JP2020180565A - Evaporated fuel treatment device - Google Patents

Abstract

To provide an evaporated fuel treatment device for preventing the worsening of exhaust gas performance and a fluctuation of A/F while executing purge right before the stop of an internal combustion engine to secure a purge amount.SOLUTION: An evaporated fuel treatment device 1 includes a stop timing prediction part 31 for predicting a stop timing for an engine ENG to turn on a stop estimate demand flag, and a stop waiting time calculation part 32 for calculating a predetermined time from closing a purge control valve 14 to stopping the engine ENG. A control part 17 gradually reduces the flow amount of purge gas flowing in a purge passage 12 When the stop estimate demand flag is turned on by the stop timing prediction part 31, allows the purge control valve 14 to be closed in the state that the flow amount of the purge gas is equal to or smaller than a predetermined flow amount, and stops the engine ENG when a predetermine time calculated by the stop waiting time calculation part 32 passes from closing the purge control valve 14.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an evaporative fuel processing apparatus that supplies and processes evaporative fuel generated in a fuel tank to an internal combustion engine.

Evaporative fuel treatment equipment is used to prevent the emission of fuel vapor generated in the fuel tank to the atmosphere. In this evaporated fuel processing apparatus, the fuel vapor in the fuel tank is introduced into the canister containing the adsorbent and temporarily adsorbed on the adsorbent. The fuel vapor adsorbed on the adsorbent is purged when the purge execution condition determined based on the operating conditions of the internal combustion engine is satisfied, and is purged to the intake passage of the internal combustion engine via the purge passage.

In recent years, in order to improve fuel efficiency, purging is executed until the internal combustion engine is stopped, in other words, the internal combustion engine is stopped during the purging execution.

Japanese Unexamined Patent Publication No. 2007-278094

However, if the purge is executed until the internal combustion engine is stopped, the engine is stopped during the purge execution, so that the purge gas containing the fuel gas flows out to the exhaust passage or remains in the intake passage. Therefore, the exhaust gas performance may deteriorate. Here, by stopping the engine after a certain period of time has passed after stopping the purge, it is possible to prevent the purge gas from flowing out to the exhaust passage or remaining in the intake passage. As a result, deterioration of the exhaust gas performance can be suppressed, but since the flow rate of the purge gas sharply decreases when the purge is stopped, the correction of the fuel injection amount from the injector is insufficient immediately after the purge is stopped, and before the internal combustion engine is stopped. There is a risk that A / F roughness (air-fuel ratio roughness) will occur.

Therefore, the present disclosure has been made to solve the above-mentioned problems, and while purging is executed until immediately before the internal combustion engine is stopped to secure the purge amount, the exhaust gas performance is deteriorated and the A / F is roughened. It is an object of the present invention to provide an evaporative fuel processing apparatus that does not allow

A form of this disclosure made to solve the above problems is
In the vapor passage connected to the fuel tank, the canister for storing the evaporated fuel sent from the fuel tank through the vapor passage, the intake passage connected to the internal combustion engine, the purge passage connected to the canister, and the purge passage. In an evaporative fuel processing apparatus having a purge pump provided, a purge control valve provided on the downstream side of the purge pump, and a control unit for controlling the internal combustion engine, the purge pump, and the purge control valve.
A stop timing prediction unit that predicts the stop timing of the internal combustion engine and turns on the stop prediction request flag.
It has a stop standby time calculation unit that calculates a predetermined time from the closing of the purge control valve to the stop of the internal combustion engine.
When the stop prediction request flag is turned on by the stop timing prediction unit, the control unit gradually reduces the flow rate of the purge gas flowing through the purge passage, and the flow rate of the purge gas becomes equal to or less than a predetermined flow rate. The purge control valve is closed while the purge control valve is closed, and the internal combustion engine is stopped when the predetermined time calculated by the stop standby time calculation unit elapses from the closing of the purge control valve.

In this evaporated fuel processing device, the stop timing of the internal combustion engine is predicted by the stop timing prediction unit, and the purge control valve is closed after gradually reducing the flow rate of the purge gas prior to the stop of the internal combustion engine based on the predicted timing. Stop purging. Then, the internal combustion engine is stopped when a predetermined time calculated by the stop standby time calculation unit elapses after the purge is stopped. Therefore, it is possible to prevent the purge gas from flowing out to the exhaust passage or remaining in the intake passage, and to burn the purge gas remaining in the intake passage before stopping the internal combustion engine. In addition, since the flow rate of the purge gas is reduced before the purge is stopped, the fuel injection amount from the injector is appropriately corrected when the purge is stopped, so that A / F roughness does not occur before the internal combustion engine is stopped. .. As described above, according to this evaporative fuel processing apparatus, it is possible to prevent deterioration of exhaust gas performance and A / F roughness while purging is executed until immediately before the internal combustion engine is stopped and the purge amount is secured.

