JPH08193536A - Fuel injection controller of cylinder injection type internal combustion engine - Google Patents

Abstract

PURPOSE: To enable it to start an engine with a modicum of fuel by spraying an amount of fuel more than a portion of energy so as to make a flame ignited by a spark plug so as to be propagable in a cylinder in an intake stroke in time of engine starting, and then injecting the minimal fuel capable of forming an ignitable air-fuel mixture in a compression stroke at the engine starting. CONSTITUTION: A fuel injection valve 5 is set up on the top of a cylinder chamber as pointing downward aslant, and also it is set up so as to spray fuel toward the vicinity of a spark plug 65. Then, at an electronic control unit 20, a fact of whether an engine is starting or not is judged, while a water temperature in the engine is read, and in time of starting the engine, a first fuel injection quantity capable of forming an air-fuel mixture of more than a portion of energy making the engine rotatable in a cylinder is calculated from a map of the water temperature, and simultaneously a second fuel injection quantity capable of forming the air-fuel mixture being ignitable in the vicinity of the spark plug 65 in a combustion chamber is calculated. In brief, a span of injection timing is controlled so as to spray the first fuel injection quantity at the time of an intake stroke, and the second fuel injection quantity at the time of a compression stroke, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for a cylinder injection type internal combustion engine, and more particularly, to a fuel for a cylinder injection type internal combustion engine capable of separately injecting required fuel into an intake stroke and a compression stroke when the engine is started. The present invention relates to an injection control device.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 2-146239 discloses a fuel injection valve for injecting fuel into a concave combustion chamber which is formed at the lower end of a cylinder head of an engine or at the top of a piston so as to open into the cylinder, and an intake passage. In a cylinder direct injection spark ignition engine equipped with an intake throttle device that adjusts the throttle ratio, fuel is injected from a fuel injection valve during the intake stroke during engine warm-up operation, and the throttle ratio during warm-up of the intake throttle device is adjusted. An engine is disclosed in which the throttle ratio is made larger than that after completion of warm-up, and the throttle ratio is reduced as the fuel injection amount increases. According to this engine, fuel is injected into the intake stroke during warm-up to evaporate and atomize the fuel for a long time, so the fuel adhering to the wall of the combustion chamber is evaporated and the intake air amount is limited during warm-up operation. Therefore, the heat radiation to the excess intake air that does not contribute to the combustion is reduced, and the evaporation and atomization of the fuel is promoted.

[0003]

However, in the above-described direct injection type spark ignition engine for a cylinder, the intake air amount is not sufficient during the cranking rotation at the time of engine start, and the fuel is not discharged even if the fuel is injected in the intake stroke. It is difficult to form and it is difficult to diffuse the air-fuel mixture into the entire combustion chamber, and it is difficult to form a good air-fuel mixture near the spark plug. This occurs especially when the engine is cold. Further, when the fuel is injected in the compression stroke, the amount of fuel is large, so that the fuel may not be vaporized and may adhere to the combustion chamber, or may bounce due to the injection and adhere to the ignition plug, resulting in ignition failure or misfire.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above problems and to provide a fuel injection control device for a cylinder injection type internal combustion engine which forms a favorable air-fuel mixture at the time of engine start and does not cause a start failure.

[0005]

FIG. 1 is a basic block diagram of the present invention. A fuel injection control device for a cylinder injection type internal combustion engine according to a first aspect for achieving the above object is a fuel for a cylinder injection type internal combustion engine comprising a fuel injection valve capable of directly injecting required fuel into a cylinder of the engine. In the injection control device, first injection amount calculation means for calculating a first fuel injection amount required to form a homogeneous air-fuel mixture in the combustion chamber of the engine when the engine is started, and ignition near a spark plug in the combustion chamber when the engine is started. A second injection amount calculation means for calculating a second fuel injection amount required to form a possible air-fuel mixture, and injecting the first fuel injection amount of fuel during an intake stroke to compress the second fuel injection amount of fuel. And an injection timing control means for controlling the fuel injection timing so that the fuel is injected during the stroke.

According to a second aspect of the present invention, there is provided a fuel injection control device for a cylinder injection type internal combustion engine, wherein the rotation detection means for detecting the rotation speed of the engine and the higher the rotation speed of the engine detected by the rotation detection means. And an injection timing correction means for correcting the fuel injection timing during the compression stroke to the advance side of the compression stroke.

