A vehicle high-pressure tank refueling and venting active control system and method

Abstract

The application discloses a kind of automobile high-pressure oil tank refueling discharge active control system and method, including main carbon canister, auxiliary carbon canister, three-way electromagnetic valve, electronic gravimeter, vacuum pump, high-pressure oil tank, engine, automobile controller (ECU);Before automobile refueling, ECU will calculate its remaining working ability based on the weight of main carbon canister, calculate the working ability required for main carbon canister based on the amount of oil gas generated;According to the remaining working ability and required working ability of main carbon canister, ECU takes different control strategies;If ECU determines that the remaining working ability of main carbon canister is insufficient, will send instruction to vacuum pump, and vacuum pump will quantitatively desorb oil gas in main carbon canister to auxiliary carbon canister;After completing refueling, auxiliary carbon canister is quantitatively desorbed during engine operation, and auxiliary carbon canister will share the oil gas generated during non-refueling period before the next refueling has sufficient remaining working ability.The present application makes full use of carbon canister working ability, realizes refueling discharge active control function, effectively solves the problem of automobile high-pressure oil tank refueling discharge.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of automobile emission control, and particularly relates to an automobile high-pressure fuel tank refueling emission active control system and method. BACKGROUND

[0002] Gasoline is a mixed fuel composed of various hydrocarbons and has strong volatility. Automobile evaporative emission mainly refers to the emission generated by fuel evaporation. Generally, vehicles use carbon canister adsorption / desorption technology to control fuel evaporation emission. The carbon canister adsorbs gasoline vapor discharged from the fuel tank, and then the engine provides a desorption flow to desorb the adsorbate into the combustion chamber to participate in combustion. With the continuous tightening of emission regulations, in recent years, many automobile manufacturers have adopted high-pressure fuel tanks to control evaporative emission. Gasoline vapor is stored in the high-pressure fuel tank, which means that the carbon canister mostly works only during the refueling stage of the automobile. The popularity of high-pressure fuel tanks makes refueling emission likely to become the main source of automobile evaporative emission in the future. Whether during the pressure relief process of the high-pressure fuel tank or the refueling process, there will be a violent movement of oil gas molecules, and a large amount of gasoline vapor will enter the carbon canister in a short time, so the carbon canister is easily broken. Reducing the refueling emission of the automobile high-pressure fuel tank is a technical problem that needs to be solved urgently at present.

[0003] The existing patents CN115182830A and CN117571334A respectively propose methods for controlling refueling emission from the aspects of desorption efficiency and structural design, which can reduce the refueling emission of the automobile to a certain extent, but cannot achieve efficient adsorption of refueling emission every time. The existing patent CN105802492B proposes a vehicle-mounted oil gas control device and method applied to a hybrid electric vehicle, in which refueling emission is adsorbed by a first carbon canister, other evaporative emission is adsorbed by a second carbon canister, and the first carbon canister is preferentially desorbed during engine operation. This method can effectively control refueling emission, but lacks active control function and wastes the effective working capacity of the carbon canister. At present, there is a lack of an active control system for the refueling emission of the automobile high-pressure fuel tank, and it is of great significance to propose an efficient control method for reducing the carbon emission of the vehicle. SUMMARY

[0004] The present application provides an automobile high-pressure fuel tank refueling emission active control system and method, which realizes the active control function of refueling emission under the premise of fully utilizing the working capacity of the carbon canister and effectively solves the problem of refueling emission of the automobile high-pressure fuel system.

[0005] Technical scheme: An automobile high-pressure fuel tank refueling emission active control system, comprising a high-pressure fuel tank system, an oil vapor recovery system, an engine system, a control system and a power supply, wherein the high-pressure fuel tank system is connected to the oil vapor recovery system through a pressure relief pipeline, the oil vapor recovery system is connected to the engine system through a desorption pipeline, and the control system is signal-connected with the high-pressure fuel tank system, the oil vapor recovery system and the engine system.

