Fuel tank pressure control device

Abstract

To suppress increasing of an internal pressure of a fuel storage tank, while suppressing an occurrence of a vapor lock in a fuel supply system.SOLUTION: A pressure control device of a fuel storage tank according to the invention, is to adjust an internal pressure of a fuel storage tank by opening and closing a closure valve provided between a fuel storage tank of a vehicle and a canister. When the closure valve is opened with a vapor concentration within the fuel storage tank being high, a target pressure of the fuel tank is set in consideration of variation of the atmospheric pressure, and the closure valve is opened so that the internal pressure of the fuel storage tank comes into the target pressure.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to a fuel tank pressure control device that adjusts the internal pressure of a fuel tank of a vehicle. [Background technology]

[0002] Conventionally, there is known an internal pressure control device that adjusts the internal pressure of a fuel tank of a vehicle equipped with a fuel pump inside (see, for example, Patent Document 1). This internal pressure control device includes a vapor conduit that is provided between the fuel tank and the canister and that guides fuel vapor (evaporated fuel) generated in the fuel tank to the canister, a control valve (close valve) that is provided in the vapor conduit and that controls the opening and closing of the flow path of the vapor conduit, and a surge tank that is provided in the vapor conduit so as to be located between the control valve and the fuel tank and that temporarily stores the vapor generated in the fuel tank. The control valve of this internal pressure control device is basically open, but is closed when the altitude is above a predetermined altitude, the temperature of the fuel in the fuel tank is above a predetermined temperature, and the pressure in the surge tank is below a predetermined pressure. This makes it possible to suppress the internal pressure of the fuel tank from being reduced at high altitudes, which would cause the boiling point of the fuel to drop, and to suppress the generation of a large amount of vapor in the fuel tank. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 06-031576 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned fuel tank, it is necessary to suppress an increase in internal pressure in order to protect the fuel tank and prevent the cap from becoming stuck on the filler opening. For this reason, a control valve (shutoff valve) between the fuel tank and a surge tank or the like is opened in response to an increase in the internal pressure in order to lower the internal pressure by directing vapor in the fuel tank to the surge tank or the like. However, depending on the properties of the fuel in the fuel tank and the surrounding environment (atmospheric pressure, temperature, etc.), a large amount of vapor may be generated in the fuel tank in response to the decrease in internal pressure caused by the opening of the control valve, which may cause vapor lock in a fuel supply system connected to a fuel pump that pumps fuel from the fuel tank.

[0005] Therefore, a primary object of the present disclosure is to suppress the occurrence of vapor lock in a fuel supply system while suppressing an increase in internal pressure of a fuel tank. [Means for solving the problem]

[0006] The fuel tank pressure control device disclosed herein is a fuel tank pressure control device that adjusts the internal pressure of the fuel tank by opening and closing a shut-off valve arranged between a fuel tank and a canister of a vehicle, and when the shut-off valve is opened when the vapor concentration in the fuel tank is high, a target internal pressure of the fuel tank is set taking into account fluctuations in atmospheric pressure, and the shut-off valve is opened so that the internal pressure becomes the target internal pressure. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic configuration diagram of a vehicle including a fuel tank pressure control device according to the present disclosure. [Diagram 2] 2 is a schematic diagram showing the configuration of an evaporated fuel treatment device for an internal combustion engine of the vehicle shown in FIG. 1. [Diagram 3] 3 is a control block diagram of the evaporated fuel processing device shown in FIG. 2. [Figure 4] 5 is a flowchart showing an example of a routine executed to determine whether or not pressure relief is required for a fuel tank. [Diagram 5]4 is a flowchart showing an example of a routine executed to properly operate an internal combustion engine and an evaporated fuel treatment device in a state where the vapor concentration in a fuel tank is high. [Figure 6] 10 is a flowchart for determining whether or not to open the shutoff valve 30, i.e., whether or not to resume depressurization of the fuel tank 10, after the shutoff valve is closed. [Figure 7] 5 is a time chart showing the change over time in the state of the fuel pressure and the shutoff valve in the fuel supply system when the vapor concentration in the fuel tank is high. [Figure 8] 5 is a flowchart showing an example of a routine executed to set a target internal pressure of a fuel tank. [Figure 9] 5 is a flowchart illustrating an example of a routine executed to suppress a sudden decrease in internal pressure while a shutoff valve is opened to depressurize the fuel tank. [Figure 10] 5 is a time chart showing the change over time in the state of the fuel pressure and the shutoff valve in the fuel supply system when the vapor concentration in the fuel tank is high. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Next, an embodiment of the present disclosure will be described with reference to the drawings.

