JPH08200137A - Injection controller of cylinder injection-type internal combustion engine - Google Patents

Abstract

PURPOSE: To enable combustible mixture to be formed near a spark plug in the ignition timing by making the suitable dispersion time of spray injected during the compression stroke in an injection controller for a cylinder injection- type internal combustion engine. CONSTITUTION: An injection controller is constituted of an injection amount calculating means provided with a fuel injection valve for directly injecting fuel into a cylinder of an engine, and for calculating the fuel injection amount to be injected from the fuel injection valve during the compression stroke, an injection completion timing calculating means for calculating the injection completion timing AINJ2 on the basis of the basic fuel injection amount required for one combustion cycle of the engine, and a fuel control means for controlling the fuel injection amount in the compression stroke so that fuel may be injected from the fuel injection valve only for the fuel injection time τ2 by taking the injection completion timing as the reference. The dispersing time of spray after injection is made appropriate by controlling fuel injection by taking the injection completion timing of the fuel as the reference, and combustible mixture suitable for ignition is formed near a spark plug in the ignition timing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection control device for a cylinder injection type internal combustion engine, and more particularly to an injection control device for a cylinder injection type internal combustion engine which injects fuel in a compression stroke based on an injection end timing.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 5-113146 is provided with a fuel injection valve capable of directly injecting fuel into an engine cylinder, and the entire required fuel injection amount obtained according to the engine operating state is used in a compression stroke. A cylinder that determines the fuel injection timing in the compression stroke based on the fuel injection amount and ignition timing in the compression stroke in an engine in which injection is performed in the vicinity of the spark plug in the cylinder to create a favorable air-fuel mixture around the ignition plug. An internal injection internal combustion engine is disclosed. In addition, in the intake stroke, most of the fuel is injected into the engine cylinder to create a premixed air mixture, and in the compression stroke, a small amount of fuel is injected into the engine cylinder to create a fuel-air mixture near the spark plug. An in-cylinder injection internal combustion engine is disclosed that determines the injection timing in the compression stroke based on the fuel injection quantity in the compression stroke, the ignition timing, and the fuel injection quantity in the intake stroke.

FIG. 16 is an explanatory view of the problems of the prior art in a cylinder injection type internal combustion engine. (A) is a swirl flow,
(B) is a diagram showing the fuel distribution after the compression stroke injection, and (C) is a diagram showing the relationship between the injection timing and the misfire rate. FIG. 16A is a view of the cylinder as seen from above, and shows the location where the fuel A injected from the fuel injection valve 5 toward the ignition plug 65 is diffused by the swirl flow. FIG. 16B shows the fuel distribution in the cylinder of the fuel A injected in the compression stroke. The vertical axis represents the air-fuel ratio, and the horizontal axis represents the position in the cylinder circumferential direction. When the air-fuel mixture having the air-fuel ratio in the illustrated cylinder circumferential position a region and region b comes to the vicinity of the spark plug 65, ignition becomes possible.
16C, the horizontal axis shows the injection timing when the ignition timing is the point c, and the vertical axis shows the misfire rate when the fuel is injected at the injection timing. 16C, the air-fuel mixture corresponding to FIG. 16B corresponding to FIG. 16B is ignited when it reaches the vicinity of the spark plug 65 at the ignition timing, and the region other than the regions a and b is ignited. When the air-fuel mixture existing in (3) comes near the spark plug 65 at the ignition timing, it is not ignited.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The injection control device for a cylinder injection type internal combustion engine described in 3145 controls the fuel injection amount and the injection timing in the compression stroke so that the air-fuel mixture good for ignition is formed near the spark plug at the ignition timing. If the air-fuel ratio of the air-fuel mixture near the spark plug deviates from the target air-fuel ratio due to the effect of canister purge, etc., and the fluctuation of the air-fuel ratio becomes large, the diffusion time of the spray after fuel injection will change and the air-fuel mixture that is suitable for ignition at ignition timing Will not be generated in the vicinity of the spark plug, resulting in a misfire.

