JP2001012286A - Fuel injection control device for cylinder fuel injection internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device which can suppress a sticking amount of fuel to a piston top surface even when a fuel amount is increased in a cylinder fuel injection internal combustion engine. SOLUTION: In an intake stroke injection, the start timing of fuel injection is delayed in accordance with an increase correction amount of injection fuel. In this way, as compared with a liquid-state fuel flying region Al without increase correction, a direct hit to a piston top surface is eliminated in a liquid- state fuel flying region D1 applying increase correction, and the piston top surface is prevented from being exposed in liquid-state fuel for a long time. Accordingly, even when fuel is increased, increasing of a sticking amount of fuel to the piston top surface can be suppressed, so as to prevent generation of a problem by deposition of carbon.

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 direct injection internal combustion engine in which fuel is directly injected from a fuel injection valve into a combustion chamber.

[0002]

2. Description of the Related Art A cylinder that enhances flammability even at a lean air-fuel ratio and increases theoretical thermal efficiency by injecting fuel directly into a combustion chamber during a compression stroke to cause a combustible air-fuel mixture to exist in a stratified form near an ignition plug. 2. Description of the Related Art An internal injection internal combustion engine is known (Japanese Patent Application Laid-Open No. 10-176562). In such an in-cylinder injection type internal combustion engine, an intake stroke injection is performed under a medium to high load in addition to the compression stroke injection.

In the intake stroke injection, in order to prevent the generation of smoke and obtain an optimum output torque, the fuel injection start timing is set to an advanced phase position, that is, the piston position is set to a phase position close to the top dead center. Is set. In such an intake stroke injection, when the engine is at a low temperature, the fuel injected from the fuel injection valve may reach the top surface of the piston before being sufficiently vaporized, and the fuel may adhere to the top surface of the piston as a liquid film. This may cause smoke.

Therefore, in the prior art, in order to avoid such a formation of the fuel liquid film on the piston top surface, when performing the intake stroke injection at a low engine temperature, the fuel injection start timing is corrected by retarding the fuel injection start timing. The amount of fuel adhering to the piston top surface is suppressed.

[0005]

However, in a direct injection internal combustion engine, the amount of fuel adhering to the piston top surface increases due to factors other than the engine low temperature, and carbon may be deposited on the piston top surface. It turns out.

That is, as described above, in the intake stroke injection, if the fuel injection start timing is set at a phase position where the piston is close to the top dead center, some fuel increase correction may be performed. For example, when the ignition timing is retarded for knock control, a fuel increase correction may be performed to suppress a rise in exhaust gas temperature.

When such fuel increase correction is performed, the amount of fuel adhering to the piston top surface increases. As a result, a part of the fuel is not completely burned but becomes carbon and accumulates, and there is a possibility that carbon may be trapped between the side surface of the piston and the inner peripheral surface of the cylinder. Besides this,
There is a possibility that the combustion chamber is reduced due to the deposition of carbon and the compression ratio is increased to easily cause knocking, or that the deformation of the combustion chamber adversely affects stratified combustion.

The accumulation of carbon caused by such an increase in fuel may occur even when the amount of fuel is increased in accordance with an increase in required torque due to operation of the accelerator pedal.

According to the present invention, an in-cylinder internal combustion engine in which fuel is directly injected into a combustion chamber from a fuel injection valve can suppress the amount of fuel adhering to a piston top surface even when fuel is increased. It is an object of the present invention to provide a fuel injection control device for an injection type internal combustion engine.

[0010]

According to a first aspect of the present invention, there is provided a fuel injection control apparatus for a direct injection internal combustion engine which injects fuel directly from a fuel injection valve into a combustion chamber. When the fuel injected from the fuel injection valve is increased, the distance between the fuel injection valve and the piston top surface during fuel injection is longer than the distance that naturally changes in response to the increase in fuel. The fuel injection by the fuel injection valve is adjusted so as to be longer.

As described above, when the fuel injection amount is increased,
Normally, the fuel injection by the fuel injection valve is adjusted so that the distance between the fuel injection valve and the top surface of the piston at the time of fuel injection is longer than the distance that naturally changes due to an increase in the amount of fuel. For this reason, even if the fuel increases, the distance from the fuel injection valve to the piston top surface becomes longer than usual, and the rate at which the injected fuel reaches the liquid state decreases. Therefore, even if the amount of fuel increases, the amount of fuel adhering to the piston top surface can be suppressed.

According to a second aspect of the present invention, there is provided a fuel injection control apparatus for an in-cylinder injection type internal combustion engine, wherein the increase in the fuel is based on an increase in the amount of fuel. As described above, the increase in fuel may include an increase correction amount such as an increase in fuel for suppressing the temperature of the catalyst from increasing, in addition to the increase according to the required torque. Also in this case, the fuel injection by the fuel injection valve is adjusted so that the distance between the fuel injection valve and the piston top surface at the time of fuel injection becomes longer than usual when the fuel injection correction is performed. An effect can be produced.

According to a third aspect of the present invention, in the fuel injection control device for a direct injection internal combustion engine, the fuel is increased in the fuel injection mode in which the fuel is injected in the intake stroke with respect to the configuration of the first or second aspect. In this case, the fuel injection start timing is retarded.

Since the piston is moving away from the fuel injection valve during the intake stroke, when fuel is injected during the intake stroke, the fuel injection valve and the piston are delayed by delaying the fuel injection start timing if there is an increase in fuel. The distance from the top surface can be longer than usual. Therefore, the function and effect of claim 1 or 2 can be produced.

According to a fourth aspect of the present invention, in the fuel injection control apparatus for a direct injection internal combustion engine, the fuel injection start timing is retarded when the fuel is increased, as compared with the configuration of the third aspect. It is performed when fuel is injected in a later intake stroke.

The retardation of the fuel injection start timing when the fuel is increased by the intake stroke injection may be performed only after the engine is warmed up. As a result, the effect of the third aspect can be produced especially when increasing the amount of fuel such as increasing the amount of fuel for suppressing the temperature of the catalyst from increasing.

According to a fifth aspect of the present invention, there is provided a fuel injection control apparatus for a direct injection internal combustion engine, wherein the fuel is increased in a fuel injection mode in which fuel is injected in an intake stroke. In this case, the fuel injection time is made longer than the fuel injection time that naturally changes in response to an increase in fuel.

When fuel is injected during the intake stroke, if there is an increase in the fuel, the fuel injection time is made longer than the fuel injection time that naturally changes in response to the increase in the fuel. During the intake stroke, the piston is moving away from the fuel injection valve. Therefore,
When injecting fuel during the intake stroke, by making the fuel injection time longer than the normal fuel injection time, the distance between the fuel injection valve and the piston top surface during the entire fuel injection time is longer than during the normal increase. Can be longer.

That is, when the fuel injection time is increased when the fuel injection time is longer than the length caused by the fuel increase, the fuel injection time as a whole is shifted to a more retarded side than usual. In the intake stroke, the distance between the fuel injection valve and the piston top surface becomes longer as the fuel injection time approaches the end. Therefore, if the amount of fuel increases, the distance between the fuel injection valve and the piston top surface becomes longer during the entire fuel injection time. This makes it possible to increase the distance between the fuel injection valve and the top surface of the piston during the entire fuel injection time.
Therefore, the function and effect of claim 1 or 2 can be produced.