[0009] Fig. 1 is a schematic diagram of a vehicle including a fuel tank pressure control device according to the present disclosure. The vehicle 1 shown in the figure is a hybrid vehicle including an engine 2, a single-pinion planetary gear 3 as a power distribution mechanism, a gear train 4, motor generators MG1 and MG2, both of which are synchronous generator motors (three-phase AC motors), a battery (electricity storage device) 5, a power control device (hereinafter referred to as "PCU") 6 connected to the battery 5 and driving the motor generators MG1 and MG2, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 100 that controls the entire vehicle.

[0010] The engine 2 of the vehicle 1 is an internal combustion engine that converts the reciprocating motion of a piston PS (see FIG. 2) caused by the combustion of a mixture of air and gasoline (hydrocarbon fuel) in a plurality of combustion chambers (cylinders) 2c into the rotational motion of a crankshaft (output shaft) CS. That is, in the engine 2, air cleaned by an air cleaner 2a is drawn into each combustion chamber 2c via an intake pipe 2i, a throttle valve 2s, an intake valve (not shown), etc., and fuel is injected into the intake air from a port injection valve 2jp of an intake port 2p and / or an in-cylinder injection valve 2jd of each combustion chamber 2c. Furthermore, the mixture of air and fuel explodes and burns in each combustion chamber 2c due to an electric spark from an ignition plug (not shown), causing the piston PS to reciprocate and rotate the crankshaft CS. The engine 2 is controlled by an engine electronic control unit (hereinafter referred to as an "engine ECU") 200. The engine ECU 200 includes a microcomputer having a CPU, ROM, RAM, input / output interface, etc. (not shown), various drive circuits, various logic ICs, etc., and performs intake air amount control, fuel injection control, ignition timing control, etc. of the engine 2.

[0011] The planetary gear 3 is a differential rotation mechanism including a sun gear 3s, a ring gear 3r, and a planetary carrier 3c that rotatably supports a plurality of pinion gears 3p. As shown in FIG. 1, the sun gear 3s is connected to a rotor of a motor generator MG1, and the planetary carrier 3c is connected to a crankshaft CS of an engine 2 via a damper mechanism DD. The ring gear 3r rotates coaxially and integrally with a counter drive gear 4a (output member) of a gear train 4. In addition to the counter drive gear 4a, the gear train 4 includes a counter driven gear 4b and a final drive gear (drive pinion gear) 4c. The final drive gear 4c meshes with a differential ring gear Dr of a differential gear DF, and is connected to left and right wheels (drive wheels) W via the differential gear DF ​​and a drive shaft DS. As a result, the planetary gear 3, the gear train 4, and the differential gear DF ​​constitute a transaxle that transmits a portion of the output torque of the engine 2, which serves as a power generation source, to the wheels W and connects the engine 2 and the motor generator MG1 to each other.

[0012] The motor generator MG1 mainly operates as a generator that converts at least a part of the power from the engine 2 operated under load into electric power. The motor generator MG2 is connected to the left and right wheels W via a differential gear DF ​​including a drive gear 4d, a counter driven gear 4b, a final drive gear 4c and a differential ring gear Dr, and a drive shaft DS. The motor generator MG2 mainly operates as an electric motor that is driven by at least one of the electric power from the battery 5 and the electric power from the motor generator MG1 to generate a drive torque on the drive shaft DS.