Therefore, the present invention solves the above problem, that is, the fuel injected in the compression stroke is injected so as to generate a combustible air-fuel mixture which is good for ignition at the ignition timing in the vicinity of the ignition plug without being affected by the canister purge or the like. An object of the present invention is to provide an injection control device for an in-cylinder injection type internal combustion engine which makes the diffusion time of the spray afterwards appropriate.

[0006]

An injection control device for a cylinder injection type internal combustion engine according to the present invention, which achieves the above object, comprises a fuel injection valve for directly injecting fuel into a cylinder of the engine, and a fuel injection valve is provided during a compression stroke. The injection amount calculation means for calculating the fuel injection amount injected from the injection valve, the injection end timing calculation means for calculating the injection end timing AINJ2 based on the basic fuel injection amount required for one combustion cycle of the engine, and the injection end timing Injection control means for controlling so as to inject the fuel injection amount in the compression stroke from the fuel injection valve as a reference.

[0007]

The injection control system for a cylinder injection type internal combustion engine according to the present invention is a fuel injection system which injects fuel in a compression stroke based on an injection end timing obtained based on a basic fuel injection amount required for one combustion cycle of the engine. The injection start timing corresponding to the amount is calculated, and the fuel injection valve is opened to inject the fuel injection amount in the compression stroke from the injection start timing to the injection end timing. The spray diffuses into the fuel cell, and a combustible air-fuel mixture suitable for ignition is generated near the spark plug at the ignition timing.

[0008]

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 comprises a digital computer, 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 / D.
It is input to the input port 25 via the 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. The output voltage of the load sensor 30 that generates an output voltage proportional to the depression amount L of the accelerator pedal (not shown) is A /
It is input to the input port 25 via the D converter 31. A water temperature sensor 32 attached to the engine body 1 detects the engine cooling water temperature, and the detection signal is the A / D converter 3
3 is input to the input port 25. 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. The fuel injection valve 5 may be a solenoid type instead of the piezo element type described above.

FIG. 3 is a vertical sectional view of the engine of the embodiment. This figure is a diagram showing the engine during fuel injection in the latter half of the compression stroke.
In this figure, 60 is a cylinder block, 61 is a cylinder head, 62 is a piston, 63 is a substantially cylindrical recess formed on the top surface of the piston 62, and 64 is formed between the top surface of the piston 62 and the inner wall surface of the cylinder head 61. The respective cylinder chambers are shown. The spark plug 65 faces the cylinder chamber 64 and is attached to a substantially central portion of the cylinder head 61. Although not shown, an intake port and an exhaust port are formed in the cylinder head 61, and an intake valve 66 (see (a) of FIG. 4) and an exhaust gas are respectively provided at openings of the intake port and the exhaust port into the cylinder chamber 64. The valve is arranged.
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. In addition, the fuel injection valve 5
The fuel injection direction and the fuel injection timing are determined such that the injected fuel is directed to the recess 63 formed at the top of the piston 62.

FIG. 4 is an explanatory view of the operation of the engine shown in FIG. 1, where (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). 8] is a diagram showing a state in a cylinder of an engine in a combustion stroke.
In the embodiment of the present invention, during low load operation of the engine, the entire required fuel injection amount determined according to the operating state of the engine is injected in the latter stage of the compression stroke shown in FIG. 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. This injection fuel has a weak penetration,
Further, since the pressure in the cylinder chamber 64 is high and the air flow is weak, the injected fuel is unevenly distributed in the region K near the spark plug 65. The fuel distribution in this region K is non-uniform and changes from the rich air-fuel mixture layer to the air layer. Therefore, in the region K, a combustible air-fuel mixture near the stoichiometric air-fuel ratio is most likely to burn.
Therefore, the combustible mixture layer near the ignition plug 65 is easily ignited, and this ignition flame propagates to the entire heterogeneous mixture layer to complete combustion. In this way, in the low load region, by injecting fuel near the ignition plug 65 in the latter stage of the compression stroke, a combustible mixture layer is formed near the ignition plug 65, and good ignition and combustion can be obtained.

