JPH0571350A - Inter-cylinder injection type internal combustion engine - Google Patents

Abstract

PURPOSE:To promote vaporization of injected fuel. CONSTITUTION:A shallow tray part 12 is formed in the top surface of a piston 3 and a deep tray part 13 is formed in the central are of the shallow tray part 12. During low load running of an engine, fuel is injected toward a corner part 19a, formed at a connection part between the shallow tray part 12 and the deep tray part 13, through a fuel injection valve 11 arranged in a combustion chamber 5. A peripheral wall surface 12b of the shallow tray part, at which injected fuel distributed by the corner part 19a and flowing along a shallow tray part surface 12a arrives, is formed of a heat insulating material 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder injection type internal combustion engine.

[0002]

2. Description of the Related Art A shallow pan is formed on the top surface of a piston, and a deep pan is formed in the center of the shallow pan. When the engine load is low, the fuel injection valve located in the combustion chamber inserts the deep pan into the deep pan. The present applicant has already proposed a cylinder injection internal combustion engine in which fuel is injected and the air-fuel mixture formed in the basin portion is ignited by an ignition plug (see Japanese Patent Application No. 210410/1990). In this case, if all the injected fuel is supplied into the deep dish portion when the engine load increases and the fuel injection amount increases, the air-fuel mixture formed in the deep dish portion becomes excessively rich. Therefore, in this in-cylinder injection internal combustion engine, when the engine load becomes high, the fuel is injected from the fuel injection valve toward the corner formed at the connection between the shallow dish and the deep dish, and the injected fuel is injected into the deep dish. I try to distribute it in the shallow plate part.

[0003]

However, when the injected fuel is distributed into the deep dish and the shallow dish in this manner, the injected fuel distributed in the shallow dish flows on the surface of the shallow dish due to the inertial force, and the circumference of the shallow dish goes around. There is a problem that it reaches the wall surface and stays in liquid form on the peripheral wall surface of the shallow dish.

[0004]

In order to solve the above problems, according to the present invention, a shallow dish portion is formed on the top surface of the piston, and a deep dish portion is formed at the center of the shallow dish portion. In a cylinder injection internal combustion engine in which fuel is injected from a fuel injection valve arranged in a combustion chamber toward a corner formed at a connecting portion between a deep section and a deep section, a shallow dish is distributed by the corner. A peripheral wall surface portion of the shallow dish portion to which the injected fuel flowing along the surface of the portion reaches is formed by a heat insulating member.

[0005]

When the peripheral wall surface portion of the shallow dish portion is formed by the heat insulating member, the peripheral wall surface portion of the shallow dish portion is maintained at a high temperature. Therefore, the injected fuel that has reached the peripheral wall surface of the shallow dish is immediately evaporated.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, an engine body 1 has four cylinders 1.
2 to 5, the combustion chamber structure of each cylinder 1a is shown. 2 to 5, 2 is a cylinder block, 3 is a reciprocating piston in the cylinder block 2, 4 is a cylinder head fixed on the cylinder block 2, and 5 is between the piston 3 and the cylinder head 4. The formed combustion chamber, 6a is a first intake valve, 6b is a second intake valve, 7a is a first intake port, 7b is a second intake port,
Reference numeral 8 indicates a pair of exhaust valves, and 9 indicates a pair of exhaust ports.
As shown in FIG. 2, the first intake port 7a is a helical intake port, and the second intake port 7b is a straight port that extends almost straight. Further, as shown in FIG. 2, a spark plug 10 is arranged at the center of the inner wall surface of the cylinder head 4, and the first intake valve 6a and the second intake valve 6 are provided.
A fuel injection valve 11 is arranged near the inner wall surface of the cylinder head 4 near b. Fuel is injected from the fuel injection valve 11 as indicated by F ₁ and F ₂ in FIGS. 2 and 3.