Here, in order to gradually reduce the flow rate of the purge gas, in the above-mentioned evaporated fuel processing apparatus, the control unit gradually reduces the rotation speed of the purge pump to a predetermined rotation speed to reduce the flow rate of the purge gas. The flow rate may be gradually reduced to the predetermined flow rate or less.

Alternatively, in the evaporative fuel processing apparatus described above, the control unit gradually reduces the drive duty of the purge control valve to a predetermined duty value, thereby gradually reducing the flow rate of the purge gas to be equal to or lower than the predetermined flow rate. It may be.

Further, in the above-mentioned evaporated fuel processing apparatus, the control unit gradually reduces the upper limit guard value of the injector that injects and supplies fuel to the internal combustion engine to a predetermined guard value, thereby gradually increasing the flow rate of the purge gas. It may be reduced to be equal to or less than the predetermined flow rate.

Then, in the above-mentioned evaporated fuel processing apparatus,
It is preferable that the stop standby time calculation unit determines the predetermined time based on the intake air amount of the internal combustion engine.

By doing so, the purge gas remaining in the intake passage can be burned before the internal combustion engine is stopped, so that the purge gas can be reliably prevented from flowing out to the exhaust passage or remaining in the intake passage. it can. Therefore, deterioration of exhaust gas performance can be reliably prevented.

Further, in the above-mentioned evaporated fuel processing apparatus,
In the case of a hybrid vehicle equipped with a motor and a battery in addition to the internal combustion engine, the stop timing prediction unit preferably turns on the stop prediction request flag based on the state of charge of the battery.

Since the hybrid vehicle can accurately predict the stop timing of the internal combustion engine from the charged state of the battery, the stop prediction request flag can be turned on accurately. Therefore, it is possible to reliably prevent deterioration of exhaust gas performance and A / F roughness while ensuring a sufficient purge amount until immediately before the internal combustion engine is stopped.

Further, in the above-mentioned evaporated fuel treatment apparatus,
The stop timing prediction unit may turn on the stop prediction request flag based on the vehicle speed or the accelerator opening degree of the vehicle equipped with the internal combustion engine.

By doing so, even if the vehicle is not a hybrid vehicle, it is possible to prevent deterioration of exhaust gas performance and A / F roughness while ensuring a purge amount until immediately before the internal combustion engine is stopped.

According to the present disclosure, it is possible to provide an evaporative fuel treatment apparatus that does not cause deterioration of exhaust gas performance and A / F roughness while ensuring a purge amount until immediately before the internal combustion engine is stopped.

It is the schematic which shows the whole structure of the engine system including the evaporative fuel processing apparatus. It is a figure which shows the control flowchart of the purge control of 1st Embodiment. It is a figure which shows an example of the map which determines the stop waiting time. It is a figure which shows an example of the control time chart of 1st Embodiment. It is a figure which shows the control flowchart of the purge control of 2nd Embodiment. It is a figure which shows an example of the control time chart of 2nd Embodiment. It is a figure which shows the control flowchart of the purge control of 3rd Embodiment. It is a figure which shows an example of the control time chart of 3rd Embodiment.

The evaporated fuel treatment apparatus according to the embodiment of the present disclosure will be described in detail with reference to the drawings. In the following embodiment, a case where the evaporated fuel treatment device of the present disclosure is applied to an engine system mounted on a hybrid vehicle equipped with a motor and a battery in addition to the engine will be described.

<Overall system configuration>
The engine system to which the evaporative fuel processing device 1 of the present embodiment is applied is mounted on a vehicle such as an automobile, and includes an engine ENG, a motor MG, and a battery BAT as shown in FIG. An intake passage IP for supplying air (intake air, intake air) to the engine ENG is connected to this engine ENG. The intake passage IP is provided with an electronic throttle THR (throttle valve) that opens and closes the intake passage IP to control the amount of air flowing into the engine ENG (intake air amount). An air cleaner AC for removing foreign matter from the air flowing into the intake passage IP is provided on the upstream side (upstream side in the flow direction of the intake air) of the electronic throttle THR in the intake passage IP. As a result, in the intake passage IP, air passes through the air cleaner AC and is sucked toward the engine ENG. Further, an air flow meter AFM is provided on the downstream side of the air cleaner AC. This air flow meter AFM detects the amount of air that passes through the air cleaner AC and is introduced into the intake passage IP from the atmosphere. Then, the detection signal of the air flow meter AFM is input to the control unit 17 (stop standby time calculation unit 32) described later.