At the time of medium load operation of the engine, the total amount of the required fuel injection amount obtained according to the operating state of the engine is shown in the initial stage of the intake stroke shown in FIG. 4 (a) and in the latter stage of the compression stroke shown in FIG. 4 (c). It is divided into and injected. 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.
This 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 impinges on the recess 63. These injected fuels are disturbed in the cylinder chamber 64 by the intake air flow flowing into the cylinder chamber 64 from the intake port, so that the cylinder chamber 6 is disturbed.
4 is diffused in the fuel cell 4, and the premixed air P is formed during the intake stroke to the compression stroke as shown in FIG. 4 (b). The air-fuel ratio of the premixed air P is such that the ignition flame can propagate. In the state of FIG. 4B, since the extension of the central axis of the injected fuel is directed toward the cylinder wall, there is a possibility that 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.
Fuel is injected in the latter half of the compression stroke in the direction of 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. Since the fuel distribution in this region K is also non-uniform and changes from the rich air-fuel mixture layer to the air layer, in this region K there is a combustible air-fuel mixture layer near the stoichiometric air-fuel ratio where combustion is most likely to occur. Therefore, in the combustion stroke of FIG.
When the flammable mixture layer in the vicinity is ignited, the heterogeneous mixture region K
Combustion proceeds mainly. 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 medium load region, the fuel is injected in the early stage of the intake stroke to create the air-fuel mixture for flame propagation in the entire cylinder chamber 64, and the fuel is injected in the latter stage of the compression stroke to the vicinity of the spark plug 65. A relatively rich mixture can be created, resulting in good ignition and combustion with high air utilization.

During high load operation of the engine, since the fuel injection amount is large, the concentration of the premixed air produced in the intake stroke injection is sufficiently high for ignition, so the compression stroke injection for ignition is stopped and the engine is operated. All of the required fuel injection amount determined according to the state is injected in the intake stroke.

FIG. 5 is a diagram showing the fuel injection amount and the fuel injection timing according to the load of the engine. In this figure, L on the horizontal axis indicates the depression amount of an accelerator pedal (not shown), the upper vertical axis indicates the fuel injection amount Q _all , and the lower vertical axis indicates the injection timing.
For convenience of explanation, this figure shows the case where the fuel injection amount Q _all is the basic fuel injection amount calculated from the engine speed and the load.
As will be described with reference to FIG. 6 and subsequent figures, the actual fuel injection amount Q _all A is obtained by multiplying the basic fuel injection amount Q _all by a correction coefficient such as the air-fuel ratio correction coefficient FAF and adding other correction coefficients. It is equal to the injection amount obtained by adding the amount Q ₁ and the compression stroke injection amount Q _2, and is represented by the following equation. Q _all A = Q _all × (FAF + α) + β = Q ₁ + Q ₂ where α is a correction coefficient other than FAF, and β is another correction term. The air-fuel ratio correction coefficient FAF is a coefficient for performing feedback control so that the air-fuel ratio of the engine becomes the target air-fuel ratio according to the output of the air-fuel ratio sensor provided in the exhaust system of the engine and correcting the fuel injection amount. .

As can be seen from this figure, during engine low load operation in which the accelerator pedal depression amount L is smaller than L _1, fuel is injected by the injection amount Q _{2 at the} end of the compression stroke. On the other hand, during engine load operation in which the accelerator pedal depression amount L is between L ₁ and L ₂ , fuel is injected by the injection amount Q ₁ during the intake stroke, and by the injection amount Q _{2 at the} end of the compression stroke. That is, during the engine medium load operation, the fuel injection is performed twice in the intake stroke and the end of the compression stroke. Further, during the engine high load operation in which the accelerator pedal depression amount L is larger than L _{2, the} fuel is injected by the injection amount Q ₁ during the intake stroke. In this figure, θS1 and θE1 respectively indicate the injection start timing and the injection end timing of the fuel injection amount Q ₁ performed during the intake stroke, and θS2 and θE2 are the fuel injection amount Q performed at the end of the compression stroke. ₂ shows the injection start timing and the injection end timing, respectively.