As shown in FIGS. 3 and 4, on the top surface of the piston 3, a shallow dish portion 12 having a substantially circular contour shape extending from below the fuel injection valve 11 to below the ignition plug 10.
Is formed, and a deep dish portion 13 having a substantially hemispherical shape is formed in the central portion of the shallow dish portion 12. In addition, a recess 14 having a substantially spherical shape is formed in the connecting portion between the shallow dish portion 12 and the deep dish portion 13 below the spark plug 10. The shallow plate portion 12 includes an annular flat bottom wall surface 12a and a peripheral wall surface 12b extending upward from a peripheral edge portion of the bottom wall surface 12a. Further, on the inner peripheral wall surface of the deep plate portion 13, the step portion 1 extending from the lower end of the recess 14 to the left and right.
3a is formed. Further, a heat insulating member 29 made of, for example, ceramic is embedded around the upper portions of the shallow dish portion 12 and the deep dish portion 13 on the side opposite to the fuel injection valve 11. Figure 3
The embedded region of the heat insulating member 29 is shown by hatching.
As can be seen from FIG. 3, this heat insulating member 29 extends around the basin portion 13 over a half circumference in the direction in which the injected fuels F ₁ and F ₂ travel. As shown in FIG. 4, the heat insulating member 29 extends from the stepped portion 13a to the top surface of the piston 3. Therefore, in the region shown by hatching in FIG. 3, the peripheral wall surface portion 13b of the basin 13 above the stepped portion 13a, Recessed portion 14, shallow pan bottom wall surface 12a and shallow pan peripheral wall surface 12b
Will be formed by the heat insulating member 29.

6 and 7 show another embodiment of the heat insulating member by reference numeral 29 ', and like FIG. 3, the hatching in FIG. 6 shows the embedded region of the heat insulating member 29'. 6 and 7, in the embodiment shown in FIG.
The outer peripheral portion of 2a and the peripheral wall surface 12b of the shallow dish portion are formed by a heat insulating member 29 '. This heat insulating member 29' of the shallow dish portion 12 in the advancing direction of the injected fuels F ₁ and F ₂ as shown in FIG. It extends around about 1/3 of the circumference.

As shown in FIG. 1, the first intake port 7a and the second intake port 7b of each cylinder 1a respectively pass through a first intake passage 15a and a second intake passage 15b formed in each intake branch pipe 15. Connected in the surge tank 16,
An intake control valve 17 is arranged in each second intake passage 15b. These intake control valves 17 have a common shaft 18
Is connected to the actuator 19 composed of, for example, a step motor. The step motor 19 is controlled based on the output signal of the electronic control unit 30. The surge tank 16 is connected to an air cleaner 21 via an intake duct 20, and a throttle valve 23 driven by a step motor 22 is arranged in the intake duct 20. The throttle valve 23 is closed to some extent only when the engine load is extremely low, and is kept fully open when the engine load is slightly higher. On the other hand, the exhaust port 9 of each cylinder 1a is connected to the exhaust manifold 24.

The electronic control unit 30 is composed of a digital computer and has a RAM (random access memory) 32 and a ROM connected to each other via a bidirectional bus 31.
A (read only memory) 33, a CPU (microprocessor) 34, an input port 35 and an output port 36 are provided. The accelerator pedal 25 includes a load sensor 26 that generates an output voltage proportional to the depression amount of the accelerator pedal 25.
Is connected, and the output voltage of the load sensor 26 is the AD converter 3
It is input to the input port 35 via 7. The top dead center sensor 27 generates an output pulse, for example, when the first cylinder 1a reaches the intake top dead center, and this output pulse is input to the input port 35.
Entered in. The crank angle sensor 28 generates an output pulse each time the crankshaft rotates 30 degrees, for example, and this output pulse is input to the input port 35. CPU3
In 4, the current crank angle is calculated from the output pulse of the top dead center sensor 27 and the output pulse of the crank angle sensor 28,
The engine speed is calculated from the output pulse of the crank angle sensor 28. On the other hand, the output port 36 is the corresponding drive circuit 3
8 through each fuel injection valve 11 and each step motor 1
9 and 22 are connected.

