JP2020133444A - Evaporated fuel treatment device - Google Patents

Abstract

To provide an evaporated fuel treatment device capable of improving detection accuracy for purge concentration right after switching between execution and stop of purge control.SOLUTION: In one aspect of the present disclosure, an evaporated fuel treatment device 1 has a pressure sensor P that detects the pressure of purge gas flowing through a purge passage 23, and a concentration detection unit 41 that detects a purge concentration. The concentration detection unit 41 detects the purge concentration based on the pressure PS of the sensor after a lapse of a predetermined time TA from the switching between execution and stop of the purge control.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.

The evaporative fuel processing apparatus disclosed in Patent Document 1 detects the pressure in the purge passage by driving the pressurizing pump with the air release valve open and the purge valve closed in a predetermined engine operating state. Estimate the concentration of fuel vapor based on the value detected by the pressure sensor.

Japanese Unexamined Patent Publication No. 2018-17184

Immediately after switching between execution and stop of purge control in the evaporated fuel processing device, the pressure in the purge passage tends to fluctuate. Therefore, if the purge concentration (concentration of evaporated fuel) is detected based on the pressure in the purge passage detected by the pressure sensor. , The detection accuracy of purge concentration may decrease. It should be noted that Patent Document 1 does not suggest any decrease in the detection accuracy of the purge concentration immediately after switching between execution and stop of such purge control.

Therefore, the present disclosure has been made to solve the above-mentioned problems, and provides an evaporative fuel treatment apparatus capable of improving the detection accuracy of the purge concentration immediately after switching between execution and stop of purge control. The purpose.

One embodiment of the present disclosure made to solve the above problems controls a canister for storing evaporated fuel, a purge passage for flowing a purge gas containing the evaporated fuel from the canister to the internal combustion engine, and a flow rate of the purge gas. Purge control for supplying the purge gas from the canister to the internal combustion engine via the purge passage by driving the purge pump and the purge valve, which has a purge pump for opening and closing the purge passage. A pressure sensor for detecting the pressure of the purge gas flowing through the purge passage and a concentration detecting unit for detecting the purge concentration which is the concentration of the evaporated fuel in the purge gas. The concentration detection unit is characterized in that the purge concentration is detected based on the pressure detected by the pressure sensor after a predetermined time has elapsed from the switching between execution and stop of the purge control.

According to this aspect, the concentration detector does not detect the purge concentration based on the pressure detected by the pressure sensor immediately after the execution and stop of the purge control are switched, and the pressure sensor does not detect the purge concentration after a predetermined time elapses. Detect the purge concentration based on the pressure detected in. As a result, immediately after switching between execution and stop of purge control, the fluctuation of the rotation speed of the purge pump converges and the fluctuation of the pressure of the purge gas flowing through the purge passage converges, and then the fluctuation is stabilized based on the pressure detected by the pressure sensor. The purge concentration can be detected. Therefore, erroneous detection of the purge concentration can be suppressed. Therefore, it is possible to improve the detection accuracy of the purge concentration immediately after switching between execution and stop of purge control.

Another embodiment of the present disclosure made to solve the above problems is a canister for storing evaporated fuel, a purge passage for flowing a purge gas containing the evaporated fuel from the canister to the internal combustion engine, and a flow rate of the purge gas. It has a purge pump to be controlled and a purge valve for opening and closing the purge passage, and by driving the purge pump and the purge valve, a purge that supplies the purge gas from the canister to the internal combustion engine via the purge passage. The evaporative fuel processing apparatus that executes control includes a pressure sensor that detects the pressure of the purge gas flowing through the purge passage, and a concentration detection unit that detects the purge concentration that is the concentration of the evaporative fuel in the purge gas. The concentration detection unit is based on the pressure detected by the pressure sensor when the fluctuation range of the parameter related to the pressure of the purge gas becomes a predetermined value or less after the execution and stop of the purge control are switched. It is characterized in that the purge concentration is detected.

According to this aspect, the concentration detector does not detect the purge concentration based on the pressure detected by the pressure sensor immediately after the execution and stop of the purge control are switched, and the parameter related to the pressure of the purge gas fluctuates. Detects the purge concentration based on the pressure detected by the pressure sensor when is converged. As a result, the concentration detector is detected by the pressure sensor immediately after switching between execution and stop of purge control, after the fluctuations of the parameters related to the pressure of the purge gas have converged and the fluctuations of the pressure of the purge gas flowing through the purge passage have converged. The purge concentration can be detected stably based on the pressure. Therefore, erroneous detection of the purge concentration can be suppressed. Therefore, it is possible to improve the detection accuracy of the purge concentration immediately after switching between execution and stop of purge control.

In addition, since the concentration detector looks at the fluctuation range of the parameter related to the pressure of the purge gas, the fluctuation of the parameter related to the pressure of the purge gas is settled immediately after switching between the execution and the stop of the purge control, and the purge gas flowing through the purge passage As soon as the pressure fluctuation subsides, detection of the purge concentration can be started based on the pressure detected by the pressure sensor. Therefore, immediately after switching between execution and stop of purge control, the non-detection time (mask time) in which the purge concentration is not detected based on the pressure detected by the pressure sensor can be shortened. Therefore, immediately after switching between execution and stop of purge control, appropriate purge control can be performed using the purge concentration detected based on the pressure detected by the pressure sensor as soon as possible.

In the above aspect, the parameter related to the pressure of the purge gas is the rotation speed of the purge pump, and the concentration detection unit subtracts the rotation speed of the target purge pump from the actual rotation speed of the purge pump. When the absolute value of the calculated deviation of the pump rotation speed becomes equal to or less than a predetermined deviation value, it is preferable to detect the purge concentration based on the pressure detected by the pressure sensor.