[0006] The high-pressure oil tank system comprises a high-pressure oil tank, an oil quantity sensor arranged in the high-pressure oil tank, a pressure sensor arranged at the top of the high-pressure oil tank, a refueling electronic button and a refueling locking device arranged at the refueling port of the high-pressure oil tank, and a pressure relief valve arranged on the pressure relief pipeline.

[0007] The engine system comprises an engine, a desorption electromagnetic valve arranged on a desorption pipeline, a flow sensor, and an intake manifold.

[0008] In the oil gas recovery system, the desorption port of the main carbon tank, the suction port of the desorption pump, and the second three-way electromagnetic valve are connected through the first three-way electromagnetic valve, the exhaust port of the desorption pump is connected with the adsorption port of the auxiliary carbon tank, the desorption port of the auxiliary carbon tank, the first three-way electromagnetic valve, and the intake manifold are connected through the second three-way electromagnetic valve, the main carbon tank and the auxiliary carbon tank are respectively placed on the first electronic weight instrument and the second electronic weight instrument, and the volume of the auxiliary carbon tank is smaller than that of the main carbon tank.

[0009] The control system comprises an automobile controller ECU and a power supply; the ECU is in signal connection with the desorption pump, the first electronic weight instrument, the second electronic weight instrument, the pressure sensor, the oil quantity sensor, the refueling electronic button, the refueling locking device, the desorption electromagnetic valve, the first three-way electromagnetic valve, the second three-way electromagnetic valve, and the pressure relief valve, and the ECU and the desorption pump are powered by the power supply.

[0010] An automobile high-pressure oil tank refueling and discharging active control method, specifically comprising the following steps:

[0011] S1, determining refueling information: the ECU receives the triggering information of the refueling electronic button and determines that the automobile is about to be refueled;

[0012] S2, calculating the remaining working capacity of the main carbon tank: according to the weight of the main carbon tank, the ECU calculates the remaining working capacity W Remaining of the main carbon tank;

[0013] S3, calculating the required working capacity of the main carbon tank: according to the amount of oil gas generated during refueling, the ECU calculates the required working capacity W Need of the main carbon tank;

[0014] S4, refueling and discharging control: according to the remaining working capacity W Remaining and the required working capacity W Need of the main carbon tank, the ECU adopts a corresponding control strategy;

[0015] S5, before the next refueling: if the weight of the auxiliary carbon tank changes, the auxiliary carbon tank will be quantitatively desorbed during the operation of the engine before the next refueling;

[0016] The S2 specifically comprises: W Remaining (g) is calculated by the following method:

[0017]

[0018] M initial (g) is the weight of the carbon canister when it has not adsorbed any fuel vapor, M max (g) is the maximum mass of fuel vapor that the carbon canister can adsorb; M now K is a mass conversion coefficient.

[0019] The S3 is specifically:

[0020] The fuel vapor generation amount is the sum of the relief vapor amount and the fuel vapor generation amount during refueling, the relief vapor amount M Drain and the fuel vapor generation amount M Refueling are respectively calculated by the ideal gas equation and an empirical coefficient;

[0021] The relief vapor amount is:

[0022]

[0023] k is the fuel molar flux, P is the high-pressure tank pressure, R is the molar gas constant, T is the temperature, h is the height from the fuel surface to the top of the tank, P s is the fuel surface partial pressure, and t is the relief time;

[0024] The fuel vapor generation amount during refueling is taken as an empirical coefficient of 1 g / L, i.e., 1 L of fuel generates 1 g of fuel vapor, and the fuel filling amount is taken as a maximum value V max (L), i.e., the maximum volume of the high-pressure tank minus the current fuel volume;

[0025] M Refueling = V max * 1

[0026] Subsequently, the ECU calculates the required working capacity of the main carbon canister according to the fuel vapor generation amount;

[0027] The required working capacity of the main carbon canister is:

[0028]

[0029] is the relief vapor amount; is the fuel filling amount, multiplied by the empirical coefficient 1 (g / L), i.e., the fuel vapor generation amount during refueling; ) is the fuel vapor generation amount; multiplied by the mass conversion coefficient K, i.e., the required working capacity of the main carbon canister.

