Fuel vapor control system

Abstract

To prevent water vapor from adhering to an adsorbent of a canister.SOLUTION: The vehicle 1 of the present disclosure includes the canister 52 that temporarily adsorbs the evaporated fuel, the purge passage 54 that supplies the purge gas containing the evaporated fuel purged from the canister 52 to the intake passage 20 of the engine 10, the regulating valve 55 that regulates the flow rate of the purge gas supplied to the intake passage 20 through the purge passage 54, and the acquisition unit that acquires the humidity information of the outside air. The evaporated fuel control device 60 prevents water vapor from adhering to the adsorbent of the canister 52 by controlling the opening and closing of the regulating valve 55 based on the humidity information acquired by the acquisition means.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for vaporized fuel. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there has been known an engine in which evaporated fuel generated in a fuel tank is adsorbed by a canister, and purge gas containing the evaporated fuel purged from the canister is supplied to an intake passage of the engine.

[0003] Patent Document 1 discloses an evaporated fuel treatment device including a canister containing an adsorbent that adsorbs evaporated fuel, a vapor passage connecting the canister to a fuel tank, an atmosphere communication pipe provided in the canister and opening the vapor to the atmosphere, and a purge device that performs a purge process by supplying purge gas separated from the canister to an intake passage of an internal combustion engine. In this evaporated fuel treatment device, outside air is introduced into the canister via the atmosphere communication pipe when the purge gas is supplied to the intake passage of the internal combustion engine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-123699 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the fuel vapor treatment device of Patent Document 1, when humidity is high, such as on rainy days, it is expected that air containing a large amount of water vapor will flow into the canister through the atmosphere communication pipe. If air containing a large amount of water vapor flows into the canister and a large amount of water vapor adheres to the adsorbent material of the canister, the canister's fuel vapor adsorption and desorption performance may be reduced.

[0006] The present invention has been made in view of the above-mentioned problems, and has as its object to prevent water vapor from adhering to the adsorbent material of the canister. [Means for solving the problem]

[0007] The present invention provides a control device for evaporative fuel in a vehicle that includes a canister that temporarily adsorbs evaporative fuel, a purge passage that supplies purge gas containing evaporative fuel purged from the canister to an intake passage of an engine, an adjustment valve that adjusts the flow rate of purge gas supplied to the intake passage through the purge passage, and an acquisition means for acquiring humidity information of the outside air, wherein the control device controls the opening and closing of the adjustment valve based on the humidity information acquired by the acquisition means. [Effects of the Invention]

[0008] According to the present invention, it is possible to prevent water vapor from adhering to the adsorbent material of the canister. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing a schematic configuration of a vehicle equipped with a control device for evaporated fuel; [Figure 2] 10 is a flowchart illustrating an example of processing by a control device. [Figure 3] 10 is a timing chart showing an example of changes in each item. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention is an evaporated fuel control device 60 for a vehicle 1, which includes a canister 52 that temporarily adsorbs evaporated fuel, a purge passage 54 that supplies purge gas containing evaporated fuel purged from the canister 52 to the intake passage 20 of the engine 10, a regulating valve 55 that adjusts the flow rate of the purge gas supplied to the intake passage 20 through the purge passage 54, and an acquisition means for acquiring humidity information about the outside air. The control device 60 prevents water vapor from adhering to the adsorbent material of the canister 52 by controlling the opening and closing of the regulating valve 55 based on the humidity information acquired by the acquisition means. [Example]

[0011] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a diagram showing a schematic configuration of a vehicle 1 equipped with a fuel vapor control device (hereinafter referred to as the control device) according to this embodiment. Note that Fig. 1 is simplified for the sake of convenience in explaining this embodiment, and components that are normally included in a vehicle are assumed to be included even if they are not shown in the figure. A vehicle 1 according to the embodiment includes an engine 10 as an internal combustion engine, an intake passage 20, an exhaust passage 30, a fuel tank 40, a humidity sensor 41, an accelerator opening sensor 42, and the like.

[0012] Engine 10 performs a series of strokes consisting of an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke. Engine 10 has a combustion chamber 12 in which a piston 11 is housed so that it can reciprocate, an ignition plug 13 disposed within combustion chamber 12, an intake valve 15 located between combustion chamber 12 and an intake port 14, and an exhaust valve 17 located between combustion chamber 12 and an exhaust port 16. The configuration of engine 10 is not particularly limited, and various known engines can be used.