According to a sixth aspect of the present invention, there is provided a fuel injection control device for a direct injection type internal combustion engine, wherein the fuel pressure is decreased when the fuel is increased, thereby reducing the fuel injection. It is characterized in that the time is made longer than the fuel injection time which naturally changes in response to an increase in fuel.

As described above, as a method of making the fuel injection time longer than the normal fuel injection time, there is a method of lowering the fuel pressure. As a result, the function and effect of claim 5 can be produced.

According to a seventh aspect of the present invention, in the fuel injection control apparatus for a direct injection internal combustion engine, the fuel is increased in the fuel injection mode in which the fuel is injected in the compression stroke. In this case, the fuel injection time is shortened.

As described above, when fuel is injected in the compression stroke, the distance between the fuel injection valve and the piston top surface during the entire fuel injection time can be increased by reducing the fuel injection time when the fuel is increased. Can be longer than time.

That is, if the fuel injection time is shortened without changing the fuel injection start timing, the entire fuel injection time shifts to the advance side. In the compression stroke, the piston approaches the fuel injection valve. Therefore, in the compression stroke, the earlier the end of the fuel injection time, the longer the distance between the fuel injection valve and the piston top surface in the entire fuel injection time. Therefore, the function and effect of claim 1 or 2 can be produced.

According to a fuel injection control device for an in-cylinder injection type internal combustion engine according to the present invention, when the fuel is increased, the fuel pressure is increased by increasing the fuel pressure. It is characterized by shortening the time.

As described above, as a technique for shortening the fuel injection time, there is a technique for increasing the fuel pressure. As a result, the function and effect of claim 7 can be produced.

[0027]

[First Embodiment] FIG. 1 shows a schematic configuration of a direct injection internal combustion engine to which the above-described invention is applied and a control system thereof.

A gasoline engine (hereinafter, abbreviated as "engine") 2 as an in-cylinder injection type internal combustion engine is mounted on an automobile to drive the automobile with its output. This engine 2 has four cylinders 2a. FIG.
As shown in FIG. 5, each cylinder 2a has a cylinder block 4, a piston 6 reciprocating in the cylinder block 4, and a combustion chamber 10 defined by a cylinder head 8 mounted on the cylinder block 4. Each is formed.

Each combustion chamber 10 has a first intake valve 12a, a second intake valve 12b, and a pair of exhaust valves 16a.
Is provided. The first intake valve 12a is connected to the first intake port 14a, the second intake valve 12b is connected to the second intake port 14b, and the pair of exhaust valves 16 are connected to the pair of exhaust ports 18, respectively. .

FIG. 2 is a plan sectional view of the cylinder head 8. As shown, the first intake port 14a and the second intake port 14b are straight type intake ports that extend substantially linearly. In addition, an ignition plug 20 is arranged at the center of the inner wall surface of the cylinder head 8. Furthermore, the first
A main injector (corresponding to a fuel injection valve) 22 is disposed near the inner wall surface of the cylinder head 8 near the intake valve 12a and the second intake valve 12b so that fuel can be directly injected into the combustion chamber 10. .

FIG. 3 is a plan view of the top surface of the piston 6, FIG. 4 is a sectional view taken along line XX in FIG. 2, and FIG. 5 is a sectional view taken along line YY in FIG. As shown in the drawing, a recess 24 having a dome-shaped profile extending from below the main injector 22 to below the spark plug 20 is formed on the top surface of the piston 6 formed in a substantially mountain shape.

As shown in FIG. 1, the first intake port 14a of each cylinder 2a is connected to the surge tank 32 via a first intake passage 30a formed in the intake manifold 30. The second intake port 14b is connected to the surge tank 32 via a second intake passage 30b. Of these, an airflow control valve 34 is disposed in each of the second intake passages 30b. These airflow control valves 34
Are connected via a common shaft 36 and through this shaft 36
7 is opened and closed. When the airflow control valve 34 is closed, a strong swirling flow S (FIG. 2) is generated in the combustion chamber 10 by the intake air only from the first intake port 14a.

The surge tank 32 is connected to an air cleaner 42 via an intake duct 40. Intake duct 40
Inside is a motor 44 (DC motor or step motor)
A throttle valve 46 driven by the engine is disposed. The opening of the throttle valve 46 (the throttle opening T
A) is detected by the throttle opening sensor 46a, and the opening is controlled in accordance with the operating state. Further, each exhaust port 18 of each cylinder 2a is connected to an exhaust manifold 48. The exhaust manifold 48 purifies the exhaust via a catalytic converter 49 and discharges the exhaust to the outside.

First intake valve 12a and second intake valve 12b
A fuel distribution pipe 50 is provided in the nearby cylinder head 8. The main injector 22 provided in each cylinder 2a is connected to the fuel distribution pipe 50. When performing stratified combustion and homogeneous combustion, fuel is directly injected from the main injector 22 into the combustion chamber 10.

Further, a sub-injector 52 is attached to the surge tank 32. At the time of low temperature start, fuel is temporarily injected from the sub-injector 52 into the surge tank 32. The sub-injector 52 can inject fuel in a highly atomized state having an extremely small particle diameter as compared with the main injector 22.

The fuel distribution pipe 50 that distributes fuel to the main injector 22 is connected to a high-pressure pump 54 via a high-pressure fuel passage 54a. The high-pressure fuel passage 54a is provided with a check valve 54b for restricting fuel from flowing backward from the fuel distribution pipe 50 to the high-pressure pump 54 side. The low-pressure pump 58 provided in the fuel tank 56 is connected to the high-pressure pump 54 via a low-pressure fuel passage 54c.

The low pressure pump 58 sucks and discharges the fuel in the fuel tank 56 to pump the fuel to the high pressure pump 54 through the low pressure fuel passage 54c. At the same time, the low-pressure fuel passage 54c branches off in the middle and is connected to the sub-injector 52. Therefore, the fuel in the fuel tank 56 is supplied from the low-pressure pump 58 to the low-pressure fuel passage 54c.
Through the sub-injector 52.

The high-pressure pump 54 is driven by a crankshaft (not shown) of the engine 2 to pressurize the fuel to a high pressure, and transfers the pressurized fuel into the fuel distribution pipe 50 through the high-pressure fuel passage 54a. Pump. The high-pressure pump 54 is provided with an electromagnetic spill valve 54d inside. When the electromagnetic spill valve 54d is open,
The fuel supplied to the high-pressure pump 54 is returned to the fuel tank 56 without being sent to the fuel distribution pipe 50 under pressure.
On the other hand, when the electromagnetic spill valve 54d is closed, the fuel is pressure-fed from the high-pressure pump 54 to the fuel distribution pipe 50 through the high-pressure fuel passage 54a. An electronic control unit (hereinafter, referred to as an “ECU”) 60 is configured to detect a value detected by a fuel pressure sensor 50 a attached to
The open / close timing of the electromagnetic spill valve 54d is controlled with reference to the fuel injection amount separately controlled by the CU 60. Thus, the ECU 60 adjusts the amount of fuel pressurized and fed from the high-pressure pump 54 to the fuel distribution pipe 50, and adjusts the fuel pressure in the fuel distribution pipe 50 to a required pressure. It should be noted that a return route for excess fuel in the fuel distribution pipe 50 and the low-pressure fuel passage 54c is not shown.

