JPH07139387A - Fuel injection amount control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent deterioration of air-fuel ratio controllability owing to a delay in an actual purge amount occurring because of a canister being separated away from an intake pipe. CONSTITUTION:When it is detected that an idle switch 35 is switched from ON to OFF or from OFF to ON a logic value of a purge flow rate available when purge is effected for a given time is calculated. Further, the change of the pressure of a canister part 17 changed for the given time is calculated from a detecting value from a canister pressure sensor 38. From a detecting pressure change amount DELTAPCN and a computed logic value DELTAQPG, a purge flow rate correction factor KNQPG is calculated by a formula of KNQPG=-1-d(DELTAPCN<1/2>/DELTAQPG). From the purge flow rate correction factor KNQPG, a fuel injection amount is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to a fuel injection amount control device for an internal combustion engine equipped with a fuel evaporative gas diffusion prevention device for preventing diffusion of fuel evaporative gas generated in a fuel supply system of an automobile.

[0002]

2. Description of the Related Art Conventionally, vaporized fuel generated from a fuel tank is adsorbed on activated carbon, and this is purged into an intake system for processing. For example, JP-A-63-28
In Japanese Patent No. 9243, in addition to the feedback correction at the time of executing the purge, the correction of the fuel injection amount by the purge is performed, and the purge correction amount is set according to the evaporated fuel concentration obtained from the average value of the feedback correction coefficient, and the air-fuel ratio controllability is improved. Is improving.

[0003]

However, since the intake pipe and the canister are actually separated from each other, the actual purge amount is delayed due to the pressure loss of the supply pipe and the like. Further, since the purge amount does not increase in proportion to the start of the purge but gradually increases, this also causes a delay in the actual purge amount. Therefore, the controllability of the air-fuel ratio at the time of transition is deteriorated, and the emission and drivability are affected. Further, in recent years, it has been considered that a large-sized canister is mounted on the rear part of the vehicle in order to suppress the generation of evaporated fuel, and it is considered that the air-fuel ratio controllability is further deteriorated in such a vehicle.

An object of the present invention is to provide a fuel injection amount control device for an internal combustion engine in which air-fuel ratio controllability is not impaired due to a delay in the actual purge amount.

[0005]

SUMMARY OF THE INVENTION Therefore, according to the present invention, a canister having an adsorbent for adsorbing a fuel evaporative gas generated in a fuel tank containing a liquid fuel, and a fuel evaporative gas purged from the canister are provided. Of the internal combustion engine, which comprises: a purge flow rate delay detecting means for detecting a purge flow rate delay occurring in the fuel injection amount; and a fuel injection amount correcting means for correcting the fuel injection amount based on the detection result of the purge flow rate delay detecting means. An injection amount control device is provided.

[0006]

In the present invention, the canister has an adsorbent for adsorbing the fuel evaporative gas generated in the fuel tank containing the liquid fuel, and the purge flow rate delay detecting means is provided when the fuel evaporative gas is purged from the canister. The purge flow delay that occurs in 1) is detected. Then, the fuel injection amount correction means corrects the fuel injection amount based on the detection result of the purge flow rate delay detection means.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram around an engine mounted on an automobile. An intake pipe 2 and an exhaust pipe 3 are connected to the engine 1. An air cleaner 4 that filters air is arranged upstream of the intake pipe 2, and the air is drawn into the intake pipe 2 via the air cleaner 4. Inside the intake pipe 2, a throttle valve 6 that opens and closes in conjunction with an accelerator pedal 5 is provided. A bypass passage 7 is provided so as to bypass the throttle valve 6, and a rotation speed control valve 8 is arranged in the middle of the bypass passage 7. By adjusting the opening degree by the duty control of the rotation speed control valve 8,
The engine speed can be changed by adjusting the intake air amount when the engine 1 is idling.

The air from the intake pipe 2 is supplied to the combustion chamber 10 via the intake valve 9. Exhaust gas in the combustion chamber 10 is exhausted to the exhaust pipe 3 via the exhaust valve 11. The exhaust pipe 3 is provided with an O ₂ sensor 12. On the other hand, a fuel pump 14 is connected to the fuel tank 13 that stores the liquid fuel, and the fuel in the fuel tank 13 is conveyed under pressure by the fuel pump 14. The fuel from the fuel pump 14 is supplied to a fuel injection valve 15 provided in the intake pipe 2, and the fuel is injected by opening and closing the fuel injection valve 15. Further, the fuel tank 13 is connected to a canister 17 by a communication pipe 16, and a canister body 18
An adsorbent 19 for adsorbing the fuel evaporative gas, for example, activated carbon, is housed therein. Thereby, the fuel evaporative gas generated in the fuel tank 13 is adsorbed to the adsorbent 19 of the canister 17 via the communication pipe 16.
Further, the canister body 18 is formed with an atmosphere opening hole 20 which is open to the atmosphere, so that air can be sucked into the inside.