[0030] The S4 is specifically:

[0031] According to the remaining working capacity W Remainingand the required work capacity W Need The ECU control strategy is divided into two cases,

[0032] When W Need W Remaining , the pressure relief valve opens the pressure relief, and the refueling locking device is unlocked after pressure relief, allowing the start of refueling;

[0033] When W Need > W Remaining , the ECU sends a timed desorption command to the desorption pump, and the desorption pump desorbs at a constant speed, and the desorption time is W Need The difference between W Remaining and the ratio of the desorption speed, and the refueling locking device is normally closed during this process, and the pressure relief valve opens the pressure relief after desorption is completed, and the refueling locking device is unlocked after pressure relief, allowing the start of refueling;

[0034] The S5 is specifically:

[0035] If the auxiliary carbon tank weight changes during this refueling process, the ECU calculates the required desorption amount of the auxiliary carbon tank, and the engine will desorb the auxiliary carbon tank quantitatively during operation, and the actual desorption amount is calculated by the flow sensor; After desorption is completed, if the ECU determines that the main carbon tank has no remaining work capacity before the next refueling, the desorption pump will be instructed to desorb the main carbon tank quantitatively, and the remaining work capacity of the auxiliary carbon tank is less than 1 / 2, and the desorption is stopped.

[0036] Beneficial effects: The present application proposes a kind of automobile high-pressure tank refueling emission active control system and method, including main carbon tank, auxiliary carbon tank, three-way electromagnetic valve, electronic weight instrument, desorption pump, high-pressure tank, engine, automobile controller (ECU);Before automobile refueling, ECU will calculate the remaining work capacity of main carbon tank based on the weight of main carbon tank, and calculate the required work capacity of main carbon tank based on the amount of refueling gas generated;According to the remaining work capacity and the required work capacity of main carbon tank, ECU takes different control strategies;If ECU determines that the remaining work capacity of main carbon tank is insufficient, it will send instructions to the desorption pump, and the desorption pump will quantitatively desorb the oil and gas in the main carbon tank to the auxiliary carbon tank;After completing refueling, auxiliary carbon tank is quantitatively desorbed during engine operation, and under the premise of ensuring sufficient remaining work capacity for the next refueling, auxiliary carbon tank will share the oil and gas generated during non-refueling period.The present application realizes the function of refueling emission active control under the premise of fully utilizing the work capacity of carbon tank, effectively solves the problem of automobile high-pressure tank refueling emission. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings described below only represent a part of the embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort based on the drawings provided.

[0038] Fig. 1 The structure diagram of the automobile high-pressure oil tank refueling emission active control system is described in the present application.

[0039] Fig. 2 The refueling emission control strategy flow chart when refueling is described in the present application.

[0040] Fig. 3 The system control strategy flow chart before the next refueling is described in the present application. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments only represent a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort belong to the scope of protection of the present application.

[0042] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0043] In the present application, unless otherwise explicitly specified and limited, "on" or "under" of the first feature to the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "on", "above" and "above" of the first feature to the second feature include that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. "Below", "below" and "below" of the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0044] As Figs. 1 to 3As shown, a kind of automobile high-pressure oil tank refueling discharge active control system, including high-pressure oil tank system, oil gas recovery system, engine system, control system and power supply, the high-pressure oil tank system is connected oil gas recovery system by pressure relief pipeline, the oil gas recovery system is connected engine system by desorption pipeline, the control system is connected with high-pressure oil tank system, oil gas recovery system, engine system signal;

[0045] The high-pressure oil tank system includes high-pressure oil tank 1, oil level sensor 2 is provided in the high-pressure oil tank 1, pressure sensor 3 is provided at the top of the high-pressure oil tank 1, oil filling electronic button 5 and oil filling locking device 6 are provided at the oil filling port of the high-pressure oil tank 1, pressure relief valve 18 is provided on the pressure relief pipeline;

[0046] The engine system includes engine 7, desorption electromagnetic valve 8 arranged in desorption pipeline, flow sensor 9 and intake manifold 10;

