JP2006002574A - Evaporated fuel treating device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent emission deterioration by performing suitable purge control at the time of automatic start of an internal combustion engine after idling stop (automatic stop). <P>SOLUTION: In the purge control at normal operation of the internal combustion engine 1, a purge valve 33 is opened or closed in accordance with an operation condition of the internal combustion engine 1 and evaporated fuel stored in a canister 30 is discharged into an intake passage 2 of the internal combustion engine 1. In contrast, during the idling stop of the internal combustion engine 1, since the purge control is not performed, an evaporative emission concentration learning value in the purge control is corrected in accordance with an elapsed time of the idling stop specifying a condition of the internal combustion engine 1. This allows the evaporative emission learning value in the purge control to be suitably set even immediately after automatic start after idling stop and therefore emission deterioration can be prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an evaporative fuel processing apparatus for an internal combustion engine that performs purge control of evaporative fuel generated in a fuel tank, and in particular, has a so-called idle stop function that automatically stops an internal combustion engine and then automatically starts the engine when idling. The present invention relates to an evaporated fuel processing apparatus for an internal combustion engine applied to the internal combustion engine.

  Conventionally, as a prior art document related to an evaporative fuel processing apparatus for an internal combustion engine, one disclosed in Japanese Patent Application Laid-Open No. 2001-295688 is known.

In this case, the purge rate is changed so that the air-fuel ratio feedback correction amount set based on the output value from the oxygen sensor falls within a predetermined region, and the purge rate and the air-fuel ratio feedback correction amount before and after the purge rate is changed. Shows a technique for detecting the concentration of evaporated fuel.
JP 2001-295688 A (pages 2 to 3)

  By the way, in the above, the purge control of the internal combustion engine having the idle stop function is not disclosed. Here, immediately after the automatic start of the internal combustion engine having the idle stop function, immediately after the automatic start, the learned value of the evaporated fuel concentration differs from the learned value of the evaporated fuel concentration in the purge control during the normal operation before the automatic stop. As a result, there is a problem in that proper purge control cannot be performed and emission is deteriorated.

  Accordingly, the present invention has been made to solve such a problem, and provides an evaporated fuel processing apparatus for an internal combustion engine that can execute appropriate purge control at the time of automatic start after the internal stop of the internal combustion engine and can prevent emission deterioration. Is an issue.

  According to the evaporated fuel processing apparatus for an internal combustion engine according to claim 1, the automatic start / stop control means is stored in the canister during the automatic stop when the internal combustion engine is idling or during a predetermined period after the automatic start of the internal combustion engine thereafter. Vaporized fuel generated in the fuel tank is switched by the purge control switching means so that the purge control means has a purge control different from the purge control during the normal operation which is discharged into the intake passage according to the operating state of the internal combustion engine. . Thus, the actual purge control is suspended during the automatic stop when the internal combustion engine is idling. However, the purge control is different from the normal operation in preparation for the restart of the purge control, and the predetermined start from the automatic start after the automatic stop is performed. During the period, switching to purge control different from that during normal operation is performed, and even during a predetermined period immediately after the automatic start of the internal combustion engine, appropriate purge control can be performed and the effect of preventing emission deterioration can be obtained. It is done.

  In the purge control switching means in the evaporated fuel processing apparatus for an internal combustion engine according to claim 2, during the automatic stop of the internal combustion engine by the automatic start / stop control means, the learning value of the concentration of the evaporated fuel in the purge control is determined according to the state of the internal combustion engine. It is corrected. In other words, during the automatic stop of the internal combustion engine that is not during normal operation, the concentration of the evaporated fuel gradually increases with the elapsed time, so learning of the concentration of the evaporated fuel in the purge control is commensurate with that. The value is corrected. Thereby, the effect that appropriate purge control can be performed immediately after the automatic start of the internal combustion engine after the automatic stop is obtained.