Further, a hose connecting portion 21 is formed in the canister body 18, a canister pressure sensor 38 is provided in the hose connecting portion 21, and one end of the supply pipe 22 is inserted. The other end of the supply pipe 22 is connected to the purge control valve 23. One end of the supply pipe 24 is connected to the purge control valve 23, and the other end of the supply pipe 24 is connected to the intake pipe 2. Therefore, the purge control valve 23 is interposed between the two supply pipes 22 and 24 so that the intake pipe 2 and the canister 17 are connected to each other by the supply pipe 22, the purge control valve 23, and the supply pipe 24.
It is possible to communicate via. In this communication state, the fuel evaporative gas adsorbed by the adsorbent 19 of the canister 17 can be guided into the intake pipe 2 by the negative pressure generated in the intake pipe 2 of the engine 1. The opening degree of the purge control valve 23 can be adjusted by duty control, and both supply pipes 2 can be adjusted according to the opening degree.
The purge flow rate passing through 2, 24 is changed. Figure 2
The characteristic diagram of the purge amount at this time shows the relationship between the duty of the purge control 23 and the purge amount when the negative pressure in the intake pipe is constant. From this figure, the duty of the purge control valve 23 is 0%. It is understood that the purge amount, that is, the amount of air sucked into the engine 1 via the canister 17 increases substantially linearly as the amount of air is increased. The supply pipes 22 and 24 are generally formed of a flexible material such as a rubber hose or a nylon hose.

The electronic control circuit 25 includes a CPU 26 and a ROM.
27, a RAM 28, and an input / output circuit 29, which are connected to each other via a common bus 30. ROM2
A control program and data for the CPU 26 are stored in advance in the RAM 7, and the RAM 28 can be read and written. C
The PU 26 inputs various signals via the input / output circuit 29. That is, a signal from the O ₂ sensor 12, a signal from the canister pressure sensor 38, a signal from the water temperature sensor 31 that detects the temperature of the engine cooling water, and a signal from the throttle opening sensor 39 that detects the opening of the throttle valve 6. Signal, a signal from the air conditioner switch 32 that detects the on / off operation of the car air conditioner, a signal from the headlight switch 33 that detects the lighting operation of the headlight, and a signal from the heater blower switch 34.
A signal from an idle switch 35 that turns on when the accelerator pedal 5 is not depressed, a signal from a vehicle speed sensor 36, and a signal from a rotation speed sensor 37 that detects an engine rotation speed are input.

FIG. 3 shows a full-open purge rate map, which is determined by the engine speed Ne and the load (in this case, the intake pipe pressure, as well as the intake air amount and the throttle opening). This map shows the engine 1 through the intake pipe 2.
The ratio of the amount of air flowing through the supply pipe 24 when the duty of the purge control 23 is 100% with respect to the total amount of air flowing in is shown in FIG.

The CPU 26 then sends these signals, R
The fuel injection valve 15, the purge control valve 23, and the rotation speed control valve 8 are drive-controlled via the input / output circuit 29 based on programs and data in the OM 27 and RAM 28. That is, the CPU 26 adjusts the opening degree of the purge control valve 23 according to the operating state of the engine 1 to supply the supply pipes 22, 2
Control the purge flow rate of 4. In other words, the purge control valve opening is calculated by the CPU 26 so that the purge flow rate becomes a predetermined ratio with respect to the intake amount by the intake amount sensor (not shown),
Controlled. Further, the CPU 26 controls the intake air amount by adjusting the opening degree of the rotation speed control valve 8 so as to reach the target rotation speed during the idle operation of the engine 1, and further, to the engine 1 detected by the O ₂ sensor 12. The air-fuel ratio of the air-fuel mixture is controlled to be constant. That is, the CPU 26
Is the basic injection time obtained from the engine speed by the rotation speed sensor 37 and the intake air quantity by the intake air quantity sensor (not shown).
The basic injection time is corrected by the feedback correction coefficient FAF or the like to obtain the final injection time, and the fuel injection is performed by the fuel injection valve 15 at a predetermined injection timing.

First, the feedback control of the air-fuel ratio is shown in FIG.
It will be described based on. This process is executed every predetermined time. As shown in FIG. 5, the CPU 26 compares the output voltage of the O ₂ sensor 12 with the comparison voltage Vref to determine whether the mixture is rich or lean. Then, the CPU 26 determines in step S100 whether or not the condition for the feedback control is satisfied. It is determined that the conditions are met when the engine water temperature by the water temperature sensor 31 is 40 ° C. or higher and the throttle opening by the throttle opening sensor 39 is 70 ° or less. If the condition is not satisfied, the CPU 26 sets the feedback correction coefficient FAF = 1.0 in step S101, and proceeds to step S109.