A fuel injection control device for a cylinder injection type internal combustion engine according to a third aspect of the invention is a fuel injection control for a cylinder injection type internal combustion engine having a fuel injection valve capable of directly injecting required fuel into a cylinder of the engine. In the device, a first injection amount calculation means for calculating a first fuel injection amount required to form a homogeneous air-fuel mixture in the combustion chamber of the engine when the engine is started, and ignition can be performed near the ignition plug in the combustion chamber when the engine is started. Second injection amount calculation means for calculating the second fuel injection amount required to form the air-fuel mixture,
Injection timing control means for controlling the fuel injection timing so as to inject the first fuel injection amount of fuel during the intake stroke and the second fuel injection amount of fuel during the compression stroke, and to detect the engine speed. It is characterized by further comprising rotation detecting means and first fuel injection amount correcting means for correcting the first fuel injection amount to decrease as the engine speed detected by the rotation detecting means increases.

According to a fourth aspect of the present invention, there is provided a fuel injection control device for a cylinder injection type internal combustion engine, which comprises a counting means for counting the number of fuel injections from the start of engine start to the completion of start, and the fuel injection counted by the counting means. Second fuel injection amount correction means for correcting the first fuel injection amount to decrease as the number of times increases,
Is further provided.

[0009]

A fuel injection control device for a cylinder injection type internal combustion engine according to a first aspect of the present invention enables a flame ignited by a spark plug to propagate into a cylinder during an intake stroke at engine startup.
Prior to the ignition, the first injection amount calculation means calculates the first injection fuel amount for vaporizing and diffusing the fuel in the amount equal to or more than the energy for starting the engine rotation in the cylinder, and the compression stroke at the engine start. The minimum amount of second injected fuel that can form an ignitable mixture is calculated by the second injection amount calculation means, and the first fuel injection amount is injected during the intake stroke and the second fuel injection amount is injected during the compression stroke. Since the fuel injection timing is controlled by the injection timing control means so that a favorable air-fuel mixture is formed in the vicinity of the spark plug.

In the fuel injection control device for a cylinder injection type internal combustion engine according to the second aspect, the higher the engine speed detected by the rotation detection means, the higher the engine speed of the engine detected by the injection timing correction means. Is corrected to the advance side, so even if there are variations in the number of revolutions at the start of the engine, an appropriate time to vaporize the fuel injected in the compression stroke is from the fuel injection timing to the ignition timing in the compression stroke. It is controlled according to the number of revolutions of the engine so that the optimum state of the air-fuel mixture near the ignition plug at the time of ignition is obtained.

In the fuel injection control device for a cylinder injection type internal combustion engine according to the third aspect of the present invention, the higher the engine speed detected by the rotation detecting means, the more the fuel in the intake stroke by the first fuel injection amount correcting means. Since the injection amount is reduced and corrected, the injection fuel amount in the intake stroke becomes appropriate with respect to the intake air amount according to the engine speed, and the vaporization and diffusion of the fuel in the cylinder becomes appropriate.

According to a fourth aspect of the present invention, there is provided a fuel injection control device for a cylinder injection type internal combustion engine, wherein the counting means counts the number of fuel injections from the start of engine start to the completion of start. Since the second fuel injection amount correcting means corrects the fuel injection amount in the intake stroke to be reduced, it is possible to prevent the injected fuel from adhering to the combustion chamber, and thus to prevent the adhered fuel from scattering into the combustion chamber and adhering to the ignition plug. .

[0013]

1 is a block diagram of a four-cylinder gasoline engine adopted in an embodiment of the present invention. In the figure, 1 is the engine body,
2 is a surge tank, 3 is an air cleaner, 4 is an intake pipe connecting the surge tank 2 and the air cleaner 3, 5 is an electrostrictive high pressure fuel injection valve for injecting fuel into each cylinder, 6 is a high pressure reservoir tank, 7 Is a high-pressure fuel pump capable of controlling the discharge pressure for pumping high-pressure fuel to the reservoir tank 6 via the high-pressure conduit 8, 9 is a fuel tank, and 10 is fuel from the fuel tank 9 to the high-pressure fuel pump 7 via the conduit 11. The low-pressure fuel pump to be supplied and 65 are spark plugs, respectively. The discharge side of the low-pressure fuel pump 10 is connected to a piezoelectric element cooling introduction pipe 12 for cooling the piezoelectric element of each fuel injection valve 5. The piezoelectric element cooling return pipe 13 is connected to the fuel tank 9, and the fuel flowing through the piezoelectric element cooling introduction pipe 12 via the piezoelectric element cooling return pipe 13 is collected in the fuel tank 9. Each branch pipe 14 connects each high-pressure fuel injection valve 5 to the high-pressure reservoir tank 6.