[0047] In the oil gas recovery system, the desorption port of main carbon canister 17, the suction port of desorption pump 15, the second three-way electromagnetic valve 11 are connected by the first three-way electromagnetic valve 19, the gas outlet of the desorption pump 15 is connected with the adsorption port of auxiliary carbon canister 13, the desorption port of auxiliary carbon canister 13, the first three-way electromagnetic valve 19, the intake manifold 10 are connected by the second three-way electromagnetic valve 11, the main carbon canister 17 and the auxiliary carbon canister 13 are placed on the first electronic weight instrument 16 and the second electronic weight instrument 12 respectively, and the volume of the auxiliary carbon canister 13 is less than that of the main carbon canister 17.

[0048] The control system includes automobile controller ECU 4 and power supply 14;The ECU 4 is connected with desorption pump 15, first electronic weight instrument 16, second electronic weight instrument 12, pressure sensor 3, oil level sensor 2, oil filling electronic button 5, oil filling locking device 6, desorption electromagnetic valve 8, first three-way electromagnetic valve 19, second three-way electromagnetic valve 11 and pressure relief valve 18 signal, and the ECU 4 and desorption pump 15 are powered by power supply 14.

[0049] An automobile high-pressure oil tank refueling discharge active control method, specifically comprising the following steps:

[0050] S1, determine refueling information: ECU 4 receives the trigger information of oil filling electronic button 5, and judges that the automobile is about to be refueled;

[0051] S2, main carbon canister remaining working capacity calculation: according to the weight of main carbon canister 17, ECU 4 calculates the remaining working capacity W Remaining Of main carbon canister 17;

[0052] S3, main carbon canister required working capacity calculation: according to the amount of oil gas generated by refueling, ECU 4 calculates the required working capacity W Need Of main carbon canister 17;

[0053] S4, fueling emission control: according to the remaining working capacity W of the main carbon canister 17 Remaining and the required working capacity W Need , the ECU 4 takes the corresponding control strategy;

[0054] S5, before the next fueling: if the auxiliary carbon canister 13 has a weight change, before the next fueling, the engine 7 will quantitatively desorb the auxiliary carbon canister 13 during operation;

[0055] The S2 is specifically: W Remaining g calculation method is:

[0056]

[0057] M initial g is the weight of the carbon canister when it does not adsorb any oil gas, M max g is the maximum fueling oil gas mass that the carbon canister can adsorb; M now is the current main carbon canister weight, and K is the mass conversion coefficient.

[0058] The S3 is specifically:

[0059] The fueling oil gas generation amount is the sum of the pressure relief oil gas amount and the fueling process oil gas generation amount, the pressure relief oil gas amount M Drain and the fueling process oil gas generation amount M Refueling are calculated by the ideal gas equation and empirical coefficients, respectively;

[0060] The pressure relief oil gas amount is:

[0061]

[0062] k is the fuel molar flux, P is the high-pressure tank pressure, is the molar gas constant, T is the temperature, h is the height from the fuel surface to the top of the tank, P s is the fuel surface partial pressure, and t is the pressure relief time;

[0063] The fueling process oil gas generation amount takes an empirical coefficient of 1 g / L, that is, 1 L of fuel generates 1 g of oil gas, and the fuel filling amount takes the maximum value V max (L), that is, the maximum volume of the high-pressure tank 1 minus the current fuel volume;

[0064] M Refueling =V max *1

[0065] Subsequently, the ECU 4 calculates the required working capacity of the main carbon canister 17 according to the fueling oil gas generation amount;

[0066] The required working capacity of the main carbon canister is:

[0067]

[0068] is the relief gas amount; is the refueling amount, multiplied by the empirical coefficient 1g / L, which is the gas amount generated during refueling; is the refueling gas amount; multiplied by the mass conversion coefficient K, which is the required working capacity of the main carbon tank.

