

According to a fourth aspect of the invention, there is provided a direct in-cylinder injection spark ignition engine according to the first aspect, wherein a plane including the center line of the cylinder and orthogonal to a rotation center axis of the crankshaft is a cylinder center plane C. The combustion chamber is formed symmetrically with respect to the cylinder center plane C, and the top surface of the projection is disposed on the cylinder center plane C.

According to a fifth aspect of the present invention, there is provided a direct in-cylinder injection spark ignition engine according to any one of the first to fourth aspects, wherein a cavity that is concavely recessed is formed in a crown portion of the piston. A cavity is defined by the slope.

According to a sixth aspect of the present invention, there is provided a direct in-cylinder injection type spark ignition engine according to any one of the first to fifth aspects, wherein the ceiling wall of the combustion chamber is inclined toward the intake port where the intake port is open. Surface and an exhaust port side inclined surface that is open to the exhaust port, and the intake port is set at the cylinder center line so that the intake air flowing into the cylinder from the intake port descends along the exhaust port side inclined surface as the tumble generating means. Incline.

According to a seventh aspect of the present invention, there is provided a direct in-cylinder injection spark ignition engine according to any one of the first to sixth aspects, wherein the fuel injection direction of the injector is opposed to a slope.

According to an eighth aspect of the invention, in the direct in-cylinder injection spark ignition engine according to any one of the first to seventh aspects, the fuel injection timing of the injector is set to an intake stroke at a high load. The fuel injection timing of the injector is set to the compression stroke at a low load.

[0018]

In the direct in-cylinder injection spark ignition engine according to the first aspect, air is drawn into the cylinder from the intake port as the intake valve is opened. A tumble swirling around an axis parallel to the rotation center axis of the crankshaft is generated in the intake air sucked into the cylinder through the intake port.

For example, in a lean burn region operated at a lean air-fuel ratio, the injector opens during a compression stroke in which the piston rises, and fuel is injected into the combustion chamber. In a state where the air sucked into the cylinder through the intake port is compressed by the piston, the fuel is ignited and burned through the spark plug.

The fuel spray swirling with the tumble on the cavity in the compression stroke in which the piston rises,
By ascending along the slope towards the spark plug,
A rich mixture is collected near the spark plug.

On the other hand, when the piston reaches the vicinity of the top dead center, squish is produced toward the center of the combustion chamber in the air compressed between the piston crown and the combustion chamber ceiling wall. When the squish moves toward the vicinity of the spark plug, the rich mixture collected near the spark plug is blown off by the tumble before being ignited, so that the mixture is not stratified.

In order to cope with this, the present invention has a configuration in which the squish is made to flow by avoiding the spark plug by the convex portion protruding from the piston crown, so that the rich mixture collected near the spark plug is ignited. The air-fuel mixture is stratified without being blown off before being blown.

By thus concentrating the fuel in the vicinity of the ignition plug, ignition is reliably performed. As a result, the limit value of the lean air-fuel ratio at which flammability is ensured is increased, and the fuel efficiency is reduced. Further, it is not necessary to increase the fuel injection amount during the cold period, and the emission can be improved.

In the direct in-cylinder injection spark ignition engine according to the second aspect of the present invention, the squish is separated from the cylinder center plane C behind the slope by disposing the ridge of the projection on the cylinder center plane C. The rich mixture is effectively collected at the center of the combustion chamber without flowing away the rich mixture collected near the spark plug before being ignited. As a result, the limit value of the lean air-fuel ratio at which flammability is ensured is increased, and the fuel efficiency is reduced.

In the direct in-cylinder injection spark ignition engine according to the third aspect, the apex of the projection is disposed on the cylinder center plane C, so that the squish is separated from the cylinder center plane C behind the slope. The rich mixture is effectively collected at the center of the combustion chamber without flowing away the rich mixture collected near the spark plug before being ignited. As a result, the limit value of the lean air-fuel ratio at which flammability is ensured is increased, and the fuel efficiency is reduced.

In the direct in-cylinder injection spark ignition engine according to the fourth aspect, the top surface of the projection is disposed on the cylinder center plane C so that the squish is separated from the cylinder center plane C behind the slope. The diverted mixture does not blow off the rich mixture collected near the spark plug before being ignited, and the rich mixture is effectively collected at the center of the combustion chamber. As a result, the limit value of the lean air-fuel ratio at which flammability is ensured is increased, and the fuel efficiency is reduced.