The electronic control unit 20 is composed of a digital computer, and has a ROM (Read Only Memory) 22, a RAM (Random Access Memory) and a CP by a microprocessor which are mutually connected by a bidirectional bus 21.
A U (Central Processing Unit) 24, an input port 25 and an output port 26 are provided. The pressure sensor 27 attached to the high pressure reservoir tank 6 detects the pressure in the high pressure reservoir tank 6, and the detection signal is A /
It is input to the input port 25 via the D converter 28. The output pulse of the crank angle sensor 29 that generates an output pulse proportional to the engine speed NE is input to the input port 25. An output voltage of an accelerator opening sensor 30 that generates an output voltage according to an opening θA of an accelerator pedal (not shown) is input to an input port 25 via an A / D converter 31. Water temperature sensor 3 attached to the engine body 1
2 detects the engine cooling water temperature, and the detection signal is input to the input port 25 via the A / D converter 33. On the other hand, each fuel injection valve 5 is connected to the output port 26 via each drive circuit 34. Further, each spark plug 65 is connected to the output port 26 via each drive circuit 35. Further, the high-pressure fuel pump 7 is connected to the output port 26 via the drive circuit 36. The engine fuel injection control routine according to the present invention is executed by the electronic control unit 20.

FIG. 2 is a side sectional view of the fuel injection valve 5. In this figure, 40 is a needle inserted in the nozzle 50,
Reference numeral 41 is a pressure rod, 42 is a movable plunger, 43 is a compression spring which is arranged in the spring accommodating chamber 44 and presses the needle 40 downward, 45 is a pressure piston, 46 is a piezoelectric element, and 47 is a movable plunger. A pressure chamber formed between the top of 42 and the piston 45 and filled with fuel, 48
Indicate needle pressurizing chambers, respectively. Needle pressure chamber 48
Is connected to the high-pressure reservoir tank 6 (FIG. 1) via the fuel passage 49 and the branch pipe 14, so that the high-pressure fuel in the high-pressure reservoir tank 6 passes through the branch pipe 14 and the fuel passage 49 to the needle pressurizing chamber 48. Supplied within. When the piezoelectric element 46 is charged with electric charge, the piezoelectric element 46 expands, thereby increasing the fuel pressure in the pressurizing chamber 47.
As a result, the movable plunger 42 is pressed downward, and the nozzle opening 53 is kept closed by the needle 40. On the other hand, when the electric charge charged in the piezoelectric element 46 is discharged, the piezoelectric element 46 contracts and the fuel pressure in the pressurizing chamber 47 decreases. As a result, the movable plunger 42 rises, the needle 40 rises, and the fuel is injected from the nozzle port 53.

FIG. 3 is a longitudinal sectional view of the engine in the latter stage of the compression stroke of the first embodiment. In this figure, 60 is a cylinder block, 61 is a cylinder head, 62 is a piston, and 63.
Is a substantially cylindrical recess formed on the top surface of the piston 62, 64
Indicates a cylinder chamber formed between the top surface of the piston 62 and the inner wall surface of the cylinder head 61. Spark plug 65
Is attached to a substantially central portion of the cylinder head 61 so as to face the cylinder chamber 64. Although not shown, the cylinder head 61
An intake port and an exhaust port are formed inside, and an intake valve 66 (see (a) of FIG. 4) and an exhaust valve are arranged at openings of the intake port and the exhaust port into the cylinder chamber 64, respectively. The fuel injection valve 5 is a swirl type fuel injection valve, and injects a fuel in the form of a spray having a wide spread angle and a large dispersion of the spray, and a weak penetration force. The fuel injection valve 5 is arranged diagonally downward at the top of the cylinder chamber 64 and is arranged so as to inject fuel toward the vicinity of the spark plug 65. Further, the fuel injection direction and the fuel injection timing of the fuel injection valve 5 are determined so that the injected fuel is directed to the recess 63 formed at the top of the piston 62.