According to this aspect, after the execution and stop of the purge control are switched, the timing of detecting the purge concentration based on the pressure detected by the pressure sensor is the pump rotation speed which is an index of the fluctuation of the rotation speed of the purge pump. It can be judged by the deviation of. Therefore, it is possible to more reliably improve the detection accuracy of the purge concentration immediately after switching between execution and stop of purge control.

In the above aspect, the parameter related to the pressure of the purge gas is the rotation speed of the purge pump, and the concentration detection unit represents the ratio of the actual rotation speed of the purge pump to the rotation speed of the target purge pump. It is preferable to detect the purge concentration based on the pressure detected by the pressure sensor when the ratio of the pump rotation speeds is within a predetermined ratio range.

According to this aspect, after the execution and stop of the purge control are switched, the timing of detecting the purge concentration based on the pressure detected by the pressure sensor is the pump rotation speed which is an index of the fluctuation of the rotation speed of the purge pump. It can be judged by the ratio of. Therefore, it is possible to more reliably improve the detection accuracy of the purge concentration immediately after switching between execution and stop of purge control.

Another embodiment of the present disclosure made to solve the above problems is a canister for storing evaporated fuel, a purge passage for flowing a purge gas containing the evaporated fuel from the canister to the internal combustion engine, and a flow rate of the purge gas. It has a purge pump to be controlled and a purge valve for opening and closing the purge passage, and by driving the purge pump and the purge valve, a purge that supplies the purge gas from the canister to the internal combustion engine via the purge passage. The evaporative fuel processing apparatus that executes control includes a pressure sensor that detects the pressure of the purge gas flowing through the purge passage, and a concentration detection unit that detects the purge concentration that is the concentration of the evaporative fuel in the purge gas. After the execution and stop of the purge control are switched, the concentration detection unit corrects the pressure detected by the pressure sensor to suppress the influence of fluctuations in the rotation speed of the purge pump. Is calculated, and the purge concentration is detected based on the calculated pressure after the correction.

According to this aspect, the concentration detector does not detect the purge concentration based on the pressure detected by the pressure sensor, which is susceptible to fluctuations in the rotation speed of the purge pump, after the execution and stop of the purge control are switched. The purge concentration is detected based on the corrected pressure in which the influence of the fluctuation of the rotation speed of the purge pump is suppressed. As a result, even if the pressure detected by the pressure sensor fluctuates due to the fluctuation of the rotation speed of the purge pump and the pressure of the purge gas flowing through the purge passage immediately after switching between the execution and the stop of the purge control, the correction is made. The purge concentration can be stably detected based on the subsequent pressure. Therefore, erroneous detection of the purge concentration can be suppressed. Therefore, it is possible to improve the detection accuracy of the purge concentration immediately after switching between execution and stop of purge control.

In the above aspect, the corrected pressure is calculated by correcting the pressure detected by the pressure sensor using a predetermined correction coefficient, and the predetermined correction coefficient is the rotation of the target purge pump. Calculated using the ratio of the pump rotation speed, which represents the actual ratio of the rotation speed of the purge pump to the number, and the ratio of the fixed value, which represents the ratio of the fluctuation of the pressure to the fluctuation of the rotation speed of the purge pump. That is preferable.

According to this aspect, the pressure detected by the pressure sensor is represented by the ratio of the pump rotation speed, which is an index of the fluctuation of the purge pump rotation speed, and the ratio of the fluctuation of the purge gas pressure to the fluctuation of the purge pump rotation speed. The corrected pressure is calculated by correcting the pressure using the ratio of the fixed values. Therefore, the corrected pressure is appropriately calculated according to the magnitude of the fluctuation of the rotation speed of the purge pump. Therefore, it is possible to more reliably improve the detection accuracy of the purge concentration immediately after switching between execution and stop of purge control.

According to the evaporated fuel treatment apparatus of the present disclosure, it is possible to improve the detection accuracy of the purge concentration immediately after switching between execution and stop of purge control.

It is a schematic block diagram of the internal combustion engine system which has the evaporative fuel processing apparatus of this disclosure. It is a flowchart which shows the content of 1st Embodiment of the detection method of a purge concentration. It is a time chart diagram which shows the content of 1st Embodiment of the detection method of a purge concentration. It is a figure which shows the outline of the 2nd Embodiment of the detection method of a purge concentration. It is a flowchart which shows the content of the 2nd Embodiment of the detection method of a purge concentration. It is a time chart diagram which shows the content of the 2nd Embodiment of the detection method of a purge concentration. It is a flowchart which shows the content of 3rd Embodiment of the detection method of a purge concentration. It is a time chart diagram which shows the content of the 3rd Embodiment of the detection method of a purge concentration. It is a time chart diagram explaining that the pressure detected by the pressure sensor fluctuates immediately after switching between execution and stop of purge control.

Hereinafter, embodiments of the evaporated fuel treatment apparatus of the present disclosure will be described.

<Overview of internal combustion engine system>
First, before explaining the evaporative fuel treatment device 1 of the present disclosure, an outline of the internal combustion engine system 10 having the evaporative fuel treatment device 1 will be described. The internal combustion engine system 10 is used for vehicles such as automobiles.

As shown in FIG. 1, in the internal combustion engine system 10, the engine 11 (denoted as "ENG" in the figure) is connected to an intake passage 12 for supplying air (intake air, intake air) to the engine 11. .. The engine 11 is an example of the "internal combustion engine" of the present disclosure. Further, the intake passage 12 is provided with an electronic throttle 13 (for example, a throttle valve) that opens and closes the intake passage 12 to control the amount of air (intake air amount) flowing into the engine 11. Further, on the upstream side of the electronic throttle 13 in the intake passage 12 (upstream side in the flow direction of the intake air), a supercharger 14 and an air cleaner 15 for removing foreign matter from the air flowing into the intake passage 12 are provided. .. Then, air passes through the air cleaner 15 and is sucked into the intake passage 12 toward the engine 11.

