JP2019210838A - Evaporated fuel treatment device - Google Patents

Abstract

To provide an evaporated fuel treatment device having a purge pump provided in an atmosphere passage of a canister, for suppressing the influences of vapor on the air-fuel ratio of an engine by preventing excessive vapor from flowing into an intake passage at a time when purge is finished and then the purge is restarted.SOLUTION: The evaporated fuel treatment device includes a canister 21, a vapor passage 22 for guiding vapor from a fuel tank 5 to the canister 21, a purge passage 23 for guiding the vapor from the canister 21 to an intake passage 3, a purge valve 25 for opening/closing the purge passage 23, an atmosphere passage 24 for introducing the atmosphere to the canister 21, a purge pump 26 provided in the atmosphere passage 24, and an electronic control unit (an ECU) 50 for controlling the purge valve 25 and the purge pump 26 to purge the vapor. The ECU 50 controls at least either the pressurization degree of pressurized air in the purge pump 26 or the opening of the purge valve 25 to be lower or smaller when the purge is restarted next, in proportion as the generation degree of the vapor in the fuel tank 5 after the purge is finished is higher.SELECTED DRAWING: Figure 1

Description

  The technology disclosed in this specification relates to an evaporated fuel processing apparatus that processes evaporated fuel generated in a fuel tank.

  Conventionally, as this type of technology, for example, an “evaporated fuel processing apparatus” described in Patent Document 1 below is known. This device includes a canister that collects evaporated fuel (vapor) generated in a fuel tank, a purge passage that guides the vapor collected in the canister to an intake passage of an engine, a purge valve that opens and closes the purge passage, and a canister A purge pump that supplies pressurized air, a tank internal pressure sensor that detects the internal pressure of the fuel tank, and an electronic control unit (ECU) that controls the operating state of the purge pump based on the internal pressure of the fuel tank. The ECU controls the purge pump so that the internal pressure of the fuel tank is maintained at substantially atmospheric pressure during the purge execution.

JP 2004-68609 A

  In the apparatus described in Patent Document 1, the vapor pressure is controlled to be almost atmospheric pressure by the purge pump. Therefore, when the negative pressure generated in the intake passage is small, the purge of the vapor to the intake passage is limited to a small amount. As a result, the vapor may not be sufficiently purged. On the other hand, if the purge pump is operated at a high speed in order to sufficiently purge the vapor, excessive pressure may act on the purge passage, the canister, the fuel tank, and the like. In particular, since the fuel tank is easily deformed as compared with other pipes and the like, it is necessary to control the purge pump in a range where the internal pressure does not exceed the withstand pressure.

  Here, even if the purge pump is controlled within a range in which the internal pressure of the fuel tank does not exceed the withstand pressure, the above apparatus may cause the following problem. That is, during the purge execution, the internal pressure of the fuel tank increases, so that vapor does not easily occur in the fuel tank even at high temperatures. Once the purge is completed in this state, pressure from the purge pump no longer acts on the fuel tank, a large amount of vapor is generated in the fuel tank, and the vapor flows to the canister and is collected. For this reason, when purging is resumed next, excessive vapor may flow from the canister to the intake passage at once. As a result, the air-fuel ratio of the engine may be greatly affected by the vapor.

  This disclosed technology has been made in view of the above circumstances, and the purpose thereof is to restart the purge after the purge is completed in a configuration in which the purge pump is provided in the atmospheric passage for introducing the atmosphere into the canister. An object of the present invention is to provide an evaporative fuel processing apparatus that prevents excessive evaporative fuel from flowing into the intake passage all at once and suppresses the influence of the evaporative fuel on the air-fuel ratio of the engine.

  In order to achieve the above-mentioned object, the technology according to claim 1 includes a canister for collecting evaporated fuel generated in a fuel tank, an evaporated fuel passage for guiding evaporated fuel from the fuel tank to the canister, and a canister A purge passage for guiding the evaporated fuel collected in the engine to the intake passage of the engine for purging, a purge valve for opening and closing the purge passage, an air passage for introducing air into the canister, and an air passage An evaporative fuel processing apparatus comprising: a purge pump for supplying pressurized air to the canister; and a control means for controlling at least the purge valve and the purge pump to purge the evaporative fuel from the canister to the intake passage. Obtaining the degree of evaporative fuel generation to obtain the degree of evaporative fuel generation that will occur in the fuel tank after the fuel purge is completed The control means includes the stage, and when the purge of the evaporated fuel is completed and then the purge is restarted, at least one of the degree of pressurization of the pressurized air by the purge pump and the opening of the purge valve is terminated. The purpose is to control so as to decrease as the acquisition result by the evaporative fuel generation degree acquisition means increases.

  According to the configuration of the above technique, when the purge of the evaporated fuel is completed, the generation degree of the evaporated fuel that will be generated in the fuel tank after that is acquired by the evaporated fuel generation degree acquisition unit. Then, when the purge of the evaporated fuel is finished and then the purge is resumed, at least one of the degree of pressurization of the pressurized air by the purge pump and the opening of the purge valve is the evaporated fuel when the purge is finished. The larger the acquisition result by the generation degree acquisition means, the lower the value. Therefore, even if a large amount of evaporated fuel generated in the fuel tank is collected in the canister between the end of the purge and the next restart of the purge, when the purge is resumed, the pressurized air of the purge pump Since at least one of the degree of pressurization and the opening of the purge valve is reduced, the amount of evaporated fuel pushed away from the canister to the intake passage can be reduced.

