Fuel vapor treatment device

Abstract

It processes evaporated fuel inside the fuel tank while suppressing fluctuations in the engine's A / F ratio. [Solution] When the processor of the evaporative fuel treatment device determines that the internal pressure of the fuel tank is above a predetermined value, it executes processing including: starting a direct purge to supply the evaporative fuel inside the fuel tank to the engine through the first purge pipe, the canister, and the second purge pipe; determining a first correction amount representing the proportion of the evaporative fuel supplied to the engine by the direct purge relative to the total flow rate of fuel supplied to the engine; calculating a target opening degree of the first purge valve based on the first correction amount; and controlling the opening degree of the first purge valve so that it becomes the calculated target opening degree.

Description

[Technical Field]

[0001] The present invention relates to a fuel vapor treatment device. [Background technology]

[0002] For example, Patent Document 1 discloses an evaporated fuel treatment device that purges evaporated fuel from inside a fuel tank into an intake pipe, bypassing a canister. The evaporated fuel treatment device in Patent Document 1 adjusts the amount of evaporated fuel supplied to the intake pipe using the pressure of the vapor gas in the fuel tank detected by a pressure sensor and the concentration of evaporated fuel in the vapor gas detected by a concentration sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-32204 Summary of the Invention [Problem to be solved by the invention]

[0004] One method for treating fuel vapor generated inside a fuel tank is to supply the fuel vapor from the fuel tank to the engine and consume the fuel vapor. However, the fuel vapor supplied to the engine can be a disturbance factor that disrupts the feedback control of the engine's air-fuel ratio (A / F). For this reason, when supplying and treating fuel vapor to the engine, it is desirable to suppress fluctuations in the engine's A / F.

[0005] In addition, in Patent Document 1, a concentration sensor is provided to detect the concentration of evaporated fuel in the gas phase gas in the fuel tank in order to adjust the amount of evaporated fuel supplied, which requires space to be secured for the concentration sensor and increases the cost associated with the concentration sensor.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an evaporated fuel treatment device that can treat evaporated fuel inside a fuel tank while suppressing fluctuations in the A / F of an engine. [Means for solving the problem]

[0007] In order to solve the above problems, an evaporated fuel treatment device according to one embodiment of the present invention comprises: a fuel tank that stores fuel to be supplied to the engine; a first purge pipe that guides evaporated fuel inside the fuel tank to a canister; a second purge pipe connecting the canister and an intake passage connected to the engine; a first purge valve capable of adjusting the opening degree of the first purge pipe; a control device capable of controlling the opening degree of the first purge valve; Equipped with The control device one or more processors; one or more memories coupled to said processor; and The processor: when it is determined that the internal pressure of the fuel tank is equal to or greater than a predetermined value, starting a direct purge of supplying evaporated fuel inside the fuel tank to the engine through the first purge pipe, the canister, and the second purge pipe; determining a first correction amount representing a ratio of evaporated fuel supplied to the engine by the direct purge to a total flow rate of fuel supplied to the engine; calculating a target opening degree of the first purge valve based on the first correction amount; controlling the opening degree of the first purge valve so as to reach the calculated target opening degree; Execute the process including. [Effects of the Invention]

[0008] According to the present invention, it is possible to treat the evaporated fuel inside the fuel tank while suppressing fluctuations in the A / F of the engine. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing the configuration of a vehicle to which an evaporated fuel treatment device according to this embodiment is applied. [Figure 2] FIG. 2 is a cross-sectional view illustrating an example of the first purge valve. [Figure 3] FIG. 3 is a diagram illustrating an example of an opening degree map showing the relationship between the direct purge flow rate, the pressure ratio of the first purge valve, and the opening degree of the first purge valve. [Figure 4] FIG. 4 is a time chart for explaining an outline of the operation of the control device according to this embodiment. [Figure 5] FIG. 5 is a flowchart illustrating the flow of operations of the valve control unit when the engine is started. [Figure 6] FIG. 6 is a flowchart illustrating the flow of operations of the valve control unit while the engine is running. [Figure 7] FIG. 7 is a flowchart illustrating the flow of the direct purge process. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for facilitating understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0011] 1 is a block diagram showing the configuration of a vehicle 2 to which an evaporated fuel treatment device 1 according to this embodiment is applied. The vehicle 2 is, for example, an engine vehicle equipped with an engine 10 as a drive source. The vehicle 2 may also be a hybrid electric vehicle equipped with the engine 10 and a motor generator as drive sources.