[0013] The intake passage 20 is a passage that guides intake air taken in from outside the vehicle 1 to the combustion chamber 12 via the intake port 14. The intake passage 20 is formed, for example, by an intake pipe. In the intake passage 20, a throttle valve 21, a surge tank 22, and a fuel injector 23 are arranged in this order from the upstream side.

[0014] The throttle valve 21 adjusts the flow rate of intake air by opening and closing. The throttle valve 21 adjusts the flow rate of intake air based on the control of the control device 60. The surge tank 22 temporarily stores the intake air, rectifies the flow, and guides it to the combustion chamber 12. An intake pressure sensor 24 is disposed in the surge tank 22. The intake pressure sensor 24 transmits information about the detected intake pressure to the control device 60. The fuel injector 23 injects fuel pressure-fed from the fuel tank 40 into the intake passage 20. The fuel injector 23 adjusts the amount of fuel injected based on the control of the control device 60. Note that the fuel injector 23 is not limited to injecting fuel into the intake passage 20, and may be configured to inject fuel into the combustion chamber 12.

[0015] The exhaust passage 30 is a passage through which exhaust gas burned in the combustion chamber 12 is exhausted to the outside of the vehicle 1 via the exhaust port 16. The exhaust passage 30 is formed, for example, by an exhaust pipe. An air-fuel ratio sensor 31 is disposed in the exhaust passage 30. The air-fuel ratio sensor 31 transmits information on the detected air-fuel ratio of the exhaust gas to the control device 60.

[0016] Fuel tank 40 stores liquid fuel to be supplied to fuel injector 23. Note that, in fuel tank 40, evaporated fuel (vapor) is generated from the liquid fuel. The humidity sensor 41 measures and acquires humidity information of the outside air, and transmits the acquired humidity information to the control device 60. The humidity sensor 41 corresponds to an example of an acquisition unit. The accelerator opening sensor 42 detects information about the amount of accelerator pedal operation by the driver, and transmits the detected information about the amount of accelerator pedal operation to the control device 60 .

[0017] The vehicle 1 also includes an evaporated fuel treatment device 50 for supplying evaporated fuel to the intake passage 20 without discharging it into the atmosphere. The evaporated fuel treatment device 50 includes a vapor passage 51, a canister 52, a purge passage 54, an adjustment valve 55, and the like.

[0018] The vapor passage 51 is a passage that guides evaporated fuel generated in the fuel tank 40 to the canister 52. The vapor passage 51 is formed by a pipe that connects the fuel tank 40 and the canister 52 to each other.

[0019] The canister 52 temporarily adsorbs the evaporated fuel generated in the fuel tank 40. The canister 52 has activated carbon as an adsorbent inside, and adsorbs the evaporated fuel that flows in from the fuel tank 40 through the vapor passage 51. The canister 52 is also open to the atmosphere through an atmospheric passage 53.

[0020] The atmospheric passage 53 is a passage that is connected to the canister 52 and is open to the atmosphere. When purge gas is supplied to the intake passage 20, air flows into the canister 52 through the atmospheric passage 53. On the other hand, when purge gas is not supplied to the intake passage 20 and evaporated fuel flows from the fuel tank 40 into the canister 52 in an amount that exceeds the adsorption capacity of the adsorbent of the canister 52, the evaporated fuel in the canister 52 is released through the atmospheric passage 53. A pressure regulating valve is disposed in the atmospheric passage 53. The pressure regulating valve opens when the pressure inside the canister 52 becomes negative to allow outside air to enter the canister 52, and opens when the pressure inside the canister 52 becomes positive at a predetermined level or higher to release the air containing evaporated fuel inside the canister 52 into the atmosphere.

[0021] Here, the atmospheric passage 53 may be composed of a first atmospheric passage and a second atmospheric passage. Specifically, a first check valve may be disposed in the first atmospheric passage, which allows air to flow from the outside air to the canister 52 when negative pressure is created inside the canister 52 and prohibits air from flowing from the canister 52 to the outside air. On the other hand, a second check valve may be disposed in the second atmospheric passage, which allows air to flow from the canister 52 to the outside air and prohibits air from flowing from the outside air to the canister 52 when positive pressure is created inside the canister at a predetermined level or higher.

