JPH0783096A - Canister purge device - Google Patents

Abstract

PURPOSE:To prevent break through of a canister by way of practicing purge by carrying out purge flow rate control by a purge control valve so as to get as close to a limit as possible within the limit of loss compensation of fuel injection quantity in air-fuel ratio control by way of adding detection results of a density detection means and a driving state detection means. CONSTITUTION:A purge pipe 11 extending from an upper part of a fuel tank 7 is communicated to a surge tank 12 of an inlet pipe 2, and in the middle of the purge pipe 11, a canister 13 storing activated carbon as an absorbent to absorb evaporating fuel generated in the fuel tank 7 is arranged. Additionally, on the canister 13, an atmospheric air release hole 14 to introduce outside air is provided. The side of the surge tank 12 of the purge pipe 11 is a discharge passage 15, and in the middle of this discharge passage 15, a variable flow rate electromagnetic valve 16 is provided. Consequently, a control signal is supplied to the variable flow rate electromagnetic valve 16 from a CPU 21, canister purge is carried out by having the canister 13 communicated to the inlet pipe 2 and break through of the canister 13 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a canister purging device for adsorbing vaporized fuel gas generated in a fuel tank of an internal combustion engine to a canister and purging the vaporized fuel gas into an intake pipe under a predetermined engine operating condition.

[0002]

2. Description of the Related Art In recent years,
Canisters are becoming larger in size in response to US evaporative emission and OVR regulations. Therefore, it is required to purge a large amount of the evaporated fuel gas adsorbed by the large canister in a short period of time. Therefore, conventionally, there has been proposed a technique for improving the air-fuel ratio controllability by correcting the fuel injection amount according to the evaporated fuel concentration during purging and the purge flow rate (for example, JP-A-63-289243). .

However, in this technique, the purge valve was controlled only to be fully closed or fully open. Therefore, even if the purge valve is fully opened when the concentration of evaporated fuel is maximum, the fully open opening is set to a small value so as not to become overrich in all operating states, such as during high load operation. Even in a situation where more evaporated fuel gas may be purged,
The amount of purge could not be increased. Alternatively, since the purge valve is controlled only to be fully opened or fully closed, purging cannot be performed at all in an operating state in which the purge valve is overrich when fully opened. For this reason, even if it could be purged for a while, it could not be purged. Therefore, even when a very large amount of evaporated fuel gas is generated, such as when running in the summer, it is not possible to increase the purge amount or expand the operating conditions in which purging is possible, causing the canister to break through. However, there is a problem in that evaporated fuel gas may be released into the atmosphere.

There has also been a system in which the purge flow rate can be varied by duty control, but this system determines the purge amount from the intake air amount and the engine speed, and how much evaporated fuel gas is adsorbed by the canister. Since the purge flow rate is controlled regardless of whether the fuel concentration is purged or not, the structure is such that the purge is performed only in an operating state in which no matter what fuel concentration is purged, there is no problem.

As described above, conventionally, there was only a system capable of purging only in a very small part of the operating state or purging only very little. Therefore, the present invention makes it possible to increase the purge amount and the range in which the purge operation can be performed, prevent the canister from breaking through by executing the purge as much as possible, and
An object of the present invention is to provide a canister purge device that does not hinder the air-fuel ratio control by such a purge.

[0006]

According to the present invention, as means for solving the above-mentioned problems, as described in claim 1, the vaporized fuel gas generated in the fuel tank of the internal combustion engine is adsorbed to the canister, and a predetermined value is obtained. In a canister purge device for purging the adsorbed evaporated fuel gas into the intake pipe when the engine is operating, the canister purge device is arranged between the canister and the intake pipe, and the purge amount of the evaporated fuel gas is adjusted according to the open / closed state. A purge control valve having a flow rate control function capable of controlling, a concentration detecting means for directly or indirectly detecting the concentration of evaporated fuel gas in the purge gas purged from the canister, and an operation for detecting an engine operating state of the internal combustion engine Taking into account the detection results of the state detection means, the concentration detection means and the operating state detection means, the fuel injection amount reduction correction in the air-fuel ratio control is limited to the limit or less. In adopted a canister purge apparatus characterized by comprising a limit purge means for purging flow control by as close as possible so as to the purge control valve 該限 field.

