JP3531213B2 - Evaporative fuel processing control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a canister for evaporating fuel.
Internal combustion engine that stores it in the air and discharges it to the intake passage for processing
The present invention relates to an evaporative fuel processing control device of Seki. [0002] 2. Description of the Related Art Conventionally, fuel is supplied to a fuel tank by a fuel pump.
To the fuel injectors of the internal combustion engine,
Surplus fuel that was not injected is sent back to the fuel tank.
Is done. At this time, since the fuel injection valve is hot,
The fuel sent back to the tank becomes hot, and the fuel temperature in the tank
Degree may rise. Also, while the engine is stopped and the outside temperature
Fuel tank heats up when fuel is high, fuel temperature rises
Sometimes. Therefore, internal combustion engines mounted on automobiles, etc.
Is the evaporation generated from the fuel in the hot fuel tank.
Fuel (hereinafter referred to as purge gas)
As the pressure rises, purge gas is released to the atmosphere.
You. However, the purge gas is released to the atmosphere as it is
For example, conventional cars may have
Equipped with a device that traps purge gas called
The purge gas is adsorbed. And suck into the canister
The purge gas is supplied to the intake passage of the internal combustion engine during engine operation.
Combustion (hereinafter, referred to as purge)
Then, the purge gas is processed. This kind of internal combustion engine
Many evaporative fuel processing control devices have been disclosed in the past.
Among them, for example, JP-A-04-72453 discloses the following:
The following points are disclosed. With the prior art of the above publication
Is shown in the exhaust system of the engine.
Air-fuel ratio sensor installed to control engine air-fuel ratio to stoichiometric air-fuel ratio
In the air-fuel ratio feedback control device to be
Purge control to control the flow rate of purge gas at the start of purge
The duty ratio indicating the opening of the valve is
If the method of increasing by a constant value is used, rapid acceleration or
Will respond to sudden changes in the amount of intake air when there is deceleration.
Change in purge gas volume from the canister follows with good response
The air-fuel ratio feedback correction coefficient
There was a problem that the movement became large and the air-fuel ratio was disturbed.
In the above publication, the purge system is
By quickly changing the duty ratio of the valve,
The fluctuation of the air-fuel ratio was kept small. However, the intake air amount
Response of purge control valve or purge control valve, or purge control valve
Of the purge control valve in the purge passage from
That the purge gas exists before the ratio changes
There is a response delay. For this reason, the amount of intake air
Accuracy even if the purge control valve is changed according to the change
The fluctuation of the air-fuel ratio cannot be suppressed well. In particular, inhalation
At the time of deceleration that changes suddenly from when the air volume is large to when it is small
Is the ratio of the purge flow rate to the intake air amount after deceleration.
In contrast, the fluctuation due to purge is large, and
The effect on the air-fuel ratio is significant. In addition, par
When the fuel concentration is high, the purge passage
Gas before the duty ratio of the charge control valve changes
Air-fuel ratio fluctuates even more
Even if the purge control valve is controlled by the above conventional technology,
The ratio fluctuates greatly and the engine output torque becomes unstable
There is a problem. In the present invention, the purge air has a high concentration
If the amount is large, change the duty ratio of the purge control valve.
Response to sudden changes in operating conditions.
To change the duty ratio of the purge control valve
Control the duty ratio so that the desired air-fuel ratio is always obtained.
The porpose is to do. [0003] [MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
The present invention has the following configuration. Evaporated fuel temporarily
Store canister and evaporative fuel in intake passage of internal combustion engine
A purge line that connects to the canister intake passage for purging
Controls the flow rate of purge gas flowing through the purge passage and the purge passage
Control valve and the control valve opens as the intake air amount of the internal combustion engine increases.
And a purge flow control means M1 for controlling the flow rate greatly.
In the evaporative fuel processing control device of the fuel engine,
Purge to detect the fuel concentration of the purge gas to be purged
The purge concentration detected by the concentration detector exceeds a predetermined value.
Is set by the purge flow rate control means M1.
Control valve openingDo not increase more than the specified openingPurge flow
It is characterized in that a limiting means M2 is provided. [0004] According to the steam fuel processing control device of the present invention, the purge concentration is controlled.
When the degree is within the specified value, purge control is performed as the intake air amount increases.
By increasing the valve opening, evaporative fuel is
Evaporates to the maximum amount of fuel vapor that does not affect operating conditions
Fuel is purged into the intake pipe. Also, the purge concentration
If it exceeds the specified value, the amount of intake air exceeds the specified value.