The internal combustion engine system 10 includes an evaporative fuel processing device 1. The evaporative fuel processing device 1 is a device that supplies purge gas containing evaporative fuel generated in a fuel tank 21 for storing fuel to be supplied to the engine 11 to the engine 11 via an intake passage 12 for processing.

Further, the internal combustion engine system 10 has a control unit 16. The control unit 16 is a part of an ECU (not shown) mounted on the vehicle. The control unit 16 may be arranged separately from the ECU. The control unit 16 includes a CPU and memories such as ROM and RAM. The control unit 16 controls the internal combustion engine system 10 according to a program stored in the memory in advance. Further, the control unit 16 acquires the detection result from each of the sensors of the first pressure sensor 29, the second pressure sensor 30, and the third pressure sensor 31, which will be described later. The control unit 16 is also a control unit of the evaporative fuel treatment device 1 and controls the evaporative fuel treatment device 1.

<Overview of evaporative fuel treatment equipment>
Next, the outline of the evaporated fuel processing apparatus 1 will be described.

As shown in FIG. 1, the evaporative fuel processing device 1 includes a canister 22, a purge passage 23, a purge pump 24, a purge valve 25, an atmospheric passage 26, a vapor passage 27, a filter 28, and a first pressure sensor. It has (P1) 29, a second pressure sensor (P2) 30, a third pressure sensor (P3) 31, a concentration detection unit 41, and the like.

The canister 22 is connected to the fuel tank 21 via the vapor passage 27, and stores the evaporated fuel flowing from the fuel tank 21 through the vapor passage 27. Further, the canister 22 communicates with the purge passage 23 and the atmospheric passage 26.

The purge passage 23 is connected to the intake passage 12 and the canister 22. As a result, the purge gas (gas containing evaporated fuel) flowing out of the canister 22 flows through the purge passage 23, flows into the intake passage 12, and then flows into the engine 11. That is, the purge passage 23 is a passage for flowing purge gas from the canister 22 to the engine 11. In the example shown in FIG. 1, the purge passage 23 is connected to the intake passage 12 at a position between the supercharger 14 and the air cleaner 15.

The purge pump 24 is provided in the purge passage 23, and controls the flow rate of the purge gas flowing through the purge passage 23. That is, the purge pump 24 sends the purge gas in the canister 22 to the purge passage 23, and supplies the purge gas sent to the purge passage 23 to the intake passage 12.

The purge valve 25 is provided in the purge passage 23 at a position downstream of the purge pump 24 (downstream in the flow direction of the purge gas when purging control is executed), that is, at a position between the purge pump 24 and the intake passage 12. There is. The purge valve 25 opens and closes the purge passage 23. Then, when the purge valve 25 is closed (when the valve is closed), the purge gas in the purge passage 23 is stopped by the purge valve 25 and does not flow toward the intake passage 12. On the other hand, when the purge valve 25 is opened (when the valve is open), the purge gas flows into the intake passage 12.

One end of the air passage 26 is open to the atmosphere, and the other end is connected to the canister 22 to communicate the canister 22 with the atmosphere. Then, air taken in from the atmosphere flows through the air passage 26 through the filter 28.

The vapor passage 27 is connected to the fuel tank 21 and the canister 22. As a result, the evaporated fuel in the fuel tank 21 flows into the canister 22 through the vapor passage 27.

The first pressure sensor 29 detects the pressure at a position downstream of the purge pump 24 in the purge passage 23. The second pressure sensor 30 detects the pressure difference between the pressure at the position upstream of the purge pump 24 and the pressure at the position downstream of the purge pump 24 in the purge passage 23. The third pressure sensor 31 detects the pressure at a position upstream of the purge pump 24 in the purge passage 23. In the following description, the pressure sensor P is a general term for the first pressure sensor 29, the second pressure sensor 30, and the third pressure sensor 31.

Further, the concentration detection unit 41 detects the purge concentration, which is the concentration of the evaporated fuel in the purge gas, based on the pressure detected by the pressure sensor P (hereinafter, appropriately referred to as “sensor pressure PS”). The concentration detection unit 41 is not limited to being provided in the control unit 16 as shown in FIG. 1, and may be provided separately from the control unit 16.

It is not necessary that the first pressure sensor 29, the second pressure sensor 30, and the third pressure sensor 31 are all provided, and at least one of the first pressure sensor 29, the second pressure sensor 30, and the third pressure sensor 31 is provided. It suffices if one is provided.

Therefore, for example, as a first example, only the first pressure sensor 29 is provided, and the concentration detection unit 41 detects the purge concentration based on the detection value (pressure PS of the sensor) of the first pressure sensor 29. You may. Further, as a second example, only the second pressure sensor 30 is provided, and even if the concentration detection unit 41 detects the purge concentration based on the detection value (pressure PS of the sensor) of the second pressure sensor 30. Good. Further, as a third example, a first pressure sensor 29 and a third pressure sensor 31 are provided, and the concentration detection unit 41 subtracts the detection value of the third pressure sensor 31 from the detection value of the first pressure sensor 29. The purge concentration may be detected based on the value (pressure PS of the sensor).

In the evaporative fuel processing device 1 having such a configuration, when the purge condition is satisfied during the operation of the engine 11, the control unit 16 executes the purge control by driving the purge pump 24 and the purge valve 25. The "purge control" is a control in which purge gas is supplied from the canister 22 to the engine 11 via the purge passage 23 and the intake passage 12 for processing. Further, the control unit 16 drives the purge valve 25 to open and close by duty control when performing purge control.