[0007]

According to the canister purge apparatus of the present invention, the limit purging means takes into account the detection results of the concentration detecting means and the operating state detecting means, and within the limit of the fuel injection amount reduction correction in the air-fuel ratio control, The purge flow rate is controlled by the purge control valve so as to be as close as possible to the limit. Therefore, when the concentration of the evaporated fuel gas in the purge gas is low, a large amount of purge can be performed. Moreover, the purge flow rate is determined so as to be within the limit of the correction of the reduction of the fuel injection amount in the air-fuel ratio control, so that the air-fuel ratio control is not hindered. Further, even when the evaporated fuel gas concentration in the purge gas is high, the purge flow rate is determined so that it falls within the limit of the reduction correction of the fuel injection amount in the air-fuel ratio control, so even during low load operation such as idling. Allows for purging.

As a result, according to the canister purging apparatus of the present invention, it is possible to increase the amount of purge and the range in which the purging operation is possible, and to perform purging as much as possible to prevent the canister from breaking through. In addition, such a purge has a remarkable effect that air-fuel ratio control is not hindered.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a vehicle is equipped with a multi-cylinder internal combustion engine (engine) 1, and an intake pipe 2 and an exhaust pipe 3 are connected to the engine 1. An electromagnetic injector 4 is provided at the inner end of the intake pipe 2, and a throttle valve 5 is provided upstream of the electromagnetic injector 4.
Further, the exhaust pipe 3 is provided with an oxygen sensor 6, which outputs a voltage signal according to the oxygen concentration in the exhaust gas.

The fuel supply system for supplying fuel to the injector 4 has a fuel tank 7, a fuel pump 8, a fuel filter 9 and a pressure regulating valve 10. Then, the fuel (gasoline) in the fuel tank 7 is pressure-fed to each injector 4 by the fuel pump 8 via the fuel filter 9. The fuel supplied to each injector 4 is adjusted to a predetermined pressure by the pressure regulating valve 10.

A purge pipe 1 extending from the upper portion of the fuel tank 7.
1 is connected to a surge tank 12 of an intake pipe 2, and a canister 1 containing an activated carbon as an adsorbent for adsorbing evaporated fuel generated in a fuel tank is provided in the middle of the purge pipe 11 thereof.
3 are provided. Further, the canister 13 is provided with an atmosphere opening hole 14 for introducing outside air. The purge pipe 11 has a discharge passage 15 on the side closer to the surge tank 12 than the canister 13, and a variable flow solenoid valve 16 (hereinafter referred to as a purge solenoid valve) is provided in the discharge passage 15. In this purge solenoid valve 16, the valve body 17 is always biased by a spring (not shown) in the direction of closing the seat portion 18. However, by exciting the coil 19, the valve body 17 opens the seat portion 18. Has become.
Therefore, the discharge passage 15 is closed by demagnetizing the coil 19 of the purge solenoid valve 16, and the discharge passage 15 is opened by exciting the coil 19. The opening of the purge solenoid valve 16 is adjusted steplessly from fully closed to fully opened by a CPU 21 described later by duty ratio control based on pulse width modulation.

Therefore, the purge solenoid valve 16 has a C
If a control signal is supplied from the PU 21 so that the canister 13 communicates with the intake pipe 2 of the engine 1, new air Qa is introduced from the atmosphere, and this is the canister 1
3 is ventilated and sent from the intake pipe 2 of the engine 1 into the cylinder, and canister purge is performed.
The recovery of the adsorption function of No. 3 will be obtained. Then, at this time, the new air Qa introduction amount Qp (liter /
min) is adjusted by changing the duty of the pulse signal supplied from the CPU 21 to the purge solenoid valve 16. FIG. 2 is a characteristic diagram of the purge amount at this time, showing the purge solenoid valve 16 when the negative pressure in the intake pipe is constant.
Shows the relationship between the duty of the purge solenoid valve 16 and the purge amount, and from this figure, as the duty of the purge solenoid valve 16 is increased from 0%, the purge amount is almost directly, that is, the purge is sucked into the engine 1 via the canister 13. It can be seen that the amount of air taken in increases.

The CPU 21 includes a throttle opening signal from a throttle sensor 5a for detecting the opening of the throttle valve 5, an engine rotation speed signal from a rotation speed sensor (not shown) for detecting the rotation speed of the engine 1, and a throttle valve. The intake pressure signal from the intake pressure sensor 5b that detects the pressure of the intake air that has passed through the intake valve 5 (or the intake air amount signal from the intake air amount sensor) and the cooling from the water temperature sensor 5c that detects the temperature of the engine cooling water. A water temperature signal and an intake air temperature signal from an intake air temperature sensor (not shown) that detects the intake air temperature are input.