The evaporative fuel processing device 1 of the present embodiment is a device that supplies the evaporative fuel in the fuel tank FT to the engine ENG via the intake passage IP in such an engine system. The evaporative fuel processing device 1 includes a canister 11, a purge passage 12, a purge pump 13, a purge control valve 14, an atmospheric passage 15, a vapor passage 16, a control unit 17, a filter 18, and an atmospheric shutoff valve. It has 19 mag.

The canister 11 is connected to the fuel tank FT via the vapor passage 16, and temporarily stores the evaporated fuel flowing from the fuel tank FT through the vapor passage 16. Further, the canister 11 communicates with the purge passage 12 and the atmospheric passage 15.

The purge passage 12 is connected to the intake passage IP and the canister 11. As a result, the purge gas (gas containing evaporated fuel) flowing out of the canister 11 flows through the purge passage 12 and is introduced into the intake passage IP. In the example shown in FIG. 1, the purge passage 12 is connected to a position on the downstream side (downstream side in the flow direction of the intake air) of the electronic throttle THR. Further, the purge passage 12 is located between the upstream passage 12a located on the upstream side of the purge pump 13 (between the canister 11 and the purge pump 13) and the downstream side of the purge pump 13 (between the purge pump 13 and the intake passage IP). ) Is provided with a downstream passage 12b.

The purge pump 13 is provided in the purge passage 12 and controls the flow of the purge gas flowing through the purge passage 12. That is, the purge pump 13 sends the purge gas in the canister 11 to the purge passage 12, and supplies the purge gas sent to the purge passage 12 to the intake passage IP.

The purge control valve 14 is provided in the purge passage 12 at a position on the downstream side of the purge pump 13 (downstream in the flow direction of the purge gas when the purge control is executed), that is, at a position between the purge pump 13 and the intake passage IP. Has been done. The purge control valve 14 opens and closes the purge passage 12. When the purge control valve 14 is closed (when the valve is closed), the purge gas in the purge passage 12 is stopped by the purge control valve 14 and does not flow to the intake passage IP. On the other hand, when the purge control valve 14 is opened (when the valve is open), the purge gas flows into the intake passage IP.

One end of the air passage 15 is open to the atmosphere, and the other end is connected to the canister 11, which communicates the canister 11 with the atmosphere. Then, the air taken in from the atmosphere flows through the air passage 15. A filter 18 and an air shutoff valve 19 are provided in the air passage 15. The filter 18 removes foreign matter from the atmosphere (air) flowing into the atmospheric passage 15. The atmospheric shutoff valve 19 opens and closes the atmospheric passage 15.

The vapor passage 16 is connected to the fuel tank FT and the canister 11. As a result, the evaporated fuel in the fuel tank FT flows into the canister 11 through the vapor passage 16.

The control unit 17 is a part of the ECU (not shown) mounted on the vehicle, and is integrally arranged with other parts of the ECU (for example, a part that controls the engine ENG). The control unit 17 may be arranged separately from other parts of the ECU. The control unit 17 includes a CPU and memories such as ROM and RAM. The control unit 17 controls the evaporative fuel processing device 1 and the engine system according to a program stored in the memory in advance. For example, the control unit 17 controls the purge pump 13, the purge control valve 14, the injector INJ, and the like. In addition, the control unit 17 acquires an output signal (air amount detection result) from the air flow meter AFM.

In the present embodiment, the control unit 17 includes a stop timing prediction unit 31 and a stop standby time calculation unit 32. The stop timing prediction unit 31 predicts the stop timing of the engine ENG and turns on the stop prediction request flag. The stop timing prediction unit 31 of the present embodiment predicts the stop timing of the engine ENG based on the charge state of the battery BAT and turns on the stop prediction request flag. When the engine ENG is stopped, the stop standby time calculation unit 32 calculates the stop standby time from the closing of the purge control valve 14 to the stop of the engine ENG. The stop standby time calculation unit 32 of the present embodiment calculates the stop standby time based on the intake air amount detected by the air flow meter AFM. As the stop standby time, the time during which the purge gas remaining in the intake passage IP can be completely burned is calculated. The stop timing prediction unit 31 and the stop standby time calculation unit 32 may be provided independently of the control unit 17.