When the feedback control condition is satisfied, the CPU 26 determines from the signal from the O ₂ sensor 12 whether the air-fuel ratio is rich in step S102. If rich, the previous detection result is obtained in step S103. It is determined whether or not the lean is reversed to the rich by comparing with. When the CPU 26 reverses from lean to rich, the feedback correction coefficient FAF-α (α
Is the skip amount) is a new feedback correction coefficient FAF
If there is no inversion from lean to rich, feedback correction coefficient FAF-β (β
Is the integration amount, and α> β) is a new feedback correction coefficient F
AF. Then, the process proceeds to step S109.

In step S109, the average value FAFAV of the calculated feedback correction coefficient FAF is calculated from the following equation.

[0016]

## EQU1 ## FAFAV = (63 × FAFAV _(-1) + FAF) / 64 where FAFAV _(-1) is the value of the previously calculated FAFAV. Further, in step S102, the CPU 26, in the case of lean, compares with the previous detection result in step S106 and determines whether the state is reversed from rich to lean. When the CPU 26 reverses from rich to lean, in step S107, the feedback correction coefficient FAF + α
(Α is the skip amount) is a new feedback correction coefficient F
If AF is set and there is no inversion from rich to lean, step S108 feedback correction coefficient FAF + β
(Β is the integrated amount) is a new feedback correction coefficient FAF
And Then, the process proceeds to step S109, and the above-described processing is performed.

Therefore, if there is a reversal between rich and lean due to the processing of steps S102 to S108, the feedback correction coefficient F is set so as to increase or decrease the fuel injection amount.
The AF is changed stepwise (skipping), and the feedback correction coefficient FAF is set in the rich or lean state.
Gradually increase or decrease. FIG. 6 shows a target idle speed control processing routine that is executed every predetermined time.

The CPU 26 determines in step S200 whether or not the engine is idling. This is the idle switch 35
Is turned on and the vehicle speed detected by the vehicle speed sensor 36 is 2K.
When m / h or less, it is determined that the engine is idling. When the CPU 26 is in the idle operation, the CPU 26 detects the operation state of the air conditioner switch 32 and the alternator load state (the operation state of the headlight switch 33 and the heater blower switch 34) in step S201, and the engine temperature detected by the water temperature sensor 31 in step S202. Read the cooling water temperature. The CPU 26 determines the target rotation speed NT in step S203. This is to determine the target speed NT by the load state (no load, with alternator load, air conditioner on) corresponding to the engine cooling water temperature using the map of FIG. 7.

Next, in step S204, the CPU 26 calculates a deviation ΔNE (= NT-NE) between the target revolution speed NT and the actual engine revolution speed NE detected by the revolution speed sensor 37,
In step S205, the control opening amount Q of the rotation speed control valve 8 is calculated. The control opening amount Q is calculated by using the map shown in FIG. 8 and corresponding to the rotation speed deviation ΔNE.
Is to seek. Further, the CPU 26 executes step S
206 a value obtained by adding the controlled opening degree Q in opening theta _i-1 of the previous speed control valve 8 and opening theta _i of this speed control valve 8, the rotation so that the opening theta _i The number control valve 8 is duty-controlled.

The main routine of the purge execution control is shown in FIG. This routine is also executed by the CPU 2 every predetermined time (about 4 _ms ).
5 is executed by the base routine. In step S501, it is determined whether or not the air-fuel ratio F / B is in the air-fuel ratio F / B. For example, it is determined whether the cooling water temperature is 40 ° C. or higher when the engine is not started. When the water temperature is 50 ° C. or more in the air-fuel ratio F / B, it is determined in step S505 whether the fuel is being cut, and when it is determined that the fuel is not being cut,
After proceeding to step S506 to perform the normal purge rate control, the purge incomplete flag XIPGR is set to 0 in step S507 to execute the purge rate control. When the purge rate condition is not satisfied in steps S501, S502, and S505, the process proceeds to step S512 to set the purge rate to 0, and then proceeds to step S513 to set the purge incomplete flag XIPGR to 1.

FIG. 10 shows the normal purge rate control subroutine in step S506 of FIG. First, in step S601, it is detected which of the three areas (,,) the FAF value (or FAF smoothed value) is with respect to the reference value 1.0. Here, as shown in FIG. 11A, when the area is within 1.0 ± F% and the area is separated by 1.0 ± F% or more and within ± G% (where F <G), the area is 1 Indicates the time when it is over 0.0 ± G%.

If it is in the region, the process proceeds to step S602 and the purge rate (PGR) is increased by a predetermined value D%. In the case of the area, the process proceeds to step S603 and the PGR is not increased or decreased. If it is in the region, the process proceeds to step S604, and PGR is set to a predetermined value E%.
Gradually decrease. Here, it is preferable that the predetermined values D and E are changed according to the evaporation concentration (FGPG) as shown in FIG. Then, the next step S605
Check the upper and lower limits of PGR. Here, the upper limit is
Purging start time shown in (c) of FIG. 11, (d) of FIG.
11 is the smallest value among various conditions such as the water temperature and the operating condition (full open purge rate map) shown in FIG.