Further, the CPU 21 inputs a signal (voltage signal) from the oxygen sensor 6 and makes a rich / lean determination of the air-fuel mixture. Then, the CPU 21 changes (skips) the feedback correction coefficient stepwise in order to increase / decrease the fuel injection amount when changing from rich to lean and when changing from lean to rich, and at the time of rich or lean, the feedback correction coefficient is changed. Is gradually increased or decreased. It should be noted that this feedback control is not performed when the engine cooling water temperature is low, and when the vehicle is running under high load and high rotation. Further, the CPU 21 obtains the basic injection time from the engine speed and the intake pressure, corrects the basic injection time with a feedback correction coefficient or the like, and then the final injection time T
AU is obtained, and fuel injection is performed by the injector 4 at a predetermined injection timing.

The ROM 34 stores programs and maps for controlling the operation of the entire engine. RAM
Reference numeral 35 temporarily stores various data, for example, detection data such as the opening of the throttle valve 5 and the engine speed. Then, the CPU 21 controls the operation of the engine based on the program stored in the ROM 34.

FIG. 3 shows a full open purge rate map, which is determined by the engine speed Ne and the load (in this case, intake pressure, intake air amount, throttle opening). This map shows the ratio of the amount of air flowing through the discharge passage 15 when the duty of the purge solenoid valve 16 is 100% to the total amount of air flowing into the engine 1 through the intake pipe 2, and is stored in the ROM 34. .

This system uses the air-fuel ratio feedback (F
The fuel injection control is executed through the processes of AF) control, purge rate control, evaporated fuel (evaporation) concentration detection, fuel injection amount control, and purge solenoid valve control. Less than,
The operation of the embodiment will be described for each control.

[Air-fuel ratio feedback control] The air-fuel ratio feedback control will be described with reference to FIG. This air-fuel ratio feedback control is executed by the base routine of the CPU 21 about every 4 msec. First, step S40
Check if feedback (F / B) control is possible. F /
B is judged to be possible mainly when all the following conditions are satisfied.

(1) Not at the time of starting. (2) Fuel is not being cut. (3) Cooling water temperature (THW) ≧ 40 ° C. (4) T
AU> TAU _min . (5) The oxygen sensor is in an active state.
If the condition is satisfied, the process proceeds to step S42, the oxygen sensor output is compared with the predetermined determination level, and the delay time (H
msec, Imsec) and operate the air-fuel ratio flag XOXR. Specifically, XOXR = 0 (means lean) after Hmsec after the oxygen sensor output reverses from rich to lean.
Then, the flag is operated to XOXR = 1 (means rich) Imsec after the oxygen sensor output is inverted from lean to rich. Next, in step S43, the value of FAF is manipulated based on this XOXR. That is, when XOXR changes (0 → 1), (1 → 0), the value of FAF is skipped by a predetermined amount, and integration control of the FAF value is performed while XOXR continues to be 1 or 0. After advancing to the next step S44, the upper and lower limits of the FAF value are checked, and then advancing to step S45
Based on the value, smoothing (averaging) processing is performed for each skip or for every predetermined time to obtain the smoothed value FAFAV. When the F / B control is not established in step S40, the process proceeds to step S46 and the value of FAF is set to 1.0.

[Purge Rate Control] The purge rate control will be described with reference to FIG. First, it is confirmed that the air-fuel ratio is F / B, the cooling water temperature THW is 60 ° C. or higher, and the fuel cut is not performed (S501 to S503). Step S501 is for eliminating the state such as the start control, step S502 is for eliminating the state in which the fuel amount increase correction other than the purge is applied by the water temperature correction, and step S503 does not perform the purge during the fuel cut. To do so.

If steps S501 and S502 are YES,
Only when step S503 is NO, step S504
Then, the purge execution flag XPRG is set to 1. Otherwise, the process proceeds to S509, where the purge execution flag XPRG is set.
Is set to 0, and the final purge rate PGR is set to 0 in S510, and the process ends. The final purge rate PGR = 0 means that
This means no purging.