[0027] In the direct in-cylinder injection spark ignition engine according to the fifth aspect, the fuel spray swirling with the tumble on the cavity rises along the slope toward the spark plug so that the rich mixture becomes a spark plug. Is effectively collected in the vicinity of. As a result, the limit value of the lean air-fuel ratio at which flammability is ensured is increased, and the fuel efficiency is reduced.

In the direct in-cylinder injection spark ignition engine according to the present invention, the intake air flowing into the cylinder through the intake port descends along the exhaust port side inclined surface and the cylinder wall, and then the piston crown. Produce a forward tumble that turns upward and turns. The fuel spray swirling with the forward tumble rises along the slope toward the spark plug, whereby the rich mixture is effectively collected near the spark plug. As a result, the limit value of the lean air-fuel ratio at which flammability is ensured is increased, and the fuel efficiency is reduced.

In the direct in-cylinder injection spark ignition engine according to the present invention, since the fuel injection direction of the injector is opposed to the slope, the fuel spray from the injector rises toward the spark plug along the slope. The tumble mixes and a rich mixture is collected near the spark plug. As a result, the limit value of the lean air-fuel ratio at which flammability is ensured is increased, and the fuel efficiency is reduced.

In the direct in-cylinder injection spark ignition engine according to the present invention, at low load, fuel is injected from the injector 6 during a compression stroke in which the piston rises. The fuel spray merges with the tumble, travels along the slope to the vicinity of the spark plug, and a rich mixture is collected near the spark plug.
As a result, the limit value of the lean air-fuel ratio at which flammability is ensured is increased, and the fuel efficiency is reduced.

When the load is high, the fuel spray injected from the injector during the suction stroke in which the piston descends is diffused by the tumble and squish gas flows generated in the cylinder. Thus, when the ignition timing is reached, a homogeneous air-fuel mixture is formed in the combustion chamber, ignition is reliably performed, and flame propagation is promoted. As a result, even if the gas flow enhancing means is not additionally provided, stable flammability which is not affected by the cycle fluctuation is secured, and the output is improved.

[0032]

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

As shown in FIGS. 1 and 3, a combustion chamber 3 is defined between a piston 1 and a combustion chamber ceiling wall 20 formed in a cylinder head 2.

Combustion chamber ceiling wall 2 inclined in a pent roof type
At 0, an intake port 21 branching into two and an exhaust port 22 branching into two are open facing each other. That is, the combustion chamber ceiling wall 20 is constituted by the intake port side inclined surface 23 where each intake port 21 opens and the exhaust port side inclined surface 24 where each exhaust port 22 opens.

An injector 6 and a spark plug 4 are provided to face the combustion chamber 3 from the center of the ceiling wall 20 of the combustion chamber. Two intake valves 7 sandwiching the injector 6 and the ignition plug 4
And two exhaust valves 8 are provided to face each other.

In FIG. 1, a line segment O is a center line of the cylinder 5. The injector 6 is arranged coaxially with the cylinder center line O, is located between each intake valve 7 and each exhaust valve 4, and faces the combustion chamber 3.

The ignition plug 4 faces the combustion chamber 3 on the side of the injector 6 and between the intake valves 7.
That is, the ignition plug 4 faces the combustion chamber 3 from a position closer to each intake port 21 than the injector 6 between each intake port 21 and each exhaust port 22 of the combustion chamber ceiling wall 20.

The intake air flowing into the combustion chamber 3 from each intake port 21 is lowered along the exhaust port side inclined surface 24 and the cylinder 5 as shown by arrows in FIGS. 5 and 7 to generate a forward tumble. Means are provided. As the forward tumbling generating means, each intake port 21 is largely inclined with respect to the cylinder center line O such that the passage center line faces each exhaust port side inclined surface 24 and the cylinder 5.

The crown 10 of the piston 1 is formed with a cavity 11 that is recessed. The cavity 11 is disposed below the exhaust port side inclined surface 24 from the center of the piston crown 10.

The injector 6 has a nozzle 1 whose cavity is
1, the fuel spray injected from the injection port radially spreads toward the cavity 11.