FIG. 12 shows a purge control valve control routine executed by the CPU 26 by interrupting every 100 _ms . In step S161, the purge non-execution flag XIPG
When R is 1, the process proceeds to step S163 and the duty of the purge control valve 23 is set to 0. Otherwise, the process proceeds to step S164 and the drive cycle of the purge control valve 23 is set to 1
If it is 00 _ms ,

[0024]

## EQU2 ## Duty = (PGR / PGR _fo ) × (100 _ms
The duty of the purge control valve 23 is calculated by the equation −P _Y ) × P _pa + P _v . Here, PGR is the purge rate obtained in FIG. 10, PGR _fo is the purge rate in each operating state when the purge control valve 23 is fully open (see FIG. 3), P _Y is the voltage correction value for variations in the battery voltage, P _pa is an atmospheric pressure correction value for variations in atmospheric pressure.

Next, FIG. 13 shows a main routine for evaporative concentration detection which is executed in the base routine of the CPU 26 every predetermined time (about 4 _ms ). First, when the key switch is turned on in step S300, S315, S316, and S31
7 and evaporative concentration FGPG, evaporative concentration average value FG
PGAV to 1.0, first concentration detection flag XNFGPG
Is initialized to 0. After the key switch is turned on in step S300, first, if the purge control is started in step S301 and the purge non-execution flag XIPGR is not 1, the process proceeds to step S302, and the flag XIPGR is 1 and the purge control is not yet started. In this case, the concentration detection is completed. In step S302, it is determined whether acceleration / deceleration is being performed. Here, the determination as to whether or not the acceleration / deceleration is being performed may be performed by a generally well-known method by detecting an idle switch, a throttle valve opening change, an intake pipe pressure change, a vehicle speed, and the like.

If it is determined in step S302 that the vehicle is accelerating, the process ends. If it is determined that the vehicle is not accelerating, the process proceeds to step S303 to determine whether the first concentration detection end flag XNFGPG is 1, and when it is 1, The process proceeds to the next step S304, and when it is not 1, the process bypasses step S304 and proceeds to step S305. Then, when the initial concentration detection is completed, it is determined in step S304 whether or not the purge rate PGR is a predetermined value (β%) or more. If not, the process is ended as it is, and if it is above, the next step S3.
Go to 05.

In this step S305, it is judged whether the deviation of the FAFAV from the reference value 1 obtained in step S109 of FIG. 4 is a predetermined value (ω%) or more, and if not, the process ends as it is, and if so, the next step S308. Proceed to and detect the evaporative density. FAFA in step S308
The deviation from the reference value 1 of V divided by PGR is added to the previous evaporation concentration FGPG, and this time the evaporation concentration FG
Find the PG. Therefore, the value of the evaporation concentration FGPG in this embodiment is 1 when the evaporation concentration in the supply pipe 24 is 0 (air is 100%), and is set to a value smaller than 1 as the evaporation concentration in the supply pipe 24 is higher. It is what is done. Here, in step S308 of FIG.
It is also possible to replace AV with 1 and obtain the evaporation concentration by setting the value of FGPG to a value greater than 1 as the evaporation concentration increases.

Then, in the next step S309, it is determined whether or not the initial concentration detection end flag XNFPGG is 1, and if it is not 1, the process proceeds to the next step S310, and if it is 1, the steps 310 and S311 are bypassed and the process proceeds to step S312. Then, in step S310, the evaporation concentration FGPG
It is judged whether the variation between the previous detection value and the current detection value of 3 is equal to or less than the predetermined value (θ%) continuously for 3 times or more, and if the evaporation concentration is stable, the process proceeds to the next step S311 and the first time After setting the density detection end flag XNFPGG to 1, the process proceeds to the next step S312. Also, step S3
If it is determined in 10 that the evaporation concentration is not stable, the process proceeds to step S312. In this step S312, the present evaporation concentration FGPG is subjected to predetermined averaging for averaging (for example,
1/64 averaging) Calculated, Evaporative concentration average value FGPGA
Find V.

Next, the calculation process of the purge flow rate correction coefficient, which is a feature of the present invention, will be described. In this embodiment, a purge flow rate correction coefficient calculation process using the canister pressure sensor 38 will be described with reference to the flowchart shown in FIG. It should be noted that this process is executed at every predetermined time after the ignition is turned on until the purge flow rate correction coefficient at the time of acceleration and deceleration is once detected. Further, as the initialization processing, the acceleration correction coefficient detection flag FU and the deceleration correction coefficient detection flag FD are set to 0, respectively.

When this processing is executed, first, step S
At 713, it is determined whether the correction coefficient detection flag FU during acceleration is 1 and the correction coefficient detection flag FD during deceleration is 1. That is, it is determined whether or not the purge flow rate correction coefficient for acceleration and deceleration has been detected even once after the execution of this process. If both are detected and both flags are 1, this process is ended, and if neither one is detected, the process proceeds to step S701.