  In order to achieve the above object, according to a second aspect of the present invention, in the technique according to the first aspect, the evaporative fuel generation degree acquisition means determines the purge duration time until the evaporative fuel purge is completed. It is intended to include an electronic control device that is acquired as the degree of occurrence.

  According to the configuration of the above technique, in addition to the operation of the technique described in claim 1, the purge duration time until the purge of the evaporated fuel is completed is acquired by the electronic control unit as the generation degree of the evaporated fuel. Therefore, the generation degree of the evaporated fuel is acquired without providing any special detection means other than the electronic control device.

  In order to achieve the above object, according to a third aspect of the present invention, in the technique according to the first aspect, the evaporative fuel generation degree obtaining means includes a fuel temperature sensor for detecting the fuel temperature in the fuel tank, and The electronic control unit, and the electronic control unit obtains the difference between the upper limit value and the lower limit value of the fuel temperature detected by the fuel temperature sensor by the time when the purge of the evaporated fuel is finished as the generation degree of the evaporated fuel. The purpose is that.

  According to the configuration of the above technique, in addition to the operation of the technique described in claim 1, the difference between the upper limit value and the lower limit value of the fuel temperature detected by the fuel temperature sensor until the purge of the evaporated fuel is completed is the evaporation. Obtained by the electronic control unit as the degree of fuel generation. Accordingly, since the fuel temperature detected by the fuel temperature sensor is used, a more reliable degree of occurrence is obtained.

  In order to achieve the above object, according to a fourth aspect of the present invention, in the technique according to the first aspect, the evaporative fuel generation degree obtaining means detects the tank internal pressure in the fuel tank. The electronic control device includes a sensor and an electronic control device, and the electronic control device acquires the tank internal pressure detected by the tank internal pressure sensor when the purge of the evaporated fuel is completed as the generation degree of the evaporated fuel.

  According to the configuration of the above technique, in addition to the operation of the technique according to claim 1, the tank internal pressure detected by the tank internal pressure sensor when the purge of the evaporated fuel is finished is the electronic control device as the generation degree of the evaporated fuel. Obtained by Therefore, since the tank internal pressure detected by the tank internal pressure sensor is used, a more reliable generation degree is acquired.

  According to the first aspect of the present invention, in the configuration in which the purge pump is provided in the atmospheric passage for introducing the atmosphere into the canister, when the purge is once resumed after the purge is once completed, the excess evaporated fuel is sucked into the intake air. It is possible to prevent the fuel from flowing into the passage at once, and to suppress the influence of the evaporated fuel on the air-fuel ratio of the engine.

  According to the technique described in claim 2, in addition to the effect of the technique described in claim 1, the configuration for acquiring the generation degree of the evaporated fuel in the fuel tank can be simplified.

  According to the technique described in claim 3, in addition to the effect of the technique described in claim 1, the purge pump and the purge valve can be accurately controlled in accordance with the degree of generation of the evaporated fuel.

  According to the technique described in claim 4, in addition to the effect of the technique described in claim 1, the purge pump and the purge valve can be accurately controlled in accordance with the degree of generation of the evaporated fuel.

1 is a schematic diagram showing an engine system including an evaporated fuel processing device mounted on a vehicle according to a first embodiment. The flowchart which shows the content of purge control correction | amendment processing concerning 1st Embodiment. The map referred to in order to calculate the increase rate of the purge rate according to 1st Embodiment, the update amount of purge concentration learning value, and the increase amount of target pump rotation speed according to the last purge continuation time. The time chart which shows an example of the behavior of the various parameters accompanying a purge control correction process according to the first embodiment. The schematic diagram which shows the engine system which concerns on 2nd Embodiment and contains an evaporative fuel processing apparatus. The flowchart which shows the content of purge control correction | amendment processing in connection with 2nd Embodiment. The map referred to in order to calculate the increase rate of the purge rate according to the last fuel temperature change amount, the update amount of the purge concentration learning value, and the increase amount of the target pump speed according to the second embodiment. The time chart which concerns on 2nd Embodiment and shows an example of the behavior of the various parameters accompanying a purge control correction process. The schematic diagram which shows the engine system which concerns on 3rd Embodiment and contains an evaporative fuel processing apparatus. The flowchart which shows the content of purge control correction | amendment processing concerning 3rd Embodiment. The map referred to in order to calculate the increase rate of the purge rate according to the previous tank internal pressure, the update amount of the purge concentration learning value, and the increase amount of the target pump speed according to the third embodiment. The time chart which shows an example of the behavior of the various parameters accompanying a purge control correction process according to the third embodiment.

<First Embodiment>
Hereinafter, a first embodiment in which the fuel vapor processing apparatus is embodied will be described in detail with reference to the drawings.

[About engine system overview]
FIG. 1 is a schematic view showing an engine system including an evaporated fuel processing device mounted on a vehicle. The engine 1 includes an intake passage 3 for allowing air or the like to be sucked into the combustion chamber 2 and an exhaust passage 4 for discharging exhaust gas from the combustion chamber 2. The fuel stored in the fuel tank 5 is supplied to the combustion chamber 2. That is, the fuel in the fuel tank 5 is discharged to the fuel passage 7 by the fuel pump 6 built in the tank 5 and is pumped to the injector 8 provided in the intake port of the engine 1. The pumped fuel is injected from the injector 8 and introduced into the combustion chamber 2 together with the air flowing through the intake passage 3 to form a combustible air-fuel mixture, which is used for combustion. The engine 1 is provided with an ignition device 9 for igniting a combustible air-fuel mixture.