The ECU 60 is composed of a digital computer and connected to each other via a bidirectional bus 62.
M (random access memory) 64, ROM (read only memory) 66, CPU (microprocessor) 6
8, an input port 70 and an output port 72 are provided.

The throttle opening sensor 46a for detecting the throttle opening TA inputs an output voltage proportional to the opening of the throttle valve 46 to an input port 70 via an AD converter 73. Fuel pressure sensor 5 provided in fuel distribution pipe 50
Numeral 0 a inputs an output voltage proportional to the fuel pressure in the fuel distribution pipe 50 to the input port 70 via the AD converter 73. An accelerator opening sensor 76 is attached to the accelerator pedal 74, and an output voltage proportional to the amount of depression of the accelerator pedal 74 is input to an input port 70 via an AD converter 73.
Is being entered. The top dead center sensor 80 is, for example, the cylinder 2
An output pulse is generated when the No. 1 cylinder reaches the intake top dead center, and this output pulse is input to the input port 70. The crank angle sensor 82 generates an output pulse every time the crankshaft rotates 30 degrees, and the output pulse is input to the input port 70. The CPU 68 calculates the current crank angle from the output pulse of the top dead center sensor 80 and the output pulse of the crank angle sensor 82, and calculates the engine speed N from the frequency of the output pulse of the crank angle sensor 82.
E is calculated.

The surge tank 32 has an intake pressure sensor 84
The output voltage corresponding to the intake pressure PM (pressure of intake air: absolute pressure) in the surge tank 32 is converted by the AD converter 7.
3 to the input port 70. Engine 2
The cylinder block 4 is provided with a water temperature sensor 86,
The cooling water temperature THW of the engine 2 is detected and the cooling water temperature TH is detected.
The output voltage corresponding to W is input to the input port 70 via the AD converter 73. A knock sensor 87 is provided in the cylinder block 4 of the engine 2, detects a frequency band of vibration caused by knocking among the vibrations of the engine 2, and outputs an output voltage according to the intensity via the AD converter 73. Input to the input port 70. Exhaust manifold 48
Is provided with an air-fuel ratio sensor 88, and outputs an output voltage corresponding to the air-fuel ratio to an input port 70 via an AD converter 73.

The output port 72 is connected to the corresponding drive circuit 90
Are connected to the main injector 22, the sub-injector 52, the negative pressure actuator 37, the motor 44, the electromagnetic spill valve 54d, and the igniter 92 to connect the devices 22, 52, 37, 44, 54d, 92 as necessary. Drive control.

Next, a description will be given of fuel injection control and related processing performed after the start of the engine 2 is completed. FIG. 6 shows a flowchart of a process for setting an operation area required for fuel injection control. This process is a process that is periodically executed for each preset crank angle.

First, the engine speed NE obtained from the signal of the crank angle sensor 82 and the depression amount of the accelerator pedal 74 obtained from the signal of the accelerator opening sensor 76 (hereinafter referred to as the accelerator opening) ACCP. And R
The data is read into the work area of AM64 (S100).

Next, a lean fuel injection amount QL is calculated based on the engine speed NE and the accelerator opening ACCP (S110). This lean fuel injection amount QL is
It shows the optimal fuel injection amount for making the output torque the required torque when performing stratified combustion. Lean fuel injection amount QL
Is obtained in advance by experiments, and is stored in the ROM 66 as a map using the accelerator opening ACCP and the engine speed NE as parameters as shown in FIG. In step S110, the lean fuel injection amount QL is calculated based on this map.

Next, three operating regions R1, R2, and R3 as shown in FIG. 8 are determined based on the lean fuel injection amount QL and the engine speed NE thus obtained (S115). Thus, the process is once ended.

When the operation regions R1, R2, and R3 are determined as described above, the fuel injection mode is controlled according to each of the operation regions R1 to R3. That is, in the operation region R1 in which the lean fuel injection amount QL is smaller than the threshold value QQ1, an amount of fuel corresponding to the lean fuel injection amount QL is injected at the end of the compression stroke. After the fuel injected by the injection at the end of the compression stroke advances into the concave portion 24 of the piston 6, the peripheral wall surface 26 of the concave portion 24
Collide with The fuel colliding with the peripheral wall surface 26 moves while being vaporized, and a combustible mixture layer is formed in the recess 24 near the ignition plug 20. Then, the stratified combustible air-fuel mixture is ignited by the spark plug 20 to perform stratified combustion.

The lean fuel injection amount QL is equal to the threshold Q
In the operating region R2 between Q1 and the threshold value QQ2,
An amount of fuel corresponding to the lean fuel injection amount QL is injected twice in the intake stroke and the end of the compression stroke. That is, the first fuel injection is performed during the intake stroke, and then the second fuel injection is performed at the end of the compression stroke. The first injected fuel flows into the combustion chamber 10 together with the intake air, and the injected fuel forms a homogeneous lean mixture throughout the combustion chamber 10. Further, as a result of the fuel injection being performed at the end of the compression stroke, a combustible mixture layer is formed in the recess 24 near the ignition plug 20 as described above. Then, the stratified combustible mixture is ignited by an ignition plug 20, and a lean mixture occupying the entire combustion chamber 10 is burned by the ignition flame. That is, in the operation region R2, stratified combustion having a lower degree of stratification than in the above-described operation region R1 is performed.

In an operation region R3 where the lean fuel injection amount QL is larger than the threshold value QQ2, an amount of fuel corresponding to the stoichiometric air-fuel ratio basic fuel injection amount QBS is injected during the intake stroke. The injected fuel flows into the combustion chamber 10 together with the intake air, and the injected fuel causes the entire combustion chamber 10 to have a uniform stoichiometric air-fuel ratio (as will be described later, a rich air-fuel ratio whose fuel concentration is higher than the stoichiometric air-fuel ratio due to increase correction). (May be controlled), resulting in homogeneous combustion.

FIG. 9 shows a flowchart of the fuel injection amount control process executed based on the operation region set by the above-described operation region setting process. This process is a process executed after the operation region setting process.

When the fuel injection amount control process is started, first, the engine speed NE obtained from the signal of the crank angle sensor 82, the intake pressure PM obtained from the signal of the intake pressure sensor 84, and the air-fuel ratio The oxygen concentration detection value Vox obtained from the signal of the sensor 88 is read into the work area of the RAM 64 (S120).

Next, it is determined whether or not the operation region R3 is currently set (S122). When it is determined that the current operation state is set as the operation region R3 (“YES” in S122), the intake pressure PM and the engine speed are determined using the map of FIG. NE, the stoichiometric air-fuel ratio basic fuel injection amount QBS
Is calculated (S130).

Next, the high load increase OTP calculation processing (S14)
0) is performed. This high load increase OTP calculation process will be described with reference to the flowchart of FIG. In the high load increase OTP calculation process, first, the accelerator opening ACCP
Is determined to exceed the high load increase determination value KOTPAC (S141).

