JPH07109937A - Fuel injection quantity control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To restrict deterioration of air-fuel ratio controllability due to the pressure loss in a purge piping or in a canister. CONSTITUTION:When not-purged flag XIPGR is zero, the number of revolutions NE of an engine 1 is read from output of an engine speed sensor 37. The intake pipe pressure PM is then read from output of a pressure sensor of an intake pipe 2 so as to calculate the difference between the intake pipe pressure and the atmospheric pressure. Further, the pressure PCN between a canister 17 and a purge control valve 23 is read to calculate the difference between the intake pipe pressure PM and it. A purge-flow correction factor KNQPG is then determined by the following formula; KNQPG=alpha{(PCN-PM)/(ATP-PM)}<1/2>. The purge- flow correction factor determined by the formula is reflected in the calculation of the fuel injection quantity.

Description

Detailed Description of the Invention

More particularly, the present invention relates to a fuel injection amount control device for an internal combustion engine equipped with a fuel evaporative gas diffusion preventing 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
According to Japanese Patent No. 9243, correction of the fuel injection amount by purging is performed separately from the feedback correction at the time of executing the purge, and the purge correction amount is set according to the evaporated fuel concentration obtained from the average value of the feedback correction coefficient to control the air-fuel ratio. Is improving.

[0003]

However, since the actual purge flow rate is actually lower than the calculated control purge rate due to the pressure loss of the purge pipe and the canister, the air-fuel ratio controllability is deteriorated especially in the transient state. , Problems that affect emissions and drivability are occurring. In particular, in recent years, regulations regarding evaporated fuel have become stricter, and it is considered to mount a large-sized canister in the rear part of the vehicle, 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, which suppresses deterioration of air-fuel ratio controllability due to pressure loss of a purge pipe and a canister.

[0005]

Therefore, in the present invention, a canister having an adsorbent for adsorbing the fuel evaporative gas generated in the fuel tank containing the liquid fuel, and the fuel evaporative gas adsorbed by the canister are predetermined. When the target purge flow rate calculating means for calculating the flow rate to be purged into the intake pipe based on the condition of (1) and the flow rate calculated by the target purge amount calculating means are purged, the actual purge flow rate actually purged from the canister is calculated. An actual purge flow rate detecting means for detecting, and a decrease amount detecting means for detecting a decrease amount of the actual purge flow rate based on the flow rate calculated by the target purge flow rate calculating means and the flow rate detected by the actual purge flow rate detecting means. And an injection amount correction unit that corrects the fuel injection amount based on the decrease amount detected by the decrease amount detection unit. A fuel injection control device for an internal combustion engine that.

[0006]

The target purge flow rate calculating means calculates the flow rate for purging the fuel vaporized gas adsorbed by the canister into the intake pipe under a predetermined condition. Further, the actual purge flow rate detecting means detects the actual purge flow rate actually purged from the canister when the flow rate calculated by the target purge amount calculating means is purged.

The decrease amount detecting means detects the decrease amount of the actual purge flow rate based on the flow rate calculated by the target purge flow rate calculating means and the flow rate detected by the actual purge flow rate detecting means. The injection amount correction means corrects the fuel injection amount based on the decrease amount detected by the decrease amount detection means.

[0008]

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 the canister 17 by a communication pipe 16, and the canister body 1
An adsorbent 19 for adsorbing the fuel evaporative gas, for example, activated carbon is accommodated in the inside 8. As a result, the fuel tank 13
The fuel evaporative gas generated therein 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 valve 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 almost linearly as the percentage increases from%. 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, intake pipe pressure, other intake air amount, 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 valve 23 is 100% with respect to the total amount of air flowing in is stored in the ROM 27.

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 air-fuel ratio feedback control 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.

When the feedback control condition is satisfied, the CPU 26 determines from the signal from the O ₂ sensor 12 whether or not the air-fuel ratio is rich in step S102. If it is 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.