In the evaporative fuel processing device 1 having such a configuration, when the purge condition is satisfied during the operation of the engine ENG, the control unit 17 controls the purge pump 13 and the purge control valve 14, that is, drives the purge pump 13. While opening the purge control valve 14, the purge control is executed. The purge control is a control for introducing the purge gas from the canister 11 to the intake passage IP via the purge passage 12.

Then, while the purge control is being executed, the air sucked into the intake passage IP, the fuel injected from the fuel tank FT via the injector INJ, and the fuel injected into the intake passage IP by the purge control are supplied to the engine ENG. Purging gas and is supplied. Then, the control unit 17 adjusts the injection time of the injector INJ, the valve opening time of the purge control valve 14, and the like to adjust the air-fuel ratio (A / F) of the engine ENG to the optimum air-fuel ratio (for example, the ideal air-fuel ratio). adjust.

Here, if the purge control is executed until just before the engine ENG is stopped in order to improve fuel efficiency, the purge gas containing the fuel gas may flow out to the exhaust passage or remain in the intake passage, resulting in deterioration of the exhaust gas performance. there were. Therefore, in order to eliminate the residual purge gas, it is conceivable to stop the engine ENG after a certain period of time has elapsed after stopping the purge control. However, in this case, the correction of the fuel injection amount from the injector INJ becomes insufficient from the stop of the purge control to the stop of the engine ENG, and A / F roughness (air-fuel ratio roughness) occurs before the engine ENG is stopped. There was a risk of doing so.

<Details of purge control>
Therefore, the stop timing at which the engine ENG is stopped is predicted, and prior to the stop of the engine ENG, the flow rate of the purge gas is gradually reduced, the purge control is terminated, and then the purge control is performed so as to stop the engine ENG. .. This purge control will be specifically described below by exemplifying three forms.

[First Embodiment]
First, the purge control of the first embodiment will be described with reference to FIGS. 2 to 4. In the first embodiment, the control unit 17 performs purge control based on the control chart shown in FIG. That is, the control unit 17 first opens the purge control valve 14 when the purge condition is satisfied. The purge pump 13 is driven at a constant rotation speed (for example, 10,000 rpm) when the engine ENG is started. Then, it is determined whether or not a predetermined time (for example, 3 seconds) has elapsed after the purge control valve 14 is opened (step S1).

When a predetermined time elapses after the purge control valve 14 is opened (S1: YES), the control unit 17 increases the rotation speed of the purge pump 13 (step S2). In the present embodiment, for example, the rotation speed of the purge pump 13 is increased from 10,000 rpm to 40,000 rpm. In this way, the purge control is performed, the purge gas in the canister 11 is sent to the purge passage 12, and the purge gas sent to the purge passage 12 is supplied to the intake passage IP.

Then, the stop timing prediction unit 31 predicts the stop timing of the next engine ENG based on the charge amount of the battery BAT. This is because the stop timing of the engine ENG can be accurately predicted from the charged state of the battery BAT. Specifically, if the stop timing prediction unit 31 (control unit 17) charges the battery BAT to a predetermined amount A or more (for example, 70% or more) (step S3: YES), the engine stop prediction request flag is turned ON. (Step S4). On the other hand, if the charge amount of the battery BAT is less than the predetermined amount A (for example, less than 70%) (S3: NO), the engine stop prediction request flag is turned off (step S5).

Next, the control unit 17 determines whether or not the engine stop prediction request flag is ON (step S6). At this time, if the engine stop prediction request flag is ON (S6: YES), the control unit 17 gradually reduces the flow rate of the purge gas. Specifically, the control unit 17 gradually reduces the rotation speed of the purge pump 13 (step S7). In the present embodiment, for example, the rotation speed of the purge pump 13 is gradually reduced from 40,000 rpm to 10,000 rpm.

After that, the control unit 17 closes the purge control valve 14 to stop purging (step S8). As a result, purging is stopped when the flow rate of the purge gas is reduced. Therefore, when the purge is stopped, the flow rate of the purge gas does not decrease sharply, so that the fuel injection amount from the injector INJ is appropriately corrected when the purge is stopped. Therefore, A / F roughness does not occur when the purge is stopped.