[0013] The battery 5 is, for example, a lithium ion secondary battery or a nickel-hydrogen secondary battery. The battery 5 is managed by a battery management electronic control device (hereinafter referred to as "battery ECU") 500 including a microcomputer having a CPU and the like (not shown). The PCU 6 includes a first inverter that drives the motor generator MG1, a second inverter that drives the motor generator MG2, a boost converter that can boost the power from the battery 5 and reduce the power from the motor generators MG1 and MG2 (all not shown). The PCU 6 is controlled by a motor electronic control device (hereinafter referred to as "MGECU") 600 including a microcomputer having a CPU and the like (not shown). The HVECU 100 includes a microcomputer having a CPU and the like, various drive circuits, various logic ICs, and the like. The HVECU 100 exchanges information with the above-mentioned ECUs 200, 500, 600, a brake electronic control device (not shown) that controls a hydraulic brake actuator (not shown), and the like to comprehensively control the vehicle 1.

[0014] FIG. 2 is a schematic diagram showing an evaporated fuel processing device 20, which is an auxiliary device of the engine 2, and FIG. 3 is a control block diagram of the evaporated fuel processing device 20. The evaporated fuel processing device 20 is for suppressing leakage of fuel vapor (evaporated fuel) generated in a fuel tank 10 that stores fuel to be supplied to each combustion chamber 2c of the engine 2 to the outside. The fuel tank 10 has a fuel inlet pipe 11 for supplying fuel into the fuel tank 10 through a fuel filler port (not shown) of the vehicle 1, a vent line 12, a check valve 13 for regulating the backflow of fuel from the inside of the fuel tank 10 to the fuel filler port, a fuel sender gauge 14 for detecting the liquid level of the fuel in the fuel tank 10 by a float, and a tank internal pressure sensor 15 for detecting the internal pressure (tank internal pressure) Pt of the fuel tank 10. In this embodiment, the tank internal pressure sensor 15 detects the pressure (absolute pressure) in the fuel tank 10 and the atmospheric pressure Pt. atm The fuel sender gauge 14 and the tank internal pressure sensor 15 each transmit a signal indicating the detected value to an engine ECU 200, which serves as a pressure control device for the fuel tank 10, as shown in FIG. atm The atmospheric pressure sensor AP is provided to detect an atmospheric pressure, and the atmospheric pressure sensor AP transmits a signal indicative of the detected value to the engine ECU 200.

[0015] A low-pressure fuel passage (fuel supply system) 16L is connected to the upper part of the fuel tank 10, and a fuel pump (pump module) 17 connected to the low-pressure fuel passage 16L is disposed in the fuel tank 10. The fuel pump 17 is an electric pump driven by electric power from an auxiliary battery (not shown) and controlled by the engine ECU 200. Fuel pumped by the fuel pump 17 is supplied to each port injection valve 2jp of the engine 2 through the low-pressure fuel passage 16L and a low-pressure delivery pipe. Furthermore, a high-pressure fuel passage 16H branches off from the middle of the low-pressure fuel passage 16L. The high-pressure fuel passage 16H includes, in order from the branching point with the low-pressure fuel passage 16L, an electromagnetic fuel pressure control valve 18 and a mechanical pump 19, which is, for example, a piston pump driven by the engine 2. Fuel pumped by the mechanical pump 19 is supplied to each in-cylinder injection valve 2jd of the engine 2 through a check valve (not shown) and a high-pressure delivery pipe.