Further, in the case of lean in step S102, the CPU 26 determines in step S106 whether or not the state is changed from rich to lean in comparison with the previous detection result. 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
In addition to AF, if there is no inversion from rich to lean, feedback correction coefficient FAF + β in step S108.
(Β is the integrated amount) is a new feedback correction coefficient FAF
And

Therefore, steps S102 to S108
If there is a reversal between rich and lean by the processing of step S1, the feedback correction coefficient FAF is stepwise changed (skip) to increase or decrease the fuel injection amount, and at the time of rich or lean, the feedback correction coefficient FAF is gradually increased or decreased. . 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 base routine of the CPU 25 about every 4 _ms . In step S501, it is determined whether the air-fuel ratio F / B is in progress, and in step S50
2 determines whether the cooling water temperature is 50 ° C or higher, and the air-fuel ratio F /
When the water temperature in B is a predetermined value of 50 ° C. or higher, step S505
If it is determined that the fuel is not being cut. If it is determined that the fuel is not being cut, the process proceeds to step S506 to perform the normal purge rate control, and then the purge non-execution flag XIPGR is set in step S507 to execute the purge rate control. Set to 0.
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 solenoid valve control routine executed by the CPU 21 by interrupting every 100 _ms . In step S161, the purge non-execution flag X
When IPGR is 1, the routine proceeds to step S163, where the duty of the purge solenoid valve 16 is set to 0. Otherwise, the process proceeds to step S164, and if the drive cycle of the purge solenoid valve 16 is 100 _ms ,

[0024]

## EQU1 ## Duty = (PGR / PGR _fo ) × (100 _ms
The duty of the purge solenoid valve 16 is calculated by the equation −P _Y ) × P _pa + P _Y. Here, PGR is the purge rate obtained in FIG. 10, P
GR _fo is a purge rate in each operating state when the purge solenoid valve 16 is fully opened (see FIG. 3), P _Y is a voltage correction value for battery voltage fluctuations, and P _pa is an atmospheric pressure correction value for atmospheric pressure fluctuations. .

FIG. 13 shows the main routine for the evaporation concentration detection which is executed in the base routine of the CPU 25 about every 4 _ms . First, if the key switch is turned on in step S300, the process proceeds to steps S315, S316, and S317 to set the evaporation concentration FGPG and the evaporation concentration average value FGPGAV to 1.0.
First, the initial concentration detection flag XNFGPG is initialized to 0. After turning on the key switch in step S300, first,
If the purge control is started in step S301 and the purge non-execution flag XIPGR is not 1, step S302
If the flag XIPGR is 1 and the purge control has not been started yet, the concentration detection ends. In step S302, it is determined whether acceleration / deceleration is being performed.
Here, whether the acceleration / deceleration is being performed is determined by the idle switch,
A generally well-known method may be used by detecting a change in throttle valve opening, a change in intake pipe pressure, 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 S45 of FIG. 4 is a predetermined value (ω%) or more, and if not, the process is ended as it is, and if it is more than the next step S308. Go to,
Detect the evaporative concentration. 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 becomes 1 when the evaporation concentration in the discharge passage 15 is 0 (air is 100%), and becomes smaller than 1 as the evaporation concentration in the discharge passage 15 increases. It is set. Here, in step S308 of FIG.
AFAV and 1 may be replaced with each other, and the evaporative concentration may be obtained by setting the value of FGPG to a value larger than 1 as the evaporative concentration increases.