When the purge is stopped, the stop standby time calculation unit 32 (control unit 17) determines the stop standby time W from the purge stop to the stop of the engine ENG (step S9). In this embodiment, the stop standby time W is determined according to the amount of intake air. Specifically, as shown in FIG. 3, the stop standby time W is defined according to the intake air amount, and is defined so as to become shorter as the intake air amount increases. As a result, the purge gas remaining in the intake passage IP can be reliably burned before the engine ENG is stopped. Therefore, it is possible to prevent deterioration of exhaust gas performance. It should be noted that the map data for calculating the stop standby time W may be obtained in advance from an experiment to be optimal according to the specifications of the engine system (evaporated fuel processing device 1).

Then, when the stop standby time W determined in S9 elapses after the purge control valve 14 is closed (purge is stopped), the control unit 17 turns on the engine stop request flag (step S10). .. As a result, the engine ENG is stopped.

As described above, in the purge control of the present embodiment, the stop timing of the engine ENG is predicted by the stop timing prediction unit 31, and the rotation speed of the purge pump 13 is gradually reduced based on the predicted timing prior to the stop of the engine ENG. By doing so, the flow rate of the purge gas is reduced, and then the purge control valve 14 is closed to stop the purge. Then, the engine ENG is stopped when the stop standby time W calculated by the stop standby time calculation unit 32 elapses after the purge is stopped.

As a result, when the purge is stopped, the purge gas is suppressed from flowing out to the exhaust passage or remaining in the intake passage, and the purge gas remaining in the intake passage is burned before the engine ENG is stopped, and then the engine ENG is stopped. Further, since the flow rate of the purge gas is reduced before the purge is stopped, the fuel injection amount from the injector is appropriately corrected when the purge is stopped, so that A / F roughness does not occur before the engine ENG is stopped. .. As described above, according to the purge control of the present embodiment, the purge is executed until immediately before the engine ENG is stopped, the purge amount is secured, and the deterioration of the exhaust gas performance and the A / F roughness can be prevented.

By performing control based on the control chart shown in FIG. 2, an example of the control time chart as shown in FIG. 4 is implemented. As shown in FIG. 4, at time T1, the engine ENG is started and the purge pump 13 is driven at a predetermined rotation speed (for example, 10,000 rpm). Then, at time T2, the purge control valve 14 is opened and purging is started. The rotation speed of the purge pump 13 increases at time T3 when a predetermined time (for example, 3 seconds) has elapsed from the start of purging. This increases the flow rate of the purge gas.

After that, when the charge amount of the battery BAT reaches a predetermined amount A (for example, 70%) at time T4, the stop prediction request flag is turned on by the stop timing prediction unit 31, and the rotation speed of the purge pump 13 is turned on by the control unit 17. Is gradually reduced to the number of revolutions at the start of driving (for example, 10,000 rpm) at time T5. Then, at time T6, the purge control valve 14 is closed, the purge pump 13 is stopped, and the purge is completed. Then, at the time T7 when the stop standby time W has elapsed from the time T6, the engine stop request flag is turned ON and the engine ENG is stopped. As a result, A / F roughness does not occur before the engine ENG is stopped as in the conventional example shown by the broken line.

[Second Embodiment]
Next, the purge control of the second embodiment will be described with reference to FIGS. 5 and 6. In the second embodiment, the control unit 17 performs purge control based on the control chart shown in FIG. That is, the control unit 17 first opens the purge control valve 14 when the purge condition is satisfied. At this time, the opening degree of the purge control valve 14 is not fully opened but about half (for example, drive duty 50%). Further, the purge pump 13 is driven at a constant rotation speed (for example, 30,000 rpm) when the engine ENG is started. Then, it is determined whether or not a predetermined time (for example, 3 seconds) has elapsed after the purge control valve 14 is opened (step S21).

When a predetermined time elapses after the purge control valve 14 is opened (S21: YES), the control unit 17 increases the drive duty of the purge control valve 14 (step S22). In this embodiment, for example, the drive duty of the purge control valve 14 is increased from 50% to 100%. In this way, the purge control is performed, the purge gas in the canister 11 is sent to the purge passage 12, and the purge gas sent to the purge passage 12 is supplied to the intake passage IP.

Then, the stop timing prediction unit 31 predicts the stop timing of the next engine ENG based on the charge amount of the battery BAT. Specifically, if the stop timing prediction unit 31 (control unit 17) charges the battery BAT to a predetermined amount A or more (for example, 70% or more) (step S23: YES), the engine stop prediction request flag is turned ON. (Step S24). On the other hand, if the charge amount of the battery BAT is less than the predetermined amount A (for example, less than 70%) (S23: NO), the engine stop prediction request flag is turned off (step S25).