  An air cleaner 10, a throttle device 11, and a surge tank 12 are provided in the intake passage 3 from the inlet side to the engine 1. The throttle device 11 includes a throttle valve 11 a and is opened and closed to adjust the intake flow rate flowing through the intake passage 3. The opening and closing of the throttle valve 11a is linked to the operation of an accelerator pedal (not shown) by the driver. The surge tank 12 smoothes the pulsation of intake air in the intake passage 3.

[Configuration of Evaporative Fuel Treatment System]
In FIG. 1, the evaporated fuel processing apparatus of this embodiment is configured to process evaporated fuel (vapor) generated in the fuel tank 5 without releasing it into the atmosphere. That is, this apparatus takes in the canister 21 for collecting the vapor generated in the fuel tank 5, the vapor passage 22 for guiding the vapor from the fuel tank 5 to the canister 21, and the vapor collected in the canister 21. A purge passage 23 for leading to the passage 3 for purging, an atmospheric passage 24 for introducing the atmosphere into the internal space of the canister 21, and a purge valve 25 for opening and closing the purge passage 23 to adjust the purge flow rate of the vapor And a purge pump 26 for supplying pressurized air to the canister 21 so as to pressure-feed vapor from the canister 21 to the purge passage 23.

  The canister 21 contains an adsorbent such as activated carbon. The canister 21 includes an air inlet 21a for introducing air, an inlet 21b for introducing vapor, and a lead-out port 21c for deriving vapor. The tip of the air passage 24 extending from the air port 21 a communicates with the inlet of the fuel tank 5 a of the fuel tank 5. A filter 29 is provided in the air passage 24 upstream of the purge pump 26 to collect dust in the air. The tip of the vapor passage 22 extending from the introduction port 21 b of the canister 21 communicates with the inside of the fuel tank 5. The tip of the purge passage 23 extending from the outlet 21 c of the canister 21 communicates with the intake passage 3 between the throttle device 11 and the surge tank 12.

  In this embodiment, the purge valve 25 is composed of a motor-operated valve (VSV), and is configured to have a variable opening in order to adjust the vapor flow rate. The purge pump 26 is a motor drive type, and the discharge pressure of air is variably configured by changing the rotation speed (pump rotation speed) of the motor. As the purge pump 26, for example, a turbine pump can be employed.

  The evaporative fuel processing apparatus configured as described above introduces vapor generated in the fuel tank 5 into the canister 21 via the vapor passage 22, and temporarily collects the canister 21. When the engine 1 is in operation, the throttle device 11 (throttle valve 11a) is opened, the purge valve 25 is opened, and the purge pump 26 is operated. Thus, the vapor collected in the canister 21 is purged from the canister 21 through the purge passage 23 to the intake passage 3 and led to the combustion chamber 2 of the engine 1 for combustion.

[Electric configuration of engine system]
In this embodiment, various sensors 41 to 46 are provided. The air flow meter 41 provided near the air cleaner 10 detects the amount of air sucked into the intake passage 3 as the amount of intake air, and outputs an electrical signal corresponding to the detected value. A throttle sensor 42 provided in the throttle device 11 detects the opening of the throttle valve 11a as a throttle opening, and outputs an electric signal corresponding to the detected value. The intake pressure sensor 43 provided in the surge tank 12 detects the pressure in the surge tank 12 as the intake pressure, and outputs an electrical signal corresponding to the detected value. The water temperature sensor 44 provided in the engine 1 detects the temperature of the cooling water flowing inside the engine 1 as the cooling water temperature, and outputs an electrical signal corresponding to the detected value. A rotation speed sensor 45 provided in the engine 1 detects the rotation speed per unit time of a crankshaft (not shown) of the engine 1 as the engine rotation speed NE, and outputs an electric signal corresponding to the detected value. The oxygen sensor 46 provided in the exhaust passage 4 detects the oxygen concentration in the exhaust gas and outputs an electrical signal corresponding to the detected value.

  In this embodiment, an electronic control unit (ECU) 50 that controls various controls inputs various signals output from various sensors 41 to 46. The ECU 50 controls the fuel injection control, ignition timing control, purge control (including purge pump control), and purge control correction by controlling the injector 8, ignition device 9, purge valve 25 and purge pump 26 based on these input signals. Processing is to be executed.

  Here, the fuel injection control is to control the fuel injection amount and the fuel injection timing by controlling the injector 8 in accordance with the operating state of the engine 1. The ignition timing control is to control the ignition timing of the combustible mixture by controlling the ignition device 9 according to the operating state of the engine 1. The purge control is to control the vapor purge flow rate from the canister 21 to the intake passage 3 by controlling at least one of the purge valve 25 and the purge pump 26 in accordance with the operating state of the engine 1. In this embodiment, in order to execute purge control, both the purge valve 25 and the purge pump 26 are controlled. Here, when controlling the purge valve 25 to execute the purge control, the ECU 50 calculates the target purge opening and executes the purge control by controlling the purge valve 25 based on the target purge opening. It is like that. The ECU 50 calculates a purge rate and a purge concentration learned value, which will be described later, and calculates a target purge opening based on various parameters including them. Further, when controlling the purge pump 26 in order to execute the purge control, the ECU 50 calculates the target pump rotational speed, and executes the purge pump control by controlling the purge pump 26 based on the target pump rotational speed. It is like that. The purge control correction process is to calculate correction values for the purge rate, purge concentration learning value, and target pump speed necessary for purge control.