  In the purge control switching means in the evaporative fuel processing apparatus for an internal combustion engine according to claim 3, the automatic stop period, the oil temperature, the cooling water temperature, the intake air temperature, the outside air temperature, the combustion temperature, or the rate of change or change of these are shown. The learned value of the concentration of the evaporated fuel in the purge control is corrected according to at least one of the amount and the integrated value. That is, according to at least one of these various parameters representing the state of the internal combustion engine, the learning value of the evaporated fuel concentration during the automatic stop of the internal combustion engine is accurately corrected. As a result, there is an effect that appropriate purge control can be executed even immediately after the automatic start of the internal combustion engine.

  In the purge control switching means in the evaporative fuel processing apparatus for an internal combustion engine according to claim 4, the automatic stop period, the oil temperature, the cooling water temperature, the intake air temperature, the outside air temperature, the combustion temperature, or the rate of change or change of these are shown. When at least one of the quantity and the integrated value is equal to or greater than a predetermined value, the learning value of the evaporated fuel concentration during the automatic stop of the internal combustion engine is returned to the initial value. In other words, when at least one of these various parameters representing the state of the internal combustion engine is equal to or greater than a predetermined value, the learning value of the evaporated fuel concentration at the time of restarting the purge control is assumed to be unreliable and returned to the initial value. As a result, it is possible to perform the purge control that prevents the emission deterioration even immediately after the automatic start of the internal combustion engine.

  In the purge control switching means in the evaporated fuel processing apparatus for an internal combustion engine according to claim 5, unlike the purge control during normal operation in a predetermined period after the automatic start return after the automatic stop of the internal combustion engine by the automatic start / stop control means, The increase rate per unit time of the purge rate of the air containing the evaporated fuel in the purge control is set to be slower than that in the normal operation. In other words, during the predetermined period after automatic start recovery after automatic stop that is not during normal operation, the learning value of the evaporated fuel concentration in purge control is not reliable, so the increase rate of the purge rate takes safety into consideration. Set later than during normal operation. As a result, it is possible to perform the purge control that prevents the emission deterioration even immediately after the automatic start of the internal combustion engine.

  In the purge control switching means in the evaporated fuel processing apparatus for an internal combustion engine according to claim 6, in a predetermined period after the automatic start return after the automatic stop of the internal combustion engine by the automatic start / stop control means, unlike the purge control during normal operation, The evaporative fuel concentration learning speed in the purge control is set to be faster than in normal operation. In other words, during a predetermined period after the automatic start return after the automatic stop that is not during normal operation, the evaporative fuel concentration learning speed in the purge control is determined so that the accurate evaporative fuel concentration learned value can be obtained as quickly as possible. Set faster than normal operation. As a result, it is possible to obtain an effect that the learning value of the concentration of the evaporated fuel can be quickly transferred during the normal operation while preventing the emission deterioration in the purge control after the automatic start of the internal combustion engine.

  Hereinafter, the best mode for carrying out the present invention will be described based on examples.

  FIG. 1 is a schematic configuration diagram showing an internal combustion engine and peripheral devices to which an evaporated fuel processing apparatus for an internal combustion engine according to an embodiment of the present invention is applied.

  In FIG. 1, an internal combustion engine 1 composed of a plurality of cylinders is mounted on a vehicle, and an intake passage 2 and an exhaust passage 3 are connected to the internal combustion engine 1. An air cleaner 4 for filtering air is disposed upstream of the intake passage 2, and air is introduced into the intake passage 2 through the air cleaner 4. The air cleaner 4 is provided with an intake air temperature sensor 5, and the intake air temperature, which is the temperature of intake air introduced into the intake passage 2, is detected by the intake air temperature sensor 5.

  A throttle valve 6 for adjusting the amount of intake air to the internal combustion engine 1 is disposed downstream of the air cleaner 4. The throttle valve 6 is provided with a throttle opening sensor 7. The throttle opening sensor 7 detects the throttle opening of the throttle valve 6. An intake pressure sensor 9 is provided in the surge tank 8 in the intake passage 2 on the downstream side of the throttle valve 6, and the intake pressure downstream of the throttle valve 6 is detected by the intake pressure sensor 9.