Then, in the next step S309, it is judged whether or not the initial concentration detection end flag XNFPGG is 1, and when it is not 1, the process proceeds to the next step S310, and when it is 1, the steps S310 and S311 are bypassed and the process proceeds to step S312. Then, in step S310, the evaporation concentration FGP
The change between the previous detection value and the current detection value of G is a predetermined value (θ%)
It is determined whether or not the evaporative concentration is stable for three or more times, and when the evaporative concentration is stable, the process proceeds to the next step S311, the initial concentration detection end flag XNFGPG is set to 1, and then 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 purge flow rate correction coefficient detection process, which is a feature of the present invention, will be described. FIG. 14 is a flowchart showing a purge flow rate correction coefficient detection process using the canister pressure sensor 38. Hereinafter, description will be given according to this flowchart. In this embodiment, the pressure difference is detected instead of detecting the flow rate. When this process is executed, first, in step S701, it is determined whether the purge incomplete flag XIPGR is 1. If it is 1, the process is ended as it is, and if it is 0, the engine speed NE is read from the output of the speed sensor 37 in the next step S702. Next, in step S703, the intake pipe pressure PM is read from the output of the intake pipe pressure sensor and the difference from the atmospheric pressure is calculated.
Further, in step S704, the canister pressure sensor 3
The pressure _PCN between the canister 17 and the purge control valve 23 is read from 8, and the difference with the intake pipe pressure PM read in step S704 is calculated. Then, step S705
In, the purge flow rate correction coefficient KNQPG is calculated from the following equation.

[0030]

[Number 2] _{KNQPG = α {(P CN -PM} ) / (ATP-
PM)} ^1/2 Here, α is a coefficient when the disturbance is taken into consideration, and is set so that the value of the above equation becomes 1 when the canister 17 is new. ATP is atmospheric pressure. In other words, when the canister 17 is new, the value of P _CN becomes almost atmospheric pressure, so assuming that there is no disturbance, the value in the parenthesis on the right side of the above expression is 1. Then, since the pressure loss increases as the canister 17 ages, the values of P _CN is reduced, the actual purge flow rate is reduced.

Then, the process proceeds to step S706, and based on this value, it is stored in the RAM as a map of the engine speed NE. Next, the purge flow rate correction coefficient detection processing using idle speed control (ISC) will be described with reference to the flowchart shown in FIG. When this processing is executed, in step S801, it is determined whether or not the engine is idling, and if it is not idling, this processing is ended as it is, and if it is idling, the next step S80.
Go to 2. In step S802, it is determined whether the purge incomplete flag XIPGR is 1. If it is 1, this process is terminated as it is, and if it is not 1, the process proceeds to step S803. In step S803, the theoretical purge flow rate QPG is calculated from the following equation.

[0032]

## EQU3 ## QPG = QA × PGR where QA is the flow rate when the purge rate is 100%.
Next, in step S804, the ISC correction flow rate QISC is obtained. Then, in step S805, the purge flow rate correction coefficient KNQPG _IDL at idle is obtained from the following equation.

[0033]

[Formula 4] KNQPG _IDL = QISC / QPG That is, when the canister 17 is new, the theoretical (target) purge flow rate QPG to be purged becomes equal to the ISC correction flow rate that corrects the ISC amount by the actual purge flow rate. Therefore, the value of the above equation is 1. When the canister 17 becomes old, the actual purge flow rate becomes smaller than the theoretical purge flow rate QPG calculated as the flow target, and the correction is performed accordingly.

Next, at step S806, the idling purge flow rate correction coefficient K obtained at step S805.
Based on NQPG _IDL , KNQPG for each engine speed N _e is calculated from the following equation.

[0035]

KNQPG = KNQPG _IDL × α (N _e / N _eIDL ) ^1/2 Then, the obtained value is updated and stored in the RAM ₂₈ as a one-dimensional map for the engine speed N _e . Next, the calculation routine of the purge TAU correction coefficient FPG is shown in the flowchart of FIG. 16, and will be described below according to this flowchart.

When this routine is executed, step S
In 901, it is determined whether the purge non-execution flag XIPGR is 1, and if it is 1, the purge TAU correction coefficient FPG is set to 0 in step S909, and this routine is ended. When it is 0, in step S902, the theoretical purge flow rate QPG is obtained from the following equation.

[0037]

QPG = QA × PGR Next, in step S903, the purge flow rate correction coefficient KNQPG corresponding to the current engine speed N _e is read. In the next step S904, the actual purge flow rate QPGSM
Is calculated from the following equation.