Then, while the purge control is being executed, the air sucked into the intake passage 12 is injected (supplied) into the engine 11 from the fuel tank 21 via a fuel injection valve (fuel supply unit, not shown). The fuel and the purge gas supplied by executing the purge control are supplied. Then, the control unit 16 adjusts the air-fuel ratio (A / F) of the engine 11 to the optimum air-fuel ratio (for example, the ideal air-fuel ratio) by adjusting the injection time of the fuel injection valve, the valve opening time of the purge valve 25, and the like. Air-fuel ratio control is performed.

<About the detection method of the purge concentration immediately after switching between execution and stop of purge control>
Next, a method of detecting the purge concentration immediately after switching between execution and stop of purge control will be described. Note that "switching between execution and stop of purge control" means switching from a state in which purge control is being executed to a state in which purge control is stopped, and execution of purge control from a state in which purge control is stopped. It means to include both switching to the state.

As shown in FIG. 9, when the purge control is switched between execution (ON) and stop (OFF) (time t1 and time t2 in the figure), the purge valve 25 is driven (the purge valve 25 is opened and closed by duty control). ("Duty control execution" in the figure) and stop ("Duty control stop" in the figure) are switched. As a result, immediately after switching between execution and stop of purge control (immediately after time t1 and immediately after time t2), pulsation of purge gas is generated in the purge passage 23, and the blades (not shown) of the purge pump 24 are affected. On the other hand, a force (load) that fluctuates due to the pulsation of the purge gas acts. Then, feedback control is performed so as to control the rotation speed of the purge pump 24 to the target rotation speed in a state where a force (load) that fluctuates due to the pulsation of the purge gas acts on the blades of the purge pump 24 in this way. If this happens, the actual rotation speed of the purge pump 24 cannot be controlled to the target rotation speed, and the rotation speed of the purge pump 24 may fluctuate.

When the rotation speed of the purge pump 24 fluctuates in this way, the pressure of the purge gas flowing through the purge passage 23 fluctuates, so that the pressure PS of the sensor fluctuates. Therefore, when the concentration detection unit 41 detects the purge concentration based on the pressure PS of the sensor that fluctuates in this way, the purge concentration may be erroneously detected and the detection accuracy of the purge concentration may decrease.

[First Embodiment]
Therefore, in the present embodiment, when the execution and stop of the purge control are switched, the concentration detection unit 41 measures the pressure PS of the sensor from the time when the execution and stop of the purge control are switched until the predetermined time TA and TB elapse. A non-detection time (mask time) in which the purge concentration is not detected is provided based on. Then, the concentration detection unit 41 detects the purge concentration based on the pressure PS of the sensor after a predetermined time TA and TB have elapsed from the time when the purge control is switched between execution and stop.

(Explanation of flowchart)
Specifically, the concentration detection unit 41 detects the purge concentration based on the flowchart shown in FIG.

As shown in FIG. 2, when the concentration detection unit 41 is executing the purge control (during purge control) (step S1: YES), the concentration detection unit 41 is switching from the stop of the purge control to the execution (purge control OFF). → ON) to determine whether or not the predetermined time TA has elapsed (step S2). The predetermined time TA is, for example, 1.5 seconds.

Then, when the predetermined time TA has not elapsed since the switching from the stop of the purge control to the execution (step S2: NO), the concentration detection unit 41 detects the previous value (previous detection based on the flowchart shown in FIG. 2). The purge concentration value) is detected as the current purge concentration value (purge concentration ← previous value) (step S3). That is, when the predetermined time TA has not elapsed from the time when the purge control is switched from the stop to the execution, the concentration detection unit 41 refers to the rotation speed of the purge pump 24 (hereinafter, appropriately referred to as “pump rotation speed RP”. ) Is fluctuating, and it is considered that the pressure of the purge gas flowing through the purge passage 23 is fluctuating, so that the purge concentration is not detected based on the pressure PS of the sensor.

On the other hand, when the predetermined time TA has elapsed from the time when the purge control is switched from the stop to the execution (step S2: YES), the concentration detection unit 41 stores the pressure PS of the sensor while the purge valve 25 is closed. Then, the purge concentration is detected based on the stored pressure PS of the sensor (step S4). That is, when the predetermined time TA has elapsed from the time when the purge control is switched from the stop to the execution, the concentration detection unit 41 converges the fluctuation of the pump rotation speed RP and the fluctuation of the pressure of the purge gas flowing through the purge passage 23. Is considered to have converged, so the purge concentration is detected based on the pressure PS of the sensor. Here, "during closing of the purge valve 25" means while the purge valve 25 is closed when the purge valve 25 is driven to open and close by duty control.

Further, when the concentration detection unit 41 stops the purge control (when the purge control is not in progress) (step S1: NO), the concentration detection unit 41 switches from the execution of the purge control to the stop (purge control ON → OFF). It is determined whether or not the predetermined time TB has elapsed from (step S5). The predetermined time TB is, for example, 1.5 seconds. Further, the predetermined time TB is not limited to the same as the predetermined time TA, and may be different from the predetermined time TA.

Then, when the predetermined time TB has not elapsed since the switching from the execution of the purge control to the stop (step S5: NO), the concentration detection unit 41 detects the previous value as the value of the current purge concentration (step S5: NO). Step S6). That is, when TB does not elapse for a predetermined time from the time when the purge control is switched from the execution to the stop, the concentration detection unit 41 fluctuates the pump rotation speed RP and the pressure of the purge gas flowing through the purge passage 23 fluctuates. Since it is considered that the purge concentration is not detected based on the pressure PS of the sensor.

On the other hand, when the predetermined time TB has elapsed from the time when the purge control is switched from the execution to the stop (step S5: YES), the concentration detection unit 41 stores the pressure PS of the sensor for each predetermined time TC. , The purge concentration is detected based on the pressure PS of the stored sensor (step S7). That is, when the predetermined time TB has elapsed from the time when the purge control is switched from the stop to the execution, the concentration detection unit 41 converges the fluctuation of the pump rotation speed RP and the fluctuation of the pressure of the purge gas flowing through the purge passage 23. Is considered to have converged, so the purge concentration is detected based on the pressure PS of the sensor. The predetermined time TC is, for example, 3 seconds.