Next, the control unit 17 determines whether or not the engine stop prediction request flag is ON (step S26). At this time, if the engine stop prediction request flag is ON (S26: YES), the control unit 17 gradually reduces the flow rate of the purge gas. Specifically, the control unit 17 gradually reduces the drive duty of the purge control valve 14 (step S27). In this embodiment, for example, the drive duty of the purge control valve 14 is gradually reduced from 100% to 50%.

After that, the control unit 17 closes the purge control valve 14 to stop purging (step S28). As a result, purging is stopped when the flow rate of the purge gas is reduced. Therefore, when the purge is stopped, the flow rate of the purge gas does not decrease sharply, so that the fuel injection amount from the injector INJ is appropriately corrected when the purge is stopped. Therefore, A / F roughness does not occur when the purge is stopped.

When the purge is stopped, the stop standby time calculation unit 32 (control unit 17) determines the stop standby time W from the purge stop to the stop of the engine ENG (step S29). The stop standby time W is determined according to the intake air amount as in the first embodiment (see FIG. 3). As a result, the purge gas remaining in the intake passage IP can be reliably burned before the engine ENG is stopped. Therefore, it is possible to prevent deterioration of exhaust gas performance.

Then, when the stop standby time W determined in S29 elapses after the purge control valve 14 is closed (purge is stopped), the control unit 17 turns on the engine stop request flag (step S30). .. As a result, the engine ENG is stopped.

As described above, in the purge control of the present embodiment, the stop timing of the engine ENG is predicted by the stop timing prediction unit 31, and the drive duty of the purge control valve 14 is set based on the predicted timing prior to the stop of the engine ENG. By gradually reducing the flow rate, the flow rate of the purge gas is reduced, and then the purge control valve 14 is closed to stop the purge. Then, the engine ENG is stopped when the stop standby time W calculated by the stop standby time calculation unit 32 elapses after the purge is stopped.

As a result, when the purge is stopped, the purge gas is suppressed from flowing out to the exhaust passage or remaining in the intake passage, and the purge gas remaining in the intake passage is burned before the engine ENG is stopped, and then the engine ENG is stopped. Further, since the flow rate of the purge gas is reduced before the purge is stopped, the fuel injection amount from the injector is appropriately corrected when the purge is stopped, so that A / F roughness does not occur before the engine ENG is stopped. .. As described above, according to the purge control of the present embodiment, the purge is executed until immediately before the engine ENG is stopped, the purge amount is secured, and the deterioration of the exhaust gas performance and the A / F roughness can be prevented.

By performing control based on the control chart shown in FIG. 5, an example of the control time chart as shown in FIG. 6 is implemented. As shown in FIG. 6, at time T21, the engine ENG is started and the purge pump 13 is driven at a predetermined rotation speed (for example, 30,000 rpm). Then, at time T22, the purge control valve 14 is opened and purging is started. At this time, the drive duty of the purge control valve 14 is, for example, 50%. At time T23, when a predetermined time (for example, 3 seconds) has elapsed from the start of purging, the drive duty of the purge control valve 14 increases to, for example, 100%. This increases the flow rate of the purge gas.

After that, when the charge amount of the battery BAT reaches a predetermined amount A (for example, 70%) at time T24, the stop prediction request flag is turned on by the stop timing prediction unit 31, and the purge control valve 14 is driven by the control unit 17. The duty is gradually reduced to the drive duty (for example, 50%) at the start of purging at time T25. Then, at time T26, the purge control valve 14 is closed, the purge pump 13 is stopped, and the purge is completed. Then, at the time T27 when the stop standby time W has elapsed from the time T26, the engine stop request flag is turned ON and the engine ENG is stopped. As a result, the A / F roughness that has occurred when the purge is completed at time T24 as in the conventional example shown by the broken line is eliminated.

[Third Embodiment]
Finally, the purge control of the third embodiment will be described with reference to FIGS. 7 and 8. In the second embodiment, the control unit 17 performs purge control based on the control chart shown in FIG. 7. That is, the control unit 17 first opens the purge control valve 14 when the purge condition is satisfied. The purge pump 13 is driven at a constant rotation speed (for example, 30,000 rpm) when the engine ENG is started. Then, it is determined whether or not a predetermined time (for example, 3 seconds) has elapsed after the purge control valve 14 is opened (step S31).