[0069] The S4 is specifically:

[0070] According to the remaining working capacity W Remaining and the required working capacity W Need of the main carbon tank 17, the ECU 4 control strategy is divided into two cases,

[0071] When W Need W Remaining , the relief valve 18 opens to relieve pressure, and after relieving pressure, the refueling locking device 6 is unlocked to allow refueling to start;

[0072] When W Need > W Remaining , the ECU 4 sends a timed desorption command to the desorption pump 15, and the desorption pump 15 desorbs at a constant speed. The desorption time is the difference between W Need and W Remaining , and the ratio of the desorption speed. During this process, the refueling locking device 6 is normally closed, and after desorption is complete, the relief valve 18 opens to relieve pressure, and after relieving pressure, the refueling locking device 6 is unlocked to allow refueling to start;

[0073] The S5 is specifically:

[0074] If the weight of the auxiliary carbon tank 13 changes during this refueling process, the ECU 4 calculates the required desorption amount of the auxiliary carbon tank 13, and the engine 7 will desorb the auxiliary carbon tank 13 quantitatively during operation. The actual desorption amount is calculated by the flow sensor 9. After desorption is complete, if the ECU 4 determines that the main carbon tank 17 has no remaining working capacity before the next refueling, it will instruct the desorption pump 15 to desorb the main carbon tank 17 quantitatively, and if the remaining working capacity of the auxiliary carbon tank 13 is less than 1 / 2, desorption will be stopped.

[0075] In the present specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between each embodiment can be referred to each other. For the device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method part.

[0076] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An active control system for refueling and discharging fuel from a high-pressure fuel tank in automobiles, characterized in that, It includes a high-pressure fuel tank system, an oil vapor recovery system, an engine system, a control system, and a power supply. The high-pressure fuel tank system is connected to the oil vapor recovery system through a pressure relief pipeline. The oil vapor recovery system is connected to the engine system through a desorption pipeline. The control system is signal-connected to the high-pressure fuel tank system, the oil vapor recovery system, and the engine system. The high-pressure oil tank system includes a high-pressure oil tank (1), an oil quantity sensor (2) is installed inside the high-pressure oil tank (1), a pressure sensor (3) is installed on the top of the high-pressure oil tank (1), an electronic refueling button (5) and a refueling locking device (6) are installed at the refueling port of the high-pressure oil tank (1), and a pressure relief valve (18) is installed on the pressure relief pipeline. The engine system includes an engine (7), a desorption solenoid valve (8) installed in the desorption line, a flow sensor (9), and an intake manifold (10). In the oil and gas recovery system, the desorption port of the main carbon canister (17), the intake port of the desorption pump (15), and the second three-way solenoid valve (11) are connected through the first three-way solenoid valve (19). The outlet of the desorption pump (15) is connected to the adsorption port of the auxiliary carbon canister (13). The desorption port of the auxiliary carbon canister (13), the first three-way solenoid valve (19), and the intake manifold (10) are connected through the second three-way solenoid valve (11). The main carbon canister (17) and the auxiliary carbon canister (13) are placed on the first electronic weighing instrument (16) and the second electronic weighing instrument (12), respectively. The volume of the auxiliary carbon canister (13) is smaller than the volume of the main carbon canister (17). The control system includes an ECU (4) and a power supply (14); the ECU (4) is connected to the desorption pump (15), the first electronic weight (16), the second electronic weight (12), the pressure sensor (3), the oil level sensor (2), the refueling electronic button (5), the refueling lock device (6), the desorption solenoid valve (8), the first three-way solenoid valve (19), the second three-way solenoid valve (11), and the pressure relief valve (18). The ECU (4) and the desorption pump (15) are powered by the power supply (14).