[0012] The engine 10 is, for example, a reciprocating engine, and generates driving force by burning a mixture containing fuel and air. The generated driving force is transmitted to the wheels of the vehicle 2, for example.

[0013] In addition to the engine 10, the vehicle 2 is equipped with an intake passage 12, an intake port 14, an exhaust passage 16, an exhaust port 18, and an A / F sensor 20. A / F stands for air-fuel ratio.

[0014] The intake flow path 12 allows a fluid to flow through it. An intake port 14 is provided at one end of the intake flow path 12. The other end of the intake flow path 12 is connected to the engine 10. Air is introduced into the intake flow path 12 through the intake port 14. The air introduced into the intake flow path 12 flows through the intake flow path 12 and is supplied to the engine 10.

[0015] The exhaust flow path 16 allows a fluid to flow through it. One end of the exhaust flow path 16 is connected to the engine 10. An exhaust port 18 is provided at the other end of the exhaust flow path 16. The engine 10 discharges gas produced by combustion of an air-fuel mixture into the exhaust flow path 16 as exhaust gas. The exhaust gas discharged from the engine 10 into the exhaust flow path 16 flows through the exhaust flow path 16. The exhaust gas flowing through the exhaust flow path 16 is purified by a purification device (not shown) and then discharged to the outside through the exhaust port 18.

[0016] The A / F sensor 20 is provided in the exhaust flow path 16. The A / F sensor 20 detects the air-fuel ratio of the exhaust gas flowing through the exhaust flow path 16.

[0017] The vehicle 2 further includes a fuel tank 30, a fuel pipe 32, and an injector 34. The fuel tank 30 stores fuel to be supplied to the engine 10. One end of the fuel pipe 32 is connected to the fuel tank 30. The other end of the fuel pipe 32 is connected to the injector 34 of the engine 10. The fuel pipe 32 guides the fuel stored in the fuel tank 30 to the injector 34. The injector 34 injects the fuel supplied through the fuel pipe 32 into a combustion chamber of the engine 10.

[0018] Furthermore, some of the liquid fuel stored in the fuel tank 30 may evaporate due to, for example, the temperature inside the fuel tank 30. As a result, evaporated fuel that has turned into gas may accumulate inside the fuel tank 30. For example, in FIG. 1, the hatched portion of the fuel tank 30 represents liquid fuel. The evaporated fuel inside the fuel tank 30 is contained, for example, in the non-hatched space in FIG. 1.

[0019] The vehicle 2 further includes a canister 40 , a first purge pipe 42 , a second purge pipe 44 , a first purge valve 46 , a relief valve 48 , a second purge valve 50 , a tank internal pressure sensor 52 , an atmospheric pressure sensor 54 , and a control device 60 .

[0020] One end of the first purge pipe 42 is connected to the top of the fuel tank 30. The other end of the first purge pipe 42 is connected to the canister 40. The first purge pipe 42 guides evaporated fuel inside the fuel tank 30 to the canister 40. The canister 40 includes an adsorbent 40A, such as activated carbon, that can adsorb evaporated fuel. A portion of the evaporated fuel sent from the fuel tank 30 to the canister 40 is adsorbed by the adsorbent 40A and accumulated in the adsorbent 40A of the canister 40. The interior of the canister 40 is open to the outside, and the adsorbent 40A adsorbs the evaporated fuel, preventing it from being released into the atmosphere.

[0021] One end of the second purge pipe 44 is connected to the canister 40. The other end of the second purge pipe 44 is connected to the intake passage 12. The second purge pipe 44 guides evaporated fuel, which is fuel vaporized from fuel stored in the canister 40, to the intake passage 12. The evaporated fuel introduced into the intake passage 12 through the second purge pipe 44 is supplied to the combustion chamber of the engine 10 through the intake passage 12.

[0022] The first purge valve 46 and the relief valve 48 are provided in parallel with each other in the first purge pipe 42. The first purge valve 46 may be, for example, a solenoid valve including an actuator. The actuator is driven, for example, under the control of the control device 60. The first purge valve 46 can adjust the flow rate by adjusting the opening of the first purge pipe 42 according to the driving of the actuator.