  Further, the liquid fuel stored in the fuel tank 20 is pumped out by an in-tank type fuel pump 21 having a built-in pressure regulator (not shown). For this reason, the liquid fuel discharged from the fuel pump 21 passes through the fuel supply path 22 after its fuel pressure is adjusted to a predetermined pressure, and is filtered by the fuel filter 23 on the way, and is injected from the injector (fuel injection valve) 10 into the internal combustion engine. Injection is supplied toward the intake port 11 side of each cylinder of the engine 1. The air-fuel mixture obtained by mixing the liquid fuel injected and supplied from the injector 10 and the intake air that has passed through the throttle valve 6 and passed through the surge tank 8 in the intake passage 2 is an intake port of each cylinder of the internal combustion engine 1. 11 is supplied into the combustion chamber 13 of each cylinder at the timing when the intake valve 12 is opened.

  On the other hand, the fuel tank 20 is connected to the canister 30 via the evaporated fuel passage 25. An adsorbent 31 made of activated carbon is accommodated in the canister 30. For this reason, the evaporated fuel generated in the fuel tank 20 is successively adsorbed and held by the adsorbent 31 in the canister 30. Then, the evaporated fuel adsorbed and held by the adsorbent 31 in the canister 30 is desorbed from the adsorbent 31 with the opening and closing of the purge valve 33 corresponding to the operating state of the internal combustion engine 1, and is connected to the canister 30. The gas is introduced into the intake passage 2 from a purge passage 34 that passes through the purge valve 32 and the purge valve 33 and is connected to the upstream side of the surge tank 8. The atmospheric hole 35 formed in the canister 30 is provided with a closing valve 36, and the opening degree of the closing valve 36 is adjusted as necessary to pass through the atmospheric hole 35 and be introduced into the canister 30. The amount of air is controlled.

The air-fuel mixture supplied into the combustion chamber 13 of each cylinder of the internal combustion engine 1 is combusted at a predetermined combustion timing by a spark plug 14 disposed at the top of the cylinder. Then, the exhaust gas after combustion is discharged from the combustion chamber 13 into the exhaust passage 3 via the exhaust valve 15. An oxygen sensor 16 for detecting the oxygen (O ₂ ) concentration in the exhaust gas is disposed in the exhaust passage 3. Reference numeral 17 denotes a water temperature sensor for detecting the cooling water temperature of the internal combustion engine 1, and reference numeral 18 denotes a crank angle sensor for detecting the engine rotation speed of the internal combustion engine 1.

  Reference numeral 40 denotes an ECU (Electronic Control Unit). The ECU 40 stores a CPU as a central processing unit that executes various known arithmetic processes, a ROM that stores a control program and a control map, and various data. The logic operation circuit includes a RAM, a B / U (backup) RAM, an input / output circuit, and a bus line connecting them.

  In this ECU 40, in order to determine the operating state of the internal combustion engine 1, the intake air temperature from the intake air temperature sensor 5, the throttle opening from the throttle opening sensor 7, the intake pressure from the intake pressure sensor 9, the oxygen from the oxygen sensor 16 The concentration, the coolant temperature from the water temperature sensor 17, the engine speed from the crank angle sensor 18 and other various sensor signals are read. Then, an injector 10 for injecting and supplying liquid fuel based on a control signal calculated and set by the ECU 40, a fuel pump 21 for discharging and supplying the liquid fuel, a purge valve 33 for purging the evaporated fuel, and the canister 30 in the atmosphere Energization to the closing valve 36 and the like for introduction is performed.

  Next, an evaporation (evaporative emission) according to an idle stop elapsed time (automatic stop period during idling) in the ECU 40 used in the evaporated fuel processing apparatus for an internal combustion engine according to one embodiment of the present invention. ) Based on the flowchart of FIG. 2 showing the processing procedure of the density learning value calculation, it will be described with reference to FIG. Here, FIG. 3 is a time chart showing transition states of various control amounts corresponding to the processing of FIG. The evaporation concentration learning value calculation routine is repeatedly executed by the ECU 40 at predetermined time intervals. As shown in FIG. 3, the evaporation concentration in the canister 30 gradually increases linearly in accordance with the automatic stop period of the internal combustion engine 1 in which the idle stop execution flag is “ON”.