(Explanation of time chart)
Then, by detecting the purge concentration based on the flowchart shown in FIG. 2, the purge concentration is detected as shown in the time chart of FIG.

As shown in FIG. 3, first, it is assumed that the purge control is switched from stop (OFF) to execution (ON) at time T1. Then, from the time T1 to the time T2 when the predetermined time TA elapses, the purge concentration is not updated (the update timing does not exist) and the previous value is retained. That is, between time T1 and time T2, the purge concentration is not detected based on the pressure PS of the sensor. Then, after time T2 (up to time T3), the purge concentration is detected and updated based on the pressure PS of the sensor while the purge valve 25 is closed.

Then, after that, at time T3, it is assumed that the purge control is switched from execution (ON) to stop (OFF). Then, from the time T3 to the time T4 when the predetermined time TB elapses, the purge concentration is not updated and the previous value is maintained. That is, between time T3 and time T4, the purge concentration is not detected based on the pressure PS of the sensor. Then, after the time T4, the purge concentration is detected and updated based on the pressure PS of the sensor every predetermined time TC.

It is considered that the purge concentration is unlikely to change suddenly when switching between execution and stop of purge control. Therefore, it is considered that there is no problem even if it is not detected based on the pressure PS of the sensor for a short time immediately after switching between execution and stop of purge control.

(About the action and effect of this embodiment)
As described above, in the evaporative fuel processing apparatus 1 of the present embodiment, the concentration detection unit 41 has the purge concentration based on the pressure PS of the sensor after the predetermined time TA and TB have elapsed from the switching between the execution and the stop of the purge control. Is detected.

In this way, the concentration detection unit 41 does not detect the purge concentration based on the pressure PS of the sensor immediately after the execution and stop of the purge control are switched, and the concentration detection unit 41 does not detect the purge concentration immediately after the predetermined time TA and TB have elapsed. The purge concentration is detected based on the pressure PS. As a result, immediately after switching between execution and stop of purge control, the fluctuation of the pump rotation speed RP converges and the fluctuation of the pressure of the purge gas flowing through the purge passage 23 converges, and then the purge is stably performed based on the pressure PS of the sensor. The concentration can be detected. Therefore, erroneous detection of the purge concentration can be suppressed. Therefore, it is possible to improve the detection accuracy of the purge concentration immediately after switching between execution and stop of purge control.

Further, it is possible to determine whether or not to detect the purge concentration based on the pressure PS of the sensor by a simple control according to the elapsed time from the time when the purge control is executed and the stop is switched.

[Second Embodiment]
In the present embodiment, the concentration detection unit 41 purges based on the pressure PS of the sensor when the fluctuation range δ of the pump rotation speed RP becomes a predetermined value A or less after the execution and stop of the purge control are switched. Detect the concentration. That is, as shown in FIG. 4, the concentration detection unit 41 has a fluctuation range δ of the pump rotation speed RP equal to or less than a predetermined value A (predetermined fluctuation range) from the time of switching between execution (ON) and stop (OFF) of purge control. Until, the purge concentration is not detected based on the pressure PS of the sensor as the non-detection time (mask time). Then, the concentration detection unit 41 detects the purge concentration based on the pressure PS of the sensor after the fluctuation width δ of the pump rotation speed RP becomes a predetermined value A or less (“detection time” in the figure). The pump rotation speed RP is an example of the "parameter related to the pressure of the purge gas" of the present disclosure.

(Explanation of flowchart)
Specifically, the concentration detection unit 41 detects the purge concentration based on the flowchart shown in FIG.

As shown in FIG. 5, the concentration detection unit 41 corresponds to the detection timing (concentration detection timing) of the purge concentration, and within a predetermined time TD from the switching of the purge control execution (ON) and stop (OFF). If there is (step S11: YES), the deviation of the pump rotation speed RP (“deviation” in the figure) is calculated (step S12). Here, the deviation of the pump rotation speed RP is calculated by subtracting the target pump rotation speed (target pump rotation speed) from the actual pump rotation speed (actual pump rotation speed). The predetermined time TD is, for example, 3 seconds. Further, the actual pump rotation speed is detected by, for example, a sensor (a sensor that detects the rotation speed) (not shown).

Next, the concentration detection unit 41 determines whether or not the absolute value of the deviation of the pump rotation speed RP (“| deviation |” in the figure) is equal to or less than the predetermined value B (predetermined deviation value) (step S13). ). The predetermined value B is, for example, 200 rpm.

Then, when the absolute value of the deviation of the pump rotation speed RP is larger than the predetermined value B (step S13: NO), the concentration detection unit 41 has the previous value (previously detected purge concentration based on the flowchart shown in FIG. 5). (Value of) is detected as the value of the purge concentration this time (step S14). That is, when the absolute value of the deviation of the pump rotation speed RP is larger than the predetermined value B, the concentration detection unit 41 has a large fluctuation range δ of the pump rotation speed RP, and the pressure of the purge gas flowing through the purge passage 23 greatly fluctuates. Since it is considered that the purge concentration is not detected based on the pressure PS of the sensor.

On the other hand, when the absolute value of the deviation of the pump rotation speed RP is equal to or less than the predetermined value B (step S13: YES), the concentration detection unit 41 detects the purge concentration based on the pressure PS of the sensor (step S15). .. That is, when the absolute value of the deviation of the pump rotation speed RP is equal to or less than the predetermined value B, the concentration detection unit 41 has a small fluctuation range δ of the pump rotation speed RP, and the fluctuation of the pressure of the purge gas flowing through the purge passage 23 changes. Since it is considered to have converged, the purge concentration is detected based on the pressure PS of the sensor.