[0016] As shown in FIG. 2, the low-pressure fuel passage 16L is supplied with a low-pressure fuel pressure (hereinafter, simply referred to as "fuel pressure") P, which is the pressure of the fuel supplied from the fuel pump 17 to the low-pressure fuel passage 16L (each port injection valve 2jp). FL A low-pressure fuel pressure sensor LFP that detects the pressure of the fuel supplied from the mechanical pump 19 to each in-cylinder injection valve 2jd is provided in the high-pressure fuel passage 16H. A high-pressure fuel pressure sensor (not shown) that detects the high-pressure fuel pressure, which is the pressure of the fuel supplied from the mechanical pump 19 to each in-cylinder injection valve 2jd, is also provided in the high-pressure fuel passage 16H. The low-pressure fuel pressure sensor LFP and the high-pressure fuel pressure sensor each transmit a signal indicative of the detection value to the engine ECU 200.

[0017] 2, the evaporated fuel processing device 20 includes a canister 22, a vapor passage 24 connecting the fuel tank 10 and the canister 22, a purge passage 26, an air passage 28, and a shutoff valve 30 installed midway through the vapor passage 24. The canister 22 has activated carbon as an adsorbent disposed therein, and adsorbs evaporated fuel in the fuel tank 10 by the adsorbent. One end (upstream end) of the vapor passage 24 is connected to the fuel tank 10 so as to communicate with a gas layer in the fuel tank 10, and the other end (downstream end) of the vapor passage 24 is connected to the canister 22 so as to communicate with the inside of the canister 22.

[0018] One end (upstream end) of the purge passage 26 is connected to the canister 22 so as to communicate with the inside of the canister 22, and the other end (downstream end) of the purge passage 26 is connected to the intake pipe 2i downstream of the throttle valve 2s of the engine 2. A purge valve 27 capable of blocking the purge passage 26 is provided midway through the purge passage 26. The purge valve 27 is an opening / closing valve controlled by the engine ECU 200, and is normally maintained in a closed state. One end of the air passage 28 is connected to the canister 22 via a key-off pump module 40, which is a diagnostic component used for diagnosing a malfunction of the evaporated fuel processing device 20. The key-off pump module 40 includes a switching valve (shutoff valve) 41 and a vacuum pump (reducing pump) 45, which are opening / closing valves controlled by the engine ECU 200, and a canister internal pressure sensor 47 that detects the internal pressure Pc of the canister 22 and transmits it to the engine ECU 200. The switching valve 41 allows communication between the inside of the canister 22 and the atmospheric passage 28 when it is open and blocks communication between them when it is closed, and the vacuum pump 45 is capable of reducing the pressure (creating negative pressure) inside the canister 22 when the switching valve 41 is closed. Furthermore, an air filter 29 is installed midway through the atmospheric passage 28, and the other end of the atmospheric passage 28 is open to the atmosphere.

[0019] The shutoff valve 30 is a flow rate adjustment valve controlled by the engine ECU 200, and in a closed state, shuts off the vapor passage 24 to block communication between the fuel tank 10 and the canister 22, and in an open state, adjusts the flow rate of gas flowing through the vapor passage 24. The shutoff valve 30 includes a casing 31, a valve seat 32 formed in the casing 31, a valve body 33 arranged in the casing 31 so as to be movable in the axial direction, and a stepping motor 34 arranged in the casing 31 and connected to the valve body 33 via a valve guide (not shown). The stepping motor 34 is controlled by the engine ECU 200, and moves the valve body 33 back and forth in the axial direction relative to the valve seat 32. The valve body 33 approaches the valve seat 32 as the stepping motor 34 is operated, and a seal member (not shown) of the valve body 33 abuts against the valve seat 32, thereby closing the shutoff valve 30. Furthermore, as the stepping motor 34 operates, the valve body 33 separates from the valve seat 32, and a sealing member (not shown) of the valve body 33 separates from the valve seat 32, thereby opening the shut-off valve 30. Furthermore, after the start switch of the vehicle 1 is turned on, the start switch is turned off, the shut-off valve 30 is opened or closed at high speed, and then initialization of the shut-off valve 30 is performed during failure diagnosis of the evaporated fuel processing device 20, etc. This initialization rotates the stepping motor 34 so that the rotation start position of the stepping motor 34 coincides with the opening start position of the shut-off valve 30, which is learned separately.