  In this embodiment, the ECU 50 has a known configuration including a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a backup RAM, and the like. The ROM stores in advance predetermined control programs related to the various controls described above. The ECU (CPU) 50 executes the various controls described above according to these control programs. The ECU 50 corresponds to an example of a control unit and an evaporated fuel generation degree acquisition unit in the disclosed technique.

  In this embodiment, the fuel injection control, the ignition timing control, and the purge control are assumed to employ known contents, and only the purge control correction process will be described in detail below.

[Purge control correction process]
Next, the purge control correction process will be described. FIG. 2 is a flowchart showing the processing contents. The ECU 50 periodically executes this routine every predetermined time.

  When the process proceeds to this routine, in step 100, the ECU 50 determines whether or not purge control is being executed. If this determination result is affirmative, the ECU 50 proceeds to step 110. If this determination result is negative, the ECU 50 proceeds to step 120.

  In step 110, the ECU 50 calculates the purge duration DCp. That is, the ECU 50 measures the duration (unit: second) after the purge is started (turned on). Thereafter, the ECU 50 once ends the process. In this embodiment, the purge duration DCp in the first purge control after the engine 1 is started is set to the maximum value (for example, “30 seconds”). The purge duration DCp is also set to its maximum value when the engine 1 is restarted from the idling stop.

  On the other hand, in step 120, the ECU 50 holds the previous purge duration DCpO. The previous purge duration DCpO means the purge duration DCp calculated last time.

  Next, at step 130, the ECU 50 determines whether or not the purge control is changed from OFF to ON, that is, whether or not the purge control is restarted. If this determination result is affirmative, the ECU 50 proceeds to step 140, and if this determination result is negative, the ECU 50 temporarily terminates the process.

  In step 140, the ECU 50 calculates the purge rate increase rate RRp according to the previous purge duration DCpO. The ECU 50 can calculate the rate of increase RRp according to the previous purge duration DCpO by referring to a map as shown in FIG. 3, for example. In this map, the rate of increase RRp increases from “10 (% / second)” to “1 (% / second) as the previous purge duration DCpO increases from“ 1 (second) ”to“ 30 (second) ”. Is set to become smaller toward "." The purge rate is a parameter reflected in the purge control, and is used to control the opening degree of the purge valve 25, and changes in accordance with the increase rate RRp. Here, as the previous purge continuation time DCpO becomes longer, the amount of vapor remaining in the canister 21 decreases, and when the fuel tank 5 is in a high temperature state, a large amount of vapor generated in the fuel tank 5 is immediately transferred to the canister 21 when the purge is resumed. There is a risk of being collected by flowing (hereinafter referred to as "reason 1"). Therefore, in this map, the purge rate increase rate RRp is set to be smaller as the previous purge duration DCpO becomes longer. The ECU 50 uses the increase rate RRp for calculating the purge rate (the same applies hereinafter).

  Next, at step 150, the ECU 50 calculates the update amount AUp of the purge concentration learning value according to the previous purge duration DCpO. The ECU 50 can calculate the update amount AUp corresponding to the previous purge duration DCpO by referring to a map as shown in FIG. 3, for example. In this map, the update amount AUp is set to decrease from “10” toward “1” as the previous purge duration DCpO becomes longer. The purge concentration learning value is a parameter reflected in the purge control, and indicates, for example, the purge concentration obtained from the deviation of the air-fuel ratio of the engine 1, and changes according to the update amount AUp. In this embodiment, the purge concentration is set to be higher as the purge concentration learning value is lower. In this map, for the reason 1 described above, the update amount AUp of the purge concentration learning value is set to be smaller as the previous purge duration DCpO becomes longer. The ECU 50 uses the update amount AUp for calculating the purge concentration learning value (the same applies hereinafter).

  Next, at step 160, the ECU 50 calculates an increase amount ARp of the target pump speed according to the previous purge duration DCpO. For example, the ECU 50 can calculate the increase amount ARp corresponding to the previous purge duration DCpO by referring to a map as shown in FIG. In this map, the amount of increase ARp is set to decrease from “1000 (rpm / sec)” to “100 (rpm / sec)” as the previous purge duration DCpO becomes longer. The target pump speed is a parameter reflected in the purge pump control, and changes in accordance with the amount of increase ARp. In this map, for the reason 1 described above, the target pump speed increase amount ARp is set to be smaller as the previous purge duration DCpO is longer. The ECU 50 uses the increased amount ARp for calculation of the target pump speed (the same applies hereinafter). Thereafter, the ECU 50 once ends the process.

  According to the above control, the ECU 50 acquires the purge continuation time DCp (last purge continuation time DCpO) until the vapor purge is completed as the vapor generation degree. Then, the ECU 50 increases the degree of pressurization of the pressurized air by the purge pump 26 when the purge of the vapor is resumed next as the previous purge duration DCpO (degree of occurrence of vapor) when the purge is finished increases. The purge pump 26 is controlled so as to be reduced.

  Further, according to the above control, the ECU 50 opens the opening of the purge valve 25 when the vapor purge is resumed next as the previous purge continuation time DCpO (degree of vapor generation) when the purge is finished increases. The purge valve 25 is controlled so as to reduce the above.