In the embodiment according to the present invention, the fuel injection valve 11 is designated by F ₁ and F ₂ in FIGS. 2 and 3.
The fuel is injected from the two directions. FIG. 8 shows the fuel injection amount and the fuel injection timing from the fuel injection valve 11. In FIG. 8, L is the accelerator pedal 25.
Indicates the amount of depression. As can be seen from FIG. 8, during engine low load operation in which the depression amount L of the accelerator pedal 25 is smaller than L _1, fuel injection is performed by the injection amount Q _{2 at the} end of the compression stroke. On the other hand, the depression amount L of the accelerator pedal 25 is L
During engine load operation between ₁ and L ₂ , fuel is injected by the injection amount Q ₁ during the intake stroke, and the injection amount Q is reached at the end of the compression stroke.
Only ₂ fuel is injected. That is, at the time of engine medium load operation, fuel injection is performed in two times, the intake stroke and the end of the compression stroke. Further, during the engine high load operation in which the depression amount L of the accelerator pedal 25 is larger than L ₂ , the injection amount Q during the intake stroke
Only _one fuel is injected. Note that in FIG. 8, θS1 and θE1 respectively indicate the injection start timing and the injection completion timing of the fuel injection Q ₁ performed during the intake stroke, and θS2 and θE2
E2 indicates the injection start timing and the injection completion timing of the fuel injection Q ₂ performed at the end of the compression stroke.

By the way, in the embodiment according to the present invention, as shown in FIG. 2, the injected fuels F ₁ , F ₂ are injected from the fuel injection valve 11.
Is injected so as to fly below the first intake valve 6a, and the injected fuel is injected during the first injection during engine medium load operation, that is, during intake stroke injection, and during intake stroke injection during engine high load operation. F ₁ and F ₂ are caused to collide with the back surface of the bulge portion of the first intake valve 6a. Next, this will be described with reference to FIGS. 9 and 10.

FIG. 9 shows the valve lift X of the first intake valve 6a and the second intake valve 6b and the valve lift Y of the exhaust valve 8. As can be seen from FIG. 9, the first intake valve 6a and the second intake valve 6
The valve lift X of b becomes the largest in the central part of the intake stroke. FIG. 10 shows the relationship between the first intake valve 6a and the injected fuel F ₁ . As shown in FIG. 10, the injected fuel F ₁ is injected slightly downward from the horizontal plane. Although not shown in FIG. 10, the injected fuel F ₂ is also injected slightly downward from the horizontal plane like the injected fuel F ₁ . As can be seen from FIG. 10, when the lift amount of the first intake valve 6a is small as shown in FIG. 10 (A), the injected fuel F ₁ does not collide with the first intake valve 6a, and as shown in FIG. When the lift amount of the first intake valve 6a becomes large, the relative position of the first intake valve 6a and the fuel injection valve 11 and the relative position of the fuel injection valve 11 from the fuel injection valve 11 so that the injected fuel F ₁ collides with the back surface of the bulge portion of the first intake valve 6a. The fuel injection direction is defined. Z in FIG. 9 shows a crank angle region in which the injected fuel F ₁ collides with the back surface of the bulkhead portion of the first intake valve 6a. Although not shown in FIG. 10, the injected fuel F ₂ also collides with the back surface of the bulge portion of the first intake valve 6a in the crank angle region Z.