[0023] The relief valve 48 is a safety valve that mechanically opens when the internal pressure of the fuel tank 30 reaches or exceeds a predetermined pressure. In other words, when the internal pressure of the fuel tank 30 becomes excessively high, the relief valve 48 releases the internal pressure of the fuel tank 30 to the canister 40 through the first purge pipe 42, regardless of the state of the first purge valve 46.

[0024] The second purge valve 50 is provided in the second purge pipe 44. The second purge valve 50 may be, for example, a solenoid valve including an actuator. The actuator is driven, for example, under the control of the control device 60. The second purge valve 50 can adjust the opening degree of the second purge pipe 44 in accordance with the driving of the actuator.

[0025] When both the first purge valve 46 and the second purge valve 50 are open, the fuel tank 30 is connected to the engine 10 through the first purge pipe 42, the canister 40, and the second purge pipe 44. This allows the evaporated fuel inside the fuel tank 30 to be introduced into the combustion chamber of the engine 10 through the first purge pipe 42, the canister 40, and the second purge pipe 44.

[0026] For ease of explanation, supplying evaporated fuel inside the fuel tank 30 to the engine 10 through the first purge pipe 42, the canister 40, and the second purge pipe 44 may be referred to as direct purging. Direct purging includes, for example, supplying evaporated fuel sent from the fuel tank 30 to the canister 40 to the engine 10 from the canister 40 via the second purge pipe 44. Direct purging may also include supplying evaporated fuel obtained by vaporizing fuel accumulated inside the canister 40 to the engine 10, in addition to supplying evaporated fuel inside the fuel tank 30 to the engine 10.

[0027] Furthermore, when the first purge valve 46 is closed and the second purge valve 50 is open, the fuel tank 30 and the canister 40 are separated, and evaporated fuel from the fuel tank 30 is not supplied to the engine 10 through the first purge pipe 42 or the like. However, in this state, the canister 40 is connected to the engine 10 through the second purge pipe 44. This allows evaporated fuel, which is fuel accumulated inside the canister 40, to be introduced into the combustion chamber of the engine 10 through the second purge pipe 44.

[0028] For ease of explanation, the process of supplying evaporated fuel, which is fuel accumulated inside the canister 40 and vaporized by closing the first purge valve 46 and opening the second purge valve 50, from the canister 40 through the second purge pipe 44 to the engine 10 is sometimes referred to as normal purging.

[0029] The tank internal pressure sensor 52 is provided in the fuel tank 30 and detects the pressure inside the fuel tank 30 (in other words, the tank internal pressure). The atmospheric pressure sensor 54 detects the atmospheric pressure around the vehicle 2.

[0030] The control device 60 has one or more processors 70 and one or more memories 72 connected to the processors 70. The memories 72 include a ROM in which programs and the like are stored and a RAM as a work area. The memory 72 may also include a storage in which programs and the like are stored. The processor 70 controls the entire vehicle 2 in cooperation with the programs stored in the memories and the like.

[0031] For example, the processor 70 may function as an engine control unit 80 and a valve control unit 82 by executing a program.

[0032] The engine control unit 80 performs various controls related to the engine 10, such as the state of the engine 10, including starting, driving, and stopping of the engine 10, the rotation speed of the engine 10, and the air-fuel ratio of the engine 10. The valve control unit 82 can control the opening degrees of various valves, such as the first purge valve 46 and the second purge valve 50, based on the detection results of various sensors, such as the tank internal pressure sensor 52, the atmospheric pressure sensor 54, and the A / F sensor 20.

[0033] Fig. 2 is a cross-sectional view illustrating an example of the first purge valve 46. As shown in Fig. 2, the first purge valve 46 includes a coil 102 and a movable iron core 104 as an example of an actuator.

[0034] The movable core 104 extends in a direction intersecting the longitudinal direction of the first purge pipe 42. The length of the movable core 104 is longer than the inner diameter of the first purge pipe 42. The movable core 104 is located between the coils 102. The movable core 104 is movable in the radial direction of the first purge pipe 42 as indicated by the open double-headed arrow A10 in FIG. 2 in accordance with the current flowing through the coil 102. The first purge valve 46 is a duty valve that repeatedly moves the movable core 104 between a fully open position and a fully closed position in a short cycle, and whose opening can be adjusted by the proportion of time that the movable core 104 is in the fully open position per unit time.