By not increasing the control valve beyond the specified opening,
At the time of deceleration when the amount of incoming air suddenly changes from large to small
However, since the control valve opening was originally small, much purge gas was used.
It is not introduced into the intake pipe and does not cause air-fuel ratio
No. [0005] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Will be described. FIG. 2 is a schematic diagram showing an embodiment of the present invention.
The internal combustion engine 10 includes an intake manifold 1 in an engine body 11.
2 and the exhaust manifold 13 are connected, and the intake manifold
The fuel injection valve 14, which is a fuel supply means M3,
Installed. Also, each intake manifold 12 has
A common surge tank 15 and intake duct 16 are connected,
An air cleaner 18 is connected upstream of the intake system.
You. A throttle valve 19 is provided in the intake duct 16.
The intake air amount flowing through the intake manifold 12 is controlled.
You can control. The throttle valve 19 has a slot
Slot that turns on when the valve 19 is idling
The throttle switch 38 is attached
The output of 38 is input to the input port 35. In addition,
The internal combustion engine 10 has an evaporation purge system 22.
You. One of the elements constituting the evaporation purge system 22
One is the canister 21, and the inside of the canister 21 is
Activated carbon 20 is built in, and fuel is
A steam chamber 23a and an atmosphere chamber 23b are provided. Fuel steam
On the other hand, the fuel chamber 23a is connected to the fuel tank via the vapor passage 24.
Connected to the pump 25, and on the other hand,
Connected to the storage tank 15. In the purge passage 26
Is controlled by an output signal of the electronic control unit 30
A purge control valve 27, which is a purge flow control means M1, is provided.
Have been. Also, the fuel tank generated in the fuel tank 25 is
The paper is fed into the canister 21 through the vapor passage 26.
And is adsorbed by the activated carbon 20. Where the intake passage
Means each intake manifold 12, common surge tank 1
5, the intake duct 16 and the like. When the purge control valve 27 is opened, the air becomes large.
Sent from the air chamber 23b through the activated carbon 20 into the purge passage 26
Get stuck. When the air passes through the activated carbon 20, the activated carbon
Fuel vapor adsorbed on 20 is released from activated carbon 20
And the air containing the fuel vapor passes through the purge passage 26.
Purged into the surge tank 15. Electronic control unit
30 comprises a digital computer, a bidirectional bus
ROM (read only memory)
Memory) 32, RAM (random access memory) 33,
CPU (microprocessor) 34, B-RAM (bat
Backup-random access memory) 46, input port
35, and an output port 36. Also, surge
The tank 15 has an intake pressure sensor 17 for measuring the intake pressure.
Is provided. The intake pressure is determined by the intake pressure sensor 17.
The output signal is detected via an A / D converter 37.
It is input to the input port 35. Here, the internal combustion engine 10
During operation, the pressure in the surge tank 15
The greater the valve opening of the internal combustion engine 10 is, that is,
The greater the amount of intake air supplied to the air, the closer to atmospheric pressure
Small opening of throttle valve 19 and small amount of intake air
, The negative pressure becomes. That is, the detection of the intake pressure sensor 17 is performed.
The output value indicates a value corresponding to the intake air amount of the internal combustion engine 10.
ing. [0007] The engine body 11 has a temperature proportional to the engine cooling water temperature.
Water temperature sensor 39 that generates the output voltage
The output voltage of the water temperature sensor 39 is supplied through an A / D converter 40.
And input to the input port 35. Exhaust manifold 1
3 has an air-fuel ratio sensor (O_TwoSensor) 41 attached
The output signal of the air-fuel ratio sensor 41 is
2 to the input port 35. In addition, the input port
The crankshaft rotates at, for example, 30 ° CA
Crank angle sensor 43 that generates an output pulse every time
Is connected. In the CPU 34, based on this output pulse,
Then, the engine speed (NE) is calculated. On the other hand, the output port
The fuel injection via the corresponding drive circuits 44 and 45
Connected to valve 14 and purge control valve 27. And
For other components, the electronic control unit 3
0 executes a later-described program stored in the ROM 32.
It is realized by doing. Hereinafter, the electronic control unit 30
Of the processing executed by the server and the accompanying operation of the apparatus of this embodiment.