If ACCP ≦ KOTPAC (S14)
1 and “NO”), the value “0” is set to the high load increase OTP (S142). That is, the fuel increase correction is not performed. Thus, the high load increase OTP calculation process is once exited.

If ACCP> KOTPAC (S14)
If “1” is “YES”, the value M (for example, 1>M> 0) is set as the high load increase OTP (S144). That is, the fuel increase correction is performed. This increase correction is performed in order to prevent the catalytic converter 49 from overheating at the time of a high load.

Returning to FIG. 9, after the high load increase OTP is calculated in step S140, next, the retard increase FKNK according to the ignition retard in the knock control process is calculated (S146). This is done in advance as shown in FIG.
It is determined based on a map using the engine speed NE and the knock retard reflection value AKNK set in the parameter 66 as parameters. The knock retard reflection value AKNK is an ignition timing retard correction amount calculated by a knock control process (FIGS. 13 and 14) described later. The retard angle increase FKNK is provided to prevent the catalytic converter 49 from being overheated when the ignition timing is retarded to suppress knocking in the knock control process. AKNK
If = 0, FKNK = 0 is set.

Next, it is determined whether the air-fuel ratio feedback condition is satisfied (S150). For example,
"(1) Not at startup. (2) Not in fuel cut.
(3) Warm-up has been completed. (For example, cooling water temperature THW ≧
(40 °) (4) The activation of the air-fuel ratio sensor 88 has been completed.
(5) The value of the high load increase OTP is 0. (6) The value of “the retard amount increase FKNK is 0” is all satisfied.

If the air-fuel ratio feedback condition is satisfied ("YES" in S150), the air-fuel ratio feedback coefficient FAF and its learning value KG are calculated (S16).
0). The air-fuel ratio feedback coefficient FAF is calculated based on the output of the air-fuel ratio sensor 88, and the learning value KG stores the deviation of the air-fuel ratio feedback coefficient FAF from 1.0, which is the center value. Various techniques are known for the air-fuel ratio control technique using the technique as disclosed in Japanese Patent Application Laid-Open No. 6-10736.

On the other hand, if the air-fuel ratio feedback condition is not satisfied ("NO" in S150), 1.0 is set to the air-fuel ratio feedback coefficient FAF (S17).
0). Subsequent to step S160 or S170, the fuel injection amount Q is calculated as in the following equation 1 (S180).

[0060]

Q ← QBS {1 + OTP + FKNK + (FAF-1.0) + (KG-1.0)} α + β ... [Equation 1] where α and β are the types of the engine 2 This coefficient is appropriately set according to the content of the control.

Thus, the fuel injection amount control processing is once ended. In step S122, an area other than the operation area R3,
That is, in one of the operation regions R1 and R2, (S1
22 ("NO"), the fuel injection amount Q is set to the lean fuel injection amount QL determined in step S110 of the operation region setting process (S190). Thus, the fuel injection amount control process is once ended.

The knock control process is shown in the flowcharts of FIGS. This processing is executed in the same cycle as the operation area setting processing. When the knock control process is started, first, the EC
U60 reads the engine speed NE obtained by the signal of the crank angle sensor 82 and the intake pressure PM obtained by the signal of the intake pressure sensor 84 into the RAM 64 (S20).
0).

Then, the basic ignition timing ABSE and the maximum retard value AKMAX are calculated based on the engine speed NE and the intake pressure PM (S210). Rotation speed NE
Basic ignition timing ABS using the pressure and intake pressure PM as parameters
A map for obtaining E and a map for obtaining the maximum retardation value AKMAX using the rotational speed NE and the intake pressure PM as parameters are set in the ROM 66 in advance, and are calculated from these maps. Here, the basic ignition timing ABSE is an ignition timing set so that the output torque of the engine 2 is maximized without considering the influence of knocking or the like. On the other hand, the maximum retard value AKMAX is the maximum amount when the basic ignition timing ABSE is retarded, and is set to a value that can reliably suppress the occurrence of knocking.

Next, the ECU 60 reads the knock signal KCS based on the output signal from the knock sensor 87, and determines whether or not knocking has occurred in the engine 2 based on the level of the knock signal KCS (S).
220). When it is determined that knocking has occurred (S
If “YES” at 220), “0.4 ° CA” is added to knock control value AKCS, and the result is set as new knock control value AKCS (S230). On the other hand, when it is determined that knocking has not occurred (“N” in S220).
O ”) is set to“ 0.01 ° C ”from knock control value AKCS.
A ”is subtracted, and the result is replaced with a new knock control value AKCS.
Is set (S240).

That is, the knock control value AKCS is
It is a value whose magnitude changes according to the current knocking occurrence state of the engine 2 by the processing of steps S230 and S240. Here, “° CA” represents the crank angle. In addition to the knock control value AKCS, the basic ignition timing ABSE, the maximum retardation value AKMAX, and each of the values AGKNK, AKNK, AKH, and AOP described below are all included. It is an amount in units of this crank angle.

Step S230 or Step S240
After executing the processing in (2), the ECU 60 calculates the correction value AKH according to the following equation 2 (S250).

[0067]

AKH ← AKCS−AGKNK (Equation 2) Here, the ignition timing correction learning value AGKNK is repeatedly calculated in an ignition timing correction learning process (S300) described later.
This is a value stored in the RAM 64.

Next, according to the following equation (3), a knock retard reflection value A
KNK is calculated (S260).

[0069]

(3) AKNK ← AKMAX + AKH (Equation 3) Thus, the ignition timing correction is ended, and then the ignition timing correction learning processing (S300) is executed.

FIG. 14 shows a flowchart of the ignition timing correction learning process. In this process, first, the ECU 60 determines whether or not the knock control value AKCS is larger than “2.5 ° CA” (S310). Where AKCS> 2.5
If it is ° CA (“YES” in S310), “0.5 ° CA” is subtracted from knock learning value AGKNK, and the result is set as a new knock learning value AGKNK (S320).

On the other hand, if AKCS ≦ 2.5 ° CA (“NO” in S310), it is determined whether knock control value AKCS is smaller than “0.5 ° CA” (S33).
0). If AKCS <0.5 ° CA (S
“YES” in 330), “0.5 ° CA” is added to knock learning value AGKNK, and the result is set as new knock learning value AGKNK (S340).

The knock learning value AGKNK is set relatively small when knocking tends to occur frequently, and is set relatively large when knocking occurs a small number of times. Therefore, the knock learning value AGKNK is a value reflecting factors that have a steady influence on the occurrence of knocking, such as differences in the octane number of the fuel, variations in engine characteristics, and changes with time.

Next, after step S320 or step S340, upper / lower guard processing is performed to prevent the knock learning value AGKNK from being set to an excessively large value or an excessively small value (S350).

Then, after step S350, or when it is determined “NO” in step S330,
The ignition timing correction learning process ends. Returning to FIG. 13, following the ignition timing correction learning process (S300), as shown in the following Expression 4, the knock retard reflection value A is calculated from the basic ignition timing ABSE.
The final ignition timing AOP is calculated by subtracting KNK (S4).
00).

