Control device for evaporated fuel

Abstract

The purpose is to prevent large amounts of water vapor from adhering to the canister's absorbent material. [Solution] The vehicle 1 of the present invention 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, and a control valve 55 that adjusts the flow rate of the purge gas supplied to the intake passage 20 through the purge passage 54. The evaporated fuel control device 60 prevents a large amount of water vapor from adhering to the adsorbent material of the canister 52 by controlling the opening and closing of the control valve 55 based on information on the humidity of the outside air and information on the cumulative flow rate of the purge gas.

Description

Technical Field

[0001] The present invention relates to a control device for evaporated fuel.

Background Art

[0002] Conventionally, an engine is known that adsorbs evaporated fuel generated in a fuel tank with a canister and supplies purge gas containing the evaporated fuel purged from the canister to an intake passage of the engine.

[0003] Patent Document 1 discloses an evaporated fuel treatment device including a canister having an adsorbent for adsorbing evaporated fuel, a vapor passage connecting the canister and the fuel tank, an atmosphere communication pipe provided in the canister and opened to the atmosphere, and a purge device that performs a purge process of supplying purge gas separated from the canister to an intake passage of an internal combustion engine. In such an evaporated fuel treatment device, when supplying purge gas to the intake passage of the internal combustion engine, outside air is introduced into the canister through the atmosphere communication pipe.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the evaporated fuel treatment device of Patent Document 1, when the humidity is high such as during 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 of the canister, the adsorption performance and desorption performance of the evaporated fuel of the canister may deteriorate.

[0006] This invention has been made in view of the above-mentioned problems, and aims to prevent a large amount of water vapor from adhering to the adsorbent material of a canister. [Means for solving the problem]

[0007] The present invention relates to a control device for evaporated fuel in a vehicle, comprising: a canister for temporarily adsorbing evaporated fuel; a purge passage for supplying purge gas containing evaporated fuel purged from the canister to the intake passage of an engine; and a control valve for adjusting the flow rate of the purge gas supplied to the intake passage through the purge passage, wherein the control device acquires information on the humidity of the outside air and information on the cumulative flow rate of the purge gas supplied to the intake passage, and controls the opening and closing of the control valve based on the acquired information on the humidity of the outside air and the cumulative flow rate of the purge gas. [Effects of the Invention]

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

[0009] [Figure 1] This figure shows a schematic configuration of a vehicle equipped with a control device for evaporative fuel. [Figure 2] This flowchart shows an example of processing by a control device. [Figure 3] This figure shows the change in adsorption amount according to the cumulative flow rate of the purge gas. [Figure 4] This diagram illustrates the cases where a threshold for the cumulative flow rate of purge gas is set and where it is not. [Figure 5] This is a timing chart showing an example of changes in each item. [Modes for carrying out the invention]

[0010] An embodiment of the present invention is a control device 60 for evaporated fuel in a vehicle 1, comprising a canister 52 for temporarily adsorbing evaporated fuel, a purge passage 54 for supplying purge gas containing evaporated fuel purged from the canister 52 to the intake passage 20 of the engine 10, and a control valve 55 for adjusting the flow rate of the purge gas supplied to the intake passage 20 through the purge passage 54. The control device 60 acquires information on the humidity of the outside air and information on the cumulative flow rate of the purge gas supplied to the intake passage 20, and prevents a large amount of water vapor from adhering to the adsorbent material of the canister 52 by controlling the opening and closing of the control valve 55 based on the acquired information on the humidity of the outside air and the cumulative flow rate of the purge gas. [Examples]

[0011] Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings. Figure 1 shows a schematic configuration of a vehicle 1 equipped with an evaporative fuel control device (hereinafter referred to as the control device) according to this embodiment. Note that Figure 1 is a simplified representation for the purpose of explaining this embodiment, and any configurations that a vehicle would normally have are assumed to be present even if they are not shown in the figure. 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] The engine 10 performs a series of strokes consisting of an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke. The engine 10 includes a combustion chamber 12 in which a piston 11 is reciprocally housed, a spark plug 13 located in the combustion chamber 12, an intake valve 15 located between the combustion chamber 12 and the intake port 14, an exhaust valve 17 located between the combustion chamber 12 and the exhaust port 16, and the like. The configuration of the engine 10 is not particularly limited, and various known engines can be applied.