  In FIG. 2, first, in step S101, it is determined whether an idle stop execution condition is satisfied. Here, the idle stop execution condition is that the brake switch is “ON” when the brake pedal is depressed, and the vehicle speed is “0 (zero) [km / h]”. In step S101, when the idle stop execution condition is satisfied, the process waits until the idle stop execution flag is changed from "OFF (off)" to "ON", and the process proceeds to step S102 (time t1 shown in FIG. 3). In step S102, the idle stop elapsed time is calculated by counting up the internal timer. Next, the process proceeds to step S103, and it is determined whether the idle stop elapsed time exceeds a preset elapsed time learning value clear threshold value α.

  Here, immediately after the start of idle stop execution, of course, the determination condition of step S103 is not satisfied, that is, the idle stop elapsed time is as short as the elapsed time learning value clear threshold value α, and the process proceeds to step S104. In step S104, it is determined whether the idle stop elapsed time exceeds a preset elapsed time correction start threshold value β. The elapsed time correction start threshold β is set shorter than the elapsed time learning value clear threshold α. When the determination condition of step S104 is not satisfied, that is, when the idle stop elapsed time is as short as the elapsed time correction start threshold value β or less (time t1 to time t2 shown in FIG. 3), the process proceeds to step S105, and no correction is required. Then, the learning value immediately before the start of the idle stop is directly used as the evaporation concentration learning value, and this routine is finished.

  On the other hand, if the determination condition of step S104 is satisfied, that is, if the idle stop elapsed time exceeds the elapsed time correction start threshold value β and is longer than the elapsed time learning value clear threshold value α (time t2 to time t3 shown in FIG. 3), step The process proceeds to S106. In step S106, the elapsed time correction amount at that time is added to the learning value immediately before the start of the idle stop to obtain the evaporation concentration learning value, and this routine is terminated. The elapsed time correction amount is calculated based on a table (not shown) having a characteristic that increases as the idle stop elapsed time becomes longer with the idle stop elapsed time as a parameter, as indicated by the arrow width in FIG.

  On the other hand, when the determination condition of step S103 is satisfied, that is, when the idle stop elapsed time exceeds the elapsed time learning value clear threshold value α (time t3 to time t4 shown in FIG. 3), the process proceeds to step S107. In step S107, the evaporative concentration learning value is returned to the initial value by the reset process because the idle stop elapsed time is too long, and then this routine is terminated.

  Next, a procedure for setting the purge speed when increasing the purge rate after releasing the idle stop according to the idle stop elapsed time in the ECU 40 used in the evaporated fuel processing apparatus of the internal combustion engine according to one embodiment of the present invention will be described. Based on the flowchart of FIG. 4 shown, it demonstrates with reference to FIG. Here, FIG. 5 is a time chart showing transition states of various control amounts corresponding to the processing of FIG. The purge speed setting routine is repeatedly executed by the ECU 40 every predetermined time.

  In FIG. 4, first, in step S201, it is determined whether a purge execution condition is satisfied. Here, the purge execution condition is that the engine rotation speed of the internal combustion engine 1 is a low rotation speed / low load region, the cooling water temperature is equal to or higher than a predetermined value, and the execution condition of the air-fuel ratio F / B (feedback) control is satisfied. . In step S201, when the purge execution condition is satisfied, the process waits until the purge execution flag is changed from “OFF” to “ON”, and the process proceeds to step S202. In step S202, as the purge valve control process, the purge valve 33 is driven so as to gradually open from the fully closed state, for example, and a known air-fuel ratio F / B control based on the output value from the oxygen sensor 16 is accompanied accordingly. Is executed.

  Next, the process proceeds to step S203, where it is determined whether the evaporation concentration learning execution condition is satisfied. Here, as the evaporation concentration learning execution condition, the purge rate is equal to or greater than a predetermined value (evaporation concentration learning execution purge rate), the learning of the fuel supply system is completed, the air-fuel ratio F / B correction amount is equal to or less than the predetermined value, and the internal combustion engine 1 The engine speed and load state of the engine are steady. Note that the learning of the fuel supply system is learning for suppressing an air-fuel ratio shift due to deterioration of the fuel supply system such as the intake pressure sensor 9 and the injector 10, and only the purge is performed when this learning is not completed. The resulting air-fuel ratio shift cannot be detected. In step S203, when the evaporation concentration learning execution condition is satisfied, the process waits until the evaporation concentration learning execution flag is changed from “OFF” to “ON”, and the process proceeds to step S204.