[0022] The purge passage 54 is a passage that supplies purge gas containing evaporated fuel purged from the canister 52 to the intake passage 20 of the engine 10. The purge passage 54 is formed by piping that connects the canister 52 to the intake passage 20. Here, the purge passage 54 is configured to be connected to the intake passage 20 between the throttle valve 21 and the surge tank 22, but it may also be configured to be connected to the surge tank 22. The regulating valve 55 regulates the flow rate of the purge gas supplied to the intake passage 20 through the purge passage 54. The regulating valve 55 is disposed midway through the purge passage 54. The regulating valve 55 regulates the flow rate of the purge gas under the control of the control device 60.

[0023] In the evaporated fuel treatment device 50, evaporated fuel generated in the fuel tank 40 is guided to a canister 52 via a vapor passage 51 and temporarily adsorbed by the canister 52. When the engine 10 starts, the intake passage 20 becomes negative pressure, so that by opening an adjusting valve 55, purge gas containing evaporated fuel purged from the canister 52 is supplied to the intake passage 20 via a purge passage 54. The purge gas supplied to the intake passage 20 mixes with a mixture of intake air taken in through the throttle valve 21 and fuel injected from the fuel injector 23 and flows into the combustion chamber 12. Therefore, the evaporated fuel contained in the purge gas is burned in the combustion chamber 12, preventing the evaporated fuel from being released into the atmosphere from the fuel tank 40.

[0024] The vehicle 1 also includes a control device 60. The control device 60 controls the entire vehicle 1. The control device 60 may be, for example, an ECU (Electronic Control Unit). The control device 60 has a hardware configuration including a CPU, a ROM, a RAM, etc. The ROM stores programs and predetermined information for controlling the engine 10, the evaporative fuel treatment device 50, etc. The RAM is a work memory that temporarily stores programs and data. The CPU reads out the programs stored in the ROM, expands them in the RAM, and executes them to control the engine 10, the evaporative fuel treatment device 50, etc.

[0025] The control device 60 has, as a software configuration (functional configuration), an estimation unit 61, a purge control unit 62, a regulation unit 63, and the like.

[0026] The estimation unit 61 estimates the amount of evaporated fuel adsorbed in the canister 52. In this embodiment, the estimation unit 61 estimates the amount of adsorption based on the vapor concentration of purge gas supplied to the intake passage 20 by opening the adjustment valve 55. Here, the vapor concentration is the ratio of evaporated fuel contained in the purge gas. The vapor concentration varies depending on the amount of evaporated fuel adsorbed in the canister 52 and the environment of the vehicle 1. Therefore, the estimation unit 61 calculates the vapor concentration at each sampling time and estimates the amount of adsorption from the calculated vapor concentration.

[0027] Specifically, the estimation unit 61 controls the adjusting valve 55 so that a constant amount of purge gas is supplied to the intake passage 20. Next, based on information about the air-fuel ratio detected by the air-fuel ratio sensor 31, the estimation unit 61 controls the amount of fuel injected from the fuel injector 23, etc., so that the air-fuel ratio becomes a target air-fuel ratio (e.g., a stoichiometric air-fuel ratio). At this time, the mixture flowing into the combustion chamber 12 contains evaporated fuel in the purge gas in addition to the fuel injected from the fuel injector 23, so that a difference occurs between the actual air-fuel ratio detected by the air-fuel ratio sensor 31 and the target air-fuel ratio. The difference (deviation amount) between the actual air-fuel ratio and the target air-fuel ratio is due to the amount of evaporated fuel in the purge gas. Therefore, the estimation unit 61 calculates the vapor concentration (the ratio of evaporated fuel contained in the purge gas) based on information about the difference between the actual air-fuel ratio and the target air-fuel ratio. The estimation unit 61 refers to a table in which the vapor concentration and the adsorption amount are associated, and estimates the adsorption amount of evaporated fuel from the calculated concentration. In the table, a larger adsorption amount is associated with a higher vapor concentration. The table is stored in the control device 60.