When a predetermined time elapses after the purge control valve 14 is opened (S31: YES), the control unit 17 expands the weight loss guard of the injector INJ (step S32). In this embodiment, for example, the weight loss guard of the injector INJ is doubled (30% to 60%). By expanding the weight loss guard, the injection amount ratio of the injector INJ decreases, so that the flow rate of the purge gas increases. In this way, the purge control is performed, the purge gas in the canister 11 is sent to the purge passage 12, and the purge gas sent to the purge passage 12 is supplied to the intake passage IP.

Then, the stop timing prediction unit 31 predicts the stop timing of the next engine ENG based on the charge amount of the battery BAT. Specifically, if the stop timing prediction unit 31 (control unit 17) charges the battery BAT to a predetermined amount A or more (for example, 70% or more) (step S33: YES), the engine stop prediction request flag is turned ON. (Step S34). On the other hand, if the charge amount of the battery BAT is less than the predetermined amount A (for example, less than 70%) (S33: NO), the engine stop prediction request flag is turned off (step S35).

Next, the control unit 17 determines whether or not the engine stop prediction request flag is ON (step S36). At this time, if the engine stop prediction request flag is ON (S36: YES), the control unit 17 gradually reduces the flow rate of the purge gas. Specifically, the control unit 17 gradually reduces the weight loss guard of the injector INJ (step S37). In the present embodiment, for example, the weight loss guard of the injector INJ is gradually reduced by half (for example, 60% to 30%).

After that, the control unit 17 closes the purge control valve 14 to stop purging (step S38). As a result, purging is stopped when the flow rate of the purge gas is reduced. Therefore, when the purge is stopped, the flow rate of the purge gas does not decrease sharply, so that the fuel injection amount from the injector INJ is appropriately corrected when the purge is stopped. Therefore, A / F roughness does not occur when the purge is stopped.

When the purge is stopped, the stop standby time calculation unit 32 (control unit 17) determines the stop standby time W from the purge stop to the stop of the engine ENG (step S39). The stop standby time W is determined according to the intake air amount as in the first embodiment (see FIG. 3). As a result, the purge gas remaining in the intake passage IP can be reliably burned before the engine ENG is stopped. Therefore, it is possible to prevent deterioration of exhaust gas performance.

Then, when the stop standby time W determined in S39 elapses after the purge control valve 14 is closed (purge is stopped), the control unit 17 turns on the engine stop request flag (step S40). .. As a result, the engine ENG is stopped.

As described above, in the purge control of the present embodiment, the stop timing of the engine ENG is predicted by the stop timing prediction unit 31, and the weight loss guard of the injector INJ is gradually reduced based on the prediction timing prior to the stop of the engine ENG. As a result, the flow rate of the purge gas is reduced, and then the purge control valve 14 is closed to stop the purge. Then, the engine ENG is stopped when the stop standby time W calculated by the stop standby time calculation unit 32 elapses after the purge is stopped.

As a result, when the purge is stopped, the purge gas is suppressed from flowing out to the exhaust passage or remaining in the intake passage, and the purge gas remaining in the intake passage is burned before the engine ENG is stopped, and then the engine ENG is stopped. Further, since the flow rate of the purge gas is reduced before the purge is stopped, the fuel injection amount from the injector is appropriately corrected when the purge is stopped, so that A / F roughness does not occur before the engine ENG is stopped. .. As described above, according to the purge control of the present embodiment, the purge is executed until immediately before the engine ENG is stopped, the purge amount is secured, and the deterioration of the exhaust gas performance and the A / F roughness can be prevented.

By performing control based on the control chart shown in FIG. 7, an example of the control time chart as shown in FIG. 8 is implemented. As shown in FIG. 8, at time T31, the engine ENG is started and the purge pump 13 is driven at a predetermined rotation speed (for example, 30,000 rpm). Then, at time T32, the purge control valve 14 is opened and purging is started. At this time, the weight loss guard of the injector INJ is, for example, 30%. At time T33, when a predetermined time (for example, 3 seconds) has elapsed from the start of purging, the weight loss guard of the injector INJ increases from 30% to 60%. As a result, the injection amount ratio of the injector INJ decreases, so that the flow rate of the purge gas increases.