FIG. 6 is a flow chart showing a fuel injection control routine of the engine according to the present invention. In the figure, the numbers following S indicate step numbers. The injection amount calculation means for calculating the fuel injection amount to be injected in the compression stroke of the present invention,
The injection end timing calculation means for calculating the injection end timing based on the fuel injection amount of the present invention, which is processed in steps S1 to S3 of the present routine, is processed in steps S4 to S6 of the present routine to determine the fuel injection amount of the present invention. The valve opening control means for controlling the valve opening time of the fuel injection valve so as to open the fuel injection valve from the injection start timing to the injection end timing by defining the injection start timing on the advance side from the injection end timing by the injection time. , Are processed in steps S7 to S10 of this routine. This routine is executed for each injection valve by interruption at every constant crank angle of the engine. 180 ° for a 4-cylinder engine
It is executed for each CA (crank angle).

First, in step S1, the engine speed NE and
The amount L of depression of the accelerator pedal is read. Step S
2 shows the engine speed NE and engine speed from the map 1 shown in FIG.
Based on the amount L of depression of the cell pedal (representing the load condition of the engine)
Is the basic requirement for one combustion cycle of the engine (air-fuel ratio
Correction coefficient FAF = 1, α = 0, β = 0) Each cylinder
Basic fuel injection amount Q_allTo calculate. As shown in Figure 7.
Sea urchin basic fuel injection amount Q _allIs the accelerator pedal depression amount L
Increases as the engine speed NE increases, and increases as the engine speed NE increases.
The rotation speed NE reaches the maximum value at the maximum speed of 6000 rpm.
It is understood that there is.

In step S3, the actual fuel injection amount Q _all
A is calculated from the following formula by multiplying the basic fuel injection amount Q _all by the air-fuel ratio correction coefficient FAF and the like. Q _all A = Q _all × (FAF + α) + β Next, in step S4, the injection method CQN is determined. As described with reference to FIG. 5, the engine load state is divided into low, medium, and high regions based on the accelerator pedal depression amount L representing the engine load state, and only the compression stroke of CQN = 0 is injected in the low load region. Compression stroke injection method, CQN =
It is set to a two-time injection method in which injection is performed in the compression stroke of 1 and an intake stroke, and an intake stroke injection method in which only the intake stroke of CQN = 2 is injected in the high load region.

In step S5, it is determined whether the injection method is the compression stroke injection method with CQN = 0 or 1, the double injection method, or the intake stroke injection method with CQN = 2.
= 0 or 1, the process proceeds to step S6, and CQN = 2
If so, the process proceeds to step S11.

In step S6, the injection end timing AINJ2 in the compression stroke is calculated from the engine speed NE and the basic fuel injection amount Q _all from the map 2 shown in FIG. 8 when CQN = 0, and when CQN = 1. It is calculated from a map (not shown) similar to the map 2. The basic fuel injection amount Q _all
The actual fuel injection amount Q _all A obtained by multiplying the above by the air-fuel ratio correction coefficient FAF and adding other correction terms is equal to the injection amount obtained by adding the intake stroke injection quantity Q ₁ and the compression stroke injection quantity Q ₂ .

FIG. 10 is an explanatory diagram of a method for calculating the fuel injection timing in the compression stroke. (A) shows the case where the fuel injection time is shorter than the crank angle interruption cycle, and (B) shows the fuel injection time from the crank angle interruption cycle. It is each explanatory view at the time of long. First, in step S7, the fuel injection time τ ₂ corresponding to the compression stroke injection amount Q ₂ in the actual fuel injection amount Q _all A is shown in FIG.
It is calculated from the map 3 shown in FIG. This map 3 is calculated for each fuel injection valve based on the fuel pressure in the fuel pressure accumulator, the engine speed, and the fuel injection amount obtained from the load condition. Next, the crank angle sensor is output every 10 ° CA or 30 ° CA within the fuel injection time τ ₂ for opening the fuel injection valve from the calculated fuel injection time τ ₂ and the injection end timing AINJ2 calculated in step S6. The injection end timing AIN obtained by calculating the count value CINJ2 (see FIG. 10) for counting the number of pulses generated by the interrupt signal of
The time RINJ2 (see FIG. 10) from J2 until receiving the interrupt signal of the next crank angle sensor is calculated.