[0035] 2, the pressure inside the first purge pipe 42 on the fuel tank 30 side relative to the first purge valve 46 is substantially equal to the tank internal pressure detected by the tank internal pressure sensor 52. The pressure inside the first purge pipe 42 on the canister 40 side relative to the first purge valve 46 is substantially equal to the atmospheric pressure detected by the atmospheric pressure sensor 54 because the canister 40 is open to the atmosphere.

[0036] The pressure ratio of the first purge valve 46, i.e., the degree of magnitude between the pressure on the fuel tank 30 side of the first purge valve 46 and the pressure on the canister 40 side of the first purge valve 46, is substantially given by the ratio of the tank internal pressure to atmospheric pressure (pressure ratio of the first purge valve 46 = tank internal pressure: atmospheric pressure). More specifically, the pressure ratio of the first purge valve 46 may be expressed by the ratio of the atmospheric pressure to the tank internal pressure (pressure ratio of the first purge valve 46 = atmospheric pressure / tank internal pressure).

[0037] As evaporated fuel accumulates inside the fuel tank 30, the internal tank pressure increases in accordance with the increase in the evaporated fuel inside the fuel tank 30. As the internal tank pressure increases, the first purge valve 46 is opened to prevent the fuel tank 30 from being damaged by the internal tank pressure, and the evaporated fuel inside the fuel tank 30 is discharged to the outside of the fuel tank 30 through the first purge pipe 42.

[0038] For ease of explanation, the flow rate of evaporated fuel passing through the first purge valve 46 along the first purge pipe 42, as indicated by the white arrow A12 in FIG. 2, may be referred to as the direct purge flow rate.

[0039] 3 is a diagram illustrating an example of an opening degree map 110 showing the relationship between the direct purge flow rate, the pressure ratio of the first purge valve 46, and the opening degree of the first purge valve 46. The pressure ratio in the opening degree map of the first purge valve 46 represents the ratio of the pressure on the canister 40 side of the first purge valve 46 to the pressure on the fuel tank 30 side of the first purge valve 46. Although the opening degree map 110 in FIG. 3 uses the pressure ratio of the first purge valve 46, the pressure difference of the first purge valve 46 (pressure difference of the first purge valve 46 = tank internal pressure - atmospheric pressure) may be used instead of the pressure ratio of the first purge valve 46.

[0040] The opening degree map 110 may be stored in advance in, for example, the memory 72 of the control device 60. As shown in Fig. 3, the opening degree of the first purge valve 46 can be calculated from the direct purge flow rate, the pressure ratio of the first purge valve 46 (or the pressure difference of the first purge valve 46), and the opening degree map 110.

[0041] For example, as the direct purge flow rate increases, the opening degree of the first purge valve 46 increases. Also, for example, as the pressure ratio of the first purge valve 46 decreases (or the pressure difference of the first purge valve 46 increases), the opening degree of the first purge valve 46 increases.

[0042] 4 is a time chart outlining the operation of the control device 60 according to this embodiment. As shown in FIG. 4, the normal purge execution flag is set to an ON state when the engine speed has roughly stabilized after the engine 10 has started. When the normal purge execution flag is set to an ON state, normal purge is executed. When normal purge is executed, the concentration of evaporated fuel during normal purge is learned.

[0043] 4, the direct purge execution flag is set to the on state with a delay from the time when the normal purge execution flag is set to the on state. For example, the direct purge execution flag may be set to the on state when learning of the concentration of evaporated fuel in the normal purge is substantially completed and the tank internal pressure is equal to or higher than a predetermined threshold. When the direct purge execution flag is set to the on state, direct purge is executed.

[0044] When direct purge is started, the valve control unit 82 repeatedly determines the first correction amount, calculates the direct purge flow rate, and calculates the opening degree of the first purge valve 46 at a predetermined cycle. The predetermined cycle may be set to any value within a range of, for example, several milliseconds to several seconds.

[0045] The first correction amount represents the ratio of the evaporated fuel supplied to the engine 10 by direct purge to the total flow rate of fuel supplied to the engine 10 (in other words, the total fuel flow rate).