The work will be described. First, the air-fuel ratio control device in the device of this embodiment
About the air-fuel ratio feedback control
4 and FIG. 5 will be briefly described. FIG.
Child control unit 30 is O_TwoBased on the output signal of the sensor 41
Of the main part of the feedback control unit
The chart is shown. Here, the air-fuel ratio feedback control
Means O_TwoBased on the oxygen concentration signal generated by the sensor 41
Detects air-fuel ratio of air-fuel mixture actually supplied to internal combustion engine 10
The fuel injection amount to bring the air-fuel ratio closer to the stoichiometric air-fuel ratio.
Is a control for correcting When performing such air-fuel ratio control
Calculation, the stoichiometric air-fuel ratio can be calculated according to the intake air amount
Empty enough to set the reference fuel injection amount calculated as
Exceptionally superior air-fuel ratio accuracy is ensured compared to the fuel-ratio control device
Can be The specific processing is described below with reference to FIG.
Explain the contents. Note that the routine shown in FIG.
By multiplying the reference fuel injection amount calculated according to the amount,
A feedback correction coefficient FAF that realizes appropriate correction
This is an interrupt routine that calculates and is started at regular intervals.
It is what is done. When the routine shown in FIG.
O in step 200_TwoThe sky emitted by the sensor 41
The fuel ratio signal V is detected. As described above, the internal combustion engine 10
O of exhaust gas discharged from_TwoInternal combustion engine based on concentration
10 to detect the air-fuel ratio of the mixture actually supplied
It is. When the air-fuel ratio signal V is detected, the process proceeds to step 202.
Then, the value of the air-fuel ratio signal V becomes equal to the voltage E representing the target air-fuel ratio.
It is determined whether it is higher than or not. This makes the real sky
Determines whether the fuel ratio is rich or lean
To do that. When V> E (when the target air-fuel ratio
If it is lean), go to step 204
It is determined whether or not it was lean at the time of the interruption. now
The detected leans are continuous leans,
To determine if it is lean after reversing
It is. If it was not lean at the time of the last interrupt
Decides that it has reversed from rich to lean,
06 and the feedback correction coefficient FAF at this time
Is stored as FAFR, and the process proceeds to step 208.
Add skip value S to FAF and end the current process
You. On the other hand, in step 204, the previous split
If you are determined to be lean even at the time of
Proceeding to step 210, a predetermined step value K is stored in the FAF.
(K≪S) is added, and the current process ends. Therefore,
As shown in FIG._TwoDetect by sensor
When the calculated air-fuel ratio is reversed from rich to lean
(In FIG. 5, time t₁), Feedback correction coefficient FAF
Is rapidly increased by the skip value S (see the above-described steps).
204-208). After that, the state of the fuel
If it continues (the cycle in FIG. 5), the step value K is added
, The FAF is gradually increased. In contrast
In step 202, V> E is not satisfied (exhaust gas empty).
If it is determined that the fuel ratio is rich, step 2
Proceed to step 12 to determine if the previous interrupt was rich
Judge. When it was not rich at the last interrupt
Decides that it has turned rich from lean and step 2
Proceed to 14. In step 214, the file at this point is
The feedback correction coefficient FAF is stored as FAFL.
You. Then, in step 216, the FAF skips
The current processing is terminated after subtracting the step value S. On the other hand,
In step 212, the rich
If it is determined that the
Subtract the step value K from AF and end the current process
You. Therefore, as shown in FIG.
Changes from lean to rich (in FIG. 5, time
t_Two), The feedback correction coefficient FAF is the skip value S
Only abruptly, and then the lean state continues
Then, it gradually decreases as the step value K is subtracted.
You. Thus, the feedback correction coefficient FAF is_Two
The value is varied according to the air-fuel ratio detected by the sensor 41.
You. And, for example, if the rich state continues,
Decrease the fuel injection amount by decreasing the value to change from rich to
The fuel injection amount in order to increase the fuel injection amount.
Update its value to a large value. Therefore, the reference fuel injection
If the quantity is calculated with appropriate precision, multiply by FAF
By making the correction, the amount of fuel injected into the internal combustion engine can be precisely adjusted.
Is controlled to a value that can achieve the target air-fuel ratio
Excellent air-fuel ratio accuracy can be ensured. Control of fuel injection amount in the present embodiment
Is controlled by controlling the duty of the fuel injection valve 14.