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

[0014] The throttle valve 21 adjusts the flow rate of the intake air by opening and closing. The throttle valve 21 adjusts the flow rate of the intake air based on the control by the control device 60. The surge tank 22 temporarily stores the intake air and then guides it to the combustion chamber 12 after rectifying it. An intake pressure sensor 24 is disposed in the surge tank 22. The intake pressure sensor 24 transmits the detected intake pressure information to the control device 60. The fuel injector 23 injects the fuel pumped from the fuel tank 40 into the intake passage 20. The fuel injector 23 adjusts the fuel injection amount based on the control by 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 that exhausts the exhaust gas burned in the combustion chamber 12 to the outside of the vehicle 1 via the exhaust port 16. The exhaust passage 30 is constituted by, for example, an exhaust pipe. An air-fuel ratio sensor 31 is disposed in the exhaust passage 30. The air-fuel ratio sensor 31 transmits the detected air-fuel ratio information of the exhaust gas to the control device 60.

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

[0017] The vehicle 1 also includes an evaporative fuel processing device 50 for supplying evaporative fuel to the intake passage 20 without releasing it into the atmosphere. The evaporative fuel processing device 50 includes a vapor passage 51, a canister 52, a purge passage 54, a regulating valve 55, a purge gas flow rate sensor 56, and the like.

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

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

[0020] The atmosphere passage 53 is a passage that communicates with 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 atmosphere passage 53. On the other hand, when purge gas is not supplied to the intake passage 20 and evaporative fuel exceeding the adsorption capacity of the adsorbent in the canister 52 flows into the canister 52 from the fuel tank 40, the evaporative fuel in the canister 52 is released through the atmosphere passage 53. Note that a pressure regulating valve is arranged in the atmosphere passage 53. The pressure regulating valve opens when the pressure in the canister 52 becomes negative pressure to introduce outside air into the canister 52, and opens when the pressure in the canister 52 becomes a positive pressure of a predetermined value or more to release the air containing the evaporative fuel in 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, the first atmospheric passage is equipped with a first check valve that allows air to flow from the outside air into the canister 52 when the inside of the canister 52 becomes negative pressure, and prohibits air from flowing from the canister 52 to the outside air. On the other hand, the second atmospheric passage may be equipped with a second check valve that allows air to flow from the canister 52 to the outside air when the inside of the canister becomes positive pressure above a predetermined level, and prohibits air from flowing from the outside air to the canister 52.

[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 composed of piping that connects the canister 52 and the intake passage 20. Here, the purge passage 54 is configured to connect between the throttle valve 21 and the surge tank 22 in the intake passage 20, but it may also be configured to connect to the surge tank 22.

[0023] The control valve 55 adjusts the flow rate of purge gas supplied to the intake passage 20 through the purge passage 54. The control valve 55 is located in the middle of the purge passage 54. The control valve 55 adjusts the flow rate of purge gas based on control by the control device 60. The purge gas flow sensor 56 is located between the canister 52 and the control valve 55 in the purge passage 54. It detects the flow rate information of the purge gas supplied to the intake passage 20 through the purge passage 54 and transmits the detected purge gas flow rate information to the control device 60.

[0024] In the evaporative fuel treatment device 50, evaporated fuel generated in the fuel tank 40 is guided to the canister 52 via the vapor passage 51 and temporarily adsorbed by the canister 52. When the engine 10 starts, the intake passage 20 becomes negative pressure, so the control valve 55 is opened, and purge gas containing evaporated fuel purged from the canister 52 is supplied to the intake passage 20 via the purge passage 54. The purge gas supplied to the intake passage 20 mixes with the mixture of intake air taken in from the throttle valve 21 and fuel injected from the fuel injector 23 and flows into the combustion chamber 12. Therefore, since the evaporated fuel contained in the purge gas is burned in the combustion chamber 12, it is possible to prevent evaporated fuel from being released into the atmosphere from the fuel tank 40.

[0025] Furthermore, vehicle 1 is equipped with a control device 60. The control device 60 controls the entire vehicle 1. The control device 60 can be, for example, an ECU (Electronic Control Unit). The control device 60 has a hardware configuration that includes a CPU, ROM, RAM, etc. The ROM pre-stores programs and predetermined information for controlling the engine 10, the evaporative fuel treatment device 50, etc. RAM is a work memory that temporarily stores programs and data. The CPU reads the programs stored in the ROM, loads them into the RAM, and executes them to control the engine 10, the evaporative fuel treatment device 50, etc.