[0046] Since the first correction amount represents the proportion of evaporated fuel supplied to the engine by direct purging, it is possible to calculate the target value of the direct purge flow rate based on the first correction amount and the total flow rate of fuel supplied to the engine.

[0047] Furthermore, the target opening degree of the first purge valve 46 can be calculated based on the target value of the direct purge flow rate. That is, the valve control unit 82 can calculate the opening degree of the first purge valve 46 based on the first correction amount.

[0048] In the evaporated fuel processing device 1, the opening degree of the first purge valve 46 is set to an opening degree based on the first correction amount, thereby controlling the proportion of evaporated fuel due to direct purging in the fuel supplied to the engine 10. For example, in the evaporated fuel processing device 1, by controlling the proportion of evaporated fuel due to direct purging so that it does not become too high, it is possible to suppress fluctuations in the A / F of the engine 10. Therefore, in the evaporated fuel processing device 1, it is possible to process evaporated fuel inside the fuel tank 30 while suppressing fluctuations in the A / F of the engine 10.

[0049] 4, the first correction amount may be determined so as not to exceed a predetermined upper limit amount. The upper limit amount is set to an upper limit amount of the proportion of evaporated fuel that keeps the A / F disturbance of the engine 10 within an allowable range even when evaporated fuel according to the first correction amount is supplied to the engine 10.

[0050] As a result, the evaporated fuel processing device 1 can process the evaporated fuel inside the fuel tank 30 while more reliably suppressing fluctuations in the A / F of the engine 10.

[0051] 4, the first correction amount may be determined so as to gradually increase over time from the point in time when the direct purge execution flag is switched from the OFF state to the ON state, that is, from the point in time when the direct purge starts.

[0052] For example, "Δt" in FIG. 4 is an example of a calculation cycle of the first correction amount, in other words, a period for repeating the calculation of the first correction amount. "Δy" in FIG. 4 is an example of an increase in the first correction amount during Δt. That is, in the example of FIG. 4, the first correction amount increases proportionally by Δy each time the process for determining the first correction amount is repeatedly executed. The time it takes for the first correction amount to change from 0 to the upper limit amount may be, for example, about several seconds, or may be any time that takes into account the actual state of feedback control of the A / F of the engine 10.

[0053] In this way, in the evaporated fuel processing device 1, the proportion of evaporated fuel due to direct purging increases over a relatively long period of time from the start of direct purging. Therefore, the evaporated fuel processing device 1 can suppress sudden fluctuations in the A / F of the engine 10.

[0054] 4, when the direct purge flow rate increases from the start of the direct purge, the evaporated fuel inside the fuel tank 30 is gradually discharged to the outside of the fuel tank 30. As a result, the tank internal pressure gradually decreases over time from the start of the direct purge.

[0055] When the tank internal pressure drops below a predetermined end threshold, the direct purge is ended and the direct purge execution flag is set to OFF. As shown in Fig. 4, when the direct purge is ended, for example, the first correction amount is reduced to 0%, the first purge valve 46 is closed, and the direct purge flow rate is set to 0.

[0056] 4 shows an example in which the first correction amount is suddenly reduced to 0% when the tank internal pressure falls below a predetermined end threshold. However, the first correction amount may be determined so as to gradually decrease over time from the time when the tank internal pressure falls below the predetermined end threshold. In this case, the direct purge flow rate and the opening degree of the first purge valve 46 may be gradually decreased over time in accordance with the decrease in the first correction amount.

[0057] Fig. 5 is a flowchart illustrating the flow of operations of the valve control unit 82 when the engine 10 starts. As shown in Fig. 5, when the engine 10 starts, the valve control unit 82 turns off the normal purge execution flag (S10) and turns off the direct purge execution flag (S11).

[0058] Next, the valve control unit 82 determines whether or not the conditions for executing a normal purge are met (S12). For example, the valve control unit 82 may determine that the conditions for executing a normal purge are met when the engine speed stabilizes after the engine 10 has started. If it is determined that the conditions for executing a normal purge are not met, the valve control unit 82 waits until the conditions for executing a normal purge are met (NO in S12).