Run. Therefore, the fuel supplied to the internal combustion engine 10 is:
This corresponds to the time during which the fuel injection valve 14 is open. This
Therefore, the standard fuel injection amount is
TAU, and the corrected fuel injection amount is TAU '.
Expressing each, the fuel injection time TA as shown in the following equation (1)
U can be corrected.   TAU '= TAU × FAF (1) Step 220 is performed by the above-described supplied fuel amount calculating means M.
Equivalent to 2. As described above, the fuel for the internal combustion engine of the present embodiment is
The steam processing control device is controlled by the evaporative purge system 22.
When a fuel purge is performed, the
The fuel injection time TAU is corrected, and the purge rate is corrected.
This is a configuration in which the fluctuation is reflected in the correction coefficient. Because of this,
The purge rate fluctuates according to the operating state of the fuel engine 10.
Even in such a case, an appropriate air-fuel ratio can always be ensured. In this embodiment, the air-fuel ratio control is performed.
Along with feedback control to improve accuracy
Although it is illustrated about the case where it is used, it is not limited to this.
For example, the purge rate and the TAU correction coefficient are
Actual pars that are stored as
The correction coefficient value is determined by referring to the map with the
You may. When adopting such a configuration, the control content
The air-fuel ratio can be simplified and the actual purge rate varies.
Displacement can be appropriately prevented, and the above-described embodiment device
It can be realized very easily as compared with. FIG.
Calculate the reference duty ratio DPGB of the purge control valve 27
Of the reference duty ratio calculation routine to be executed
The chart is shown. This routine is executed every predetermined time.
For example, the interrupt routine is started every 16 ms. Same figure
When the routine shown in FIG.
And the ratio of the optimal purge flow rate to the intake air quantity
Calculate the target purge rate. This target purge rate is
10 may be selected as appropriate according to the operating state of the system, etc.
You can set the value appropriately or set a constant value.
No. After calculating the target purge rate in this way,
Purge flow that can proceed to step 102 and achieve the target purge rate
Calculate the amount. Here, the purge flow rate is determined by the intake pressure sensor 1
7 and suction calculated based on the detection value of the water temperature sensor 39, etc.
It is calculated by multiplying the air amount QA by the target purge rate.
You. When the purge flow rate to be achieved is calculated,
In step 104, a data that allows the purge flow rate to flow
The duty ratio is calculated through the drive circuit 45.
The purge control valve 27 is duty-driven to terminate the current process.
Complete. The long-term average air-fuel ratio correction coefficient shown in FIG.
Refer to the flowchart of the routine for obtaining the FAFSM.
Next, the processing contents will be described. The process shown in Fig. 5 starts
Then, first, in step 300, the feedback compensation is performed.
On the basis of the positive coefficient FAF, the long-term average air-fuel ratio
Find the positive coefficient FAFSM.   FAFSM = FAFSM + (FAF−FAFSM) / N (2) In equation (2), the FAFSM on the right side is
And the FAF is the value calculated above.
N indicates the smoothing constant,
You. In other words, the FAFSM is calculated earlier than the current FAF.
Subtracted FAFSM and divide it by the smoothing constant N
The calculated value is converted to the previously calculated FAFSM
The value is the sum of the values. That is, FAFSM is
This is an average value for a relatively large period. Therefore,
In the fuel engine 10, the air-fuel ratio is accurately adjusted to near the stoichiometric air-fuel ratio.
If maintained, the value of FAFSM is close to 1.0.
When the air-fuel ratio is biased to the rich side, FAFSM
Less than 1.0, and the overall air-fuel ratio is leaner
If the value of FAFSM is larger than 1.0,
Value. That is, the value of FAFSM is
When the supplied mixture is observed for a relatively long period
Shows the degree of deviation from the stoichiometric air-fuel ratio
Will be. After obtaining FAFSM in this way,
In step 302, the value of | FAFSM-1.0 |
Is greater than a predetermined value, for example, 0.02.
Determine. Air-fuel ratio of air-fuel mixture supplied to internal combustion engine 10
However, the fuel rich side or fuel lean side exceeds the specified level
This is to determine whether or not there is a bias. The air-fuel ratio is biased beyond a predetermined level.
If it is determined that the fuel is
And proceed to steps 304 and 306.
The purge concentration learning value FGPG is calculated according to the following equation.
Is completed.   FGPG = (FAFSM-1.0) / (purge rate) (3) In the above equation (3), the FAFSM on the right side is the above step.