  In step S204, the idle stop execution flag is changed from "ON" to "OFF" (time t4 shown in FIG. 5), and it is determined whether the restart is from the idle stop. When the determination condition in step S204 is satisfied, that is, when the restart is from the idle stop, the process proceeds to step S205, and the idle stop elapsed time corresponding to the idle stop execution flag from “ON” to “OFF” before the restart. It is determined whether the elapsed time learning value clear threshold value α is exceeded. When the determination condition of step S205 is not satisfied, that is, when the idle stop elapsed time is as short as the elapsed time learning value clear threshold value α, the process proceeds to step S206.

  In step S206, it is determined whether the idle stop elapsed time exceeds the elapsed time correction start threshold β. When the determination condition of step S206 is not satisfied, that is, when the idle stop elapsed time is as short as the elapsed time correction start threshold value β or less, the process proceeds to step S207, and the evaporation concentration learned value is set to the idle stop by the above-described evaporation concentration learned value calculation routine. Since the learning value immediately before the start is maintained, the purge speed when increasing the purge rate is set to a constant (γ with a large slope) during normal operation as indicated by the solid line after time t7 in FIG. Is set.

  On the other hand, when the determination condition in step S206 is satisfied, that is, when the idle stop elapsed time exceeds the elapsed time correction start threshold value β and is shorter than the elapsed time learning value clear threshold value α, the process proceeds to step S208. In step S208, the purge concentration is increased because the elapsed time correction amount corresponding to the idle stop elapsed time is added to the learned value immediately before the start of idle stop in the evaporated concentration learned value by the above-described evaporation concentration learned value calculation routine. As shown by the broken line after time t7 in FIG. 5, the purge speed at this time is set to a constant δ that is slower than the normal operation (the inclination is smaller than that in the normal operation) with the idle stop elapsed time as a parameter.

  On the other hand, when the determination condition of step S204 is not satisfied, that is, when the restart is not from the idle stop, or when the determination condition of step S205 is satisfied, that is, when the idle stop elapsed time is longer than the elapsed time learning value clear threshold value α. The process proceeds to step S209. In step S209, since the evaporation concentration learning value is cleared and returned to the initial value by the above-described evaporation concentration learning value calculation routine, the purge speed when increasing the purge rate is two points after time t7 in FIG. As indicated by the chain line, the slowest (smallest slope) constant ε is set so as to prevent emission deterioration.

  After the purge speed is set in step S207, step S208, or step S209, the process proceeds to step S210, where a known evaporation concentration learning process is executed, and this routine ends. Note that, as the purge rate when the purge rate is increased by the purge control is faster, a larger amount of evaporated fuel is quickly discharged into the intake passage 2 of the internal combustion engine 1, so that as shown in FIG. As appropriate, the fuel F / B (feedback) value is set small, and the amount of fuel injected and supplied from the injector 10 into the intake passage 2 of the internal combustion engine 1 is set small.

  As described above, the evaporative fuel processing apparatus for an internal combustion engine according to this embodiment automatically stops the internal combustion engine 1 when the internal combustion engine 1 mounted on the vehicle satisfies the predetermined automatic stop condition when idling. When a predetermined automatic start condition is satisfied after the stop, the automatic start / stop control means achieved by the ECU 40 that controls the internal combustion engine 1 to start automatically, and the evaporated fuel generated in the fuel tank 20 are stored in the canister 30, Purge control means achieved by the ECU 40 that performs purge control for releasing the evaporated fuel stored in the canister 30 into the intake passage 2 of the internal combustion engine 1 by opening and closing the purge valve 33 according to the operating state of the engine 1 And a predetermined period from the automatic start of the internal combustion engine 1 during or after the automatic stop of the internal combustion engine 1 by the automatic start / stop control means Is for and a purge control switching means which is achieved by ECU40 to switch to normal operation with different purge control other than this.