  Here, FIG. 4 shows an example of the behavior of various parameters associated with the above control in a time chart. 4, (a) is purge control, (b) is purge duration DCp, (c) is purge rate, (d) is purge concentration learning value, (e) is target pump speed. Show.

  In FIG. 4, as shown in FIG. 4A, when the purge starts at time t <b> 1 (the purge control changes from “OFF” to “ON”), the purge duration DCp is set as shown in FIG. As shown in (c), the purge rate starts to increase stepwise, as shown in (d), the purge concentration learning value starts to decrease stepwise, and as shown in (e), The target pump speed starts to increase stepwise.

  After that, when the purge is completed at time t2 (when the purge control is changed from “ON” to “OFF”), the purge duration DCp at that time becomes the previous purge duration DCpO as shown in FIG. The purge rate is reset as shown in (c), and the target pump speed is reset to “0” as shown in (e).

  Then, when the purge is restarted at time t3 (when the purge control is changed from “OFF” to “ON” again), the purge rate increase rate RRp in (c) and the purge concentration learning value update amount in (d) are updated. The increase amount ARp of AUp and the target pump speed is calculated according to the previous purge duration DCpO. Then, as shown in (c), the increase rate RRp is reflected in the stepwise increase in the purge rate, and as shown in (d), the update amount AUp is reflected in the stepwise increase in the purge concentration learning value, As shown in (e), the increase amount ARp is reflected in the stepwise increase in the target pump speed. Here, when the previous purge duration DCpO becomes longer, a large amount of vapor generated in the fuel tank 5 may flow to the canister 21 and be collected when the purge is resumed. Therefore, in order to suppress excessive vapor supply to the engine 1 and excessive pressure supply to the fuel tank 5, an increase in the purge rate and the purge concentration learning value reflected in the calculation of the target purge opening of the purge valve 25 is increased. Thus, an increase in the target pump speed of the purge pump 26 is suppressed.

[Operation and effect of evaporative fuel treatment system]
According to the fuel vapor processing apparatus in this embodiment described above, the purge valve 25 and the purge pump 26 are controlled to purge the vapor from the canister 21 to the intake passage 3, that is, to execute the purge. Here, when the vapor purge is completed, the degree of vapor generation that will occur in the fuel tank 5 thereafter is acquired by the ECU 50 as the previous purge duration DCpO (acquisition result). The degree of pressurization of the pressurized air by the purge pump 26 is reduced when the vapor purge is restarted next, as the previous purge duration DCpO when the vapor purge is completed increases. Therefore, even if a large amount of vapor generated in the fuel tank 5 is collected in the canister 21 between the end of the purge and the next restart, when the purge is resumed, Since the degree of pressurization is reduced, less vapor is forced away from the canister 21 to the intake passage 3. Therefore, in the configuration in which the purge pump 26 is provided in the atmospheric passage 24, it is possible to prevent excessive vapor from flowing into the intake passage 3 at the same time when the purge is restarted after the purge is completed. The influence on the air-fuel ratio of the engine 1 due to can be suppressed.

  Further, according to the configuration of this embodiment, similarly, as the previous purge continuation time DCpO (acquisition result) when the vapor purge is finished increases, the purge of the purge valve 25 is resumed when the vapor purge is restarted next time. Opening is reduced. Therefore, even if a large amount of vapor generated in the fuel tank 5 is collected in the canister 21 between the end of the purge and the next restart, the opening of the purge valve 25 is reduced when the purge is resumed. Therefore, the vapor flowing from the canister 21 to the intake passage 3 is further reduced. In this sense, it is possible to more reliably prevent excessive vapor from flowing into the intake passage 3 when purging is resumed next time, and to more reliably suppress the influence of the vapor on the air-fuel ratio of the engine 1. it can.

  According to the configuration of this embodiment, the purge duration DCp until the vapor purge is completed is acquired by the ECU 50 as the degree of vapor generation. Accordingly, the degree of vapor generation is acquired without providing any special detection means other than the ECU 50. In this sense, the configuration for acquiring the degree of vapor generation in the fuel tank 5 can be simplified.

Second Embodiment
Next, a second embodiment in which the fuel vapor processing apparatus is embodied will be described in detail with reference to the drawings.

  In the following description, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted. Hereinafter, different points will be mainly described.

  This embodiment differs from the first embodiment in the configuration of the evaporated fuel processing device and the content of the purge control correction process. FIG. 5 is a schematic view showing an engine system including the evaporated fuel processing apparatus in this embodiment. In this embodiment, a fuel temperature sensor 61 for detecting the fuel temperature TF in the fuel tank 5 is provided. The ECU 50 is configured to input the detection value of the fuel temperature sensor 61. The other structure of the evaporative fuel processing apparatus is the same as that of the first embodiment.

  In this embodiment, the fuel temperature sensor 61 and the ECU 50 constitute an example of an evaporated fuel generation degree acquisition unit in the disclosed technique.

[Purge control correction process]
Next, the purge control correction process will be described. FIG. 6 is a flowchart showing the contents of the control. The ECU 50 periodically executes this routine every predetermined time.

  When the process proceeds to this routine, in step 200, the ECU 50 determines whether or not purge control is being executed. If the determination result is affirmative, the ECU 50 proceeds to step 210. If the determination result is negative, the ECU 50 proceeds to step 220.

  In step 210, the ECU 50 stores an upper limit value TFmax and a lower limit value TFmin of the fuel temperature TF detected by the fuel temperature sensor 61, respectively. Thereafter, the ECU 50 once ends the process.