[0075]

AOP ← ASE−AKNK (Equation 4) The knock control process is once ended.

FIG. 15 is a flowchart showing the fuel injection timing control process. This process is a high load increase calculation process (FIG. 1).
1) and knock control processing (FIGS. 13 and 14), which are performed in the same cycle.

When the fuel injection timing control process is started, first, it is determined whether or not the current operation is in the operating region R1 (S41).
0). If it is the operation region R1 (“YE
S "), the fuel injection is set at the end of the compression stroke (S42).
0). Fuel injection start timing θc at the end of this compression stroke
Is calculated from a fuel injection start timing map for the operating region R1 using, for example, the fuel injection amount Q and the engine speed NE as parameters. Then, the fuel injection timing control process is once ended. Here, the fuel injection start timing (θc or the like) is represented by a crank angle.

If it is not the operation region R1 ("N" in S410
O "), and then it is determined whether or not the vehicle is in the operating region R2 (S43).
0). If it is the operation region R2 ("YE" in S430)
S "), the fuel injection is set at two timings: the intake stroke and the end of the compression stroke (S440). The fuel injection start timing θa in the intake stroke and the fuel injection start timing θc in the end of the compression stroke are, for example, an intake stroke fuel injection start timing map for the operating region R2 using the fuel injection amount Q and the engine speed NE as parameters. Each is calculated from the compression stroke fuel injection start timing map for the operation region R2. Then, the fuel injection timing control process is once ended.

If it is not the operation region R2 ("N" in S430)
O "), since the operation is in the operation region R3, the fuel injection is set to the intake stroke (S470). The fuel injection start timing θa in the intake stroke is calculated, for example, from an intake stroke fuel injection start timing map for the operating region R3 using the intake pressure PM and the engine speed NE as parameters.

Next, it is determined whether or not the increase correction amount ΔQ exists in the fuel injection amount Q in the operation region R3 calculated in step S180 (S480). Specifically, the high load increase O calculated in step S140
TP and retard angle increase FKNK calculated in step S146
It is determined whether the total OTP + FKNK (= ΔQ) is a positive value. If ΔQ = 0 (“N” in S480
O "), the fuel injection timing control process is temporarily terminated.

Step S140 or step S146
If the increase correction amount occurs in any of the above cases, ΔQ>
Since it is 0 ("YES" in S480), next, the injection start timing retard correction processing is performed (S490). This injection start timing retard correction processing is performed in the operation region R3 in step S470.
The retardation correction value θd for retarding the fuel injection start timing θa at the time of the intake stroke which is set for the purpose is calculated. For example, the retard correction value θd is calculated using a map using ΔQ and the engine speed NE as parameters as shown in FIG. Then, as shown in the following equation 5, the fuel injection start timing θa is retarded and the new fuel injection start timing θad is set using the retard correction value θd.

[0082]

[Formula 5] θad ← θa + θd [Equation 5] Thus, the fuel injection timing control process is once ended.

Here, the retard angle correction value θd obtained from FIG. 16 is determined by the main injector 22 and the piston top surface 24a during fuel injection in accordance with the increase correction amount of the fuel injected from the injection port 22a of the main injector 22. The fuel injection start timing θa is corrected so that the distance from the fuel injection start position becomes large.

FIG. 17 shows an example of fuel injection in the operation region R3. If ΔQ = 0 (S48
0 and “NO”), the fuel injection start timing θa is not retarded, and the time t corresponding to the fuel injection start timing θa
Fuel injection is started at a0. And the fuel injection amount Q
The fuel is injected for the time (ta0 to ta1) corresponding to.

However, if ΔQ> 0 (S48)
0 and “YES”), the fuel injection start timing θa is retarded and becomes the fuel injection start timing θad, and the fuel injection is started at time td0 corresponding to the fuel injection start timing θad. Then, the fuel is injected for a time (td0 to td1) corresponding to the increased fuel injection amount Q.

That is, at the fuel injection start timing θa at which the retard correction is not performed, the injection is started at time ta0, but at this time, the piston top surface 24a has just begun to separate from the top dead center TDC. For this reason, the area A in which the fuel flies in a liquid form from the injection port 22a of the main injector 22
The entire period (period Fa) of 1 crosses the piston top surface 24a. Moreover, the intersection between the injection port 22a of the main injector 22 and the piston top surface 24a is sufficiently short. This causes liquid fuel to adhere to the piston top surface 24a. However, at this time, since the fuel injection amount itself has not been corrected for increase, the actual fuel adhesion amount is small,
By ignition, the fuel has fully evaporated.

On the other hand, the retarded fuel injection start timing θad
Then, injection is started at time td0. At this time, time t
The piston top surface 24a has a top dead center TD compared to the case of a0.
It is further away from C. Therefore, a region D1 in which fuel flies in a liquid form from the injection port 22a of the main injector 22
The first part of the period (period Fd) is the piston top surface 24a.
Only crossover. In addition, as compared with the case of the time ta0, the injection is performed while the distance between the injection port 22a of the main injector 22 and the piston top surface 24a is large. As a result, liquid fuel hardly adheres to the piston top surface 24a. In addition, since the fuel has flown over a long distance, the proportion of the fuel remaining substantially in a liquid state is small, so that the actual fuel adhesion amount is further reduced. Therefore, also in this case, the fuel is sufficiently evaporated by the time of ignition.

According to the first embodiment described above, the following effects can be obtained. (I). Fuel injection start timing by the main injector 22 so that the distance between the injection port 22a of the main injector 22 and the piston top surface 24a at the time of fuel injection increases according to the increase correction amount ΔQ of the fuel injected from the main injector 22. Is retarded (S490).
Accordingly, as described with reference to FIG. 17, it is possible to suppress an increase in the amount of fuel adhering to the piston top surface 24a even when the amount of fuel increases, or conversely, to reduce the amount of fuel adhering.

If the fuel injection start timing is not delayed at the time of fuel increase correction as in the prior art, the distance between the injection port 22a of the main injector 22 and the piston top surface 24a is small as shown in a period Fe in FIG. The piston top surface 24a is exposed to the liquid fuel for a long time.
For this reason, a large amount of fuel adheres to the piston top surface 24a.
Due to this, a part of the fuel is not completely burned but becomes carbon and accumulates on the piston top surface 24a and the periphery thereof, so that the combustion chamber 10 is reduced, the compression ratio is increased, and knocking is likely to occur. Or the deformation of the recess 24 of the piston 6 may adversely affect the stratified combustion. In addition, there is a possibility that carbon may bite between the piston 6 and the cylinder 2a.

In the first embodiment, even if the amount of fuel increases, an increase in the amount of fuel adhering to the piston top surface 24a can be suppressed, so that there is no problem due to carbon deposition. [Embodiment 2] Embodiment 2 is based on Embodiment 1 described above.
18 differs from the fuel injection timing control process shown in FIG. The other configuration is basically the same as that of the first embodiment. Note that, in the steps of FIG. 18, the same processes as those of the first embodiment are denoted by reference numerals obtained by adding “1000” to the reference numerals of the corresponding steps of the first embodiment.

In the fuel injection timing control process of FIG. 18, the operation regions R1 to R3 are determined (S1410, S1430),
The fuel injection mode is set for each of the operation regions R1 to R3 (S1420, S1440, S1470).