[0020] In the above-described evaporated fuel processing device 20, while the vehicle 1 is parked (while the engine 2 is not operating), the shutoff valve 30 is maintained in a closed state, and evaporated fuel in the fuel tank 10 does not flow into the canister 22. Also, while the vehicle 1 is parked, the purge passage 26 is maintained in a blocked state by closing the purge valve 27, and the canister 22 is maintained in a state in which it is communicated with the atmospheric passage 28 by opening the switching valve 41. Furthermore, in the evaporated fuel processing device 20, the engine ECU 200 diagnoses the presence or absence of leaks in the vapor passage 24 and the purge passage 26 when the start switch (ignition switch) of the vehicle 1 is turned off and the key of the vehicle 1 is turned off (when the engine 2 is not operating).

[0021] On the other hand, after the start switch is turned on, the engine ECU 200 communicates the inside of the canister 22 with the air passage 28 and opens the purge valve 27 in response to the establishment of a predetermined purge condition including at least that the engine 2 is operating. As a result, the intake negative pressure of the engine 2 (intake pipe 2i) is supplied into the canister 22 via the purge passage 26, and air flows from the air passage 28 into the canister 22. Furthermore, when the purge valve 27 is open and the internal pressure Pt of the fuel tank 10 becomes equal to or higher than a valve opening threshold (tank internal pressure threshold) Pop, the engine ECU 200 opens the shutoff valve 30 to depressurize the fuel tank 10. As a result, vapor (evaporated fuel) in the fuel tank 10 flows into the canister 22 via the vapor passage 24 (shutoff valve 30). The adsorbent in the canister 22 is purged by air flowing into the canister 22, and the vapor released from the adsorbent is guided together with the air to the intake pipe 2i of the engine 2 and combusted in the combustion chamber 2c.

[0022] Fig. 4 is a flowchart showing an example of a routine executed by the engine ECU 200 to determine whether or not pressure relief is required for the fuel tank 10. The routine shown in Fig. 4 is repeatedly executed by the engine ECU 200 at predetermined time intervals (very short time intervals) while the engine 2 is operating after the start switch is turned on. When starting the routine in Fig. 4, the engine ECU 200 acquires data necessary for determining whether or not pressure relief is required, such as the internal pressure Pt (after appropriate smoothing processing) of the fuel tank 10 detected by the tank internal pressure sensor 15, a separately set valve opening threshold Pop, and separately set values ​​of a vapor high concentration flag Fvh and a shutoff valve open flag Fop (step S100).

[0023] The valve opening threshold Pop is set when it is determined that the vapor concentration, which is the concentration of evaporated fuel (vapor) in the gas present in the fuel tank 10, is high, and when the internal pressure Pt or the atmospheric pressure P atmand is set to a predetermined constant value Pref (for example, a value of about 2 kPa) when it is not determined that the vapor concentration in the fuel tank 10 is high. The high vapor concentration flag Fvh is set to "1" when it is determined that the vapor concentration in the fuel tank 10 is high, and is set to "0" when it is not determined that the vapor concentration in the fuel tank 10 is high. The shutoff valve open flag Fop is set to "1" when the shutoff valve 30 should be opened, and is set to "0" when the shutoff valve 30 should be closed.

[0024] After the process of step S100, the engine ECU 200 judges whether the acquired internal pressure Pt of the fuel tank 10 is less than the valve opening threshold Pop (step S110). When it is judged that the internal pressure Pt of the fuel tank 10 is equal to or greater than the valve opening threshold Pop (step S110: NO), the engine ECU 200 sets the above-mentioned shutoff valve open flag Fop to "1" (step S115) and temporarily ends the routine of FIG. 4. When the shutoff valve open flag Fop is set to "1" in step S115 and the shutoff valve 30 is closed, the engine ECU 200 operates the stepping motor 34 at a low speed (e.g., 30 msec / step) that does not require the above-mentioned initialization to open the shutoff valve 30. This allows the vapor (evaporated fuel) in the fuel tank 10 to flow into the canister 22 through the vapor passage 24 (shutoff valve 30) to reduce the internal pressure Pt of the fuel tank 10.