This is calculated at 300. Equation (3)
The purge rate in the routine shown in FIG.
Calculated in step 100, the purge control valve
Purge flow rate determined by the opening degree of 27 and intake pressure sensor 17
Calculated from the ratio to the intake air amount estimated from the output of the
The purge rate. In contrast, FAFSM-1.0 is acid
It is the deviation of the output of the elementary sensor.
Represents the mass of fuel generated. That is, the predetermined purge rate
When fuel is purged at (FAFSM-1.0)
(Purge rate)
The purge concentration can be represented. In step 302, | FAF
SM−1.0 | exceeds a predetermined value α (for example, 0.02)
Is updated only when there is an error.
When the calculation value of FAFSM fluctuates temporarily due to
And the effect of this disturbance is not reflected in FGPG
This is to guard. Purge densitometry as described above
By calculating the learning value FGPG, the purge concentration can be adjusted appropriately.
Can be detected. By the way, step 30
The FGPG calculated in 4 is calculated with 1.0 as the center.
Indicates the magnitude of the air-fuel ratio deviation per unit purge rate.
If the fuel ratio is biased toward the fuel rich side, the value should be 1.0
The smaller coefficient is as described above. This
The purge concentration learning value shown here is the purge concentration learning value of this embodiment.
It corresponds to the degree detecting means M4. Next, the control duty ratio shown in FIG. 7 is determined.
This will be described with reference to the flowchart shown in FIG. Processing shown in FIG.
Starts, in step 400, purge control
Reference duty ratio DPGB for duty control of valve 27
Is calculated. Here, the reference duties shown in FIG.
This shows a program for calculating a duty ratio. Thus, the base
After calculating the quasi-duty ratio DPGB, the next step 4 is
02, the suction air per revolution of the crankshaft
The air volume GN is calculated. Here, once the crankshaft
The intake air amount GN per turn is determined by the engine speed Ne and the intake pressure.
Based on the operating conditions such as the detection values of the sensor 17 and the water temperature sensor 39, etc.
It is calculated based on Then, the intake air amount GN was calculated.
From this, the intake air amount GN is 0.8 [g / rev. ] And ratio
It is determined whether or not all are large. This allows for acceleration
This is for determining whether or not the intake air amount is large. So
When GN> 0.8 (the intake air amount during acceleration etc. is large)
If the purge concentration learning value
It is determined whether FGPG is smaller than 0.9. Par
This is to determine whether or not the density is high. And
When FGPG <0.9 (when the purge fuel concentration is high)
Proceeds to step 406. Here, purge concentration rich
Limit the duty ratio DPGG during acceleration to 25%
It proceeds to step 408. And DPGG
Is greater than the reference duty ratio DPGB.
Refuse. Thus, the current reference duty ratio DPGB
Is to determine whether or not the area is to be controlled. Soshi
When DPGG <DPGB (the current reference duty
(When the ratio is large), the routine proceeds to step 410, where the control data
The duty ratio DPG is updated to DPGG. This allows
When the purge concentration is high and the engine is accelerating,
The control duty ratio DPG of the control valve 27 is limited to a low value.
Setting the purge control valve to open the purge control valve.
And the purge flow rate can be kept low.
You. In step 402, if GN> 0.8,
When it is determined that there is no FGPG
When it is determined that the value is not <0.9, or at step 408
If it is determined that DPGG <DPGB is not satisfied,
In step 412, the DPG is updated to DPGB. This
If the purge concentration is high and the engine is not accelerating
In this case, the operation is performed at the reference duty ratio.
The image of the control by the purge flow rate limiting means M5 as described above
The page diagram is shown in FIG. Here, as shown in FIG.
When the purge fuel concentration is low (thick line),
Air-fuel of air-fuel mixture sucked into internal combustion engine 10 even in control
Although the ratio (A / F) is stable, it is shown in FIG.
When the purge fuel concentration is high (thin line),
With conventional control, the air-fuel ratio (A / F)
Turbulence is occurring and the mixture is fuel rich
I understand. Here, the intake air amount shown in FIG.
When the value of GN is large, the pattern shown in FIG.
The value of DPG indicating the valve opening of the storage control valve 27 is different from that of the prior art.
Purge at low purge concentration (thick line)
When the density is high (thin line), the value is also high.
You can see that However, in the case of this embodiment, the purge
When the fuel concentration is high (at the time of a thin line), G shown in FIG.