  Further, the purge control switching means achieved by the ECU 40 of the evaporated fuel processing apparatus for an internal combustion engine of the present embodiment corresponds to the state of the internal combustion engine 1 during the automatic stop of the internal combustion engine 1 by the automatic start / stop control means. The evaporation concentration learning value in the purge control is corrected. The purge control switching means achieved by the ECU 40 of the evaporated fuel processing apparatus for an internal combustion engine according to the present embodiment is an evaporation in the purge control in accordance with the idle stop elapsed time that is an automatic stop period that represents the state of the internal combustion engine 1. The density learning value is corrected. Further, the purge control switching means achieved by the ECU 40 of the fuel vapor processing apparatus for an internal combustion engine according to the present embodiment is an elapsed time learning in which an idle stop elapsed time, which is an automatic stop period showing the state of the internal combustion engine 1, is a predetermined value. When the value is equal to or larger than the value clear threshold value α, the evaporation concentration learning value in the purge control is returned to the initial value.

  That is, during the normal operation of the internal combustion engine 1, the purge valve 33 is opened and closed according to the operation state of the internal combustion engine 1, and the evaporated fuel stored in the canister 30 is released into the intake passage 2 of the internal combustion engine 1 to perform purge control. Executed. On the other hand, when the internal combustion engine 1 is in the idling stop, naturally, the purge control during the normal operation cannot be executed. Therefore, the automatic control for specifying the state of the internal combustion engine 1 is performed as a control different from the normal operation. The evaporation concentration learning value in the purge control is corrected according to the idle stop elapsed time as the stop period, and when the idle stop elapsed time is equal to or greater than the elapsed time learning value clear threshold value α, the evaporation concentration learning value in the purge control is initially set. Returned to value.

  That is, during the idling stop of the internal combustion engine 1 that is not during normal operation, the evaporation concentration gradually increases according to the elapsed idling stop time. It is corrected. Further, if the idle stop elapsed time becomes longer than the elapsed time learning value clear threshold value α, the reliability of the evaporation concentration learning value becomes low, so the evaporation concentration learning value in the purge control is returned to the initial value. As a result, even immediately after the automatic start after the idle stop, the evaporation concentration learning value in the purge control is set appropriately, so that the emission deterioration can be prevented.

  Furthermore, the purge control switching means achieved in the ECU 40 of the evaporated fuel processing apparatus for an internal combustion engine according to the present embodiment is the purge in a predetermined period after the automatic start of the internal combustion engine 1 by the automatic start stop means. The increase rate per unit time of the purge rate of the air containing the evaporated fuel in the control is made slower than that during normal operation. In addition, the purge control switching means achieved by the ECU 40 of the fuel vapor processing apparatus for an internal combustion engine of the present embodiment is a predetermined period after the automatic start after the automatic stop of the internal combustion engine 1 by the automatic start / stop control means. The evaporating concentration learning speed in the purge control is made higher than that in the normal operation.

  That is, in the predetermined period after the automatic start return after the idling stop of the internal combustion engine 1, the purge that is an increase rate per unit time of the purge rate of the air including the evaporated fuel in the purge control is different from the purge control in the normal operation. The speed is set to be slower than in normal operation, and the evaporation concentration learning speed in the purge control is set to be higher than in normal operation.

  That is, during a predetermined period after the automatic start return after idle stop that is not during normal operation, the evaporative concentration learning value in purge control is less reliable, so the purge speed is higher than during normal operation in consideration of safety. The learning speed of the evaporation concentration in the purge control is set to be higher than that in the normal operation so that the accurate learning value of the evaporation concentration can be obtained as soon as possible. As a result, the evaporation concentration learned value can be promptly shifted during normal operation while preventing emission deterioration in purge control after automatic start after idle stop.