In step S701, it is determined whether the purge incomplete flag XIPGR is 1. When it is 1, this processing is ended as it is. If not 1, the process proceeds to the next step S702, and it is determined whether the idle switch is off. Here, when the idle switch is off, the process proceeds to step S703. In step S703, it is detected whether the idle switch has been switched from on to off this time. That is, it is determined whether or not the vehicle has accelerated. If it has not been switched (determined as not accelerating), this processing ends. If it is switched (determined as accelerating), the next step S7
Go to 04.

In step S704, a predetermined time (t _{1 to} t
₂ ) Theoretical value of change in purge flow rate QPG ΔQPG _{t1, t2}
Is calculated from the following formula.

[0033]

[Formula 3] ΔQPG_{t1, t2}= QA × PGR where QA is the intake air flow rate and PGR is the current
It is the rate. Next, in step S705, a predetermined time
(T₁~ T₂) Changed to canister pressure ΔP _CNTo
To detect. Then, in step S706,
The purge flow rate correction coefficient KNQPGU is calculated by the following equation.

[0034]

Equation 4] _{KNQPGU = 1-α (ΔP CN} 1/2 / ΔQPG t1, t2) where, alpha is a correction coefficient when considering the disturbance. In the next step S714, the purge flow rate correction coefficient K during acceleration is set.
The acceleration correction coefficient detection flag FU indicating that NQPGU is detected is set to 1, and the process proceeds to step S707. Then, in step S707, the value calculated in step S706 is stored in the RAM 28 as the purge flow rate correction coefficient KNQPGU during acceleration.

If the idle switch is turned on in step S702, the process proceeds to step S708. In step S708, it is determined whether or not the vehicle speed is 30 km / h or more, and if a negative determination is made, the present process is terminated as it is. If an affirmative decision is made, the operation proceeds to step S709. In step S709, it is detected whether the idle switch has been switched from off to on this time. In other words, the vehicle speed is 30 km
It is determined whether or not the vehicle has decelerated from the state of / h or more. If it has not been switched (determined that the vehicle is not decelerating), this processing ends. If it has been switched (determined that the vehicle is decelerating), the process proceeds to the next step S710.

In step S710, a predetermined time (t _{3 to} t
The change amount ΔQPG _{t3, t4} of the theoretical purge flow rate QPG in ₄ ) is calculated from the following equation.

[0037]

ΔQPG _{t3, t4} = QA × PGR where QA is the intake air flow rate and PGR is the purge rate at that time. Next, in step S711, the pressure ΔP _CN of the canister portion that has changed for a predetermined time is detected. Then, in step S712, the purge flow rate correction coefficient KNQPGD during acceleration is calculated from the following equation.

[0038]

[6] KNQPGD = 1-α a ^{_{(ΔP CN 1/2 / ΔQPG t3,}} t4) the deceleration correction coefficient detection flag FD indicating that the purge flow rate correction coefficient KNQPGD during deceleration in the next step S715 has been detected 1 Then, the process proceeds to step S707. Then, in step S707, the calculated value is set as the purge flow rate correction coefficient KNQPGD during deceleration in the RAM2.
Store in 8.

As described above, in the present embodiment, the actual purge value is calculated by comparing the theoretical value of the change in purge flow rate during acceleration / deceleration obtained from Equation 4 or Equation 6 with the actually detected change amount of the canister pressure. A delay in the flow rate is detected. The change in the canister pressure is detected as the actual value because the purge flow rate depends on the canister pressure.

FIG. 15 shows the idle switch (IDSW) at the time of acceleration and deceleration, the vehicle speed, the intake air amount (m ³ / h),
6 is a time chart showing changes in theoretical purge flow rate (l) and canister pressure (mmHg). When it is detected that the idle switch IDSW is switched from ON to OFF (indicating that the vehicle is accelerated), the intake amount and the vehicle speed are increased. Theoretically, the purge flow rate should increase at the same time, but the pressure drop in the supply pipe and the purge amount may not increase proportionally with the start of the purge. It will rise later. According to the above process, this delay is detected and the error in the fuel injection amount caused by the delay is corrected. Similarly, during deceleration, the vehicle speed and the intake air amount increase slightly later than the decrease, but since the correction is performed, no error occurs in the fuel injection amount.

Next, a purging T that is executed every predetermined time is performed.
The calculation process of the AU correction coefficient FPG will be described with reference to the flowchart shown in FIG. When this processing is executed, in step S901, the purge non-execution flag XIPGR
If it is 1, if it is 1, then the purge TAU correction coefficient FPG is set to 0 in step S909, and then this processing is ended. If not 1, the process proceeds to step S902. In step S902, the theoretical purge flow rate is calculated by the following equation.