[0026] The control device 60 has a software configuration (functional configuration) that includes an acquisition unit 61, an estimation unit 62, a purge control unit 63, a setting unit 64, a regulation unit 65, and the like.

[0027] The acquisition unit 61 acquires various types of information. For example, the acquisition unit 61 acquires information by receiving information on the humidity of the outside air detected by the humidity sensor 41. The acquisition unit 61 also acquires information by calculating the integrated flow rate of the purge gas based on the flow rate information of the purge gas detected by the purge gas flow rate sensor 56.

[0028] The estimation unit 62 estimates the amount of evaporated fuel adsorbed onto the canister 52. In this embodiment, the estimation unit 62 estimates the amount of adsorption based on the vapor concentration of the purge gas supplied to the intake passage 20 by opening the control valve 55. Here, the vapor concentration is the ratio of evaporated fuel contained in the purge gas. The vapor concentration fluctuates depending on the amount of evaporated fuel adsorbed onto the canister 52 and also fluctuates depending on the environment of the vehicle 1. Therefore, the estimation unit 62 calculates the vapor concentration at each sampling time and estimates the amount of adsorption from the calculated vapor concentration.

[0029] Specifically, the estimation unit 62 controls the control valve 55 so that a constant amount of purge gas is supplied to the intake passage 20. Next, based on the air-fuel ratio information detected by the air-fuel ratio sensor 31, the estimation unit 62 controls the amount of fuel injected from the fuel injector 23 so that the air-fuel ratio becomes the target air-fuel ratio (for example, the stoichiometric air-fuel ratio). At this time, the air-fuel 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 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) 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 62 calculates the vapor concentration (the ratio of evaporated fuel contained in the purge gas) based on the information of the difference between the actual air-fuel ratio and the target air-fuel ratio. The estimation unit 62 refers to a table that associates vapor concentration and adsorption amount and estimates the amount of adsorbed evaporated fuel from the calculated concentration. The table associates larger adsorption amounts with increasing vapor concentrations. The table is stored in the control device 60.

[0030] The purge control unit 63 opens the control valve 55 and supplies 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. Furthermore, when the purge control unit 63 performs purge control, it corrects the injection amount when injecting fuel from the fuel injector 23 so that the actual air-fuel ratio becomes the target air-fuel ratio, based on the purge concentration calculated by the estimation unit 62. Specifically, the purge control unit 63 calculates and obtains the amount of evaporated fuel contained in the purge gas from the flow rate information of the purge gas detected by the purge gas flow rate sensor 56 and the vapor concentration calculated by the estimation unit 62. Next, the purge control unit 63 performs correction control by subtracting the calculated amount of evaporated fuel (fuel amount) from the injection amount that needs to be injected from the fuel injector 23 according to the amount of operation of the accelerator pedal detected by the accelerator opening sensor 42. 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.

[0031] The setting unit 64 sets a threshold for the cumulative flow rate of the purge gas based on the humidity of the outside air. The setting unit 64 sets the threshold for the cumulative flow rate of the purge gas when the humidity of the outside air is above a predetermined value, and does not set the threshold for the cumulative flow rate of the purge gas when the humidity of the outside air is below the predetermined value. Details of how the setting unit 64 sets the threshold will be described later.

[0032] The regulating unit 65 restricts the execution of purge control by turning on the purge permission condition flag when it is to execute purge control, and turning off the purge permission condition flag when it is not to execute purge control. The regulating unit 65 determines whether to turn on or off the purge permission condition flag based on information such as the humidity of the outside air and the cumulative flow rate of the purge gas acquired by the acquisition unit 61.

[0033] In the vehicle 1 configured in this way, the control device 60 of this embodiment acquires information on the humidity of the outside air and information on the cumulative flow rate of the purge gas supplied to the intake passage 20 in order to prevent a large amount of water vapor from adhering to the adsorbent material of the canister 52, and controls the opening and closing of the control valve 55 based on the acquired information on the humidity of the outside air and the cumulative flow rate of the purge gas. An example of the processing by the control device 60 will be described below with reference to the flowchart in Figure 2. The flowchart in Figure 2 starts when the engine 10 is started.

[0034] In S11, the estimation unit 62 estimates the amount of evaporated fuel adsorbed onto the canister 52. Specifically, as described above, the estimation unit 62 estimates the amount of adsorption based on the vapor concentration of the purge gas supplied to the intake passage 20 when the control valve 55 opens.