[0038]

## EQU00007 ## QPGSM = QPG.times.KNQPG Further, in step S907, the actual purge rate PGRSM is obtained from the following equation.

[0039]

PGRSM = QPGSM ₁ / QA Then, in step S908, the purge TAU correction coefficient FPG is calculated by the following equation.

[0040]

## EQU9 ## FPG = FGPGAV × PGRSM FIG. 17 is a flowchart showing the fuel injection amount control processing. Hereinafter, description will be made according to this. When this processing is executed, first, in step S191, the ROM 2
Based on the data stored as a map in FIG. 7, the basic injection amount TP is obtained from the engine speed and load (for example, intake pipe pressure), and various basic corrections (cooling water temperature correction, post-starting correction, intake air temperature correction) are performed in step S192. Etc.).
Then, in the next step S193, the purge TAU correction coefficient FPG is read, and in the next step S194, FA
Air-fuel ratio learning value K for each F, FPG engine operating range
Gj,

[0041]

[Mathematical formula-see original document] The fuel injection amount TAU is obtained as a correction coefficient by the calculation of 1+ (FAF-1) + (KGj-1) + FPG.
To reflect. In this embodiment, step S7
03 or step S803 to the target purge flow rate calculation means, step S704 or step S804 to the actual purge flow rate detection means, and step S705 or step S705.
Reference numeral 805 corresponds to the decrease amount detecting means, and step S908 corresponds to the injection amount correcting means, and functions.

[0042]

As described above, according to the present invention, the decrease in the actual purge flow rate of the canister is detected and the fuel injection amount is corrected according to the detected value, so that the air-fuel ratio can be accurately controlled. You can

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an internal combustion engine using the present invention.

FIG. 2 is a characteristic diagram showing characteristics of a purge control valve.

FIG. 3 is a characteristic diagram showing a purge rate characteristic of a canister.

FIG. 4 is a flowchart showing air-fuel ratio feedback control.

5 is a time chart showing changes in the air-fuel ratio when the process of FIG. 4 is executed.

FIG. 6 is a flowchart showing target idle speed control.

FIG. 7 is a map for obtaining a target rotation speed with respect to a cooling water temperature.

FIG. 8 is a map for obtaining a control opening amount corresponding to a deviation in rotation speed.

FIG. 9 is a flowchart showing purge execution control.

FIG. 10 is a flowchart showing a normal purge rate control subroutine.

11A to 11E are various characteristic diagrams used in the normal purge rate control subroutine in each of the above-described embodiments.

FIG. 12 is a flowchart showing control of a purge control valve.

FIG. 13 is a flowchart showing a process for detecting the evaporation concentration.

FIG. 14 is a flowchart showing a purge flow rate correction coefficient calculation process.

FIG. 15 is a flowchart showing a purge flow rate correction coefficient calculation process.

FIG. 16 is a flowchart showing a TAU correction coefficient calculation process for purging.

FIG. 17 is a flowchart showing fuel injection amount control.

[Explanation of symbols]

 1 Engine 7 Bypass Passage 8 Rotation Speed Control Valve 15 Fuel Injection Valve 16 Communication Pipe 17 Canister 23 Purge Control Valve 25 Electronic Control Circuit 38 Canister Pressure Sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) One inventor, Maeda, Nihon Denso Co., Ltd., 1-1, Showa-cho, Kariya city, Aichi prefecture

Claims (1)

[Claims] 1. 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 adsorbed by the canister is purged into an intake pipe based on a predetermined condition. Target purge flow rate calculating means for calculating the flow rate to be performed, and actual purge flow rate detecting means for detecting the actual purge flow rate actually purged from the canister when the flow rate calculated by the target purge amount calculating means is purged, A decrease amount detecting unit that detects a decrease amount of the actual purge flow amount based on the flow rate calculated by the target purge flow amount calculating unit and the flow amount detected by the actual purge flow amount detecting unit, and is detected by the decrease amount detecting unit. And a fuel injection amount correction means for correcting the fuel injection amount based on the reduced amount. .