  On the other hand, in step 220, the ECU 50 holds the upper limit value TFOmax and the lower limit value TFOmin of the previous fuel temperature TFO. The previous upper limit value TFOmax and lower limit value TFOmin mean the upper limit value TFmax and lower limit value TFmin stored so far.

  Next, in step 230, the ECU 50 determines whether or not the purge control is changed from OFF to ON (whether or not the purge control is resumed). If this determination result is affirmative, the ECU 50 proceeds to step 240, and if this determination result is negative, the ECU 50 temporarily ends the process.

  In step 240, the ECU 50 calculates the difference between the previous upper limit value TFOmax and the previous lower limit value TFOmin as the previous fuel temperature change amount ΔTFO.

  Next, in step 250, the ECU 50 calculates the purge rate increase rate RRp in accordance with the previous fuel temperature change amount ΔTFO. The ECU 50 can calculate the rate of increase RRp of the purge rate according to the previous fuel temperature change amount ΔTFO by referring to a map as shown in FIG. 7, for example. In this map, the rate of increase RRp increases from “10 (% / second)” to “1 (% / second) as the previous fuel temperature change amount ΔTFO increases from“ 1 (° C.) ”to“ 5 (° C.) ”. ) "Is set to be smaller. Here, as the previous fuel temperature change amount ΔTFO increases, a larger amount of vapor may be adsorbed to the canister 21 until the purge is restarted (hereinafter referred to as “reason 2”). Therefore, in this map, the purge rate increase rate RRp is set to decrease as the previous fuel temperature change amount ΔTFO increases.

  Next, at step 260, the ECU 50 calculates an update amount AUp of the purge concentration learning value according to the previous fuel temperature change amount ΔTFO. The ECU 50 can calculate the update amount AUp corresponding to the previous fuel temperature change amount ΔTFO by referring to, for example, a map as shown in FIG. In this map, the update amount AUp is set to decrease from “10” to “1” as the previous fuel temperature change amount ΔTFO increases. In this map, for the reason 2, the update amount AUp of the purge concentration learning value is set to be smaller as the previous fuel temperature change amount ΔTFO is larger.

  Next, at step 270, the ECU 50 calculates an increase amount ARp of the target pump speed according to the previous fuel temperature change amount ΔTFO. The ECU 50 can calculate the increase amount ARp corresponding to the previous fuel temperature change amount ΔTFO by referring to a map as shown in FIG. 7, for example. In this map, the amount of increase ARp is set to decrease from “1000 (rpm / sec)” to “100 (rpm / sec)” as the previous fuel temperature change amount ΔTFO increases. In this map, for the reason 2 described above, the increase amount ARp of the target pump speed is set to be smaller as the previous fuel temperature change amount ΔTFO is larger. Thereafter, the ECU 50 once ends the process.

  According to the above control, the ECU 50 acquires the previous fuel temperature change amount ΔTFO as the vapor generation degree until the vapor purge is completed. Then, the ECU 50 purges so as to reduce the degree of pressurization of the pressurized air by the purge pump 26 when the vapor purge is restarted next as the previous fuel temperature change amount ΔTFO when the purge is finished increases. The pump 26 is controlled.

  Further, according to the above control, the ECU 50 reduces the opening degree of the purge valve 25 when the vapor purge is restarted next as the previous fuel temperature change amount ΔTFO until the vapor purge is finished increases. The purge valve 25 is controlled so as to cause this.

  Here, FIG. 8 shows an example of the behavior of various parameters associated with the above control in a time chart. 8, (a) shows the purge control, (b) shows the fuel temperature TF, (c) shows the purge rate, (d) shows the purge concentration learning value, and (e) shows the target pump speed. .

  In FIG. 8, when the purge starts at time t1, as shown in (a), the fuel temperature TF begins to increase as shown in (b), and the purge rate gradually increases as shown in (c). As shown in (d), the purge concentration learning value starts decreasing stepwise, and as shown in (e), the target pump speed starts increasing stepwise.

  Thereafter, when the purge is completed at time t2, as shown in (b), the difference between the upper limit value TFmax and the lower limit value TFmin of the fuel temperature TF up to that time is held as the previous fuel temperature change amount ΔTFO. As shown in c), the purge rate is reset, and as shown in (e), the target pump speed is reset to “0”.

  When the purge is resumed at time t3, the purge rate increase rate RRp in (c), the purge concentration learning value update amount AUp in (d), and the target pump rotational speed increase amount ARp are respectively the previous fuel temperature. It is calculated according to the change amount ΔTFO. Then, as shown in (c), the increase rate RRp is reflected in the stepwise increase in the purge rate, and as shown in (d), the update amount AUp is reflected in the stepwise increase in the purge concentration learning value, As shown in (e), the increase amount ARp is reflected in the stepwise increase in the target pump speed. Here, when the previous fuel temperature change amount ΔTFO becomes large, a large amount of vapor may be adsorbed to the canister 21 until the purge is resumed. Therefore, in order to suppress excessive vapor supply to the engine 1 and excessive pressure supply to the fuel tank 5, an increase in the purge rate and the purge concentration learning value reflected in the calculation of the target purge opening of the purge valve 25 is increased. Thus, an increase in the target pump speed of the purge pump 26 is suppressed.