2. A method for active control of refueling and venting from a high-pressure fuel tank in automobiles, characterized in that, The active control system for refueling and venting of high-pressure fuel tanks in automobiles, as described in claim 1, specifically includes the following steps: S1. Determine refueling information: The ECU (4) receives the refueling electronic button (5) trigger information and determines that the car is about to be refueled; S2. Calculation of remaining working capacity of main charcoal canister: Based on the weight of main charcoal canister (17), ECU (4) calculates the remaining working capacity W of main charcoal canister (17). Remaining ; S3. Calculation of the required working capacity of the main charcoal canister: Based on the amount of fuel vapor generated during refueling, ECU (4) calculates the required working capacity W of the main charcoal canister (17). Need ; S4. Fueling emission control: Based on the remaining working capacity W of the main charcoal canister (17). Remaining and required work skills W Need The ECU (4) adopts the corresponding control strategy; S5. Before the next refueling: If there is a weight change in the auxiliary carbon canister (13), the engine (7) will desorb a certain amount of the auxiliary carbon canister (13) during operation before the next refueling. Specifically, S2 is: W Remaining The unit is g, and the calculation method is as follows: ， M initial The weight of the charcoal canister before it absorbs any oil or gas is in grams; M max The maximum mass of refueling vapor that the charcoal canister can absorb, in grams; M now The current weight of the main carbon canister is obtained via an electronic weighing instrument, and K is the mass conversion factor. Specifically, S3 is: The amount of vapor generated during refueling is the sum of the vapor generated during depressurization and the vapor generated during the refueling process, where the vapor generated during depressurization is M. Drain And the amount of oil and gas generated during the refueling process, M Refueling The equations were derived from the ideal gas equation and the empirical coefficients were calculated, respectively. The amount of oil and gas released is: ， k is the fuel molar flux, and P is the high-pressure fuel tank pressure. Let P be the molar gas constant, T be the temperature, h be the height from the fuel surface to the top of the fuel tank, and P be the temperature. s The pressure is the partial pressure on the fuel surface, and t is the pressure relief time. The amount of fuel vapor produced during refueling is taken as an empirical coefficient of 1g / L, that is, 1g of fuel vapor is produced for every 1L of fuel added, and the maximum amount of fuel added is taken as V. max The unit is L, which is the maximum volume of the high-pressure oil tank (1) minus the current fuel volume; M Refueling =V max *1 The ECU (4) then calculates the required working capacity of the main carbon canister (17) based on the amount of fuel vapor generated during refueling. The required working capacity of the main charcoal canister is: ， This refers to the amount of oil and gas released during pressure relief. Multiply the amount of fuel added by an empirical coefficient of 1g / L to get the amount of fuel vapor produced during the refueling process; The amount of fuel gas produced is multiplied by the mass conversion factor K to obtain the required working capacity of the main charcoal canister.

3. The active control method for refueling and venting of a high-pressure fuel tank in an automobile according to claim 2, characterized in that, Specifically, S4 is: Based on the remaining working capacity W of the main carbon canister (17) Remaining and required work skills W Need The ECU (4) control strategy is divided into two cases. When W Need W Remaining When the pressure is released, the pressure relief valve (18) opens to release pressure. After the pressure is released, the refueling locking device (6) is unlocked, allowing refueling to begin. When W Need W Remaining At that time, the ECU (4) sends a timed desorption command to the desorption pump (15), the desorption pump (15) has a constant desorption speed, and the desorption time is W. Need With W Remaining The ratio of the difference to the desorption speed, during which the refueling locking device (6) is normally closed, the pressure relief valve (18) is opened to release pressure after desorption is completed, and the refueling locking device (6) is unlocked after pressure release, allowing refueling to begin.

4. The active control method for refueling and venting of a high-pressure fuel tank in an automobile according to claim 3, characterized in that, Specifically, S5 is: If the weight of the auxiliary carbon canister (13) changes during this refueling process, the ECU (4) calculates the amount of desorption required for the auxiliary carbon canister (13). During the operation of the engine (7), the auxiliary carbon canister (13) will be desorbed in a quantitative manner. The actual amount of desorption is calculated by superimposing the flow sensor (9). After desorption is completed, if the ECU (4) determines that the main carbon canister (17) has no remaining working capacity before the next refueling, it will instruct the desorption pump (15) to desorb the main carbon canister (17) in a quantitative manner. If the remaining working capacity of the auxiliary carbon canister (13) is less than 1 / 2, desorption will stop.

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