[0028] The purge control unit 62 performs purge control by opening the regulating valve 55 to supply purge gas to the intake passage 20 when the purge permission condition flag is on, and does not perform purge control when the purge permission condition flag is off. When performing purge control, the purge control unit 62 performs correction control to correct the injection amount of fuel injected from the fuel injector 23 based on the purge concentration calculated by the estimating unit 61 so that the actual air-fuel ratio becomes the target air-fuel ratio. Specifically, the purge control unit 62 acquires information on the flow rate of purge gas supplied to the intake passage 20 based on the current opening degree of the regulating valve 55, etc. Next, the purge control unit 62 calculates and acquires the amount of evaporated fuel contained in the purge gas based on the flow rate of the purge gas and the vapor concentration calculated by the estimating unit 61. Next, the purge control unit 62 performs correction control by subtracting the calculated amount of evaporated fuel (equivalent to the fuel amount) from the injection amount that needs to be injected from the fuel injector 23 in accordance with the accelerator pedal depression amount detected by the accelerator position sensor 42, etc. In this way, by performing correction control to correct the injection amount injected from the fuel injector 23, the engine 10 can be operated so that the actual air-fuel ratio becomes the target air-fuel ratio.

[0029] The regulating unit 63 regulates the execution of purge control by turning on the flag for the purge permission condition when purge control is to be executed, and by turning off the flag for the purge permission condition when purge control is not to be executed. The regulating unit 63 determines whether to turn on or off the flag for the purge permission condition based on the amount of adsorption estimated by the estimating unit 61 and the humidity information measured by the humidity sensor 41.

[0030] In the vehicle 1 configured as described above, the control device 60 of this embodiment controls the opening and closing of the regulating valve 55 based on humidity information acquired from the humidity sensor 41 in order to prevent water vapor from adhering to the adsorbent material of the canister 52. An example of processing by the control device 60 will now be described with reference to the flowchart of Fig. 2. The flowchart of Fig. 2 begins when the engine 10 is started.

[0031] In S11, the estimation unit 61 estimates the amount of evaporated fuel adsorbed in the canister 52. Specifically, as described above, the estimation unit 61 estimates the amount of adsorption based on the vapor concentration of the purge gas supplied to the intake passage 20 when the adjustment valve 55 is opened.

[0032] In S12, the regulating unit 63 receives and acquires the humidity information transmitted from the humidity sensor 41. In S13, the estimation unit 61 determines whether the estimated amount of evaporated fuel adsorbed in the canister 52 is equal to or greater than a predetermined amount. Here, information about the predetermined amount is stored in the control device 60 in advance. If the amount of adsorption is equal to or greater than the predetermined amount, the process proceeds to S15. On the other hand, if the amount of adsorption is less than the predetermined amount, the process proceeds to S14, where the restriction unit 63 turns off the flag for the purge permission condition, thereby preventing the purge control unit 62 from executing purge control. In this way, if the amount of adsorption is less than the predetermined amount, there is no need to purge evaporated fuel from the canister 52, so the flag for the purge permission condition is turned off.

[0033] In S15, the regulating unit 63 determines whether the acquired humidity information is less than a threshold value. Here, the threshold value information is stored in advance in the control device 60. The threshold value is set based on the humidity at which the adsorption performance of the canister 52 deteriorates. If the humidity is below the threshold, the process proceeds to S16. On the other hand, if the humidity is equal to or greater than the threshold, the process proceeds to S14, where the regulating unit 63 turns off the flag for the purge permission condition, thereby preventing the purge control unit 62 from executing purge control. In this way, if the humidity is equal to or greater than the threshold, the flag for the purge permission condition is turned off to prevent the purge control from being executed, even if the amount of adsorption is equal to or greater than a predetermined amount (regardless of the amount of adsorption).

[0034] Here, when purge control is executed and purge gas is supplied to the intake passage 20, negative pressure is created inside the canister 52, causing air to flow into the canister 52 through the atmospheric passage 53. At this time, if the air flowing into the canister 52 is humid, a large amount of water vapor will adhere to the adsorbent material of the canister 52. Therefore, by not executing purge control when the humidity is equal to or higher than a threshold, humid air will not flow into the canister 52, and water vapor can be prevented from adhering to the canister 52.

[0035] In S16, the regulating unit 63 turns on the flag for the purge permission condition. In S17, because the flag for the purge permission condition is on, the purge control unit 62 executes purge control to open the adjustment valve 55 and supply purge gas to the intake passage 20. Furthermore, as described above, the purge control unit 62 executes correction control to correct the injection amount when fuel is injected from the fuel injector 23, based on the purge concentration calculated by the estimation unit 61, so that the actual air-fuel ratio becomes the target air-fuel ratio.