After the purge execution flag XPRG is set to 1, the routine proceeds to step S505, where the full open purge rate PG is determined from the map of FIG. 3 based on the intake pressure PM and the engine speed NE.
Read RMX. In the next step S506, the target T
AU correction amount KTPRG and evaporation concentration average value FGPGA
From V, the target purge rate PGR0 is calculated.

Here, the target TAU correction amount KTPRG is
When the fuel gas is replenished by purging, the maximum amount of fuel injection amount reduction correction can be performed. This target TAU correction amount KTPRG is obtained in advance based on the margin with respect to the minimum injection pulse of the injector, and the target TAU correction amount KTPRG is calculated with reference to FIG.
Are mapped and stored in the ROM 34. The example 1) is arranged with respect to whether the engine is idle or not and the engine speed NE as parameters. Example 2) is a two-dimensional map using the intake pressure PM and the engine speed NE as parameters. Example 3)
Is a two-dimensional map using the engine speed NE and the throttle opening as parameters. In all of these maps, KTPRG tends to be small in an operating state in which the basic fuel injection amount is small.

Further, the average evaporation concentration FGPGAV is
It corresponds to the amount of fuel gas adsorbed to the canister 13, is estimated by the process described below, and is updated as needed to the RAM 3
Written in 5. The target purge rate PGR0 calculated in step S506 is the target TAU correction amount KTPRG.
It corresponds to how much fuel gas should be replenished by purging when it is assumed that the injection amount is reduced to the maximum. Therefore, under the same operating conditions, the larger the evaporation concentration average value FGPGAV, the smaller the value.
The smaller the value, the larger the value.

When the target purge rate PGR0 is obtained in this way, the routine proceeds to step S507, where the purge rate gradual change value PGR is set.
Read D. The purge rate gradual change value PGRD is a control value provided to avoid this, because if the purge rate is suddenly and greatly changed, the correction cannot catch up and the optimum air-fuel ratio cannot be maintained. How the purge rate gradual change value PGRD is determined will be described in detail in the purge rate gradual change control described later.

When the full open purge rate PGRMX, the target TAU correction amount KTPRG, and the purge rate gradual change value PGRD are obtained in this manner, the minimum value of these is determined as the final purge rate PGR in step S508. Purge control is executed at this final purge rate PGR.

[Purge Rate Gradual Change Control] The purge rate gradual change control will be described with reference to FIG. First, in step S701,
Check the setting state of the purge execution flag XPRG. XP
If RG = 0, the process proceeds to step S706, the purge rate gradual change value PGRD is set to 0, and the process ends. On the other hand, XPR
When G = 1, the process proceeds to step S702, the FAF deviation amount | 1-FAFAV | is detected, and | 1-FAFAV | ≤
When it is 5%, the routine proceeds to step S703, where the value obtained by adding 0.1% to the last final purge rate PGR _i-1 is 5% <| 1-F
When AFAV | ≦ 10%, the routine proceeds to step S704, where the last final purge rate PGR _i−1 is set to | 1-FAFAV |>
When the value is 10%, the process proceeds to step S705, and the value obtained by subtracting 0.1% from the last final purge rate PGR _i-1 is set as the purge rate gradual change value PGRD.

If the FAF deviates from the stoichiometric air-fuel ratio (FAF = 1) by less than 5%, it is considered that the TAU correction will catch up sufficiently even if the purge rate is changed more. Change more. F
When the AF remains in the range of 5 to 10% with respect to the stoichiometric air-fuel ratio (FAF = 1), it is considered that the change of the purge rate and the TAU correction are relatively balanced, and the purge rate is kept as it is. Of.

It is considered that the reason why the FAF deviates so much from the stoichiometric air-fuel ratio (FAF = 1) that it exceeds 10% is that the TAU correction is not catching up as a result of changing the purge ratio too much. Therefore, the purge rate is likely to be returned to the original value because it may increase.

[Evaporation Density Detection] FIG. 8 shows the main routine of the evaporation concentration detection which is executed by the base routine of the CPU 21 about every 4 msec. First, in step S100, it is determined whether or not the key switch is turned on. This is to avoid the evaporation fuel being adsorbed to the canister 13 while the engine is stopped, and an error will occur if the previously detected value is used. If the key switch is turned on, steps S115, S116, S11
7 and evaporative concentration FGPG, evaporative concentration average value FG
PGAV to 1.0, first concentration detection flag XNFGPG
Is initialized to 0. 1.0 for FGPG and FGPGAV
This means that the evaporation concentration is 0 (no fuel gas is adsorbed). Adsorption = 0 at first
It is assumed that XNFPGG = 0 means that the evaporation concentration has not been detected yet.