If the fuel is injected from the fuel injection valve 11 in the crank angle region Z shown in FIG.
As shown in (B), the injected fuel F ₁ collides with the back surface of the bulkhead portion of the first intake valve 6a. At this time, if the flow velocity of the injected fuel F ₁ is slow, the injected fuel F ₁ collides with the back surface of the bulge portion of the first intake valve 6a and then burns on the side opposite to the fuel injection valve 11 along the back surface of the bulge portion of the first intake valve 6a. Toward the periphery of chamber 5 but injected fuel F
_When the flow velocity of ₁ is high, the injected fuel F ₁ collides with the back surface of the bulge portion of the intake valve 6a and then is reflected and travels into the first intake port 7a as shown in FIG. 10 (B). Similarly injected fuel F injected fuel F ₂ if the flow velocity is fast in ₂ toward the first intake port 7a is reflected after having collided with the rear bevel portion of the first intake valve 6a. In the embodiment according to the present invention, after the injected fuels F ₁ and F ₂ are reflected on the rear surface of the bulk of the first intake valve 6a, the flow speeds of the injected fuels F ₁ and F ₂ are directed toward the inside of the first intake port 7a. It is set. This flow velocity is mainly determined by the fuel injection pressure, and in the embodiment according to the present invention, the fuel injection pressure is 70.
It is set to kg / cm ² or more.

FIG. 11 shows the relationship between the opening degree of the intake control valve 17 and the depression amount L of the accelerator pedal 25. 11
As shown in, the depression amount L of the accelerator pedal 25 is L
_The intake control valve 17 is held in the fully closed state during engine low load operation smaller than _1, and when the depression amount L of the accelerator pedal 25 becomes larger than L ₁ , the intake control valve 17 changes the depression amount L of the accelerator pedal 25. The valve opens as it grows larger. When the intake control valve 17 is fully closed, the intake air swirls into the combustion chamber 5 through the first intake port 7a having a helical shape, and thus the combustion air flows into the combustion chamber 5 in the arrow S in FIG. A powerful swirling flow is generated as shown in. On the other hand, if the intake control valve 17 opens, the second
Intake air also flows into the combustion chamber 5 from the intake port 7b.

Returning to FIG. 8 again, FIG. 8 shows the crank angle region Z shown in FIG. As shown in FIG. 8, in the embodiment according to the present invention, both the _first fuel injection Q ₁ during the engine medium load operation and the fuel injection Q ₁ during the engine high load operation may be performed within the crank angle range Z. Recognize. Therefore, in the embodiment according to the present invention, all the fuel injected from the fuel injection valve 11 during the intake stroke is the first intake valve 6a.
After colliding with the rear surface of the bulge, it will flow into the first intake port 7a.

Next, the combustion method will be described with reference to FIGS. 12 to 15 while referring to FIG. 12 and 13 show a combustion method during engine low load operation, FIG. 14 shows a combustion method during engine medium load operation, and FIG. 15 shows a combustion method during engine high load operation. ing. 12 to 15 show the case where the heat insulating member 19 shown in FIGS. 3 and 4 is used, but instead of the heat insulating member 19, the heat insulating member 1 shown in FIGS. 6 and 7.
It is also possible to use 9 '.

As shown in FIG. 8, the accelerator pedal 25
Fuel is injected at the end of the compression stroke during engine low load operation in which the depression amount L of is smaller than L ₁ . 12 (A), (B)
And FIG. 13 (A) shows when the load is low in the engine low load operating region, and FIG. 13 (B) shows when the load is slightly higher in the engine low load operating region. ) Indicates when the load is high in the engine low load operation region.

As shown in FIGS. 12 (A), 12 (B) and 13 (A), when the load is low in the engine low load operation region, the injected fuels F ₁ and F ₂ are injected into the basin portion above the step portion 13a. It collides with the upper peripheral wall surface 13b. Upper peripheral wall surface 13 of the deep plate
The injected fuels F ₁ and F ₂ that collide with b are swirled along the upper peripheral wall surface 13b of the deep plate while being vaporized by the swirling flow S, and a part of the vaporized fuel is guided into the recess 14. .. Further, in the embodiment shown in FIGS. 12 and 13, since the deep pan upper peripheral wall surface 13b and the recess 14 are formed by the heat insulating member 19, the deep pan upper peripheral wall surface 13b.
Also, the inner wall surface of the recess 14 is kept at a high temperature, so that the injected fuel is satisfactorily evaporated in the deep dish upper peripheral wall surface 13b and the recess 14. As a result, FIG.
As shown in (C), the air-fuel mixture G is formed in the recess 14 and the deep plate portion 13 by the evaporated fuel. At this time, the inside of the combustion chamber 5 other than the concave portion 14 and the deep plate portion 13 is filled with air. Next, the air-fuel mixture G is ignited by the spark plug 10.