  By the way, in the said Example, although the evaporation density learning value is correct | amended according to the idle stop elapsed time as an automatic stop period of the internal combustion engine 1, when implementing this invention, it is not limited to this. In addition, as a parameter at this time, according to at least one of the oil temperature, the cooling water temperature, the intake air temperature, the outside air temperature, the combustion temperature, or the rate of change, the amount of change, and the integrated value of the internal combustion engine 1, The same operation and effect as the above-mentioned embodiment can be expected.

  In the above embodiment, the evaporation concentration learning value is returned to the initial value in accordance with the idle stop elapsed time as the automatic stop period of the internal combustion engine 1, but the present invention is limited to this. In addition to this, as a parameter at this time, at least one of the oil temperature, the cooling water temperature, the intake air temperature, the outside air temperature, the combustion temperature, or the rate of change, the amount of change, and the integrated value of the internal combustion engine 1 is used. According to this, the same operation and effect as the above-described embodiment can be expected.

FIG. 1 is a schematic configuration diagram showing an internal combustion engine and peripheral devices to which an evaporated fuel processing apparatus for an internal combustion engine according to an embodiment of the present invention is applied. FIG. 2 is a flowchart showing a processing procedure of the evaporation concentration learning value calculation in the ECU used in the evaporated fuel processing apparatus for an internal combustion engine according to one embodiment of the present invention. FIG. 3 is a time chart showing transition states such as various control amounts corresponding to the processing of FIG. FIG. 4 is a flowchart showing a processing procedure for setting the purge speed in the ECU used in the evaporated fuel processing apparatus for an internal combustion engine according to one embodiment of the present invention. FIG. 5 is a time chart showing transition states such as various control amounts corresponding to the processing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake passage 20 Fuel tank 30 Canister 33 Purge valve 40 ECU (electronic control unit)

Claims (6)

When the internal combustion engine mounted on the vehicle is idle, when the predetermined automatic stop condition is satisfied, the internal combustion engine is automatically stopped. When the predetermined automatic start condition is satisfied after the automatic stop, the internal combustion engine is automatically started. Automatic start / stop control means for controlling
Purging control is performed in which the evaporated fuel generated in the fuel tank is stored in the canister, and the purge valve is opened / closed according to the operating state of the internal combustion engine to release the evaporated fuel stored in the canister into the intake passage of the internal combustion engine. Purge control means to be executed;
Purge control switching means for switching to a purge control different from that during normal operation during a predetermined period from the automatic start of the internal combustion engine during or after the automatic stop of the internal combustion engine by the automatic start / stop control means. An evaporative fuel processing apparatus for an internal combustion engine characterized by the above.   The purge control switching means corrects the learning value of the evaporated fuel concentration in the purge control according to the state of the internal combustion engine during the automatic stop of the internal combustion engine by the automatic start / stop control means. The evaporative fuel processing apparatus of the internal combustion engine according to claim 1.   The purge control switching means is at least one of an automatic stop period, an oil temperature, a cooling water temperature, an intake air temperature, an outside air temperature, a combustion temperature, or a change rate, a change amount, and an integrated value of the internal combustion engine. The evaporated fuel processing apparatus for an internal combustion engine according to claim 2, wherein the learning value of the concentration of the evaporated fuel in the purge control is corrected accordingly.   The purge control switching means has at least one of an automatic stop period in which the state of the internal combustion engine is exhibited, oil temperature, cooling water temperature, intake air temperature, outside air temperature, combustion temperature, or a change rate, change amount, and integrated value thereof. The evaporative fuel processing apparatus for an internal combustion engine according to claim 2, wherein when the value is equal to or greater than the value, the learning value of the evaporative fuel concentration in the purge control is returned to an initial value.   The purge control switching means is configured to increase an increase rate per unit time of a purge rate of air including evaporated fuel in the purge control in a predetermined period after the automatic start of the internal combustion engine by the automatic start / stop control means. 2. The evaporative fuel processing apparatus for an internal combustion engine according to claim 1, wherein the evaporative fuel processing apparatus is slower than the normal operation.   The purge control switching means makes the evaporative fuel concentration learning speed in the purge control faster than during normal operation in a predetermined period after the automatic start of the internal combustion engine by the automatic start / stop control means. The evaporated fuel processing apparatus for an internal combustion engine according to claim 1, wherein

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