After that, when the charge amount of the battery BAT reaches a predetermined amount A (for example, 70%) at time T34, the stop prediction request flag is turned on by the stop timing prediction unit 31, and the weight loss guard of the injector INJ is turned on by the control unit 17. It is gradually reduced to the weight loss guard (for example, 30%) at the start of purging at time T35. Then, at time T36, the purge control valve 14 is closed, the purge pump 13 is stopped, and the purge is completed. Then, at the time T37 when the stop standby time W has elapsed from the time T36, the engine stop request flag is turned ON and the engine ENG is stopped. As a result, the A / F roughness that occurs when the purge is completed at the time T34 as in the conventional example shown by the broken line is eliminated.

It should be noted that the above-described embodiment is merely an example and does not limit the present disclosure in any way, and it goes without saying that various improvements and modifications can be made without departing from the gist thereof. For example, in the above embodiment, the evaporative fuel treatment apparatus of the present disclosure is applied to a hybrid vehicle, but of course, the evaporative fuel treatment of the present disclosure is also applied to a normal gasoline vehicle not provided with a motor MG and a battery BAT. The device can be applied. In this case, the stop timing prediction unit 31 uses the engine based on the accelerator opening state (for example, changing from 20% to 0%) and the vehicle speed (for example, less than 10 km / h) instead of the battery charge amount. The engine stop prediction request flag may be turned ON by predicting the stop timing of the ENG.

Further, although the evaporative fuel treatment device of the present disclosure is applied to a naturally aspirated engine system, of course, a purge gas is introduced upstream of the supercharger to evaporate the present disclosure even for an engine system with a supercharger. Fuel processing equipment can be applied.

1 Evaporated fuel processing device 11 Canister 12 Purge passage 13 Purge pump 14 Purge control valve 17 Control unit 31 Stop timing prediction unit 32 Stop standby time calculation unit AFM Air flow meter ENG Engine FT Fuel tank INJ injector

Claims (7)

In the vapor passage connected to the fuel tank, the canister for storing the evaporated fuel sent from the fuel tank through the vapor passage, the intake passage connected to the internal combustion engine, the purge passage connected to the canister, and the purge passage. In an evaporative fuel processing apparatus having a purge pump provided, a purge control valve provided on the downstream side of the purge pump, and a control unit for controlling the internal combustion engine, the purge pump, and the purge control valve.
A stop timing prediction unit that predicts the stop timing of the internal combustion engine and turns on the stop prediction request flag.
It has a stop standby time calculation unit that calculates a predetermined time from the closing of the purge control valve to the stop of the internal combustion engine.
When the stop prediction request flag is turned on by the stop timing prediction unit, the control unit gradually reduces the flow rate of the purge gas flowing through the purge passage, and the flow rate of the purge gas becomes equal to or less than a predetermined flow rate. Evaporation characterized in that the purge control valve is closed while the purge control valve is closed, and the internal combustion engine is stopped when the predetermined time calculated by the stop standby time calculation unit elapses from the closing of the purge control valve. Fuel processing equipment. In the evaporated fuel treatment apparatus according to claim 1,
The control unit is an evaporative fuel processing apparatus characterized in that the flow rate of the purge gas is gradually reduced to a predetermined flow rate or less by gradually reducing the rotation speed of the purge pump to a predetermined rotation speed. .. In the evaporated fuel treatment apparatus according to claim 1,
The control unit gradually reduces the drive duty of the purge control valve to a predetermined duty value, thereby gradually reducing the flow rate of the purge gas to a predetermined flow rate or less. apparatus. In the evaporated fuel treatment apparatus according to claim 1,
The control unit gradually reduces the upper limit guard value of the injector that injects and supplies fuel to the internal combustion engine to a predetermined guard value, thereby gradually reducing the flow rate of the purge gas to the predetermined flow rate or less. Evaporative fuel processing equipment characterized by. In any one of the evaporated fuel treatment devices according to claims 1 to 4.
The stop standby time calculation unit is an evaporative fuel processing apparatus characterized in that the predetermined time is determined based on the intake air amount of the internal combustion engine. In any one of the evaporated fuel treatment devices according to claims 1 to 5.
In the case of a hybrid vehicle equipped with a motor and a battery in addition to the internal combustion engine, the stop timing prediction unit turns on the stop prediction request flag based on the state of charge of the battery. .. In any one of the evaporated fuel treatment devices according to claims 1 to 5.
The stop timing prediction unit is an evaporative fuel processing device characterized in that the stop prediction request flag is turned ON based on the vehicle speed or the accelerator opening degree of the vehicle equipped with the internal combustion engine.

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