At step S8, (τ ₂ + RINJ2) <
It is determined whether or not TNE is established, and when YES (see FIG. 1).
If 0 (case (A)), the process proceeds to step S9. If NO (case (B) in FIG. 10), the process proceeds to step S10. This TNE refers to the output cycle of the crank angle sensor which is calculated moment by moment as the engine rotates. Therefore, (τ ₂ +
The fact that RINJ2) <TNE is satisfied means that there is no output pulse of the crank angle sensor within one cycle of the crank angle sensor, and (τ ₂ + RINJ2) <TN
The fact that E does not hold means that there is one output pulse of the crank angle sensor within one cycle of the crank angle sensor.

In step S9, the following equation is calculated (see FIG. 10).
(In the case of (A)), the process proceeds to step S11. TINJ2 = TNE-([tau] ₂ + RINJ2) Here, TINJ2 represents the time from the interrupt signal of the crank angle sensor, which is one position ahead of the injection end timing AINJ2, to the start of fuel injection. Since there is no crank angle interruption signal within the fuel injection time τ ₂ , CINJ2 is 0, and the injection start timing AINJ02 in the compression stroke is one pulse ahead of the injection end timing AINJ2, and TINJ2 is retarded from the crank angle interruption signal on the advance side. Becomes

In step S10, the following equation is calculated (in the case of FIG. 10B) and the process proceeds to step S11. CINJ2 = CINJ2-1 TINJ2 = 2TNE- (τ ₂ + RINJ2) Here, TINJ2 is the time from the interrupt signal of the crank angle sensor two positions ahead of the injection end timing AINJ2 to the start of fuel injection. . Since there is one crank angle interrupt signal within the fuel injection time τ ₂ , CINJ2 is 1, and the injection start timing AINJ02 in the compression stroke is two pulses behind the injection end timing AINJ2 by TINJ2 from the crank angle interrupt signal on the advance side. It will be on the corner side. CI
The calculation of NJ2 = CINJ2-1 is the injection start timing AINJ.
Is executed to calculate 02.

FIG. 12 is an explanatory diagram of a method for calculating the fuel injection timing in the intake stroke. (A) shows the fuel injection time shorter than the crank angle interruption period, and (B) shows the fuel injection time longer than the crank angle interruption period. It is each explanatory view in a case. Figure 6
In step S11 of the flowchart of FIG.
It is determined whether it is the two-time injection method of N = 1 or 2, the intake stroke injection method, or the compression stroke injection method of CQN = 0. When CQN = 1 or 2, the process proceeds to step S12, and when CQN = 0. This routine ends. In step S12, the injection start timing AINJ1 of the intake stroke injection
Is calculated from the map 4 shown in FIG. Step S13
First, the fuel injection time τ ₁ corresponding to the intake stroke injection amount Q ₁ in the actual fuel injection amount Q _all A is calculated from the map 3 shown in FIG. Next, within the fuel injection time τ ₁ for opening the fuel injection valve from the calculated fuel injection time τ ₁ and the injection start timing AINJ1 calculated in step S12, 10 ° CA
Alternatively, a count value CINJ1 (see FIG. 12) that counts the number of pulses generated by the crank angle sensor interrupt signal that is output every 30 ° CA is calculated, and then step S
Time until receiving the interrupt signal of the crank angle sensor at the first crank angle position on the advance side from the fuel injection time τ ₁ from the injection end timing AINJ1 obtained in 12 RINJ1
(See FIG. 12) is calculated. Next, at step S14, TINJ1 = RINJ1 is set and this routine is ended.

FIG. 13 is a flowchart of the injection start timing calculation routine. This routine is executed every 10 ° CA or 30 ° CA of crank angle interruption period. In step S21, CINJ (CINJ1 or CINJ2) is the crank angle interrupt signal generation timing (timing) CRNK.
It is determined whether or not it matches, and the determination result is YES.
If NO, the routine proceeds to step S22, and if NO, this routine is ended, the next crank angle interrupt signal is received, and the routine returns to step S21 to repeatedly execute this processing. By executing step 21, the crank angle position corresponding to the injection start timing of the first cylinder of the engine is calculated. In step S22, crank angle interruption time ASRNE and steps S9 and S1
Compare register CP obtained by adding TINJ2 calculated at 0 or TINJ1 calculated at step S14
R is calculated from the following equation. CPR = ASRNE + TINJ Then, the compare register CP calculated in step S22
Based on the value of R, the fuel injection valve opening bit YIN of the first cylinder
Set J on and exit this routine.