4A and 4B are explanatory diagrams of the operation of the engine of the first embodiment. FIG. 4A is an early intake stroke, FIG. 4B is a late intake stroke to an early compression stroke, and FIG. 4C is a late compression stroke, and FIG. 4] are views showing the operation of the engine in the combustion stroke, respectively.
In the first embodiment of the present invention, when the engine is started, the intake stroke injection at the beginning of the intake stroke shown in FIG. 4A and the compression stroke injection at the latter stage of the compression stroke shown in FIG. 4C are executed. First, as shown in (a) of FIG. 4, fuel is injected from the fuel injection valve 5 toward the spark plug 65 and the recess 63 on the top surface of the piston 62 in the intake stroke. The injected fuel is a spray-like fuel having a large divergence angle and a weak penetration force, and a part of the injected fuel floats in the cylinder chamber 64 and the other collides with the recess 63. These injected fuels are diffused into the cylinder chamber 64 by the turbulence R in the cylinder chamber 64 caused by the intake air flow flowing into the cylinder chamber 64 from the intake port, and are compressed from the intake stroke as shown in FIG. 4B. The premixed gas P is formed during the stroke. The air-fuel ratio of the premixed air P is such that the ignition flame can propagate. FIG.
In the state of (b), since the extension of the central axis of the injected fuel is directed toward the cylinder wall, there is a possibility that a part of the spray may directly adhere to the cylinder wall when the penetrating force of the injected fuel is strong.
By making this period a non-injection period, the effect of preventing fuel from adhering to the cylinder wall surface is enhanced.

As shown in FIG. 4 (c), the fuel injection valve 5 to the vicinity of the spark plug 65 and the concave portion 6 on the top surface of the piston 62.
Injection is performed in the latter half of the compression stroke by directing to point 3. The injected fuel originally has a weak upward penetration force directed to the spark plug 65, and the pressure in the cylinder chamber 64 is large, so that the injected fuel is unevenly distributed in the region K near the spark plug 65. This area K
Since the fuel distribution inside is also non-uniform and changes from the rich air-fuel mixture layer to the air layer, a combustible air-fuel mixture layer near the stoichiometric air-fuel ratio that is most likely to burn exists in this region K. Therefore, in the combustion stroke of FIG. 4D, when the combustible mixture layer near the ignition plug 65 is ignited, the combustion proceeds around the nonuniform mixture region K. In this combustion process, the flame is sequentially propagated to the premixed gas P from the periphery of the combustion gas B whose volume is expanded, and the combustion is completed.

As described above, in the first embodiment, by injecting the fuel at the beginning of the intake stroke at the time of starting the engine (rotating the engine, and), the air-fuel mixture for flame propagation is supplied to the cylinder chamber 6
In addition to being formed in the whole of No. 4 and by injecting fuel in the latter part of the compression stroke, a relatively rich air-fuel mixture can be formed in the vicinity of the ignition plug 65, and good ignition and combustion with a high air utilization rate can be obtained.

FIG. 5 is a flow chart showing a fuel injection control routine of the engine according to the first and second claims. The fuel injection control routine shown in this figure is executed for each injection valve by interruption every 720 ° CR. This interrupt process is started by shifting each injection valve by 180 ° CR (crank angle). In the figure, the numbers following S indicate step numbers. Note that step S4 in this flowchart relates to the second invention. First, in step S1, it is determined whether the engine is cranking or not, for example, N
E is compared with 600 RPM, and when 0 <NE <600 RPM, it is considered that cranking rotation is in progress and the process proceeds to step S2. When NE ≧ 600 RPM, it is considered that start is completed and the cranking rotation flag is set to 1 and this routine is ended. NE <400R after this flag is set to 1
The flag is kept at 1 until the PM is reached, the rotation speed drops and N
When E <400 RPM, the flag is reset to 0 and cranking rotation is considered to be in progress. That is, it is possible to prevent the combustion of the engine from becoming unstable due to frequent switching between the control during the start and the control after the start is completed by providing hysterisis.