In this way, in the example shown in FIG. 5, the concentration detection unit 41 has a fluctuation range δ of the pump rotation speed RP shown in FIG. 4 when the absolute value of the deviation of the pump rotation speed RP becomes a predetermined value B or less. Is determined to be equal to or less than the predetermined value A, and the purge concentration is detected based on the pressure PS of the sensor.

(Explanation of time chart)
Then, by detecting the purge concentration based on the flowchart shown in FIG. 5, the purge concentration is detected as shown in the time chart of FIG.

As shown in FIG. 6, first, it is assumed that the purge control is switched from stop (OFF) to execution (ON) at time T11.

Then, between the time T11 and the time T18 when the predetermined time TD elapses, the pump rotation speed RP is out of the deviation threshold range at the times T12, T13, and T15, that is, the absolute deviation of the pump rotation speed RP. Since the value is larger than the predetermined value B, the purge concentration is not updated (the update timing does not exist) and the previous value is retained. In this way, at time T12, T13, T15, the purge concentration is not detected based on the pressure PS of the sensor.

On the other hand, at times T14, T16, and T17, the pump rotation speed RP is within the deviation threshold value, that is, the absolute value of the deviation of the pump rotation speed RP is a predetermined value B or less, so that the purge concentration is the purge valve 25. It is detected and updated based on the pressure PS of the sensor during valve closing.

After that, it is assumed that the purge control is switched from execution (ON) to stop (OFF) at time T21. Then, between the time T21 and the time T25 when the predetermined time TD elapses, the pump rotation speed RP is out of the deviation threshold range at the time T22, so that the purge concentration is not updated and the previous value is maintained.

On the other hand, at times T23 and T24, since the pump rotation speed RP is within the deviation threshold value, the purge concentration is detected and updated based on the pressure PS of the sensor.

(Modification example)
Further, as a modification, the ratio of the pump rotation speed RP may be used instead of the deviation of the pump rotation speed RP. Specifically, in step S12 of FIG. 5, the concentration detection unit 41 may calculate the ratio of the pump rotation speed RP (“ratio” in the figure). Here, the ratio of the pump rotation speed RP is calculated by dividing the actual pump rotation speed by the target pump rotation speed. Then, in step S13, the concentration detection unit 41 determines whether or not the ratio of the pump rotation speed RP is within the range of the predetermined value C and the predetermined value D (that is, larger than the predetermined value C and less than the predetermined value D). Whether or not) is judged. The predetermined value C is, for example, 0.8, and the predetermined value D is, for example, 1.2. Further, the range of the predetermined value C and the predetermined value D is an example of the "predetermined ratio range" of the present disclosure.

Then, when the ratio of the pump rotation speed RP is outside the range of the predetermined value C and the predetermined value D (that is, the predetermined value C or less or the predetermined value D or more), the concentration detection unit 41 (step S13: NO). ), The previous value is detected as the value of the current purge concentration (step S14). That is, when the ratio of the pump rotation speed RP is out of the range of the predetermined value C and the predetermined value D, the concentration detection unit 41 has a large fluctuation range δ of the pump rotation speed RP and the pressure of the purge gas flowing through the purge passage 23. Is considered to fluctuate significantly, so the purge concentration is not detected based on the pressure PS of the sensor.

On the other hand, when the ratio of the pump rotation speed RP is within the range of the predetermined value C and the predetermined value D (step S13: YES), the concentration detection unit 41 detects the purge concentration based on the pressure PS of the sensor (step S13: YES). Step S15). That is, when the ratio of the pump rotation speed RP is within the range of the predetermined value C and the predetermined value D, the concentration detection unit 41 has a small fluctuation range δ of the pump rotation speed RP and the pressure of the purge gas flowing through the purge passage 23. Since it is considered that the fluctuations of the above are converged, the purge concentration is detected based on the pressure PS of the sensor.

In this way, in the modified example, when the ratio of the pump rotation speed RP is within (within) the range of the predetermined value C and the predetermined value D, the concentration detection unit 41 has the pump rotation speed shown in FIG. It is determined that the fluctuation range δ of the RP is equal to or less than the predetermined value A, and the purge concentration is detected based on the pressure PS of the sensor.

(About the action and effect of this embodiment)
As described above, in the evaporative fuel processing apparatus 1 of the present embodiment, when the concentration detection unit 41 has a fluctuation range δ of the pump rotation speed RP of a predetermined value A or less after the execution and stop of the purge control are switched. In addition, the purge concentration is detected based on the pressure PS of the sensor.

In this way, the concentration detection unit 41 does not detect the purge concentration based on the pressure PS of the sensor immediately after the execution and stop of the purge control are switched, and when the fluctuation of the pump rotation speed RP converges. The purge concentration is detected based on the pressure PS of the sensor. As a result, the concentration detection unit 41 sets the pressure PS of the sensor immediately after the fluctuation of the pump rotation speed RP converges and the fluctuation of the pressure of the purge gas flowing through the purge passage 23 converges immediately after switching between the execution and the stop of the purge control. Based on this, the purge concentration can be detected stably. Therefore, erroneous detection of the purge concentration can be suppressed. Therefore, it is possible to improve the detection accuracy of the purge concentration immediately after switching between execution and stop of purge control.

Further, since the concentration detection unit 41 sees the fluctuation range δ of the pump rotation speed RP, the fluctuation of the pump rotation speed RP is settled immediately after switching between the execution and the stop of the purge control, and the pressure of the purge gas flowing through the purge passage 23 is settled. As soon as the fluctuation of is settled, the detection of the purge concentration can be started based on the pressure PS of the sensor. Therefore, immediately after switching between execution and stop of purge control, the non-detection time (mask time) in which the purge concentration is not detected based on the pressure PS of the sensor can be shortened. Therefore, immediately after switching between execution and stop of purge control, appropriate purge control can be performed using the purge concentration detected based on the pressure PS of the sensor as soon as possible.