When the intake air amount is large such that the value of N exceeds 0.8,
Due to the limit value of the purge flow rate, rapid slot
The disturbance of the air-fuel ratio (A / F) against the decrease of the valve opening is as small as possible
It is suppressed. Evaporative fuel processing control apparatus for an internal combustion engine according to this embodiment
According to the system, the purge fuel concentration is high as described above,
Into the internal combustion engine, such as when the vehicle is accelerating or under heavy load
When the amount of air to be discharged is large, the air is purged into the intake passage.
By limiting the purge flow rate and reducing the purge flow rate
To achieve the desired air-fuel ratio even if the intake air amount decreases sharply.
It can be controlled stably. Therefore, during acceleration
When closing the throttle valve suddenly
Can also control the purge fuel, so the air-fuel ratio
Turbulent exhaust emissions do not worsen
You. In addition, the purge concentration is high,
Limit the purge flow rate only when the air volume is large, and
In this state, the purge flow rate is not reduced,
Deterioration of evaporative emissions and key
The delay of vapor release from the canister
Emissions and driver billi
Deterioration can be prevented. [0020] EFFECT OF THE INVENTIONDepartureIn the fuel processing control unit,
When the gas concentration exceeds a predetermined value and the amount of intake air is large,Pa
Purge control valve opening set by the purge flow control means
Not to be larger than the specified openingTherefore, the purge concentration is
In response to a sudden change in the amount of incoming air from large to small,
The response delay of the flow control valve can be eliminated,
Suppresses large fluctuations in air-fuel ratio caused by high concentrations
Can be When the purge concentration is low,
A large amount is purged into the intake pipe according to the operating condition of the Seki
Therefore, it is not necessary to particularly increase the capacity of the canister.
As a result, control to the desired air-fuel ratio with higher accuracy than before
Drivability can be improved by being able to do it, and
Evaporated fuel can be used with high efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a principle diagram of an evaporative fuel processing control apparatus for an internal combustion engine according to an embodiment; FIG. 2 is a configuration diagram of an evaporative fuel processing control apparatus for an internal combustion engine according to an embodiment; FIG. DPGB calculation flowchart [FIG. 4] Routine for calculating air-fuel ratio feedback coefficient FAF [FIG. 5] Time chart showing relationship between exhaust gas, air-fuel ratio and feedback correction coefficient FAF [FIG. 6] Long-term purge concentration learning value calculation routine [FIG. Flowchart showing purge flow rate limiting means M5 [FIG. 8] Image of control of purge flow rate limiting means M5 [Description of symbols] M1 ... Purge flow rate control means M3 ... Purge concentration detection means M2 ... Purge flow rate limitation Means 1 ··· Canister 2 ··· Intake passage 3 ··· Fuel supply means 10 ··· Internal combustion engine 11 ··· Engine body 12 ··· Intake manifold 13 Exhaust manifold 14 Fuel injection valve 15 Surge tank 16 Intake duct 17 Intake pressure sensor 18 Air cleaner 19 Throttle valve 20 Activated carbon 21 ... Canister 22 ... Evaporation purge system 23a ... Fuel vapor chamber 23b ... Atmosphere chamber 24 ... Vapor passage 25 ... Fuel tank 26 ... Vapor passage 27 ... Purge control valve 30 ... electronic control unit 31 ... bidirectional bus 32 ... ROM 33 ... RAM 34 ... CPU 35 ... input port 36 ... output ports 37, 40, 42 ... A / D converter 38 Throttle switch 39 Water temperature sensor 41 Air-fuel ratio sensor (O ₂ sensor) 43 Class Link angle sensors 44, 45 ... drive circuit 46 ... B-RAM

Claims (1)

(1) A canister for temporarily storing evaporative fuel, and a purge passage connecting the canister and the intake passage for purging the evaporative fuel into an intake passage of an internal combustion engine. A purge control valve for controlling a flow rate of a purge gas flowing through the purge passage; and a purge flow control means for increasing the opening of the purge control valve as the amount of intake air flowing through the intake passage increases. A purge concentration detecting means for detecting a fuel concentration of a purge gas purged from the purge passage; and a purge concentration detected by the purge concentration detecting means when the intake air amount exceeds a predetermined air amount. when exceeding the predetermined value, the purge flow rate restriction means not larger than the predetermined opening the purge control valve opening set by the purge flow control means Evaporative fuel processing control device for an internal combustion engine, characterized in that digit.