In step S2, the water temperature of the engine is read,
Go to step S3. In step S3, the map 1 of the fuel injection amount Qinj1 in the intake stroke with respect to the engine water temperature shown in FIG.
Then, the fuel injection amount Qinj1 with respect to the water temperature read in step S2 is calculated. This map is created based on the data obtained by the experiment and stored in the ROM in advance. As can be seen from this map, the lower the water temperature, the higher the fuel injection amount Qinj1 is set.

In step S4, the injection timing of the compression stroke for the current engine speed NE calculated from the crank angle sensor of the engine is calculated from the map 2 of the injection timing of the compression stroke for the engine speed NE shown in FIG. calculate. This map is also created based on the data obtained by the experiment and stored in the ROM in advance. As can be seen from this map, the injection timing is set to the advance side as the engine speed increases. This is because the time it takes for the fuel injected in the compression stroke to vaporize and become a good mixture is substantially constant, so that the injection timing is advanced and the vaporization time is increased as the engine speed increases.

The fuel injection valve is controlled to open based on the fuel injection amount in the intake stroke and the fuel injection timing in the compression stroke thus obtained. The fuel injection timing in the intake stroke is set to a predetermined crank angle for each fuel injection valve, and the fuel injection amount in the compression stroke is set to a predetermined amount for each fuel injection valve. Regarding the fuel injection amount in the compression stroke, a map for the water temperature may be provided as in FIG. As described above, the invention according to the first and second claims injects most of the fuel that generates the torque necessary for starting the engine in the intake stroke, and the injected fuel is vaporized and diffused at the injection timing of the compression stroke, Since a minimum amount of fuel required for ignition is injected, a good air-fuel mixture can be formed and engine startability is improved.

FIG. 8 is a flow chart showing a fuel injection control routine of the engine according to the third and fourth claims. The fuel injection control routine shown in this figure is executed for each injection valve by interruption every 720 ° CR. This interrupt process is started by shifting each injection valve by 180 ° CR. In the figure, the numbers following S indicate step numbers. In this flowchart, steps S5 and S6 relate to the fourth invention. First, in step S1, it is determined whether the engine is cranking or not in step S1 of FIG.
It is determined in the same manner as 1. When the cranking flag is 0, the process proceeds to step S2. When the cranking flag is set to 1, it is considered that the start is completed and the process proceeds to step S11 to clear the injection number counter IJCUT.

In step S2, the water temperature of the engine is read,
Go to step S3. In step S3, the map 1 of the fuel injection amount Qinj1 in the intake stroke with respect to the engine water temperature shown in FIG.
Then, the fuel injection amount Qinj1 with respect to the water temperature read in step S2 is calculated. This map is created based on the data obtained by the experiment and stored in the ROM in advance. As can be seen from this map, the lower the water temperature, the higher the fuel injection amount Qinj1 is set.

In step S4, a correction coefficient KN for correcting the injection amount in the intake stroke with respect to the engine speed NE shown in FIG.
From the map 3 of E, the correction coefficient KNE for the current rotational speed NE detected and calculated by the crank angle sensor of the engine is calculated. This map is also created based on the data obtained by the experiment and stored in the ROM in advance. As can be seen from this map, the lower the engine speed is, the higher the correction coefficient KNE is set, and the higher the engine speed, the more the correction coefficient KNE gradually decreases.
This is because the higher the number of revolutions, the higher the flow velocity of the intake air, so the injected fuel is likely to vaporize and diffuse, resulting in a good mixture.
This is because a small amount of fuel is wasted by adhering to the cylinder wall or the like.

In step S5, the injection number counter IJC
Increment the UT by 1. That is, IJCUT = I
Calculate JCUT + 1. In step S6, the correction coefficient KC is calculated from the map 4 of the correction coefficient KC for correcting the injection amount in the intake stroke with respect to the number of injections shown in FIG. This map is also created based on the data obtained by the experiment and stored in the ROM in advance. As can be seen from this map, the correction coefficient KC is set lower as the number of injections increases, that is, the correction coefficient KC gradually decreases as the number of injections increases. This is because it takes time to start the engine, and if the same amount of fuel is injected each time the fuel is injected, the fuel becomes excessive and the fuel adheres to the combustion chamber, causing plug fogging and smoldering, which deteriorates startability.