[0059] When it is determined that the conditions for performing the normal purge are met (YES in S12), the valve control unit 82 turns on the normal purge execution flag (S13), closes the first purge valve 46 (S14), and opens the second purge valve 50 (S15). In other words, the valve control unit 82 performs the normal purge.

[0060] In this state, the valve control unit 82 derives a learned value of the concentration of evaporated fuel during normal purge and updates the derived learned value (S16). For example, the valve control unit 82 may obtain the A / F detection value from the A / F sensor 20 and derive a correction value by feedback control to correct the deviation of the detected A / F value from the target A / F of the engine 10. The valve control unit 82 may derive the concentration of evaporated fuel during normal purge based on the correction value and update the learned value.

[0061] The valve control unit 82 determines whether learning of the concentration of evaporated fuel during normal purge is substantially completed (S17). For example, the valve control unit 82 may determine that learning is substantially completed when it is deemed that the learned value has substantially converged.

[0062] If it is determined that the learning has not substantially been completed (NO in S17), the valve control section 82 repeatedly executes learning of the concentration of evaporated fuel during normal purge (S16).

[0063] If it is determined that the learning is substantially completed (YES in S17), the valve control section 82 turns on the direct purge execution flag (S18) and ends the series of processes in FIG.

[0064] Fig. 6 is a flowchart illustrating the flow of operations of the valve control unit 82 while the engine 10 is operating. The valve control unit 82 repeatedly executes the series of processes shown in Fig. 6 at a predetermined cycle.

[0065] When the predetermined execution timing arrives, the valve control unit 82 determines whether the direct purge execution flag is on (S30). That is, in step S30, it is determined whether learning of the evaporated fuel concentration for the normal purge has substantially been completed. If the direct purge execution flag is off (NO in S30), the valve control unit 82 ends the current series of processes in FIG. 6.

[0066] If the direct purge execution flag is on (YES in S30), that is, if learning of the concentration of evaporated fuel for normal purge has substantially been completed, the valve control unit 82 acquires the tank internal pressure detected by the tank internal pressure sensor 52 (S31).

[0067] The valve control unit 82 determines whether the tank internal pressure is equal to or greater than a predetermined start threshold (S32). If it is determined that the tank internal pressure is less than the predetermined start threshold (NO in S32), it is assumed that the amount of evaporated fuel inside the fuel tank 30 is small, and the valve control unit 82 ends the current series of processes in FIG.

[0068] If it is determined that the tank internal pressure is equal to or greater than a predetermined start threshold (YES in S32), the valve control unit 82 estimates that there is a large amount of evaporated fuel inside the fuel tank 30, and therefore performs a direct purge process (S33), which is a process for performing a direct purge.

[0069] 7 is a flowchart illustrating the flow of the direct purge process (S33). In the direct purge process (S33), the following steps S40 to S45 are repeatedly performed until the tank internal pressure becomes less than a predetermined end threshold.

[0070] In the direct purge process, first, the valve control unit 82 acquires various sensor values ​​(S40). For example, the valve control unit 82 may acquire the tank internal pressure from the tank internal pressure sensor 52, the atmospheric pressure from the atmospheric pressure sensor 54, and the A / F from the A / F sensor 20.

[0071] Next, the valve control unit 82 determines a first correction amount that indicates the ratio of evaporated fuel supplied to the engine 10 by direct purging to the total flow rate of fuel supplied to the engine 10 (S41). More specifically, the valve control unit 82 performs processing based on the concept shown in the following equation (1). dprgfg = min(kDPRGFGMX , previous value of dprgfg+Δy) ···(1)

[0072] In formula (1), "dprgfg" is the first correction amount determined this time. "Previous value of dprgfg" is the previous first correction amount. "Δy" means the increase in the first correction amount in a unit calculation cycle. "Previous value of dprgfg + Δy" is the value obtained by adding the increase in the first correction amount in a unit calculation cycle to the previous first correction amount. "kDPRGFGMX" is the upper limit of the first correction amount. "min(kDPRGFGMX, previous value of dprgfg + Δy)" means a function that selects the smaller of "kDPRGFGMX" and "previous value of dprgfg + Δy." In other words, in formula (1) above, if "previous value of dprgfg + Δy" is smaller than the upper limit "kDPRGFGMX," "previous value of dprgfg + Δy" is determined as the first correction amount this time. On the other hand, if "the previous value of dprgfg+Δy" is equal to or greater than the upper limit amount "kDPRGFGMX", the upper limit amount "kDPRGFGMX" is determined as the current first correction amount.