Further, the concentration detection unit 41 detects the purge concentration based on the pressure PS of the sensor when the absolute value of the deviation of the pump rotation speed RP becomes a predetermined value B or less.

In this way, after the execution and stop of the purge control are switched, the timing of detecting the purge concentration based on the pressure PS of the sensor is determined by the deviation of the pump rotation speed RP, which is an index of the fluctuation of the pump rotation speed RP. can do. Therefore, it is possible to more reliably improve the detection accuracy of the purge concentration immediately after switching between execution and stop of purge control.

Further, the concentration detection unit 41 may detect the purge concentration based on the pressure PS of the sensor when the ratio of the pump rotation speed RP is within the range of the predetermined value C and the predetermined value D.

In this way, after the execution and stop of the purge control are switched, the timing of detecting the purge concentration based on the pressure PS of the sensor is determined by the ratio of the pump rotation speed RP, which is an index of the fluctuation of the pump rotation speed RP. can do. Therefore, it is possible to more reliably improve the detection accuracy of the purge concentration immediately after switching between execution and stop of purge control.

[Third Embodiment]
In the present embodiment, the concentration detection unit 41 corrects the pressure PS of the sensor after the execution and stop of the purge control are switched, and performs the corrected pressure PC in which the influence of the fluctuation of the pump rotation speed RP is suppressed. It is calculated, and the purge concentration is detected based on the calculated corrected pressure PC.

(Explanation of flowchart)
Specifically, the concentration detection unit 41 detects the purge concentration based on the flowchart shown in FIG. 7.

As shown in FIG. 7, the concentration detection unit 41 corresponds to the detection timing of the purge concentration (that is, the concentration detection timing), and is TE for a predetermined time from the time when the purge control execution (ON) and stop (OFF) are switched. If it is within (step S21: YES), the ratio of the pump rotation speed RP is calculated (step S22). For example, if the actual pump rotation speed is 12000 rpm and the target pump rotation speed is 10000 rpm, the ratio of the pump rotation speed RP is 1.2 (times). The predetermined time TE is, for example, 3 seconds.

Next, the concentration detection unit 41 corrects the pressure PS of the sensor and calculates the corrected pressure PC (step S23). Here, the corrected pressure PC is calculated by correcting the pressure PS in the sensor using a predetermined correction coefficient. Then, the predetermined correction coefficient is calculated by using the ratio of the pump rotation speed RP and the ratio of the fixed value. The ratio of the fixed value represents the ratio of the fluctuation of the pressure of the purge gas to the fluctuation of the pump rotation speed RP.

Specifically, the corrected pressure PC is calculated using the following mathematical formula. In this way, the corrected pressure PC is calculated by multiplying the pressure PS of the sensor by a predetermined correction coefficient.
[Number 1]
Corrected pressure PC = sensor pressure PS x {1.0 + (1.0-pump rotation speed RP ratio) x fixed value ratio}

As an example, if the pressure PS of the sensor is 5.0 kPa, the ratio of the pump rotation speed RP is 1.2, and the ratio of the fixed value is 2.0, the corrected pressure can be used by using the above formula. The PC will be 3.0 kPa.

As shown in the above formula, the corrected pressure PC is calculated using not only the ratio of the pump rotation speed RP but also the ratio of the fixed value. The reason is that there is no one-to-one relationship between the fluctuation of the pump rotation speed RP and the fluctuation of the pressure of the purge gas (specifically, the fluctuation of the pump rotation speed RP is less sensitive to the fluctuation of the pressure of the purge gas). The corrected pressure PC is calculated by correcting with a fixed value ratio representing the ratio of the pressure fluctuation of the purge gas to the fluctuation of the pump rotation speed RP. Further, the ratio of this fixed value is a ratio determined by the specifications of the evaporative fuel processing device 1, for example, the specifications of the purge passage 23 and the purge pump 24, and is obtained by an experiment.

Then, the concentration detection unit 41 calculates the corrected pressure PC in this way (step S23), and then detects the purge concentration based on the corrected pressure PC (step S24).

(Explanation of time chart)
Then, by detecting the purge concentration based on the flowchart shown in FIG. 7, the purge concentration is detected as shown in the time chart of FIG.

As shown in FIG. 8, first, it is assumed that the purge control is switched from stop (OFF) to execution (ON) at time T31. Then, from the time T31 to the time T32 when the predetermined time TE elapses, the purge concentration is detected based on the corrected pressure PC.

Further, it is assumed that the purge control is switched from execution (ON) to stop (OFF) at time T33. Then, from the time T33 to the time when the predetermined time TE elapses (not shown), the purge concentration is detected based on the corrected pressure PC.

(About the action and effect of this embodiment)
As described above, in the evaporative fuel processing apparatus 1 of the present embodiment, the concentration detection unit 41 corrects the pressure PS of the sensor after the execution and stop of the purge control are switched, and is affected by the fluctuation of the pump rotation speed RP. The suppressed corrected pressure PC is calculated, and the purge concentration is detected based on the calculated corrected pressure PC.

In this way, after the execution and stop of the purge control are switched, the concentration detection unit 41 does not detect the purge concentration based on the pressure PS of the sensor which is easily affected by the fluctuation of the pump rotation speed RP, and the pump rotates. The purge concentration is detected based on the corrected pressure PC in which the influence of the fluctuation of several RPs is suppressed. As a result, even if the pressure PS of the sensor fluctuates due to the fluctuation of the pump rotation speed RP and the pressure of the purge gas flowing through the purge passage 23 immediately after switching between the execution and the stop of the purge control, the corrected pressure The purge concentration can be stably detected based on the PC. Therefore, erroneous detection of the purge concentration can be suppressed. Therefore, it is possible to improve the detection accuracy of the purge concentration immediately after switching between execution and stop of purge control.