For the operation region R3, step S14
After 70, it is determined whether or not the increase correction amount ΔQ exists (S
1480), but what differs from the first embodiment is the processing after step S1480.

When it is determined that ΔQ> 0 (“YES” in S1480), target pressure P of the fuel pressure in fuel distribution pipe 50 is set.
Fuel pressure Pd lower than normal fuel pressure P0 is set as t (S1486). If it is determined that ΔQ = 0 (“NO” in S1480), the normal fuel pressure P0 is set as the target pressure Pt of the fuel pressure in the fuel distribution pipe 50 (S1).
484). After the fuel injection modes for the operating regions R1 and R2 are determined (S1420 and S1440), the normal fuel pressure P0 is set as the target pressure Pt (S1484). Thus, the process is once ended.

In the first embodiment, when the fuel increase correction amount ΔQ exists, the fuel injection start timing is retarded. However, in the second embodiment, the fuel injection start timing is replaced with the fuel injection start timing. In addition, the fuel pressure for determining the fuel injection rate (fuel injection amount per unit time) is reduced. That is, ΔQ>
At 0, the fuel injection rate is reduced.

As described above, by reducing the target pressure Pt, the actual fuel pressure in the fuel distribution pipe 50 is reduced by the fuel pressure control processing in which the fuel pressure in the fuel distribution pipe 50 is feedback-controlled based on the following equation (6). Is done.

[0096]

DT ← k1 × (DTp + DTi + FF) (Equation 6) Here, DT represents the duty of the control current for the electromagnetic spill valve 54d of the high-pressure pump 54, k1 is a coefficient, DT
p is a proportional term, DTi is an integral term, and FF is a feedforward term.

The proportional term DTp, the integral term DTi, and the feedforward term FF are calculated by the following equations 7 to 9, respectively.

[0098]

DTp ← k2 × ΔP (Expression 7) DTi ← DTi + k3 × ΔP (Expression 8) FF ← k4 × Q × P / P0 (Expression 9) Here, k2, k3, and k4 are coefficients. , Q are in step S18
This is the fuel injection amount obtained at zero. ΔP is a deviation between the target pressure Pt given by the following equation 10 and the actually measured value P.

[0099]

ΔP ← Pt−P (Equation 10) When the target pressure Pt is the increase correction amount ΔQ> 0 (S
If “YES” in 1480), the fuel pressure Pd is set lower than in other cases. As a result, the fuel pressure P in the fuel distribution pipe 50 is adjusted to a low fuel pressure Pd by duty control of the high-pressure pump 54 for the electromagnetic spill valve 54d.

On the other hand, when the increase correction amount ΔQ = 0 (S
"NO" at 1480) or other operating regions R1, R
In 2, the target pressure Pt is set to the normal fuel pressure P0.
Thereby, the fuel pressure in the fuel distribution pipe 50 is adjusted to the normal fuel pressure P0 by the duty control of the high-pressure pump 54 for the electromagnetic spill valve 54d.

The fuel injection amount Q is equal to the final fuel injection time τ
At the time of conversion, the fuel pressure actually measured by the fuel pressure sensor 50a is reflected so that the fuel injection amount does not change due to the fuel pressure. For this reason, if the fuel pressure is low, the final fuel injection time τ becomes longer even with the same fuel injection amount Q.

FIG. 19 shows an example of the fuel injection state in the operation region R3. If ΔQ = 0 (S1480)
Therefore, the inside of the fuel distribution pipe 50 is controlled to the normal fuel pressure P0. At time ta10 of the start of injection, the piston top surface 2
4a is a state just starting to move away from the top dead center TDC. For this reason, the injection port 22a of the main injector 22
The entire period of the region A2 in which the fuel flies in a liquid state crosses the piston top surface 24a (period Fa1). In addition, the injection port 22a of the main injector 22 and the piston top surface 24a
Crosses in a state where the distance between them is sufficiently short. This causes liquid fuel to adhere to the piston top surface 24a. However, at this time, since the fuel injection amount itself has not been corrected to increase, the actual fuel adhesion amount is small, and the fuel evaporates sufficiently before ignition.

On the other hand, if ΔQ> 0 (S148
0 (“YES”), the fuel injection start timing has not changed, but the fuel pressure P decreases. As described above, when the fuel pressure P is low, the flying speed of the liquid fuel becomes slow, and the fuel injection rate is further lowered, so that the injection time becomes long, and the fuel is dispersed and injected. For this reason, the region D2 in which the fuel flies in a liquid form from the injection port 22a of the main injector 22 does not cross the piston top surface 24a. Even if they do cross, only the first partial area of the fuel that is temporally dispersed crosses. As a result, liquid fuel hardly adheres to the piston top surface 24a.

According to the second embodiment described above, the following effects can be obtained. (I). By decreasing the fuel pressure and decreasing the injection rate in accordance with the increase correction amount ΔQ of the fuel injected from the main injector 22 (S1486), the fuel injection time by the main injector 22 is made longer than usual.
As described above, when the fuel injection time is longer than usual, the distance between the injection port 22a of the main injector 22 and the piston top surface 24a becomes large in the entire fuel injection time. Thus, as described with reference to FIG. 19, even if the fuel increases, the increase in the amount of fuel adhering to the piston top surface 24a can be reduced or suppressed. Therefore, there is no problem due to carbon deposition.

Third Embodiment The third embodiment is different from the second embodiment in the fuel injection timing control process shown in FIG. The other configuration is basically the same as that of the second embodiment. Note that, in the steps in FIG. 20, the same processes as those in the second embodiment are indicated by reference numerals obtained by adding “1000” to the reference numerals assigned to the corresponding steps in the second embodiment.

In FIG. 20, after it is determined that the engine is in the operating region R1 (“YES” in S2410), the fuel injection is set at the end of the compression stroke (S2420). This is the same as in the first and second embodiments. Then, step S2
After 420, the fuel pressure Pc is calculated from the map Map using the fuel injection amount Q and the engine speed NE shown in FIG. 21 as parameters, and set to the target pressure Pt (S2488). Thus, the process is once ended. The map Map used in step S2488 is set such that the fuel pressure P increases as the fuel injection amount Q increases, and the fuel pressure P increases as the engine speed NE increases.

The same processing as in the second embodiment is performed for the operating regions R2 and R3. As described above, even during the compression stroke injection in the operation region R1, the fuel pressure in the fuel distribution pipe 50 increases as the fuel injection amount Q increases according to the fuel injection amount Q. Even with the quantity Q, the final fuel injection time τ becomes shorter.

FIG. 22 shows an example of a fuel injection state in the operation region R1. When the fuel injection amount Q is small, the inside of the fuel distribution pipe 50 is controlled to a normal fuel pressure. Therefore, injection starts at time ta20 and ends at time ta21. Therefore, fuel flies in a liquid state from the injection port 22a of the main injector 22 as shown by the area A3, and crosses the piston top surface 24a during the period Fa2.