The cavity 11 is formed with a slope 12 inclined toward the spark plug 4. The fuel spray injected from the injector 6 turns together with the forward tumbles generated in the combustion chamber 3 and rises along the slope 12, whereby a rich mixture is collected near the spark plug 4.

Cavity 11 for piston crown 10
The opening edge portion 13 is formed in a circular shape on the front view shown in FIG. 2 and is arranged so as to surround the fuel injection range of the injector 6.

In FIG. 1, the cylinder center plane C is a plane that includes the center line O of the cylinder 5 and is orthogonal to the rotation center axis of a crankshaft (not shown). The cavity 1, the piston 1, the combustion chamber wall 20, the intake port 21, and the exhaust port 23 are formed symmetrically with respect to the cylinder center plane C.

The outer peripheral portion of the piston crown 10 is formed in a flat shape facing the combustion chamber ceiling wall 20 in parallel. Thus, a squish generating means for generating squish toward the center of the combustion chamber 3 in the air compressed between the piston crown 10 and the combustion chamber ceiling wall 20 when the piston 1 reaches the vicinity of the top dead center is configured. .

When the squish generated in the combustion chamber 3 moves toward the vicinity of the spark plug 4, the rich mixture collected in the vicinity of the spark plug 4 by the forward tumbling is blown off before being ignited. Qi stratification is not measured.

The present invention addresses this problem by providing a piston crown 1
A convex portion 15 is formed which protrudes from 0 and guides the squish away from the ignition plug 4.

As shown in FIGS. 2, 3, and 4, a convex portion 15 protruding from the outer peripheral portion of the piston crown portion 10 toward the cylinder center plane C is formed. The protrusion 15 is formed symmetrically with respect to the cylinder center plane C.

In this embodiment, the projection 15 has three inclined surfaces 16, 17, 1 inclined with respect to the piston crown 10.
8 The inclined surfaces 16 and 17 are inclined with the cylinder center plane C interposed therebetween. A ridge line 19 where the inclined surface 16 and the inclined surface 17 intersect is located on the cylinder center plane C and extends orthogonal to the cylinder center line O.

The triangular inclined surface 18 is inclined so as to descend toward the outer periphery of the piston crown 10 behind the slope 12.

The configuration is as described above. Next, the operation will be described.

As each intake valve 7 is opened, air is sucked into the cylinder 5 from each intake port 21. When the load is low, the injector 6 opens in the latter half of the compression stroke in which the piston 1 rises, and fuel is injected into the combustion chamber 3. For example, at the timing of 60 ° before the compression top dead center, the injector 6
As shown, fuel spray is radially injected toward the cavity 11.

In a state where the air sucked into the cylinder 5 through each intake port 21 is compressed by the piston 1, the fuel is ignited and burned through the ignition plug 4. The combusted gas is moved down through the crankshaft by lowering the piston 1 to extract the rotational force, and then discharged from each exhaust port 22 as the exhaust valve is opened during the exhaust stroke in which the piston 1 rises. Each of these steps is repeated continuously.

As shown by arrows in FIG. 5, the intake air flowing into the cylinder 5 through each intake port 21 is lowered along the exhaust port side inclined surface 24 and the cylinder wall 5 and then on the piston crown 10. Produces a forward tumble that turns and turns to.

The slope 12 of the cavity 11 is
, The fuel spray swirling with the forward tumble on the cavity 11 rises along the slope 12 to the center of the combustion chamber 3. Thereby, as shown in FIG. 6, the rich mixture is collected near the ignition plug 4.

On the other hand, when the piston 1 reaches the vicinity of the top dead center, the air compressed between the piston crown 10 and the combustion chamber ceiling wall 20, as shown by an arrow in FIG. A heading squish is created.

The squish flows so as to avoid the spark plug 4 by the projection 15 raised from the piston crown 10. The convex portion 15 is formed symmetrically with respect to the cylinder center plane C, and since the ridgeline 19 where the slope 16 and the slope 17 intersect is located on the cylinder center plane C, the squish slopes away from the cylinder center plane C. The mixture is diverted behind 12 and the concentrated mixture collected near the ignition plug 4 is not blown off before being ignited, so that the mixture is stratified.