[0042]

## EQU00007 ## QPR = QA.times.PGR In the next step S903, it is determined whether or not the vehicle is currently decelerating. If a negative determination is made, the processing proceeds to step S904, and if an affirmative determination is made, the processing proceeds to step S905. In other words, during steady operation,
Alternatively, during acceleration operation, the purge flow rate correction coefficient KNQPGU during acceleration is read in step S904, and the flow proceeds to step S906. During deceleration, step S9
05 Purge flow rate correction coefficient KNQPGD during deceleration
Is read, and the process proceeds to step S906.

In step S906, the actual purge flow rate QPGSM _i is calculated by the following equation.

[0044]

[Equation 8] QPGSM _i = QPGSM _i-1 × KNQPG +
(1-KNQPG) × QPG Next, in step S907, the actual purge rate PGRS
M is calculated from the following equation.

[0045]

## EQU9 ## PGRSM = QPGSM _i / QA Furthermore, in step S908, the purge TAU correction coefficient FPG is obtained from the following equation.

[0046]

[Formula 10] FPG = FGPGAV × PGRSM Then, this process ends. Next, the fuel injection amount control process considering the correction by the purge TAU correction coefficient will be described with reference to FIG.
It will be described according to the flowchart shown in FIG. This fuel injection amount control process is also executed every predetermined time.

When this processing is executed, step S191
At, the basic injection amount TP is obtained from the engine speed and load (for example, intake pipe pressure) based on the data stored as a map in the ROM 27. Next step S
In 192, various basic corrections (cooling water temperature correction, correction after starting,
Intake temperature correction, etc.) is performed. In step S193, the purge TAU correction coefficient FPG is read, and in step S194, the air-fuel ratio feedback correction coefficient FAF, the purge TAU correction coefficient FPG, and the air-fuel ratio learning value KGj for each engine operating region are read.

[0048]

[Equation 11] 1+ (FAF-1) + (KGj-1) + FPG Calculated as a correction coefficient, the fuel injection amount TAU
To reflect. Next, the air-fuel ratio learning control process executed every time the FAF value is skipped will be described with reference to the flowchart shown in FIG.

When this process is executed by skipping the FAF value, in step S1702, the cooling water temperature THW is 80 ° C. or higher during the air-fuel ratio feedback, the increase after startup is 0, the increase in warm-up is 0, and the current operation is performed. When the FAF value skipped 5 times or more after entering the area, it is judged that all the learning conditions of the battery voltage of 11.5 V or more are satisfied, and if any one of the learning conditions is not satisfied, the processing ends, and if all are satisfied, Next step S1703
After reading the FAFAV value in step S170,
KG when idle depending on the result of judgment whether it is idle in 5
₀ (step S1708) and during traveling (step S171)
0), and a predetermined number (for example, 7) of areas KG _{1 to} KG ₇ depending on the load (for example, intake pipe internal pressure) during traveling.
It is divided into two parts. When the engine speed is within the predetermined engine speed in steps S1706 and S1709 (600 to 1000 rpm during idle, 10 during running).
The learning value is updated only for 0 to 3200 rpm. Furthermore, when idle, step S1707
Thus, the learning value is updated when the intake pipe pressure PM is 173 mmHg or higher.

When the difference between FAFAV and the reference value 1.0 is larger than a predetermined value (for example, 2%), the learning values KG _{0 to} KG ₇ of the respective areas are updated by learning values KG _{0 to} KG 7.
_This is done by increasing or decreasing ₇ by a predetermined value (K%, L%) (steps S1711-S1714). Finally, the upper and lower limits of KGj are checked (step S17).
15). Here, the upper limit value of KGj is set to 1.2, the lower limit value is set to 0.8, and the upper and lower limit values can be set for each engine operating region. The learning values KG _{0 to} KG ₇ in each area are backed up by a power source so that the memory values can be retained even after the key switch is turned off.
Of course, it is stored in.

In the present embodiment, step S70.
6 and step S712 are the purge flow rate delay detection means,
Step S194 corresponds to the fuel injection amount correction means and functions. Next, as another embodiment, a purge flow rate correction coefficient KNQPG detection process using air-fuel ratio feedback control will be described with reference to the flowchart shown in FIG. It should be noted that this flowchart is executed at predetermined time intervals after the ignition is turned on until the purge flow rate correction coefficient for acceleration / deceleration is detected. Also,
As the initialization processing, the correction coefficient detection flag FU during acceleration and the correction coefficient detection flag FD during deceleration are set to 0 when the ignition is turned on.

When this processing is executed, first, step S
At 829, it is determined whether both the correction coefficient detection flag FU during acceleration and the correction coefficient detection flag FD during deceleration are 1, and if both are 1, at least once after execution of this processing, the purge flow rate during acceleration / deceleration. The present processing is ended assuming that the correction coefficient is detected. If both flags are not 1, it is determined that at least one of the purge flow rate correction coefficients has not been detected after the ignition is turned on, and step S
Proceed to 801.