[Operation and effect of evaporative fuel treatment system]
According to the evaporative fuel processing apparatus in this embodiment described above, the same operation and effect as in the first embodiment can be obtained. In addition, according to the configuration of this embodiment, the difference between the upper limit value TFmax and the lower limit value TFmin of the fuel temperature TF detected by the fuel temperature sensor 61 until the time when the purge of vapor is completed (the previous fuel temperature change amount). ΔTFO) is acquired by the ECU 50 as the degree of vapor generation. Therefore, since the fuel temperature TF detected by the fuel temperature sensor 61 is used, a more certain degree of occurrence is obtained. For this reason, the purge pump 26 and the purge valve 25 can be accurately controlled in accordance with the degree of vapor generation.

<Third Embodiment>
Next, a third embodiment in which the fuel vapor processing apparatus is embodied will be described in detail with reference to the drawings.

  This embodiment is different from each of the above embodiments in terms of the configuration of the evaporated fuel processing apparatus and the content of the purge control correction process. FIG. 9 is a schematic view showing an engine system including the evaporated fuel processing apparatus in this embodiment. In this embodiment, the fuel tank 5 is provided with a tank pressure sensor 62 for detecting the tank pressure PT therein. The ECU 50 is configured to input a detection value of the tank internal pressure sensor 62. The other structure of the evaporative fuel processing apparatus is the same as that of the first embodiment.

  In this embodiment, the tank pressure sensor 62 and the ECU 50 constitute an example of an evaporated fuel generation degree acquisition unit in the disclosed technique.

[Purge control correction process]
Next, the purge control correction process will be described. FIG. 10 is a flowchart showing the control contents. The ECU 50 periodically executes this routine every predetermined time.

  When the process proceeds to this routine, in step 300, the ECU 50 determines whether or not purge control is being executed. If this determination result is affirmative, the ECU 50 proceeds to step 310, and if this determination result is negative, the ECU 50 proceeds to step 320.

  In step 310, the ECU 50 stores the tank internal pressure PT detected by the tank internal pressure sensor 62. Thereafter, the ECU 50 once ends the process.

  On the other hand, in step 320, the ECU 50 maintains the previous tank internal pressure PTO. The previous tank internal pressure PTO means the previously stored tank internal pressure PT.

  Next, in step 330, the ECU 50 determines whether or not the purge control is changed from OFF to ON (whether or not the purge control is restarted). If this determination result is affirmative, the ECU 50 proceeds to step 340, and if this determination result is negative, the ECU 50 temporarily terminates the process.

  Next, at step 340, the ECU 50 calculates the purge rate increase rate RRp according to the previous tank internal pressure PTO. The ECU 50 can calculate the rate of increase RRp of the purge rate according to the previous tank pressure PTO by referring to a map as shown in FIG. 11, for example. In this map, the rate of increase RRp increases from “10 (% / second)” to “1 (% / second) as the previous tank pressure PTO increases from“ 2 (kPaG) ”to“ 10 (kPaG) ”. Is set to become smaller toward "." Here, as the previous tank internal pressure PTO increases, a larger amount of vapor generated in the fuel tank 5 may flow to the canister 21 and be collected at the time of restarting the purge (hereinafter referred to as “reason 3”). .) Therefore, in this map, the purge rate increase rate RRp is set to decrease as the previous tank internal pressure PTO increases.

  Next, at step 350, the ECU 50 calculates the update amount AUp of the purge concentration learning value according to the previous tank internal pressure PTO. The ECU 50 can calculate the update amount AUp corresponding to the previous tank internal pressure PTO by referring to a map as shown in FIG. 11, for example. In this map, the update amount AUp is set to decrease from “10” to “1” as the previous tank internal pressure PTO increases. In this map, for the reason 3, the update amount AUp of the purge concentration learning value is set to be smaller as the previous tank internal pressure PTO is higher.

  Next, at step 360, the ECU 50 calculates an increase amount ARp of the target pump speed according to the previous tank pressure PTO. The ECU 50 can calculate the increase amount ARp according to the previous tank internal pressure PTO by referring to a map as shown in FIG. 11, for example. In this map, the increase amount ARp is set to decrease from “1000 (rpm / sec)” toward “100 (rpm / sec)” as the previous tank internal pressure PTO increases. In this map, for the reason 3, the increase amount ARp of the target pump speed is set to be smaller as the previous tank pressure PTO is higher. Thereafter, the ECU 50 once ends the process.

  According to the above control, the ECU 50 obtains the previous tank pressure PTO as the vapor generation degree when the vapor purge is completed. Then, the ECU 50 reduces the degree of pressurization of the pressurized air by the purge pump 26 when the vapor purge is restarted next, as the previous tank internal pressure PTO when the purge is finished increases. 26 is controlled.

  Further, according to the above control, the ECU 50 reduces the opening of the purge valve 25 when the vapor purge is restarted next as the previous tank pressure PTO when the vapor purge is finished increases. The purge valve 25 is controlled.

  Here, FIG. 12 shows an example of the behavior of various parameters associated with the above control in a time chart. In FIG. 12, (a) shows the purge control, (b) the tank internal pressure PT, (c) the purge rate, (d) the purge concentration learning value, and (e) the target pump speed. Show.

  In FIG. 12, as shown in (a), when the purge is started at time t1, the in-tank pressure PT starts to increase as shown in (b), and the purge rate becomes a step as shown in (c). As shown in (d), the purge concentration learning value starts to decrease stepwise, and as shown in (e), the target pump speed starts to increase stepwise.

  Thereafter, when the purge is completed at time t2, as shown in (b), the tank internal pressure PT at that time is held as the previous tank internal pressure PTO, and the purge rate is reset as shown in (c). , (E), the target pump speed is reset to “0”.