After the key switch is turned on, first, it is determined whether or not the purge control is started in step S101, that is,
It is determined whether the purge execution flag XPRG is 1 or not. XP
When RG = 1 (after starting purge control), step S102
When XPRG = 0 (before the purge control is started), the concentration detection processing is ended. This is because the evaporation concentration cannot be detected before the start of purging.

In step S102, 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 pressure change, a vehicle speed, and the like. If it is determined in step S102 that acceleration / deceleration is being performed, the processing ends. This is because the operating state is in a transitional state during acceleration / deceleration, so that correct concentration detection cannot be performed.

On the other hand, if it is determined in step S102 that the acceleration / deceleration is not being performed, the process proceeds to step S103 to determine whether or not the initial concentration detection end flag XNFGPG is 1, and when it is 1, the process proceeds to the next step S104 and is not 1. Sometimes, step S104 is bypassed and the process proceeds to step S105.
Since the density detection is not completed at first, step S10
4 is bypassed and the process proceeds to step S105.

In step S105, it is determined whether FAFAV obtained in step S45 of FIG. 4 has a deviation of a predetermined value (ω%) or more from the reference value 1. This is because the evaporative concentration cannot be correctly detected unless the air-fuel ratio is obviously deviated by the purge. That is,
The predetermined value = ω% means the range of variation.

When the deviation is not more than the predetermined value, the process is terminated as it is, and when the deviation is not less than the predetermined value, the process proceeds to the next step S108 to detect the evaporation concentration. Step S
At 108, the deviation | FAFAV-1 | is gradually divided by PGR and added to the previous evaporation concentration FGPG to obtain the evaporation concentration FGPG at this time. 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, FAFAV and 1 may be exchanged in step S108, and the evaporative concentration may be obtained by setting the value of FGPG to a value greater than 1 as the evaporative concentration increases.

Then, in the next step S109, it is determined whether or not the first concentration detection end flag XNFPGG is 1, and if it is not 1, the process proceeds to the next step S110, and if it is 1, the steps 110 and S111 are bypassed and the step S11 is executed.
Go to 2. Then, in step S110, the evaporation concentration F
The change between the previous detected value and the present detected value of GPG is a predetermined value (θ
%) It is judged whether the evaporative emission concentration is stable or not depending on whether or not the following state continues three times or more. When the evaporation concentration becomes stable, the process proceeds to the next step S111, the initial concentration detection end flag XNFGPG is set to 1, and then the process proceeds to the next step S112. If it is determined in step S110 that the evaporation concentration is not stable, the process bypasses step S111 and proceeds to step S112. In step S112, a predetermined smoothing calculation (for example, 1/64 smoothing calculation) is performed to average the current evaporation concentration FGPG, and the average evaporation concentration value FGPGAV is obtained.

After the initial density detection is completed in this way, step S103 is always YES and step S104
Is executed and the purge rate PGR is equal to or less than the predetermined value (β%), the process is ended as it is, and only when PGR> β%, the process proceeds to the next step S105. This is the purge rate PGR
Is small, that is, when the purge solenoid valve 16 is on the low flow rate side, the degree of opening cannot be controlled accurately, so accurate evaporation concentration detection cannot be performed. In the case of, the evaporative concentration detection is executed only under the condition that it can be detected accurately,
This is to give a value with as little error as possible.

[Fuel Injection Amount Control] FIG. 9 shows the fuel injection amount control executed every about 4 msec in the base routine of the CPU 21.
Shown in. First, in step S151, the basic fuel injection amount TP is obtained from the engine speed NE and the load (for example, intake pipe pressure PM) based on the data stored in the ROM 34 as a map, and in step S152, various basic corrections ( Coolant temperature correction, post-starting correction, intake air temperature correction, etc.) are performed. In step S154, the evaporation concentration average value FGPG
The purge correction coefficient F is obtained by multiplying AV by the final purge rate PGR.
Find the PG.