[0025] On the other hand, when it is determined in step S110 that the internal pressure Pt of the fuel tank 10 is less than the valve opening threshold Pop (step S110: YES), the engine ECU 200 determines whether the above-mentioned shutoff valve open flag Fop is "1" (step S120). When it is determined that the internal pressure Pt is less than the valve opening threshold Pop and the shutoff valve open flag Fop is "0" and the shutoff valve 30 is closed (step S120: NO), the engine ECU 200 sets (maintains) the shutoff valve open flag Fop to "0" without permitting the shutoff valve 30 to open (step S170), and temporarily ends the routine of FIG.

[0026] If it is determined in step S120 that the internal pressure Pt is less than the valve opening threshold Pop and the closing valve open flag Fop is "1" and the closing valve 30 is open (step S120: YES), the engine ECU 200 determines whether the vapor high concentration flag Fvh acquired in step S100 is "0" (step S130). If it is determined that the vapor high concentration flag Fvh is "0" (the vapor concentration in the fuel tank 10 is not high) (step S130: YES), the engine ECU 200 subtracts a constant value η const (for example, a value of about 1.0 kPa) is subtracted and the resulting value is set as the valve closing threshold value Pcl (step S140).

[0027] On the other hand, when it is determined in step S130 that the high vapor concentration flag Fvh is "1" (the vapor concentration in the fuel tank 10 is high) (step S130: NO), the engine ECU 200 derives a hysteresis η(Pt) corresponding to the internal pressure Pt of the fuel tank 10 acquired in step S100 from a hysteresis setting map (not shown) (step S150). Furthermore, in step S150, the engine ECU 200 sets a value obtained by subtracting the hysteresis η(Pt) from the valve opening threshold Pop acquired in step S100 to the valve closing threshold Pcl. The hysteresis setting map used in step S150 specifies a hysteresis adapted for each of the multiple internal pressures Pt through experiments, analyses, etc. Also, in the hysteresis setting map of this embodiment, the hysteresis assigned to each of the multiple internal pressures Pt is the above-mentioned constant value η const It is set to a value less than.

[0028] After the process of step S140 or S150, the engine ECU 200 determines whether the internal pressure Pt of the fuel tank 10 acquired in step S100 is equal to or lower than the valve closing threshold Pcl set in step S140 or S150 (step S160). If it is determined that the internal pressure Pt of the fuel tank 10 is higher than the valve closing threshold Pcl (step S160: NO), the engine ECU 200 determines that the internal pressure Pt of the fuel tank 10 has not sufficiently decreased after the shutoff valve 30 is opened, sets (maintains) the shutoff valve open flag Fop to "1" without permitting the shutoff valve 30 to be closed (step S115), and temporarily ends the routine of FIG. Furthermore, when it is determined in step S160 that the internal pressure Pt of the fuel tank 10 is equal to or lower than the valve closing threshold value Pcl (step S160: YES), the engine ECU 200 determines that the internal pressure Pt of the fuel tank 10 has been sufficiently reduced by opening the shutoff valve 30, sets the shutoff valve open flag Fop to "0" to permit closing of the shutoff valve 30 (step S170), and temporarily ends the routine of Fig. 4. When the shutoff valve open flag Fop is set to "0" in step S170, the engine ECU 200 operates the stepping motor 34 at a low speed (e.g., 30 msec / step) that does not require the above-mentioned initialization, for example, to close the shutoff valve 30.