[0035] In S12, the acquisition unit 61 acquires information by receiving humidity information transmitted from the humidity sensor 41. The acquisition unit 61 also acquires information by calculating the cumulative flow rate of the purge gas based on the flow rate information of the purge gas detected by the purge gas flow rate sensor 56.

[0036] In S13, the purge control unit 63 determines whether the estimated amount of evaporated fuel adsorbed on the canister 52 is equal to or greater than a predetermined amount. Here, a predetermined amount of information is stored in the control device 60 in advance. If the amount of adsorption is greater than or equal to a predetermined amount, the process proceeds to S15. On the other hand, if the amount of adsorption is less than a predetermined amount, the process proceeds to S22, where the regulating unit 65 turns off the purge permission condition flag, thereby preventing the purge control unit 63 from executing purge control. In this way, when the amount of adsorption is less than a predetermined amount, there is no need to purge the evaporated fuel from the canister 52, so the purge permission condition flag is turned off.

[0037] In S15, the regulating unit 65 determines whether the humidity of the outside air is below a predetermined value. Here, the information of the predetermined value is stored in the control device 60 in advance. The predetermined value differs depending on the type of canister installed in the vehicle 1, and is set to a humidity level such that the amount of adsorption by the canister 52 does not change even if the cumulative flow rate of the purge gas increases. This predetermined value will be described later with reference to Figure 3. If the humidity is below the predetermined value, the process proceeds to S16.

[0038] In S16, the regulatory unit 65 turns on the flag for the purge permission condition. In S17, the purge control unit 63, seeing that the purge permission condition flag is on, opens the control valve 55 and executes purge control to supply purge gas to the intake passage 20. Also, as described above, the purge control unit 63 performs correction control to correct the injection amount when injecting fuel from the fuel injector 23 so that the actual air-fuel ratio becomes the target air-fuel ratio, based on the purge concentration estimated by the estimation unit 62.

[0039] On the other hand, if it is determined in S15 that the humidity of the outside air is above a predetermined value, the process proceeds to S18. In S18, the setting unit 64 sets a threshold for the cumulative flow rate of the purge gas based on the humidity of the outside air. Figure 3 shows the change in adsorption amount (adsorption characteristic curve) for each humidity level, corresponding to the cumulative flow rate of the purge gas. Here, the vertical axis represents the adsorption amount of the canister, and the horizontal axis represents the cumulative flow rate of the purge gas. The adsorption characteristic curve shown in Figure 3 can be obtained through experimentation or simulation.

[0040] The adsorption characteristic curve for an outside air humidity of 25% shows that as the cumulative flow rate of the purge gas increases by performing purge control, the amount of adsorption on the canister gradually decreases. In other words, when the outside air humidity is low, even if air flows into the canister 52 through the atmospheric passage 53, water vapor is not adsorbed on the canister 52, so the amount of adsorption does not increase. The adsorption characteristic curve for outside air with 50% humidity shows that as the cumulative flow rate of the purge gas increases due to purge control, the adsorption amount on the canister decreases, but then remains almost unchanged. The adsorption characteristic curves for outside air humidity at 60% and 75% show that as the cumulative flow rate of the purge gas increases due to purge control, the adsorption amount on the canister decreases, but then increases again. In other words, when the outside air humidity is high, when air flows into the canister 52 through the atmospheric passage 53, water vapor is adsorbed by the canister 52, increasing the adsorption amount.

[0041] Furthermore, in Figure 3, the adsorption amount Amax represents the maximum adsorption amount at the limit of the canister's adsorption capacity. Adsorption amount Aset represents the lower limit of adsorption amount corresponding to the minimum adsorption amount required by the canister. Adsorption amount Aset is a value set by the vehicle manufacturer, etc. In Figure 3, an example is shown where adsorption amount Aset is 55% of adsorption amount Amax, but it is preferable that it be any value within the range of 50% to 90%, for example.

[0042] Here, in the case of an outside air humidity of 60%, the integrated flow rate of the purge gas Th corresponds to the intersection of the adsorption characteristic curve for 60% humidity and the adsorption amount Aset. 60 This will be the threshold set in S18. Furthermore, in the case of an outside air humidity of 75%, the integrated flow rate of the purge gas Th corresponds to the intersection of the adsorption characteristic curve for 75% humidity and the adsorption amount Aset. 75 This will be the threshold set in S18.