[0073] Next, the valve control unit 82 calculates a target value of the direct purge flow rate based on the current first correction amount (S42). More specifically, the valve control unit 82 calculates the target value of the direct purge flow rate using the following equation (2). gdpg = fflowg × dprgfg (2)

[0074] In equation (2), "gdpg" is the target value of the direct purge flow rate calculated this time. The unit of "gdpg" is [g / s], and the target value of the direct purge flow rate in equation (2) means mass flow rate. "fflowg" is the total flow rate of fuel supplied to engine 10. "fflowg" can be derived, for example, based on the target A / F of engine 10, the amount of air detected by an air flow sensor that detects the flow rate of air passing through the intake passage, and the learned value of the concentration of evaporated fuel due to normal purge. "dprgfg" is the first correction amount determined this time using equation (1) above.

[0075] Next, the valve control unit 82 calculates the current target opening degree of the first purge valve 46 based on the current target value of the direct purge flow rate (S43).

[0076] For example, the valve control unit 82 converts the target value of the direct purge flow rate "gdpg" calculated by equation (2) into a volumetric flow rate (L / s) by dividing the target value by the vapor density (gdpg / vapor density). The valve control unit 82 also calculates the pressure ratio of the first purge valve 46 (e.g., atmospheric pressure / tank internal pressure) from the tank internal pressure and atmospheric pressure. The valve control unit 82 calculates the current target opening degree of the first purge valve 46 based on the direct purge flow rate converted into a volumetric flow rate, the pressure ratio of the first purge valve 46, and an opening degree map 110 prepared in advance.

[0077] Next, the valve control unit 82 opens the first purge valve 46 to the target opening degree for this first purge valve 46 (S44).

[0078] The valve control unit 82 also opens the second purge valve 50 to a predetermined opening degree (S45), thereby supplying evaporated fuel from the fuel tank 30 to the engine 10 as a direct purge at a flow rate corresponding to the current target opening degree of the first purge valve.

[0079] Next, the valve control unit 82 determines whether the tank internal pressure is less than a predetermined end threshold (S46). The predetermined end threshold is set to a value smaller than the start threshold used in step S32.

[0080] If it is determined that the tank internal pressure is equal to or greater than the predetermined termination threshold (NO in S46), the valve control unit 82 returns to the process of step S40 and performs the process of determining the first correction amount again.

[0081] If it is determined that the tank internal pressure is less than the predetermined termination threshold (YES in S46), the valve control unit 82 closes the first purge valve 46 (S47) and closes the second purge valve 50 (S49). That is, the valve control unit 82 terminates the direct purge. The valve control unit 82 turns off the direct purge execution flag (S50) and terminates the direct purge process of FIG. 7.

[0082] As described above, the evaporated fuel processing device 1 of this embodiment includes starting direct purging when it is determined that the internal pressure of the fuel tank 30 is equal to or greater than a predetermined value. The evaporated fuel processing device 1 of this embodiment includes determining a first correction amount that represents the proportion of evaporated fuel supplied to the engine 10 by direct purging relative to the total flow rate of fuel supplied to the engine 10. The evaporated fuel processing device 1 of this embodiment includes calculating a target opening degree of the first purge valve 46 based on the first correction amount. The evaporated fuel processing device 1 of this embodiment includes controlling the opening degree of the first purge valve 46 to achieve the calculated target opening degree.

[0083] As a result, the evaporated fuel processing system 1 of this embodiment can suppress fluctuations in the A / F of the engine 10 by controlling the proportion of evaporated fuel due to direct purging so that it does not become too high.

[0084] Therefore, according to the evaporated fuel processing device 1 of this embodiment, it is possible to process the evaporated fuel inside the fuel tank 30 while suppressing fluctuations in the A / F of the engine 10.

[0085] Furthermore, it is estimated that the amount of evaporated fuel that is vaporized from fuel accumulated in the canister 40 during direct purge and supplied to the engine 10 is roughly the same as the amount of evaporated fuel that is supplied to the engine 10 during normal purge. Therefore, it is estimated that the learned value of the concentration of evaporated fuel that is supplied to the engine 10 during normal purge is substantially the same as the concentration of evaporated fuel that is vaporized from fuel accumulated in the canister 40 during direct purge and supplied to the engine 10.