In step S7, the injection amount Qinj1 in the intake stroke is calculated from the following equation using the correction coefficient KNE obtained in step S4 and KC obtained in step S6. Qinj1 = Qinj1 x KNE x KC

In step S8, the injection timing in the compression stroke is calculated from the map 2 of the injection timing in the compression stroke with respect to the engine speed NE shown in FIG. This map is also created based on the data obtained by the experiment and stored in the ROM in advance. As can be seen from this map, the injection timing is set to the advance side as the engine speed increases. This is because the time taken for the fuel injected in the compression stroke to vaporize and become a good mixture is substantially constant, so the injection timing must be advanced as the engine speed increases.

The fuel injection valve is controlled to open based on the fuel injection amount in the intake stroke and the fuel injection timing in the compression stroke thus obtained. The fuel injection timing in the intake stroke is set to a predetermined crank angle for each fuel injection valve, and the fuel injection amount in the compression stroke is set to a predetermined amount for each fuel injection valve. Regarding the fuel injection amount in the compression stroke, a map for the water temperature may be provided as in FIG. As described above, in the inventions according to the third and fourth claims, in the intake stroke injection for starting the engine, the higher the cranking speed of the engine is, the more the correction coefficient KNE is gradually decreased and the injected fuel is decreased. While obtaining a good air-fuel mixture, and as the number of injections increases, the correction coefficient KC is gradually decreased to reduce the amount of injected fuel, so that the fuel can be prevented from adhering to the combustion chamber due to excessive fuel, and engine start failure can be prevented. .

The engine adopted in the embodiment of the present invention described above is provided with the fuel injection valve capable of directly injecting fuel into the cylinder to perform the intake stroke injection and the compression stroke injection as described above. However, in addition to this, a separate fuel injection valve for injecting fuel toward the intake port of the engine is provided, and by injecting fuel from this fuel injection valve, a homogeneous mixture similar to the above-described intake stroke injection is obtained. You may be able to obtain. Needless to say, part of the intake stroke injection may be performed from the above-described fuel injection valve that directly injects into the cylinder.

FIG. 11 is a longitudinal sectional view of the engine in the latter half of the compression stroke of the second embodiment. The recesses formed at the top of the fuel injection valve 5 and the piston 62 are different from those of the first embodiment shown in FIG. The different points will be described below. The concave combustion chamber 67 formed on the top of the piston has a double structure of a large-diameter shallow dish portion 68 on the upper side and a deep dish portion 69 on the lower side formed in the central portion of the shallow dish section 68. The dish 69 has a smaller diameter than the shallow dish 68.

The intake port (not shown) is a swirl port, and the fuel injection valve 5 has a multi-hole nozzle. Therefore, the fuel injection valve 5 injects a relatively rod-shaped fuel having a relatively high penetration force and a small spread angle. The fuel injection valve 5 is arranged diagonally downward and is arranged at the top of the cylinder chamber 64. The fuel injection direction and fuel injection timing of the fuel injection valve 5 are determined so that the injected fuel is directed into the combustion chamber 67. The spark plug 65 is arranged so as to be located in the concave combustion chamber 67 when the piston 62 is at the top dead center.

FIG. 12 is a diagram for explaining the operation of the engine of the second embodiment. (A) is the early stage of the intake stroke, (b) is the latter stage of the intake stroke to the early stage of the compression stroke, (c) is the latter stage of the compression stroke, and (d). )
[Fig. 3] is a diagram showing the operation of the engine in a combustion stroke. Similar to the first embodiment described with reference to FIG. 4, in the second embodiment of the present invention, the intake stroke injection at the beginning of the intake stroke shown in FIG. The compression stroke injection in the latter half of the compression stroke shown in is executed. First, as shown in FIG. 12A, fuel is injected from the fuel injection valve 5 toward the combustion chamber 67 in the intake stroke. The injected fuel F mainly collides with the shallow dish portion 68, a part thereof is reflected in the cylinder chamber 54, and the other part is attached to the wall surface of the shallow dish portion 68 and evaporated and atomized by heating from the wall surface. These fuels are generated by the intake vortex flow SW and the turbulence R of the intake flow in FIG.
(B), the premixed gas P is formed during the intake stroke to the compression stroke. Here, the intake swirl flow SW indicates a swirl flow generated by closing the intake control valve (not shown) and sucking air into the cylinder chamber 64 only from the helical intake valve, not from the straight intake valve. The air-fuel ratio of the premixed air P is set to an air-fuel ratio at which the ignition flame can be propagated (with a fuel amount equal to or more than the energy amount capable of starting the rotation of the engine) as in the first embodiment. Suction vortex S
When W is strong, a premixed gas is formed such that the vicinity of the outer periphery of the cylinder chamber 64 is dark and the vicinity of the center is thin. If the fuel is injected when the intake stroke injection timing is advanced and the piston 62 is closer to the top dead center, most of the fuel is injected into the deep dish portion 69 and most of the fuel is injected into the deep dish portion 69. Is premixed and vaporized.