[0043] On the other hand, when the ambient humidity is 50%, the adsorption amount characteristic curve for 50% humidity does not intersect with the adsorption amount Aset because the adsorption amount does not change according to the cumulative flow rate of the purge gas. Therefore, no threshold is set. The humidity of the adsorption amount characteristic curve where the adsorption amount does not change according to the cumulative flow rate of the purge gas is set to the predetermined value in S15. Note that the humidity when the adsorption amount does not change according to the cumulative flow rate differs depending on the type of canister installed in vehicle 1. Furthermore, in the case of an outside air humidity of 25%, the adsorption characteristic curve for 25% humidity does not intersect with the adsorption amount Aset because the adsorption amount decreases in proportion to the cumulative flow rate of the purge gas, and therefore no threshold is set.

[0044] Figure 4 illustrates the cases where a threshold for the cumulative flow rate of purge gas is not set and where a threshold for the cumulative flow rate of purge gas is set, with a predetermined humidity value as the boundary. Here, as explained in Figure 3, if the humidity of the outside air is 50% or less, which is the predetermined value set in S15, the purge permission condition flag is turned on regardless of the cumulative flow rate of purge gas. On the other hand, if the humidity of the outside air is higher than 50%, which is the predetermined value set in S15, a threshold for the cumulative flow rate of purge gas is set according to the humidity. As will be described later, if the cumulative flow rate of purge gas is less than the threshold, the purge permission condition flag is turned on, and if the cumulative flow rate of purge gas is equal to or greater than the threshold, the purge permission condition flag is turned off.

[0045] In Figure 4, plot P 60 This shows the threshold for the cumulative flow rate of purge gas at 60% humidity, plot P 75 The graph shows the threshold values ​​for the cumulative flow rate of the purge gas at 75% humidity. These threshold values ​​are derived from the adsorption characteristic curves for 60% and 75% humidity shown in Figure 3. As shown in Figure 4, by plotting and connecting the threshold values ​​for the cumulative flow rate of the purge gas for each humidity level, it is possible to derive the threshold values ​​for the cumulative flow rate of the purge gas corresponding to humidity levels above 50%. These humidity-dependent threshold values ​​for the cumulative flow rate of the purge gas are pre-stored in the control device 60. Note that the adsorption characteristic curves for each humidity level shown in Figure 3 and the threshold values ​​for the cumulative flow rate of the purge gas for each humidity level shown in Figure 4 are examples only. The adsorption characteristic curves will differ depending on the type of canister installed, and the threshold values ​​for the cumulative flow rate of the purge gas set for each humidity level will also change.

[0046] Returning to the flowchart in Figure 2, in S18 the threshold for the cumulative flow rate of the purge gas is set based on the humidity of the outside air, and then the process proceeds to S19. In S19, the regulatory unit 65 turns on the flag for the purge permission condition. In S20, the purge control unit 63, seeing that the purge permission condition flag is on, opens the control valve 55 and performs purge control to supply purge gas to the intake passage 20. Also, as described above, the purge control unit 63 performs correction control to correct the injection amount when injecting fuel from the fuel injector 23 so that the actual air-fuel ratio becomes the target air-fuel ratio, based on the purge concentration estimated by the estimation unit 62.

[0047] In S21, the regulating unit 65 determines whether the cumulative flow rate of the purge gas has exceeded a threshold. If the cumulative flow rate of the purge gas is not above the threshold, the process returns to S19. Therefore, the purge control unit 63 continues to perform purge control. On the other hand, if the cumulative flow rate of the purge gas is above the threshold, the process proceeds to S22.

[0048] In S22, the regulatory unit 65 turns off the flag for the purge permission condition. By turning off the flag for the purge permission condition, the regulatory unit 65 prevents the purge control unit 63 from executing purge control. In this way, if the cumulative flow rate of the purge gas is above the threshold, the amount of adsorption by the canister 52 is at the lower limit adsorption amount Aset, so the flag for the purge permission condition is turned off to prevent the canister 52 from adsorbing water vapor. After processing S17 and S22, the process returns to S11 and continues until engine 10 is no longer running.

[0049] Figure 5 is a timing chart showing an example of changes in adsorption amount, humidity, cumulative flow rate of purge gas, and purge permission condition flag. Figure 5(a) shows the change in the amount of evaporated fuel adsorbed on the canister, Figure 5(b) shows the change in humidity, Figure 5(c) shows the change in cumulative flow rate of purge gas, and Figure 5(d) shows the change in purge permission condition flag.