On the other hand, if the load becomes a little higher and the fuel injection amount Q is increased in the engine low load operation region, FIG.
As you can see, the injection timing is slightly advanced. At this time, the injected fuels F ₁ and F ₂ have corner portions 19a formed at the connecting portion between the shallow dish portion 12 and the deep dish portion 13 as shown in FIG. 13 (B).
Is jetted toward. At this time, the injected fuels F ₁ and F ₂ are distributed by the corner portion 19a to the upper peripheral wall surface 13b of the deep dish portion and the bottom wall surface 12a of the shallow dish portion. Therefore, at this time, a part of the injected fuel F ₁ , F ₂ is supplied onto the upper peripheral wall surface 13 b of the deep plate portion, and a further part of the distributed injected fuel is guided into the recess 14. Therefore, even if the fuel injection amount Q increases, the recess 1
The air-fuel mixture formed in 4 does not become rich, so that the air-fuel mixture is easily ignited by the spark plug 10.

On the other hand, a part of the injected fuels F ₁ and F ₂ distributed by the corners 19a flow on the bottom wall surface 12a of the shallow plate and reach the peripheral wall surface 12b of the shallow plate portion, and the peripheral wall surface 12b of the shallow plate portion.
Stay at the root of. However, the bottom wall surface 12a of the shallow plate portion
Since the shallow dish portion peripheral wall surface 12b is formed by the heat insulating member 19, the shallow dish portion low wall surface 12a and the shallow dish portion peripheral wall surface 12b are maintained at a high temperature. Therefore, a part of the injected fuel flowing on the shallow dish portion lower wall surface 12a is part of the shallow dish portion bottom wall surface 12
The vaporized fuel is satisfactorily vaporized while flowing over a, and the injected fuel that has reached the root of the shallow dish peripheral wall surface 12b is also vaporized satisfactorily. In this way, the injected fuel supplied into the shallow dish portion 12 is also vaporized satisfactorily, so that the entire injected fuel is satisfactorily burned.

As the load increases during engine low load operation, the injection timing is further advanced, as can be seen from FIG. 8. At this time, as shown in FIG. 13 (C), the injected fuel F ₁ ,
F ₂ collides with a corner portion 19b formed at the connecting portion between the top surface of the piston 3 and the shallow dish peripheral wall surface 12b. Also at this time, the injected fuels F ₁ and F ₂ are distributed to the top surface of the piston 3 and the peripheral wall surface 12b of the shallow dish by the corner portions 19b. Therefore, also at this time, part of the injected fuel distributed by the corner portion 19b is sent to the root portion of the shallow dish peripheral wall surface 12b and stays at the root portion of the shallow dish peripheral wall surface 12b. However, as described above, since the temperature around the root of the shallow dish peripheral wall 12b is maintained at a high temperature, the injected fuel that has accumulated in the root of the shallow dish peripheral wall 12b can be evaporated well. Therefore, good combustion can be obtained at this time as well.

On the other hand, in FIG. 8, the first fuel injection Q ₁ is performed in the crank angle region Z during the intake stroke during engine load operation in which the depression amount L of the accelerator pedal 25 is between L ₁ and L _2. Then, the second fuel injection Q ₂ is performed at the end of the compression stroke. That is, first of all, FIG.
As shown in (A), fuel is injected toward the back surface of the first intake valve 6a, and the injected fuel is reflected by the back surface of the first intake valve 6a and enters the first intake port 7a. Inflow. Next, these injected fuels flow into the combustion chamber 5 again together with the intake air, and the injected fuel forms a lean mixture in the combustion chambers 5.