In step S801, it is determined whether or not the engine is idling by determining whether the idling switch is on and the vehicle speed is 0 km / h. Here, if an affirmative decision is made, the operation proceeds to step S819. If a negative decision is made, the operation proceeds to step S802. In step S802,
Whether or not the vehicle is traveling steadily is judged by judging whether the change in vehicle speed is within ± 3 km / h. Here, if an affirmative determination is made, the process proceeds to step S819, and if a negative determination is made, the present processing ends. In step S819, the learning control prohibition flag FKG is set to "1" to prohibit the air-fuel ratio learning control, and the process proceeds to step S803. In step S803, it is determined whether the purge flow rate correction coefficient detection flag XQPG is 1, and if it is 1, the process proceeds to step S812.
If not 1, the process proceeds to step S804.

In step S804, purging is stopped. Further, in step S805, purge TAU correction is prohibited. Then, in step S806, it is determined whether the average value FAFAV of the feedback correction coefficient FAF is stable at the center value 1.0. Step S if stable
If it is not stable, the procedure returns to step S805, and the same processing is repeated until the FAFAV value stabilizes at the center value. In step S807, FAFAV is -0.5 based on the evaporation concentration detected by the processing of FIG.
% (FAFAV = 0.95) to obtain the purge rate, and the purge control is executed.

In the next step S808, the actual time t _-0.5 required until FAFAV reaches -0.5% is detected. The flowchart of this real-time t _-0.5 detection processing is shown in FIG.
0, and will be described below accordingly. First, in step S821, a timer for detecting the real time t _-0.5 is started. Next, in step S822, FA
It is determined whether FAV becomes -0.5%, and if a negative determination is made, this processing is repeated until FAFAV becomes -0.5%. Then, when an affirmative decision is made, the operation proceeds to step S823. In step S823, FAFAV is-
The value of the timer when it reaches 0.5% (FAFAV = 0.95) is detected as the value of t _−0.5 and stored in the RAM.
Then, in the next step S824, the timer is reset to end the present routine, and step S809 in FIG.
Proceed to.

In step S809, the purge flow rate correction coefficient KNQPGU during acceleration is calculated by the following equation.

[0057]

## EQU12 ## KNQPGU = 1-β (t ₀ / t _-0.5 ) where β is a correction coefficient when a disturbance is considered, and t
₀ is a theoretical value of the time required for FAFAV to change from 1.0 to 0.95 when purging at the purge rate obtained in step S807. In step S810, the purge flow rate correction coefficient detection flag XQPG is set to 1, and the process proceeds to step S830. In step S830, the acceleration correction coefficient detection flag FU indicating that the purge flow rate correction coefficient KNQPGU during acceleration is detected is set to 1 and step S8 is performed.
Proceed to 11. In step S811, the purge flow rate correction coefficient KNQPGU is stored in the RAM 28, and this routine ends.

When the purge flow rate correction coefficient detection flag XQPG is not 1 in step S803, the process proceeds to step S812. In step S812, FAFAV is -5 based on the evaporation concentration detected in FIG.
Purge is executed at a purge ratio of%. Next step S
At 813, the TAU correction for purging is prohibited. Then, in step S814, it is determined whether the FAFAV value has become -5%. If a positive determination is made, step S815
If the determination is negative, the process returns to step S813 to repeat the same processing. In step S815, purging is stopped.

Then, in step S816, FAFAV
Real time t _{+ -1.0} until the value of returns to within ± 1.0%
To detect. A flow chart of this real time t _{+ -1.0} detection process is shown in FIG. 21 and will be described below. When this process is executed, a timer for detecting the real time t _{+ -1.0} is started in step S825. Next, in step S826, it is determined whether the absolute value of FAFAV has returned to within 1.0%, and if not returned, this processing is repeated until it returns, and if it is determined that it has returned, step S8
Proceed to 27. In step S827, the value of the timer when the absolute value of FAFAV returns to 1.0% is stored in the RAM as the value of t _{+ -1.0} . Next, in step S828, the timer is reset, and the process proceeds to step S817 in FIG.

In step S817, the purge flow rate correction coefficient KNQPGD during deceleration is calculated from the following equation.

[0061]

[Formula 13] KNQPGD = 1-β (t ₀ / t _{+ -1.0} ) Next, in step S818, the purge flow rate correction coefficient detection flag XQPG is set to 0, and the flow advances to step S831.
In step S831, the purge flow rate correction coefficient KN during deceleration
The deceleration-time correction coefficient detection flag FD indicating that QPGD is detected is set to 1 and the process proceeds to step S811. In step S811, the purge flow rate correction coefficient KNQPGD during deceleration
Is stored in the RAM 28, and the process proceeds to step S820. Then, in step S820, the learning control prohibition flag FKG is set to "0", and then this processing is ended.