On the other hand, when the fuel injection amount Q is large, the inside of the fuel distribution pipe 50 is controlled to be higher than the normal fuel pressure. Therefore, the fuel injection rate increases, and the injection starts at time ta20 and ends at time tc. Therefore, the fuel that flies in a liquid state from the injection port 22a of the main injector 22 is as shown by the region C3, and the piston top surface 24a
Crosses during the period Fc.

As described above, as the fuel injection amount Q increases, the fuel pressure P increases, so that the time for which the fuel adheres to the piston top surface 24a becomes shorter, and the main injector 2
The distance between the second injection port 22a and the piston top surface 24a also increases. For this reason, the rate at which fuel changes to steam during the flight increases. Furthermore, since the time from when the fuel adheres to the piston top surface 24a until the ignition timing becomes longer, the amount of evaporation of the attached fuel also increases, and the fuel evaporates sufficiently before the ignition.

According to the third embodiment described above, the following effects can be obtained. (I). In the operating region R1, the fuel pressure is increased in accordance with the increase in the fuel injection amount Q injected from the main injector 22 during the compression stroke (S2488), so that the fuel injection time by the main injector 22 is shorter than usual.
As described above, when the fuel injection time is shorter than usual, the distance between the injection port 22a of the main injector 22 and the piston top surface 24a increases when viewed from the whole fuel injection time, and the fuel evaporates during the flight. Facilitate. Thus, even if the fuel injection amount Q increases, an increase in the amount of fuel adhering to the piston top surface 24a can be suppressed. In addition, the timing of fuel attachment to the piston top surface 24a is also advanced, and there is a margin for evaporation of the attached fuel. Therefore, the amount of fuel adhering to the piston top surface 24a during combustion can be reduced, and the problem due to carbon accumulation does not occur.

(B). The same effect as (a) of the second embodiment is obtained. [Other Embodiments] In the first embodiment, as shown in FIG. 17, when the fuel increase correction amount ΔQ exists, the liquid fuel flying region D1 overlaps the piston top surface 24a except for a part thereof. The fuel injection start timing was controlled to be retarded so that it did not occur. However, as shown in FIG. 23, the fuel injection start timing may be delayed to such an extent that the entire liquid fuel flying region D3 overlaps the piston top surface 24a. Also in this case, if the fuel injection start timing is retarded during the intake stroke, the injection port 2 of the main injector 22 will be maintained during the entire fuel injection time.
The distance between the piston 2a and the piston top surface 24a becomes longer, and the liquid fuel is sufficiently vaporized while flying over that distance. Therefore, even if the liquid fuel adheres to the piston top surface 24a, the amount is small and evaporates immediately, and the liquid fuel does not remain on the piston top surface 24a until the ignition timing. Therefore, the effect of the first embodiment is obtained.

Contrary to the above, as shown in FIG. 24, at the time of fuel injection, the liquid fuel flying region D4 and the piston top surface 24a
The fuel injection start timing may be controlled so as to be retarded so as not to overlap at all, and the effect of the first embodiment can be obtained.

In the operating region R2, the fuel injection amount Q is increased by increasing the fuel injection amount during the intake stroke.
In the operating region R2, based on the map, the fuel injection start timing is retarded or the fuel pressure is reduced according to the increase in the fuel injection amount Q, so that the fuel is attached to the piston top surface 24a during combustion. The amount of fuel can be reduced.

[0115]

According to the fuel injection control device for a direct injection internal combustion engine of the first aspect, when the fuel injection amount is increased, the distance between the fuel injection valve and the piston top surface during the fuel injection is usually reduced. The fuel injection by the fuel injection valve is adjusted so as to be longer than the distance that naturally changes due to an increase in the amount of fuel. For this reason, even if the fuel increases, the distance from the fuel injection valve to the piston top surface becomes longer than usual, and the rate at which the injected fuel reaches the liquid state decreases. Therefore, even if the amount of fuel increases, the amount of fuel adhering to the piston top surface can be suppressed.

In the fuel injection control device for a direct injection internal combustion engine according to the second aspect, the increase in the fuel is based on an increase correction in the configuration according to the first aspect. As described above, the increase in fuel may include an increase correction amount such as an increase in fuel for suppressing the temperature of the catalyst from increasing, in addition to the increase according to the required torque. Also in this case, the fuel injection by the fuel injection valve is adjusted so that the distance between the fuel injection valve and the piston top surface at the time of fuel injection becomes longer than usual when the fuel injection correction is performed. Can be caused.

According to a third aspect of the present invention, in the fuel injection control apparatus for a direct injection internal combustion engine, the fuel is increased in the fuel injection mode in which fuel is injected in the intake stroke with respect to the configuration of the first or second aspect. If so, the fuel injection start timing is retarded. During the intake stroke, the piston is moving away from the fuel injection valve, so when injecting fuel during the intake stroke,
If the fuel increases, the distance between the fuel injection valve and the piston top surface can be made longer than usual by delaying the fuel injection start timing. Therefore, the effect of claim 1 or 2 can be produced.

According to a fourth aspect of the present invention, in the fuel injection control apparatus for a direct injection internal combustion engine, when the fuel is increased, the fuel injection start timing is retarded when the fuel is increased. This is performed when fuel is injected during the intake stroke after the machine. The retardation of the fuel injection start timing when the fuel is increased by the intake stroke injection may be performed only after the engine is warmed up. As a result, the effect of claim 3 can be brought about particularly when increasing the amount of fuel such as increasing the amount of fuel for suppressing the temperature of the catalyst from increasing.

In the fuel injection control device for a direct injection internal combustion engine according to the fifth aspect, in the fuel injection mode in which fuel is injected in the intake stroke, the amount of fuel increases compared to the configuration according to the first or second aspect. In this case, the fuel injection time is set longer than the fuel injection time that naturally changes in response to the increase in fuel. In the case of injecting fuel in the intake stroke, if there is an increase in fuel, the fuel injection time is made longer than the fuel injection time that naturally changes in response to the increase in fuel. During the intake stroke, the piston is moving away from the fuel injection valve. Therefore, when injecting fuel in the intake stroke, the distance between the fuel injection valve and the top surface of the piston is normally increased during the entire fuel injection time by making the fuel injection time longer than the normal fuel injection time. Can be longer than That is, when the fuel injection time is increased when the fuel injection time is naturally longer than the fuel injection time, the fuel injection time as a whole is shifted to a more retarded side than usual. In the intake stroke, the distance between the fuel injection valve and the piston top surface becomes longer as the fuel injection time approaches the end. Therefore, if the amount of fuel increases, the distance between the fuel injection valve and the piston top surface becomes longer during the entire fuel injection time. This makes it possible to increase the distance between the fuel injection valve and the top surface of the piston during the entire fuel injection time. Therefore, the effect of claim 1 or 2 can be produced.

In the fuel injection control device for a direct injection internal combustion engine according to the sixth aspect, when the fuel is increased, the fuel pressure is decreased by increasing the fuel pressure. The injection time is set longer than the fuel injection time that naturally changes in response to the increase in fuel. As described above, as a method of making the fuel injection time longer than the normal fuel injection time, there is a method of lowering the fuel pressure. Thus, the effect of claim 5 can be produced.