As shown in FIG. 12 (c), most of the fuel injected from the fuel injection valve 5 in the latter stage of the compression stroke is the deep plate portion 6.
Directed within 9. Further, the air-fuel mixture in the cylinder chamber 64, which is pushed by the piston 62, generates a squish flow S flowing into the deep pan 69. The fuel adhering to the inside of the basin 69 is vaporized by heating from the wall surface and the compressed air and diffused and mixed by the vortex flow SW to form a dense and uneven mixture layer including a combustible region. In the combustion stroke of (d) of FIG. 12, a part of this air-fuel mixture layer is ignited by the spark plug 65, and combustion of the heterogeneous air-fuel mixture layer proceeds. The flame B formed by this combustion propagates to the surrounding premixed air in the process of developing in the deep pan 69, and the air-fuel mixture trapped in the deep pan 69 in the combustion process is discharged from the deep pan 69. Combustion is promoted by the reverse squish flow RS pushed toward the inside of the cylinder chamber 64.

In this way, in the second embodiment as well, as in the first embodiment, by injecting fuel at the beginning of the intake stroke at the start of the engine, a mixture for flame propagation is formed throughout the cylinder chamber 64. By injecting fuel in the latter part of the compression stroke, a relatively rich air-fuel mixture can be formed in the vicinity of the spark plug 65, and good ignition and combustion with a high air utilization rate can be obtained.

The fuel injection control of the engine of the second embodiment is the same as the fuel injection control of the engine of the first embodiment described with reference to FIGS.

[0038]

As described above, according to the fuel injection control device for a cylinder injection type internal combustion engine according to the first aspect,
In order to allow the flame ignited by the spark plug to propagate into the cylinder during the intake stroke at the time of starting the engine, fuel is injected into the cylinder in excess of the energy required to start rotation of the engine prior to the ignition, Since a minimum amount of fuel that can form an air-fuel mixture that can be ignited in the compression stroke at the time of engine start is injected, a good air-fuel mixture can be formed in the vicinity of the spark plug. Therefore, a good start can be achieved without generating a rich mixture or liquid fuel in the vicinity of the spark plug. Further, starting can be performed with a small amount of fuel, the fuel adhering to the cylinder wall surface is reduced, lubrication of the cylinder wall surface is improved, and abnormal wear and seizure can be prevented. Further, the emission amount of harmful substances (HC, CO) at low temperatures can be reduced.

According to the fuel injection control device for a cylinder injection type internal combustion engine according to the second aspect of the present invention, the higher the engine speed detected by the rotation detection means, the more the injection in the compression stroke by the injection timing correction means. Since the timing is corrected to the advance side, the time from the fuel injection timing of the compression stroke to the ignition timing is appropriately controlled according to the engine speed, even if the engine speed at start-up varies. The fuel injected into is vaporized by the ignition timing, and the air-fuel mixture near the ignition plug at the time of ignition is optimized. Therefore, starting failure can be prevented.

According to the fuel injection control device for a cylinder injection type internal combustion engine according to the third aspect, the higher the engine speed detected by the rotation detecting means, the more the intake air is taken by the first fuel injection amount correcting means. Since the amount of fuel injection in the stroke is corrected to decrease,
The amount of injected fuel in the intake stroke becomes appropriate with respect to the amount of intake air according to the engine speed, and the diffusion and vaporization of the fuel in the cylinder become appropriate. Therefore, starting failure can be prevented. Further, the fuel consumption can be improved because the engine can be started with the minimum required fuel injection amount.