Next, the second fuel injection is performed at the end of the compression stroke. As can be seen from FIG. 8, the injection timing of the compression stroke injection Q ₂ during the engine medium load operation is almost the same as the injection timing during the intermediate load during the engine low load operation. Therefore, at this time, as shown in FIG.
The fuel is injected toward the corner 19a formed at the connecting portion between the shallow dish 12 and the shallow dish 12, and as shown in FIG. 14 (C), the injected fuel causes a spark in the recess 14 and the deep dish 13. An ignitable mixture G is formed. The air-fuel mixture G is ignited by the spark plug 10, and the ignition flame burns the lean air-fuel mixture in the entire combustion chamber 5.
In this case, it suffices that the fuel injected at the end of the compression stroke produces a spark, so as shown in FIG. 8, the fuel injection amount at the end of the compression stroke is irrespective of the depression amount L of the accelerator pedal 25 during engine medium load operation. Q ₂ is kept constant. On the other hand, the fuel injection amount Q _{1 at the} beginning of the intake stroke increases as the depression amount L of the accelerator pedal 25 increases.

In FIG. 8, during the engine high load operation in which the depression amount L of the accelerator pedal 25 is larger than L ₂ , the fuel is injected in the crank angle region Z during the intake stroke. Therefore, at this time, as shown in FIG. 15, the first intake valve 6
Fuel is injected toward the rear surface of the bulkhead portion of a, and the injected fuel is reflected by the rear surface of the bulkhead portion of the first intake valve 6a and flows into the first intake port 7a. Next, these injected fuels flow into the combustion chamber 5 again together with the intake air, and the injected fuel forms a uniform air-fuel mixture in the combustion chambers 5. The fuel injection amount Q _{1 at} this time increases as the depression amount L of the accelerator pedal 25 increases as shown in FIG.

As shown in FIGS. 14A and 15, the injected fuel reflected by the first intake valve 6a is the first intake port 7a.
When injected into the first intake port 7a
The injected fuel and the intake air, which are mixed with the intake air in the inside, are then supplied into the combustion chamber 5 in a sufficiently mixed manner. That is,
Since the premixed air is supplied to the combustion chamber 5 via the first intake valve 6a, the injected fuel is uniformly dispersed in the combustion chamber 5. Further, when the flow velocity of the injected fuel is increased so that the injected fuel is reflected by the first intake valve 6a and then flows into the first intake port 7a, the injected fuel becomes the first injected fuel.
The fuel is atomized at the high speed against the back surface of the air intake valve 6a, so that the atomized fuel is the first atomized fuel.
It advances toward the inside of the intake port 7a. At this time, since the advancing direction of the fuel and the inflow direction of the intake air flow are opposite to each other, the fuel is subjected to a strong shearing force by the intake air, and thus the fuel is further atomized. Thus, the injected fuel is atomized at the time of collision and then atomized by a strong shearing force, so that the injected fuel is vaporized well. In this way, the injected fuel is vaporized well, and moreover, it is evenly dispersed in the combustion chamber 5, so that the air-fuel mixture is burned well.

In the embodiment according to the present invention, the injection start timing θS1 of the intake stroke injection Q _{1 and} the injection start timing θS2 of the compression stroke injection Q ₂ are predetermined in FIG. 8, and these injection start timings θS1 and θS2 are the accelerator pedal. Two
It is stored in advance in the ROM 33 in the form of a function of the depression amount L of 5. Therefore, the injection completion timings θE1 and θE2 are controlled based on the injection amounts Q ₁ and Q ₂ .