In the fuel injection control apparatus for a direct injection internal combustion engine according to the seventh aspect, in the fuel injection mode in which fuel is injected in the compression stroke, the fuel increases in comparison with the configuration according to the first or second aspect. If so, the fuel injection time is shortened. Thus, when injecting fuel in the compression stroke, by shortening the fuel injection time when the fuel is increased, the distance between the fuel injection valve and the piston top surface during the entire fuel injection time is longer than that in the normal increase. Can be longer. That is, if the fuel injection time is shortened without changing the fuel injection start timing, the entire fuel injection time shifts to the advance side. In the compression stroke, the piston approaches the fuel injection valve. Therefore, in the compression stroke, the earlier the end of the fuel injection time, the longer the distance between the fuel injection valve and the piston top surface in the entire fuel injection time. Therefore,
The effect of claim 1 or 2 can be produced.

In the fuel injection control device for an in-cylinder injection type internal combustion engine according to the present invention, when the fuel is increased, the fuel pressure is increased by increasing the fuel pressure. The injection time has been shortened. As described above, as a technique for shortening the fuel injection time, there is a technique for increasing the fuel pressure. Thus, the effect of claim 7 can be produced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a direct injection internal combustion engine as a first embodiment and a control system thereof.

FIG. 2 is a plan sectional view of a cylinder head of the direct injection internal combustion engine.

FIG. 3 is a plan view of a piston top surface of the direct injection internal combustion engine.

FIG. 4 is a sectional view taken along line XX in FIG. 2;

FIG. 5 is a sectional view taken along line YY in FIG. 2;

FIG. 6 is a flowchart of an operation area setting process performed in the first embodiment.

FIG. 7 is an explanatory diagram of a map for obtaining a lean fuel injection amount QL from the accelerator opening ACCP and the engine speed NE in the first embodiment.

FIG. 8 is an explanatory diagram of a relationship between an operation region and a fuel injection mode divided according to the first embodiment.

FIG. 9 is a flowchart of a fuel injection amount control process performed in the first embodiment.

FIG. 10 is an explanatory diagram of a map for obtaining a stoichiometric air-fuel ratio basic fuel injection amount QBS from the accelerator opening ACCP and the intake pressure PM in the first embodiment.

FIG. 11 is a flowchart of a high load increase calculation process performed in the first embodiment.

FIG. 12 is a diagram showing a knock retard reflection value AKN in the first embodiment.
Explanatory drawing of the map for calculating | requiring retardation increase FKNK from K and engine speed NE.

FIG. 13 is a flowchart of a knock control process performed in the first embodiment.

FIG. 14 is a flowchart of an ignition timing correction learning process performed in the first embodiment.

FIG. 15 is a flowchart of a fuel injection timing control process performed in the first embodiment.

FIG. 16 is an explanatory diagram of a map for obtaining a retard correction value θd from the fuel increase correction amount ΔQ and the engine speed NE in the first embodiment.

FIG. 17 is a timing chart illustrating an example of a process according to the first embodiment;

FIG. 18 is a flowchart of a fuel injection timing control process performed in the second embodiment.

FIG. 19 is a timing chart showing an example of a process according to the second embodiment.

FIG. 20 is a flowchart of a fuel injection timing control process performed in the third embodiment.

FIG. 21 is an explanatory diagram of a map for obtaining a fuel pressure Pc from a fuel injection amount Q and an engine speed NE in the third embodiment.

FIG. 22 is a timing chart showing an example of a process according to the third embodiment.

FIG. 23 is a timing chart showing an example of a process according to a first modification of the first embodiment.

FIG. 24 is a timing chart showing an example of a process according to a second modification of the first embodiment.

[Explanation of symbols]

2 engine, 2a cylinder, 4 cylinder block, 6 piston, 8 cylinder head, 10 combustion chamber, 12a first intake valve, 12b second intake valve, 14a
... First intake port, 14b Second intake port, 16 ... Exhaust valve, 17 ... Swirl flow control valve, 18 ... Exhaust port, 20 ...
Spark plug, 22 main injector, 22a injection port, 24 recess, 24a piston top surface, 26 peripheral wall surface, 30 intake manifold, 30a first intake passage,
30b ... second intake passage, 32 ... surge tank, 34 ... air flow control valve, 36 ... shaft, 37 ... negative pressure actuator, 40 ... intake duct, 42 ... air cleaner, 44 ... motor, 46 ... throttle valve, 46a ... throttle opening Degree sensor, 48 ... Exhaust manifold, 49 ... Catalytic converter, 50 ... Fuel distribution pipe, 50a ... Fuel pressure sensor, 52 ... Sub-injector, 54 ... High pressure pump, 54a ... High pressure fuel passage, 54b ... Check valve, 54c ... Low pressure fuel Passage, 54d
... Electromagnetic spill valve, 56 ... Fuel tank, 58 ... Low pressure pump, 60 ... Electronic control unit (ECU), 62 ... Bidirectional bus, 64 ... RAM, 66 ... ROM, 68 ... CP
U, 70: input port, 72: output port, 73: AD
Converter 74, accelerator pedal 76, accelerator opening sensor 80 top dead center sensor 82 crank angle sensor
84 ... intake pressure sensor, 86 ... water temperature sensor, 87 ... knock sensor, 88 ... air-fuel ratio sensor, 90 ... drive circuit, 92 ...
Igniter.

Claims (8)

[Claims] 1. A fuel injection control device for a direct injection internal combustion engine in which fuel is directly injected into a combustion chamber from a fuel injection valve, wherein when the fuel injected from the fuel injection valve is increased, The fuel injection by the fuel injection valve is adjusted so that the distance between the fuel injection valve and the top surface of the piston at the time of injection is longer than a distance that naturally changes in response to an increase in fuel. A fuel injection control device for an injection type internal combustion engine. 2. The fuel injection control device for a direct injection internal combustion engine according to claim 1, wherein the increase in the fuel is based on an increase correction. 3. The in-cylinder injection system according to claim 1, wherein in a fuel injection mode in which fuel is injected in an intake stroke, when fuel is increased, the fuel injection start timing is retarded. A fuel injection control device for an internal combustion engine. 4. The in-cylinder injection according to claim 3, wherein the retardation of the fuel injection start timing when fuel is increased is performed when fuel is injected in an intake stroke after warm-up. A fuel injection control device for an internal combustion engine. 5. In a fuel injection mode in which fuel is injected in an intake stroke, when fuel is increased, the fuel injection time is set to:
3. The fuel injection control device for a direct injection internal combustion engine according to claim 1, wherein the fuel injection time is longer than a fuel injection time which naturally changes in response to an increase in fuel. 6. The fuel injection system according to claim 1, wherein when the fuel is increased, the fuel injection time is made longer than the fuel injection time which naturally changes in response to the increase in the fuel by decreasing the fuel pressure. A fuel injection control device for a direct injection internal combustion engine according to claim 5. 7. The cylinder injection type internal combustion engine according to claim 1, wherein in a fuel injection mode in which fuel is injected in a compression stroke, when fuel is increased, a fuel injection time is shortened. Engine fuel injection control device. 8. The fuel injection control apparatus for a direct injection internal combustion engine according to claim 7, wherein when the fuel is increased, the fuel injection time is shortened by increasing the fuel pressure.