Further, the concentration detection unit 41 can start detecting the purge concentration based on the corrected pressure PC immediately after switching between execution and stop of the purge control. Therefore, it is possible to omit the non-detection time (mask time) in which the purge concentration is not detected immediately after switching between execution and stop of purge control. Therefore, immediately after switching between execution and stop of purge control, appropriate purge control can be performed based on the purge concentration detected based on the corrected pressure PC.

Further, the corrected pressure PS is calculated by correcting the pressure PS of the sensor using a predetermined correction coefficient. Then, the predetermined correction coefficient is calculated by using the ratio of the pump rotation speed RP and the ratio of the fixed value.

In this way, the pressure PS of the sensor is a fixed value ratio representing the ratio of the pump rotation speed RP, which is an index of the fluctuation of the pump rotation speed RP, and the ratio of the fluctuation of the pressure of the purge gas to the fluctuation of the pump rotation speed RP. The corrected pressure PC is calculated by correcting using and. Therefore, the corrected pressure PC is appropriately calculated according to the magnitude of the fluctuation of the pump rotation speed RP. Therefore, it is possible to more reliably improve the detection accuracy of the purge concentration immediately after switching between execution and stop of purge control.

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.

1 Evaporated fuel processing device 10 Internal combustion engine system 11 Engine 12 Intake passage 16 Control unit 21 Fuel tank 22 Canister 23 Purge passage 24 Purge pump 25 Purge valve 29 First pressure sensor (P1)
30 Second pressure sensor (P2)
31 Third pressure sensor (P3)
41 Concentration detector P Pressure sensor PS Sensor pressure (pressure detected by the pressure sensor)
RP pump rotation speed (purge pump rotation speed)
TA, TB, TC, TD, TE Predetermined time δ Fluctuation width A, B, C, D Predetermined value PC Corrected pressure

Claims (6)

A canister that stores evaporative fuel and
A purge passage for flowing the purge gas containing the evaporated fuel from the canister to the internal combustion engine, and
A purge pump that controls the flow rate of the purge gas and
It has a purge valve that opens and closes the purge passage.
In an evaporative fuel processing apparatus that executes purge control for supplying the purge gas from the canister to the internal combustion engine via the purge passage by driving the purge pump and the purge valve.
A pressure sensor that detects the pressure of the purge gas flowing through the purge passage, and
It has a concentration detection unit that detects the purge concentration, which is the concentration of the evaporated fuel in the purge gas.
The concentration detection unit detects the purge concentration based on the pressure detected by the pressure sensor after a predetermined time has elapsed from the switching between execution and stop of the purge control.
Evaporative fuel processing device characterized by. A canister that stores evaporative fuel and
A purge passage for flowing the purge gas containing the evaporated fuel from the canister to the internal combustion engine, and
A purge pump that controls the flow rate of the purge gas and
It has a purge valve that opens and closes the purge passage.
In an evaporative fuel processing apparatus that executes purge control for supplying the purge gas from the canister to the internal combustion engine via the purge passage by driving the purge pump and the purge valve.
A pressure sensor that detects the pressure of the purge gas flowing through the purge passage, and
It has a concentration detection unit that detects the purge concentration, which is the concentration of the evaporated fuel in the purge gas.
The concentration detection unit is based on the pressure detected by the pressure sensor when the fluctuation range of the parameter related to the pressure of the purge gas becomes a predetermined value or less after the execution and stop of the purge control are switched. To detect the purge concentration,
Evaporative fuel processing device characterized by. In the evaporated fuel processing apparatus of claim 2,
The parameter related to the pressure of the purge gas is the rotation speed of the purge pump.
When the absolute value of the deviation of the pump rotation speed calculated by subtracting the target rotation speed of the purge pump from the actual rotation speed of the purge pump becomes equal to or less than a predetermined deviation value, the concentration detection unit said. Detecting the purge concentration based on the pressure detected by the pressure sensor,
Evaporative fuel processing device characterized by. In the evaporated fuel processing apparatus of claim 2,
The parameter related to the pressure of the purge gas is the rotation speed of the purge pump.
The concentration detection unit detects with the pressure sensor when the ratio of the pump rotation speed, which represents the ratio of the actual rotation speed of the purge pump to the target rotation speed of the purge pump, is within a predetermined ratio range. Detecting the purge concentration based on the pressure applied,
Evaporative fuel processing device characterized by. A canister that stores evaporative fuel and
A purge passage for flowing the purge gas containing the evaporated fuel from the canister to the internal combustion engine, and
A purge pump that controls the flow rate of the purge gas and
It has a purge valve that opens and closes the purge passage.
In an evaporative fuel processing apparatus that executes purge control for supplying the purge gas from the canister to the internal combustion engine via the purge passage by driving the purge pump and the purge valve.
A pressure sensor that detects the pressure of the purge gas flowing through the purge passage, and
It has a concentration detection unit that detects the purge concentration, which is the concentration of the evaporated fuel in the purge gas.
After the execution and stop of the purge control are switched, the concentration detection unit corrects the pressure detected by the pressure sensor to suppress the influence of fluctuations in the rotation speed of the purge pump. And detect the purge concentration based on the calculated corrected pressure.
Evaporative fuel processing device characterized by. In the evaporated fuel processing apparatus of claim 5,
The corrected pressure is calculated by correcting the pressure detected by the pressure sensor using a predetermined correction coefficient.
The predetermined correction coefficient is the ratio of the pump rotation speed representing the ratio of the actual rotation speed of the purge pump to the target rotation speed of the purge pump, and the fluctuation of the pressure with respect to the fluctuation of the rotation speed of the purge pump. Calculated using a fixed value ratio that represents the ratio,
Evaporative fuel processing device characterized by.

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