This purge correction coefficient FPG means the amount of fuel replenished by executing purging under the conditions determined by the purge rate control process, and represents the amount of fuel that can be reduced and corrected from the basic fuel injection amount TP. ing. Then, in the next step S156, the air-fuel ratio feedback value FAF, the purge correction coefficient FPG, and the air-fuel ratio learning value KGj.
The correction coefficient is calculated from the following equation from the basic fuel injection amount T
It is multiplied by P and reflected in the fuel injection amount TAU. In addition, K
Gj is provided for each engine operating region.

[0040]

[Equation 1] 1+ (FAF-1) + (KGj-1) + FPG [Purge solenoid valve control] 100 ms by CPU21
FIG. 10 shows a purge solenoid valve control routine executed by a time interrupt every ec.

In step S161, it is determined by the purge execution flag XPRG whether the purge is being executed. XP
When RG = 0 (purging is not performed), the process proceeds to step S163, and the control value Du of the purge solenoid valve 16 is set.
Let ty be 0. Otherwise, the process proceeds to step S164, and the control value Duty of the purge solenoid valve 16 is calculated by the following equation.
Ask for.

[0042]

## EQU00002 ## Duty = (PGR / PGRMX) .times. (100-Pv) .times.Ppa + Pv In this equation, the drive cycle of the purge solenoid valve 16 is 10
It is set to 0 msec. Further, PGR is the final purge rate obtained in FIG. 5, PGRMX is the purge rate in each operating state when the purge solenoid valve 16 is fully open (see FIG. 3),
Pv is a voltage correction value for fluctuations in the battery voltage, and Ppa is an atmospheric pressure correction value for fluctuations in atmospheric pressure.

As described above, according to the present embodiment, it is possible to increase the purge rate as much as possible within the range where the limit value KTPRG of the fuel injection amount reduction correction corresponding to the engine operating condition is not exceeded. As a result, the canister 13 can efficiently perform the purge, and it is possible to prevent the accidental release of the evaporated fuel into the atmosphere due to the breakthrough of the canister. The present invention is not limited to this embodiment. For example, the detection / estimation of the evaporative concentration is disclosed in JP-A-63-28.
For example, the method described in Japanese Patent No. 9243 can be adopted, and the present invention can be implemented in various modes without departing from the scope of the invention.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a system of an embodiment.

FIG. 2 is a graph showing a flow rate characteristic of a purge solenoid valve.

[Fig. 3] Purge gas mixture rate (full open purge rate PRGMX) when the purge solenoid valve is fully opened in various operating states.
Is a map showing.

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

FIG. 5 is a flowchart of purge rate control.

FIG. 6 is a map showing a target TAU correction amount KTPRG which is a limit correction amount for various operating states in air-fuel ratio control.

FIG. 7 is a flowchart of purge rate gradual change control.

FIG. 8 is a flowchart of evaporation concentration detection control.

FIG. 9 is a flowchart of fuel injection control.

FIG. 10 is a flowchart of purge solenoid control.

[Explanation of symbols]

1 ... Engine, 2 ... Intake pipe, 3 ... Exhaust pipe,
4 ... Injector, 5 ... Throttle valve, 5a
..Throttle sensor, 5b ... Intake pressure sensor, 5c
... Water temperature sensor, 6 ... Oxygen sensor, 7 ... Fuel tank, 8 ... Fuel pump, 9 ... Fuel filter,
10 ... Pressure regulating valve, 11 ... Purge pipe, 12 ... Surge tank, 13 ... Canister, 14 ... Atmosphere opening hole, 15 ... Release passage, 16 ... Purge solenoid valve, 21 ... CPU, 34 ... ROM, 35 ...
-RAM.

Claims (1)

[Claims] 1. A canister purging device for adsorbing evaporated fuel gas generated in a fuel tank of an internal combustion engine to a canister and purging the adsorbed evaporated fuel gas into an intake pipe when a predetermined engine is operating, And a purge control valve having a flow rate control function for adjusting the purge amount of the evaporated fuel gas according to the open / closed state, and the evaporated fuel in the purge gas purged from the canister. Concentration detecting means for directly or indirectly detecting the gas concentration, operating state detecting means for detecting the engine operating state of the internal combustion engine, and taking into account the detection results of the concentration detecting means and the operating state detecting means, air-fuel ratio control Within the limit of the fuel injection amount reduction correction, the purge flow rate control by the purge control valve should be as close as possible to the limit. Canister purge system, characterized in that it comprises a limit purge means for performing.