By thus concentrating the fuel in the vicinity of the ignition plug 4, ignition is reliably performed. As a result, the limit value of the lean air-fuel ratio at which flammability is ensured is increased, and the fuel efficiency is reduced. Further, it is not necessary to increase the fuel injection amount during the cold period, and the emission can be improved.

The squish is generated in the cylinder 5 so as to avoid the spark plug 4, so that the propagation of the flame is promoted by the gas flow of the squish. As a result, the limit value of the lean air-fuel ratio at which flammability is ensured is increased, and the fuel efficiency is reduced.

When the load is high, the injector 6 opens during the suction stroke in which the piston 1 descends, and fuel is injected into the combustion chamber 3. The fuel injected from the injector 6 is heated by the piston 1 in the process of swirling along the cavity 11 of the piston 1 by forward tumbling, and the atomization and vaporization of the fuel proceeds.

In this manner, the diffusion of fuel is promoted by the forward tumble and squish gas flows generated in the cylinder 5, and when the ignition timing is reached, a homogeneous air-fuel mixture is formed in the combustion chamber 3 and ignition is reliably performed. And the propagation of the flame is encouraged. As a result, even if the gas flow enhancing means is not additionally provided, stable flammability which is not affected by the cycle fluctuation is secured, and the output is improved.

Next, the embodiment shown in FIGS. 8 and 9 will be described. 2 and FIG. 3 are denoted by the same reference numerals.

In this embodiment, the projection 15 has three inclined surfaces 26, 27, 2 inclined with respect to the piston crown 10.
8 The inclined surface 26 and the inclined surface 27 are inclined with the cylinder central inclined surface C interposed therebetween. Inclined surfaces 26, 27, 28
Are disposed on the cylinder center inclined surface C.

The triangular inclined surface 28 is inclined so as to descend toward the outer periphery of the piston crown 10 behind the slope 12.

The configuration is as described above. Next, the operation will be described.

The squish flows so as to avoid the spark plug 4 by the projection 15 raised from the piston crown 10. The convex portion 15 is formed symmetrically with respect to the cylinder center inclined surface C, and since the apex 29 where the inclined surfaces 26, 27, and 28 intersect is located on the cylinder center inclined surface C, the squish moves away from the cylinder center inclined surface C. Like slope 1
The concentrated air-fuel mixture diverted behind the spark plug 2 and collected near the spark plug 4 is not blown off before being ignited, and the air-fuel mixture is stratified.

By thus concentrating the fuel in the vicinity of the ignition plug 4, ignition is reliably performed. As a result, the limit value of the lean air-fuel ratio at which flammability is ensured is increased, and the fuel efficiency is reduced. Further, it is not necessary to increase the fuel injection amount during the cold period, and the emission can be improved.

Next, the embodiment shown in FIGS. 10 and 11 will be described. 2 and FIG. 3 are denoted by the same reference numerals.

In this embodiment, the convex portion 15 has three inclined surfaces 36, 37, 3 that are inclined with respect to the piston crown 10.
8 and one top surface 39. Slope 36 and slope 37
Are inclined with respect to the cylinder center inclined surface C. The top surface 39 connected to each of the inclined surfaces 36, 37, 38 is disposed on the cylinder center inclined surface C and is formed symmetrically with respect to the cylinder center line C.

The trapezoidal inclined surface 38 is inclined so as to descend toward the outer periphery of the piston crown 10 behind the slope 12.

The operation will be described below.

The squish flows so as to avoid the spark plug 4 by the projection 15 raised from the piston crown 10. The convex portion 15 is formed symmetrically with respect to the cylinder center inclined surface C, and the top surface 3 connected to each inclined surface 36, 37, 38 is formed.
Since 9 is located on the cylinder center inclined surface C, the squish diverges behind the slope 12 so as to separate from the cylinder center inclined surface C, and the rich mixture collected near the spark plug 4 is ignited. The mixture is stratified without being blown off before.

By thus concentrating the fuel in the vicinity of the ignition plug 4, ignition is reliably performed. As a result, the limit value of the lean air-fuel ratio at which flammability is ensured is increased, and the fuel efficiency is reduced. Further, it is not necessary to increase the fuel injection amount during the cold period, and the emission can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an engine showing an embodiment of the present invention.

FIG. 2 is a plan view of the piston.

FIG. 3 is a front view of the piston.