[0086] In light of this, the evaporated fuel processing device 1 of this embodiment includes learning the concentration of evaporated fuel supplied to the engine 10 by normal purge. The evaporated fuel processing device 1 of this embodiment includes starting a direct purge when learning in normal purge is completed and it is determined that the internal pressure of the fuel tank 30 is equal to or higher than a predetermined value. The total flow rate of fuel supplied to the engine 10 is derived based on the learned value of the evaporated fuel concentration in normal purge.

[0087] As a result, the evaporated fuel processing device 1 of this embodiment performs a direct purge after completing learning in the normal purge, thereby reducing the impact on the A / F of the evaporated fuel that is vaporized from fuel accumulated in the canister 40 during the direct purge and supplied to the engine 10. For example, the evaporated fuel processing device 1 of this embodiment can set the total flow rate of fuel supplied to the engine 10 to a value that is appropriately corrected using a learned value obtained by completing learning of the evaporated fuel concentration during the normal purge. Therefore, the evaporated fuel processing device 1 of this embodiment performs a direct purge after completing learning in the normal purge, making it possible to process the evaporated fuel inside the fuel tank 30 while further suppressing fluctuations in the A / F of the engine 10.

[0088] While the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present invention.

[0089] Furthermore, in the embodiment of the present invention, the first purge valve 46 has been described as a duty valve, but the first purge valve 46 may be a linear valve whose opening degree can be adjusted according to the position of the movable iron core 104.

[0090] It should be noted that the processes shown in this specification do not necessarily have to be performed in chronological order according to the order shown in the flowcharts, and may include parallel or subroutine processes. [Explanation of symbols]

[0091] 1. Fuel vapor treatment device 10 Engine 30 Fuel Tank 40 canisters 42 First purge pipe 44 Second purge piping 46 First purge valve 50 Second purge valve 60 Control device 70 processors 72 memory

Claims

1. a fuel tank that stores fuel to be supplied to the engine; a first purge pipe that guides evaporated fuel in the fuel tank to a canister; a second purge pipe connecting the canister and an intake passage connected to the engine; a first purge valve capable of adjusting an opening degree of the first purge pipe; a control device capable of controlling an opening degree of the first purge valve; Equipped with The control device one or more processors; one or more memories coupled to the processor; and The processor: when it is determined that the internal pressure of the fuel tank is equal to or greater than a predetermined value, starting a direct purge of supplying evaporated fuel inside the fuel tank to the engine through the first purge pipe, the canister, and the second purge pipe; determining a first correction amount representing a ratio of evaporated fuel supplied to the engine by the direct purge to a total flow rate of fuel supplied to the engine; calculating a target opening degree of the first purge valve based on the first correction amount; controlling the opening degree of the first purge valve so as to reach the calculated target opening degree; The vaporized fuel treatment device performs a process including:

2. The processor: calculating a target value of a direct purge flow rate representing a flow rate of evaporated fuel passing through the first purge valve based on the first correction amount; calculating the target opening of the first purge valve based on the target value of the direct purge flow rate; The apparatus for treating evaporated fuel according to claim 1 , wherein the apparatus performs a process including the steps of:

3. The first correction amount is determined so as to gradually increase over time from the start of the direct purge. The fuel vapor treatment device according to claim 1 .

4. The first correction amount is determined so as not to exceed a predetermined upper limit amount. The fuel vapor treatment device according to claim 1 .

5. Further provided is a second purge valve capable of adjusting the opening degree of the second purge pipe, The processor: performing a normal purge in which evaporated fuel, which is fuel accumulated in the canister and evaporated, is supplied from the canister to the engine by closing the first purge valve and opening the second purge valve; learning the concentration of evaporated fuel supplied to the engine by the normal purge; When the learning is completed and it is determined that the internal pressure of the fuel tank is equal to or greater than a predetermined value, starting the direct purge; Perform a process including 2. The fuel vapor treatment device according to claim 1, wherein the total flow rate of fuel supplied to the engine is derived based on a learned value of the concentration of fuel vapor during the normal purge.

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