[0036] After the processes of S14 and S17 are completed, the flow chart of Fig. 2 is terminated. The flow chart of Fig. 2 is periodically executed until the driving of the engine 10 is terminated.

[0037] 3A and 3B are timing charts showing an example of changes in humidity, adsorption amount, and purge permission condition flag. Figure 3A shows changes in humidity, Figure 3B shows changes in the adsorption amount of evaporated fuel adsorbed in the canister 52, and Figure 3C shows changes in the purge permission condition flag.

[0038] First, during the period from time T1 to time T2, the humidity is below the threshold value as shown in Figure 3(a), and the amount of adsorbed fuel vapor is equal to or greater than the predetermined amount as shown in Figure 3(b). Therefore, the purge permission condition flag is on as shown in Figure 3(c), and purge control is being executed. On the other hand, after time T2, the humidity exceeds the threshold value as shown in Fig. 3(a). Therefore, even if the amount of adsorbed fuel vapor is equal to or greater than the predetermined amount as shown in Fig. 3(b), the purge permission condition flag is turned off as shown in Fig. 3(c), so that the purge control is not executed and water vapor is prevented from adhering to the canister 52.

[0039] As described above, according to this embodiment, the control device 60 controls the opening and closing of the regulating valve 55 based on the humidity information. Therefore, when humid air flows into the canister 52, the control device 60 controls the regulating valve 55 to close, and when humid air does not flow into the canister 52, the control device 60 controls the regulating valve 55 to open, thereby preventing water vapor from adhering to the adsorbent in the canister 52.

[0040] Furthermore, according to this embodiment, the control device 60 includes an estimation unit 61 that estimates the amount of evaporated fuel adsorbed in the canister 52, a purge control unit 62 that, when the amount of adsorption estimated by the estimation unit 61 is equal to or greater than a predetermined amount, executes purge control by opening the adjustment valve 55 to supply purge gas to the intake passage 20, and a restriction unit 63 that, when the humidity is equal to or greater than a threshold value, restricts the purge control unit 62 from executing the purge control regardless of the amount of adsorption estimated by the estimation unit 61. In this way, the restriction unit 63 restricts the purge control unit 62 from executing the purge control when the humidity is equal to or greater than a threshold value, thereby preventing humid air from flowing into the canister 52 and preventing water vapor from adhering to the canister 52.

[0041] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and modifications and the like are possible within the scope of the present invention. In the above-described embodiment, the case where humidity information is acquired by measurement using the humidity sensor 41 has been described, but this is not limited to this. For example, the vehicle 1 may be provided with a communication means and acquire humidity information from meteorological information via the communication means. [Explanation of symbols]

[0042] 1: Vehicle 10: Engine 11: Piston 12: Combustion chamber 13: Spark plug 14: Intake port 16: Exhaust port 20: Intake passage 21: Throttle valve 22: Surge tank 23: Fuel injector 30: Exhaust passage 31: Air-fuel ratio sensor 40: Fuel tank 41: Humidity sensor 50: Evaporative fuel treatment device 51: Vapor passage 52: Canister 54: Purge passage 55: Adjusting valve 60: Control device 61: Estimation unit 62: Purge control unit 63: Restriction unit

Claims

1. a canister that temporarily absorbs evaporated fuel; a purge passage for supplying purge gas containing evaporated fuel purged from the canister to an intake passage of the engine; an adjusting valve that adjusts the flow rate of purge gas supplied to the intake passage through the purge passage; An evaporative fuel control device for a vehicle, comprising: an acquisition means for acquiring humidity information of outside air; The control device The control device for fuel vapor, characterized in that the opening and closing of the regulating valve are controlled based on humidity information acquired by the acquiring means.

2. The control device an estimation means for estimating an amount of evaporated fuel adsorbed in the canister; purge control means for executing purge control to supply purge gas to the intake passage by opening the regulating valve when the amount of adsorption estimated by the estimating means is equal to or greater than a predetermined amount; 2. The control device for evaporated fuel as described in claim 1, further comprising a regulating means for regulating the purge control means not to perform purge control when the humidity acquired by the acquisition means is equal to or greater than a threshold value, regardless of the amount of adsorption estimated by the estimation means.

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