FIG. 16 shows a routine for controlling fuel injection, and this routine is repeatedly executed. Referring to FIG. 16, first, at step 40, the fuel injection amount Q is calculated. This fuel injection amount Q is stored in advance in the ROM 33 as a function of the engine speed N and the depression amount L of the accelerator pedal 25, as shown in FIG. Next, at step 41, it is judged if the depression amount L of the accelerator pedal 25 is smaller than L ₁ , that is, if it is during low load operation. When L <L _1, the routine proceeds to step 42, where the injection start timing θS2 of the compression stroke injection is calculated. Next, at step 43, the injection start timing θS2,
Injection completion timing θE from the fuel injection amount Q and the engine speed N
2 is calculated.

On the other hand, in step 41, L ≧ L₁And
If it is determined that the accelerator pedal
Depression amount L of pedal 25 is L₂Immediately less than
Then, it is determined whether or not it is during the medium load operation. Medium load operation
Sometimes the routine proceeds to step 45, where the intake stroke injection amount Q₁And compression
Stroke injection amount Q₂Is calculated. Then in step 46
The injection start timing θS1 of the intake stroke injection is calculated. Next
At step 47, the injection start timing θS1 and the intake stroke injection
Quantity Q₁And the injection completion timing θE1 is calculated from the engine speed N
Will be issued. Next, at step 48, injection of compression stroke injection
The start timing θS2 is calculated. Then in step 49
Injection start timing θS2, compression stroke injection amount Q ₂And engine times
The injection completion timing θE2 is calculated from the number of revolutions N.

When it is determined in step 44 that L ≧ L _2, that is, when the engine is under high load operation, step 50
Then, the injection start timing θS1 of the intake stroke injection is calculated. Next, at step 51, the injection completion timing θE1 is calculated from the injection start timing θS1, the fuel injection amount Q and the engine speed N. Fuel injection is performed from each fuel injection valve 11 based on the injection start timings θS1 and θS2 and the injection completion timings θE1 and θE2 calculated in this way.

[0031]

EFFECTS OF THE INVENTION In the case where fuel is injected toward the corner formed at the connecting portion of the shallow dish and the deep dish, the injection is distributed by the corner and reaches the peripheral wall surface of the shallow dish. The evaporation of the fuel can be promoted and thus good combustion can be obtained.

[Brief description of drawings]

FIG. 1 is an overall view of an internal combustion engine.

FIG. 2 is a plan sectional view of a cylinder head.

FIG. 3 is a plan view of the top surface of the piston.

4 is a sectional view taken along line IV-IV in FIG.

5 is a cross-sectional view taken along the line VV of FIG.

FIG. 6 is a plan view of a piston top surface showing another embodiment.

7 is a sectional view taken along line VII-VII of FIG.

FIG. 8 is a diagram showing a fuel injection amount and a fuel injection timing.

FIG. 9 is a diagram showing lift amounts of an intake valve and an exhaust valve.

10 is a side sectional view taken along the same section as FIG.

FIG. 11 is a diagram showing an opening of an intake control valve.

FIG. 12 is a diagram for explaining a combustion method during low load operation.

FIG. 13 is a diagram for explaining a combustion method during low load operation.

FIG. 14 is a diagram for explaining a combustion method during medium load operation.

FIG. 15 is a diagram for explaining a combustion method during high load operation.

FIG. 16 is a flowchart for executing a main routine.

FIG. 17 is a diagram showing a fuel injection amount.

[Explanation of symbols]

 6a, 6b ... intake valve 7a, 7b ... intake port 11 ... fuel injection valve 12 ... shallow pan 12b ... shallow pan peripheral wall 13 ... dish pan 19,19 '... heat insulating member 19a ... corner

Claims (1)

[Claims] 1. A shallow dish portion is formed on a top surface of a piston, and a deep dish portion is formed at a central portion of the shallow dish portion toward a corner formed at a connecting portion between the shallow dish portion and the deep dish portion. In a cylinder injection type internal combustion engine in which fuel is injected from a fuel injection valve arranged in a combustion chamber, a peripheral wall surface portion of a shallow plate portion to which the injected fuel distributed along the surface of the shallow plate portion distributed by the corners reaches In-cylinder injection internal combustion engine in which a heat insulating member is formed.