FIG. 14 is a flow chart of the injection end timing calculation routine. This routine is executed every 10 ° CA or 30 ° CA of crank angle interruption period. In step S31, it is determined whether the fuel injection valve opening bit YINJ of the first cylinder is on or off. If the result of the determination is YES, the process proceeds to step S32. If NO, this routine is terminated and the next crank angle interruption is performed. Receiving the signal, step S3 again
It returns to 1 and repeats this processing. Step S32
Then, the fuel injection valve of the first cylinder is closed at the injection end timing based on the value of the compare register that calculates CPR = CPR + τ, and this routine is ended.

As described above, the internal combustion engine of the embodiment is
The fuel injection amount to be injected during the compression stroke is calculated, and the fuel injection valve is opened and fuel injection is performed based on the injection end timing AINJ2 obtained based on the basic fuel injection amount required for one combustion cycle of the engine. As described above, the spray after injection is diffused and a combustible mixture that is good for ignition at the ignition timing is created near the spark plug.

As described above, referring to FIGS. 13 and 14, the first engine
Although the injection start timing and the injection end timing of the fuel injection valve for the cylinders have been described, the injection start timing and the injection end timing of the fuel injection valve for the second to fourth cylinders are similarly obtained, and thus the description thereof will be omitted.

FIG. 15 is a diagram showing the fuel distribution after the compression stroke injection of the cylinder injection type internal combustion engine according to the present invention. (A) shows the fuel without canister purge, and (B) shows the fuel with canister purge. It is a figure which shows distribution. In this figure, the vertical axis represents the air-fuel ratio, and the horizontal axis represents the position in the cylinder circumferential direction. The fuel injected into the cylinder is diffused by the swirl flow with the illustrated fuel distribution. The actual fuel injection amount Q with and without the canister purge
_{The amount of all} A is smaller in the case with canister purge than in the case without canister purge because it is reduced by the amount of fuel contained in the purge gas, and as shown in FIG. 15, (A) in FIG. 15 (B). It can be seen that fuel richer than that of the above is distributed in the cylinder. Further, as shown in FIG. 15B, when the canister purge is present, the fuel injection amount is reduced by the fuel amount contained in the purge gas. Since the actual fuel injection amount Q _all A is calculated from the following equation, it can be seen that the fuel injection amount by the canister purge is reduced. Q _all A = Q _all × (FAF + FPG + α) + β where Q _all is the basic fuel injection amount calculated according to the engine speed and load, FAF is the air-fuel ratio correction coefficient, and FPG is the purge rate of the canister purge gas. The weight reduction correction coefficient calculated by α, other correction coefficients, and β, other correction terms.

Next, the features of the present invention will be described with reference to FIG. According to the conventional technique, since the fuel injection start timing is used as a reference, the point c in FIG. 15A and the point c ′ in FIG. 15B are reference points. Therefore, the region a in FIG. 15A, which is a flammable range suitable for ignition, is shown.
15 and the combustible mixture in the region a ′ in FIG. 15B reach the spark plugs at different ignition timings. This is because the time required for the combustible mixture in the region a to move to the point c due to the swirl flow,
This is because it is different from the time required for the combustible air-fuel mixture in the area a ′ to move to the point c ′. On the other hand, since the present invention is based on the injection end timing, the combustible air-fuel mixture in the region a when the canister purge is not performed and in the region a ′ when the canister purge is performed reaches the vicinity of the spark plug at the ignition timing. It is possible to prevent misfire due to the influence of canister purge. It should be noted that the region b in FIG. 15A or the region b ′ in FIG. 15B is not used for ignition, but the region a in FIG. 15A or the region a ′ in FIG. 15B is ignited. The reason is that the former air-fuel ratio changes more rapidly than the latter and the region becomes narrower, and the latter allows longer time from injection start to ignition and promotes evaporation. Because.