  When the purge is resumed at time t3, the purge rate increase rate RRp in (c), the purge concentration learning value update amount AUp in (d), and the target pump speed increase amount ARp are respectively stored in the previous tank. It is calculated according to the pressure PTO. Then, as shown in (c), the increase rate RRp is reflected in the stepwise increase in the purge rate, and as shown in (d), the update amount AUp is reflected in the stepwise increase in the purge concentration learning value, As shown in (e), the increase amount ARp is reflected in the stepwise increase in the target pump speed. Here, when the previous tank internal pressure PTO has increased, a large amount of vapor generated in the fuel tank 5 may flow to the canister 21 and be collected when the purge is resumed. Therefore, in order to suppress excessive vapor supply to the engine 1 and excessive pressure supply to the fuel tank 5, an increase in the purge rate and the purge concentration learning value reflected in the calculation of the target purge opening of the purge valve 25 is increased. Thus, an increase in the target pump speed of the purge pump 26 is suppressed.

[Operation and effect of evaporative fuel treatment system]
According to the evaporative fuel processing apparatus in this embodiment described above, the same operation and effect as in the first embodiment can be obtained. In addition, according to the configuration of this embodiment, the tank pressure PT (previous tank pressure PTO) detected by the tank pressure sensor 62 when the vapor purge is completed is acquired by the ECU 50 as the degree of vapor generation. Is done. Therefore, since the tank pressure PT detected by the tank pressure sensor 62 is used, a more certain degree of occurrence is obtained. For this reason, the purge pump 26 and the purge valve 25 can be accurately controlled in accordance with the degree of vapor generation.

  Note that the disclosed technology is not limited to the above-described embodiments, and a part of the configuration can be changed as appropriate without departing from the spirit of the disclosed technology.

  (1) In each of the above embodiments, the purge control (including when the purge is resumed) is configured to control both the purge valve 25 and the purge pump 26. However, in order to execute the purge control ( (Including purge resumption)) Either the purge valve 25 or the purge pump 26 may be controlled.

  (2) In each of the above embodiments, in the engine system not provided with the supercharger, the purge passage 23 is communicated with the intake passage 3 downstream from the throttle valve 11a to purge the vapor. On the other hand, in an engine system equipped with a supercharger, the vapor can be purged by connecting the purge passage to the intake passage upstream of the throttle valve and downstream of the air flow meter.

  This disclosed technique can be applied to an engine system including an evaporated fuel processing apparatus.

1 Engine 3 Intake Passage 5 Fuel Tank 21 Canister 22 Vapor Passage (Evaporative Fuel Passage)
23 Purge passage 24 Atmosphere passage 25 Purge valve 26 Purge pump 50 ECU (control means, evaporative fuel generation degree acquisition means)
61 Fuel temperature sensor (evaporated fuel generation degree acquisition means)
62 Tank pressure sensor (evaporated fuel generation degree acquisition means)
DCpO Last purge duration (evaporation fuel generation degree)
ΔTFO Previous fuel temperature change (evaporation fuel generation degree)
PTO Last pressure in tank (degree of evaporation fuel generation)

Claims (4)

A canister for collecting the evaporated fuel generated in the fuel tank;
An evaporative fuel passage for guiding the evaporative fuel from the fuel tank to the canister;
A purge passage for purging the evaporated fuel collected in the canister to an intake passage of an engine;
A purge valve for opening and closing the purge passage;
An air passage for introducing air into the canister;
A purge pump provided in the atmospheric passage for supplying pressurized air to the canister;
An evaporative fuel processing apparatus comprising: a control means for controlling at least the purge valve and the purge pump in order to purge the evaporative fuel from the canister to the intake passage;
Evaporative fuel generation degree acquisition means for acquiring the generation degree of the evaporative fuel that will occur in the fuel tank after the evaporative fuel purge is completed,
When the purge is restarted next after the purge of the evaporated fuel is completed, the control means determines at least one of the degree of pressurization of the pressurized air by the purge pump and the opening of the purge valve. The evaporative fuel processing apparatus is characterized in that the evaporative fuel processing apparatus performs control so as to decrease as the acquisition result by the evaporative fuel generation degree acquisition means increases. The evaporative fuel processing apparatus of Claim 1 WHEREIN:
The evaporative fuel generation degree acquiring means includes an electronic control unit that acquires a purge duration time until the evaporative fuel purge is completed as the evaporative fuel generation degree. The evaporative fuel processing apparatus of Claim 1 WHEREIN:
The evaporative fuel generation degree acquisition means includes a fuel temperature sensor for detecting a fuel temperature in the fuel tank, and an electronic control unit,
The electronic control unit acquires a difference between an upper limit value and a lower limit value of the fuel temperature detected by the fuel temperature sensor by the time when the purge of the evaporated fuel is completed as a generation degree of the evaporated fuel. Evaporative fuel processing device. The evaporative fuel processing apparatus of Claim 1 WHEREIN:
The evaporative fuel generation degree acquisition means includes a tank internal pressure sensor for detecting a tank internal pressure in the fuel tank, and an electronic control unit,
The said electronic control apparatus acquires the said tank internal pressure detected by the said tank internal pressure sensor when the purge of the said evaporated fuel is complete | finished as a generation | occurrence | production level of the said evaporated fuel, The evaporative fuel processing apparatus characterized by the above-mentioned.

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