[0050] First, during the period from time T1 to time T2, the amount of adsorption on the canister is above a predetermined amount, as shown in Figure 5(a), and the humidity is below a predetermined value, as shown in Figure 5(b). Therefore, as shown in Figure 5(d), the purge permission condition flag is turned on, and purge control is being executed. On the other hand, from time T2 onward, as shown in Figure 5(b), the humidity exceeds a predetermined value, and a threshold for the cumulative flow rate of the purge gas is set, as shown in Figure 5(c) (see the dashed line in Figure 5(c)). Note that the threshold for the cumulative flow rate of the purge gas changes depending on the humidity. At time T3, as shown in Figure 5(c), the cumulative flow rate of the purge gas exceeds a threshold, causing the purge permission condition flag to switch from on to off, as shown in Figure 5(d). This restricts the execution of purge control, preventing water vapor from adhering to the canister 52.

[0051] As described above, according to this embodiment, the control device 60 acquires information on the humidity of the outside air and information on the cumulative flow rate of the purge gas supplied to the intake passage 20, and controls the opening and closing of the control valve 55 based on the acquired information on the humidity of the outside air and the cumulative flow rate of the purge gas. Therefore, even when humid air flows into the canister 52, the control device can open and close the control valve 55 based on the cumulative flow rate of the purge gas, thereby preventing a large amount of water vapor from adhering to the adsorbent material of the canister 52.

[0052] Furthermore, according to this embodiment, the control device 60 includes a setting unit 64 that sets a threshold for the cumulative flow rate of the purge gas based on information about the humidity of the outside air, and a regulating unit 65 that restricts the purge control unit 63 from executing purge control when the cumulative flow rate of the purge gas exceeds the threshold. In this way, by setting a threshold for the cumulative flow rate of the purge gas according to the humidity, the period during which purge control is executed can be extended by executing purge control until the cumulative flow rate of the purge gas exceeds the threshold.

[0053] Furthermore, according to this embodiment, the setting unit 64 sets a threshold based on the information of the outside air humidity when the outside air humidity is above a predetermined value. In other words, when the outside air humidity is below a predetermined value, the threshold is not set and purge control is executed, thereby ensuring a longer period for which purge control is performed.

[0054] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and modifications can be made within the scope of the present invention. In the embodiments described above, the case in which humidity information is obtained by detection by the humidity sensor 41 was explained, but the invention is not limited to this case. For example, the vehicle 1 may be equipped with communication means, and the acquisition unit 61 may acquire humidity information from weather information via the communication means. In the embodiment described above, the case in which information on the cumulative flow rate of purge gas is obtained based on the flow rate information of the purge gas from the purge gas flow sensor 56 was explained, but it is not limited to this case. For example, the acquisition unit 61 may estimate the flow rate of purge gas based on the opening degree of the control valve 55, and calculate and acquire information on the cumulative flow rate of purge gas based on the estimated flow rate of purge gas. [Explanation of Symbols]

[0055] 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: Control valve 56: Purge gas flow sensor 60: Control device 61: Acquisition unit 62: Estimation unit 63: Purge control unit 64: Setting unit 65: Regulation unit

Claims

1. A canister that temporarily adsorbs evaporated fuel, A purge passage that supplies purge gas containing evaporated fuel purged from the canister to the engine's intake passage, A control device for evaporated fuel in a vehicle, comprising: an adjustment valve for adjusting the flow rate of purge gas supplied to the intake passage through the purge passage; The control device is A control device for evaporative fuel, characterized by acquiring information on the humidity of the outside air and information on the cumulative flow rate of the purge gas supplied to the intake passage, and controlling the opening and closing of the control valve based on the acquired information on the humidity of the outside air and the cumulative flow rate of the purge gas.

2. The control device is Estimation means for estimating the amount of evaporated fuel adsorbed on the canister, A purge control means that, when the amount of adsorption estimated by the estimation means is equal to or greater than a predetermined amount, opens the control valve and performs purge control to supply purge gas to the intake passage, A setting means for setting a threshold for the cumulative flow rate of purge gas based on the humidity information of the outside air, The control device for evaporated fuel according to claim 1, further comprising a restricting means for restricting the purge control means from performing purge control when the cumulative flow rate of the purge gas exceeds the threshold.

3. The setting means is, The control device for evaporating fuel according to claim 2, characterized in that when the humidity of the outside air is above a predetermined value, the threshold is set based on the information of the humidity of the outside air.

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