Further, according to the fuel injection control device for a cylinder injection type internal combustion engine according to the fourth aspect, the number of fuel injections from the start of engine start to the completion of start is counted by the counting means to increase the number of fuel injections. The second fuel injection amount correcting means reduces and corrects the fuel injection amount in the intake stroke, so that the injection fuel is prevented from adhering to the combustion chamber, and the adhering fuel is prevented from being scattered into the combustion chamber and adhering to the ignition plug. It is possible to prevent the ignition failure and the misfire which will be caused in the future. Therefore, starting failure can be prevented.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a 4-cylinder gasoline engine adopted in an embodiment of the present invention.

FIG. 2 is a side sectional view of a fuel injection valve.

FIG. 3 is a longitudinal sectional view of the engine of the first embodiment.

FIG. 4 (a) shows the operation of the engine of the first embodiment in the early stage of the intake stroke, (b) the latter half of the intake stroke to the early stage of the compression stroke, (c) the latter half of the compression stroke, and (d) the combustion stroke. FIG.

FIG. 5 is a flowchart showing a fuel injection control routine of the engine according to the first and second claims.

FIG. 6 is a diagram showing a map of a fuel injection amount in an intake stroke with respect to a water temperature of an engine.

FIG. 7 is a diagram showing a map of injection timing of compression stroke with respect to engine speed.

FIG. 8 is a flowchart showing a fuel injection control routine of the engine according to the third and fourth claims.

FIG. 9 is a diagram showing a map of an intake stroke injection amount correction coefficient with respect to the engine speed.

FIG. 10 is a diagram showing a map of the injection amount correction coefficient in the intake stroke with respect to the number of injections.

FIG. 11 is a vertical sectional view of an engine according to a second embodiment.

FIG. 12 (a) shows the operation of the engine of the second embodiment in the intake stroke early stage, (b) the intake stroke late stage to the compression stroke early stage, (c) the compression stroke late stage, and (d) the combustion stroke. FIG.

[Explanation of symbols]

 5 ... Fuel injection valve 20 ... Electronic control unit 29 ... Crank angle sensor 32 ... Water temperature sensor 61 ... Cylinder head 62 ... Piston 63 ... Recessed combustion chamber 64 ... Cylinder chamber

Claims (4)

[Claims] 1. A fuel injection control device for a cylinder injection type internal combustion engine equipped with a fuel injection valve capable of directly injecting required fuel into a cylinder of an engine, wherein a homogeneous air-fuel mixture is formed in a combustion chamber of the engine when the engine is started. And a second injection for calculating a second fuel injection amount required to form an air-fuel mixture that can be ignited in the vicinity of the spark plug in the combustion chamber when the engine is started. And an injection timing control means for controlling the fuel injection timing so that the fuel of the first fuel injection amount is injected during the intake stroke and the fuel of the second fuel injection amount is injected during the compression stroke. A fuel injection control device for a cylinder injection type internal combustion engine. 2. A rotation detecting means for detecting the number of revolutions of the engine, and the higher the engine speed detected by the rotation detecting means, the more the fuel injection timing during the compression stroke is corrected to the advance side of the compression stroke. The fuel injection control device for a direct injection internal combustion engine according to claim 1, further comprising: 3. A fuel injection control device for a cylinder injection type internal combustion engine equipped with a fuel injection valve capable of directly injecting required fuel into a cylinder of an engine, wherein a homogeneous air-fuel mixture is formed in a combustion chamber of the engine when the engine is started. And a second injection for calculating a second fuel injection amount required to form an air-fuel mixture that can be ignited in the vicinity of the spark plug in the combustion chamber when the engine is started. An amount calculation means, an injection timing control means for controlling the fuel injection timing so that the fuel of the first fuel injection quantity is injected during the intake stroke, and the fuel of the second fuel injection quantity is injected during the compression stroke, Rotation detection means for detecting the rotation speed; and a first fuel injection amount correction means for reducing the first fuel injection amount as the rotation speed of the engine detected by the rotation detection means is higher. Characteristic in-cylinder injection Fuel injection control device for an internal combustion engine. 4. A counting means for counting the number of fuel injections from the start of engine start to the completion of starting, and a second means for reducing the first fuel injection amount as the number of fuel injections counted by the counting means increases. The fuel injection control device for a cylinder injection type internal combustion engine according to claim 3, further comprising a fuel injection amount correction means.