The internal combustion engine of the embodiment described above is an engine which is arranged in the intake pipe and does not have a port injection valve for injecting fuel toward the intake port, but the present invention directly injects into the cylinder shown in FIG. In addition to the fuel injection valve, it can also be applied to a cylinder injection internal combustion engine in which such a port injection valve is provided in the intake pipe. In this internal combustion engine, the in-cylinder direct injection valve that directly injects fuel into the cylinder performs the intake stroke injection and the compression stroke injection according to the load of the engine as described above, and the fuel injection timing of the compression stroke is the main point. The port injection valve, which is controlled by the invention and injects fuel toward the intake port, performs normal intake stroke injection.

[0035]

As described above, according to the injection control device for a cylinder injection type internal combustion engine of the present invention, the fuel injection in the compression stroke is performed on the basis of the injection end timing obtained based on the basic fuel injection amount. Since this is done, the diffusion time of the spray after injection becomes appropriate, and a combustible mixture that is good for ignition is generated near the spark plug at the ignition timing.

[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 vertical cross-sectional view of the engine of the embodiment.

FIG. 4 is an explanatory view of the operation of the engine shown in FIG. 1, (a)
FIG. 4 is a diagram showing a state in the cylinder of the engine during an intake stroke early stage, (b) late intake stroke stage to early compression stroke stage, (c) late compression stroke stage, and (d) combustion stage.

FIG. 5 is a diagram showing a fuel injection amount and a fuel injection timing according to a load of the engine.

FIG. 6 is a flowchart showing a fuel injection control routine of the engine according to the present invention.

FIG. 7 is a diagram showing a map 1 for calculating a basic fuel injection amount based on an engine speed and an accelerator opening.

FIG. 8 is a diagram showing a map 2 for calculating the injection timing in the compression stroke from the engine speed and the basic fuel injection amount.

FIG. 9 is a diagram showing a map 3 for calculating a fuel injection time with respect to a fuel injection amount.

FIG. 10 is an explanatory diagram of a fuel injection timing calculation method in a compression stroke, where (A) shows a case where the fuel injection time is shorter than the crank angle interruption cycle, and (B) shows a case where the fuel injection time is longer than the crank angle interruption cycle. FIG.

FIG. 11 is a diagram showing a map 4 for calculating the injection timing in the intake stroke from the engine speed and the basic fuel injection amount.

FIG. 12 is an explanatory diagram of a fuel injection timing calculation method in the intake stroke, where (A) shows the case where the fuel injection time is shorter than the crank angle interrupt cycle, and (B) shows the case where the fuel injection time is longer than the crank angle interrupt cycle. FIG.

FIG. 13 is a flowchart of an injection start timing calculation routine.

FIG. 14 is a flowchart of an injection end timing calculation routine.

FIG. 15 is a diagram showing a fuel distribution after a compression stroke injection of a cylinder injection type internal combustion engine according to the present invention, where (A) shows a fuel distribution without a canister purge and (B) shows a fuel distribution with a canister purge. FIG.

FIG. 16 is an explanatory diagram of a problem of the prior art in a direct injection internal combustion engine, (A) is a swirl flow, (B) is a fuel distribution after compression stroke injection, and (C) is an injection timing and a misfire rate. It is a figure which shows the relationship of.

[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

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location F02D 41/02 335 41/04 301 C

Claims (1)

[Claims] 1. An injection control device for a cylinder injection type internal combustion engine comprising a fuel injection valve for directly injecting fuel into a cylinder of an engine, wherein an injection for calculating a fuel injection amount to be injected from the fuel injection valve during a compression stroke. An amount calculation means, an injection end timing calculation means for calculating an injection end timing based on a basic fuel injection amount required for one combustion cycle of the engine, and a compression stroke from the fuel injection valve based on the injection end timing. And an injection control means for controlling so as to inject the fuel injection amount in the injection control device of the in-cylinder injection type internal combustion engine.