FIG. 4 is a side view of the piston viewed from the direction of arrow A in FIG. 2;

FIG. 5 is an explanatory diagram showing a form of gas flow and fuel spray generated in a cylinder at the time of a low load.

FIG. 6 is an explanatory diagram showing a form of fuel spray at the time of a low load.

FIG. 7 is an explanatory view showing a form of gas flow and fuel spray generated in a cylinder at the time of a high load.

FIG. 8 is a plan view of a piston showing still another embodiment.

FIG. 9 is a front view of the piston.

FIG. 10 is a plan view of a piston showing still another embodiment.

FIG. 11 is a front view of the piston.

FIG. 12 is a plan view of a piston showing a conventional example.

FIG. 13 is a schematic front view of the engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piston 2 Cylinder head 3 Combustion chamber 4 Spark plug 5 Cylinder wall 6 Injector 10 Piston crown 11 Cavity 12 Slope 15 Convex part 16 Inclined surface 17 Inclined surface 18 Inclined surface 19 Ridge line 20 Combustion chamber ceiling wall 21 Intake port 22 Exhaust port 26 Inclined surface 27 Inclined surface 28 Inclined surface 29 Vertex 36 Inclined surface 37 Inclined surface 38 Inclined surface 39 Top surface

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02B 23/08 F02B 23/08 S 31/00 31/00 Z T F02D 41/02 325 F02D 41/02 325A F02F 3/26 F02F 3/26 A 3/28 3/28 B

Claims (8)

[Claims] An intake port for introducing intake air into a cylinder, an injector for injecting fuel into the cylinder, an ignition plug for igniting an air-fuel mixture in the cylinder, and an exhaust port for discharging exhaust from the cylinder. The direct in-cylinder injection spark ignition engine comprises a tumble generating means for generating a tumble in the intake air flowing into the cylinder from the intake port, and is inclined at the crown of the piston so that fuel is guided to the vicinity of the spark plug by tumble. Slopes are formed and squish generating means is provided to generate squish toward the center of the combustion chamber in the air compressed between the crown of the piston and the ceiling wall of the combustion chamber, and the squish rises from the crown of the piston to ignite the squish A direct in-cylinder injection spark ignition engine, characterized by forming a convex portion for guiding away from the engine. 2. A plane including the center line of the cylinder and orthogonal to the rotation center axis of the crankshaft is defined as a cylinder center plane C. The combustion chamber is formed symmetrically with respect to the cylinder center plane C. 2. The direct in-cylinder injection spark ignition engine according to claim 1, wherein the spark ignition engine is disposed on a cylinder center plane C. 3. A plane including the center line of the cylinder and orthogonal to the rotation center axis of the crankshaft is defined as a cylinder center plane C, and the combustion chamber is formed symmetrically with respect to the cylinder center plane C. 2. The direct in-cylinder injection spark ignition engine according to claim 1, wherein the spark ignition engine is disposed on a cylinder center plane C. 4. A plane including the center line of the cylinder and orthogonal to the rotation center axis of the crankshaft is defined as a cylinder center plane C, and the combustion chamber is formed symmetrically with respect to the cylinder center plane C. The direct in-cylinder injection spark ignition engine according to claim 1, wherein the engine is disposed on a cylinder center plane C. 5. The direct in-cylinder injection according to claim 1, wherein a cavity that is concavely recessed is formed in a crown portion of the piston, and the cavity is defined by the slope. -Type spark ignition engine. 6. A combustion chamber ceiling wall comprising an intake port-side inclined surface with an intake port opening and an exhaust port-side inclined surface with an exhaust port opening, and the intake air flowing into the cylinder from the intake port as the tumble generating means. The direct in-cylinder injection spark ignition according to any one of claims 1 to 5, wherein the intake port is inclined with respect to the cylinder center line so that the intake port descends along the exhaust port side inclined surface. engine. 7. The direct in-cylinder injection spark ignition engine according to claim 1, wherein a fuel injection direction of the injector is formed so as to face a slope. 8. The fuel supply system according to claim 1, wherein the fuel injection timing of the injector is set to an intake stroke at a high load, and the fuel injection timing of the injector is set to a compression stroke at a low load. 4. A direct in-cylinder injection spark ignition engine according to claim 1.