In the above detection method, when the purge flow rate correction coefficient KNQPGU for acceleration is calculated and then the purge flow rate correction coefficient KNQPGD for deceleration is calculated immediately after, the value of FAFAV is already -0.5. %, The steps S812 to S81 in FIG.
The processes up to 4 can be omitted. Since the air-fuel ratio learning control needs to be stopped while the purge flow rate correction coefficient is being detected by the above detection method, it is necessary to additionally execute the flow chart of the air-fuel ratio learning control shown in FIG. . That is, as shown in FIG. 22, step S
When the learning control execution condition is satisfied in 1702, it is determined in step S1720 whether the learning control prohibition flag FKG is "0". If FKG is "0", the flow advances to step S1703 to execute the air-fuel ratio learning control in the subsequent processing. The details have been described with reference to FIG. 18, and are omitted here. If a negative determination is made in step S1703, the air-fuel ratio learning control is not executed and step S
Proceed to 1715. Then, in step S1715, the upper and lower limits of the learning value KGj are checked as described above, and this processing ends.

[0063]

As described above, according to the present invention, the fuel injection amount is corrected in consideration of the purge flow rate delay from the canister, so that the air-fuel ratio control can be accurately executed.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a characteristic diagram for explaining characteristics of a purge solenoid valve.

FIG. 3 is a full open purge rate map when the purge solenoid valve is fully open.

FIG. 4 is a flowchart of an air-fuel ratio control process executed by a CPU.

FIG. 5 is a time chart showing changes in the feedback correction coefficient.

FIG. 6 is a flowchart showing target idle speed control processing executed by a CPU.

FIG. 7 is a map showing target rotation speeds with respect to cooling water temperature.

FIG. 8 is a map for obtaining an opening degree of a rotation speed control valve.

FIG. 9 is a flowchart of a purge execution control process executed by a CPU.

FIG. 10 is a flowchart of a normal PGR control process executed by a CPU.

11 (a) to (e) are various characteristic diagrams generally used in PGR control processing.

FIG. 12 is a flowchart showing a purge solenoid valve control process executed by a CPU.

FIG. 13 is a flowchart of an evaporation concentration detection process executed by a CPU.

FIG. 14 is a flowchart showing a purge flow rate correction coefficient detection process executed by a CPU.

FIG. 15 is a time chart showing changes in vehicle speed, intake air amount, theoretical purge flow rate, and canister pressure during acceleration and deceleration.

FIG. 16 is a flowchart of TAU correction coefficient calculation processing executed by a CPU.

FIG. 17 is a flowchart of a fuel injection amount control process executed by a CPU.

FIG. 18 is a flowchart of air-fuel ratio learning control executed by a CPU.

FIG. 19 is a flowchart showing a purge flow rate correction coefficient detection process executed by the CPU of another embodiment.

FIG. 20 is a flowchart showing a real-time t _−0.5 detection process executed by a CPU.

FIG. 21 is a flowchart showing a real-time t _{+ -1.0} detection process executed by the CPU.

FIG. 22 is a flowchart showing an air-fuel ratio learning control process executed by a CPU of another embodiment.

[Explanation of symbols]

1 engine 2 intake pipe 3 exhaust pipe 12 O ₂ sensor 15 fuel injection valve 17 canister 23 purge control valve 25 electronic control circuit 38 canister pressure sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02M 25/08 301 MN (72) Inventor Maeda One, 1-chome, Showa-cho, Kariya city, Aichi Japan Denso Co., Ltd.

Claims (3)

[Claims] 1. A canister having an adsorbent for adsorbing fuel evaporative gas generated in a fuel tank containing a liquid fuel, and a purge flow rate for detecting a purge flow rate delay generated when purging the fuel evaporative gas from the canister. A fuel injection amount control device for an internal combustion engine, comprising: a delay detection unit; and a fuel injection amount correction unit that corrects a fuel injection amount based on a detection result of the purge flow rate delay detection unit. 2. A canister pressure detecting means, which is provided in a supply pipe through which fuel vaporized gas purged from the canister flows, for detecting a pressure in the vicinity of the canister, and within a predetermined period of at least one of acceleration and deceleration. A theoretical purge flow rate calculation means for calculating a theoretical value of the purge flow rate purged from the canister, wherein the purge flow rate delay detection means is detected by the calculation result of the theoretical purge flow rate calculation means and the canister pressure detection means. 2. The fuel injection amount control device for an internal combustion engine according to claim 1, further comprising means for detecting a purge flow rate delay based on a pressure change amount near the canister that has changed within the predetermined period. 3. At least one of air-fuel ratio control means for performing feedback control so that the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine becomes a target air-fuel ratio, and at least one of idle running or steady running in which the vehicle speed hardly changes. In the operating state, the purge flow rate is set so that the target air-fuel ratio deviates by a predetermined value, and a theoretical period calculation unit that calculates a theoretical value of a period required to shift by the predetermined value is provided. The detection means sets the purge flow rate so that the target air-fuel ratio shifts by the predetermined value in the operating state, and actually measures the period required for the target air-fuel ratio to shift by the predetermined value, and this value 2. The fuel injection amount control device for an internal combustion engine according to claim 1, further comprising means for detecting a purge flow rate delay from the theoretical value and the theoretical value.