[0029] As described above, the engine ECU 200 as a pressure control device for the fuel tank 10 closes the shutoff valve 30 when the internal pressure Pt of the fuel tank 10 becomes equal to or lower than the closing threshold Pcl which is lower than the opening threshold Pop after opening the shutoff valve 30 to release the pressure in the fuel tank 10 (step S110: NO, step S170). When the engine ECU 200 determines that the high vapor concentration flag Fvh is "1" (step S130: NO), the engine ECU 200 reduces the hysteresis indicating the difference between the opening threshold Pop and the closing threshold Pcl compared to when the high vapor concentration flag Fvh is determined to be "0" (steps S140, S150). As a result, even if the shut-off valve 30 is opened so that the internal pressure Pt of the fuel tank 10 changes gradually in accordance with the reference pressure reduction amount ρref described below when the vapor concentration in the fuel tank 10 is high, it is possible to prevent the internal pressure Pt of the fuel tank 10 from decreasing suddenly between when it becomes equal to or greater than the valve opening threshold Pop and when it becomes equal to or less than the valve closing threshold Pcl.

[0030] Furthermore, when the engine ECU 200 determines that the high vapor concentration flag Fvh is "1" (the vapor concentration in the fuel tank 10 is high) (step S130: NO), the engine ECU 200 sets a hysteresis indicating the difference between the valve opening threshold Pop and the valve closing threshold Pcl based on the internal pressure Pt of the fuel tank 10 (step S150). That is, the higher the internal pressure Pt of the fuel tank 10, the greater the amount of vapor passing through the stop valve 30 within a unit time. Therefore, by setting the difference between the valve opening threshold Pop and the valve closing threshold Pcl based on the internal pressure Pt of the fuel tank 10, it is possible to effectively suppress a sudden decrease in the internal pressure Pt of the fuel tank 10 from the time the internal pressure Pt becomes equal to or higher than the valve opening threshold Pop until the internal pressure Pt becomes equal to or lower than the valve closing threshold Pcl.

[0031] Fig. 5 is a flowchart showing an example of a routine executed by the engine ECU 200 to properly operate the engine 2 and the evaporated fuel treatment device 20 in a state where the vapor concentration in the fuel tank 10 is high. The routine shown in Fig. 5 is also repeatedly executed by the engine ECU 200 at predetermined time intervals (very short time intervals) while the engine 2 is operating after the start switch is turned on. When starting the routine of Fig. 5, the engine ECU 200 detects the internal pressure Pt of the fuel tank 10 detected by the tank internal pressure sensor 15 and the fuel pressure P FL , the atmospheric pressure (current atmospheric pressure) P detected by the atmospheric pressure sensor AP atm Data required for determining the degree of vapor concentration in the fuel tank 10 is acquired (step S200), such as the intake air temperature Ta, which is the temperature of the intake air detected by a temperature sensor (not shown) installed in the intake pipe 2i, and the estimated vapor concentration Cv, which is an estimated value of the vapor concentration in the fuel tank 10. The estimated vapor concentration Cv is calculated separately by the engine ECU 200 based on the difference between the air-fuel ratio in each combustion chamber 2c when the purge valve 27 is open and the target air-fuel ratio, etc.

[0032] Next, the engine ECU 200 calculates the fuel pressure P FL , atmospheric pressure P atm In step S210, the engine ECU 200 determines whether the vapor concentration in the fuel tank 10 is high based on the intake air temperature Ta and the estimated vapor concentration Cv (step S210). atm In step S210, the engine ECU 200 determines whether the estimated vapor concentration Cv is greater than or equal to the atmospheric pressure P atm In step S210, the engine ECU 200 determines whether the fuel pressure P FLis sufficiently close to a target lower limit fuel pressure (target fuel pressure) Ptag, which is the lower limit of the target value of the pressure of the fuel in the low-pressure fuel passage 16L, i.e., the lower limit of the fuel pressure to be supplied to the low-pressure fuel passage 16L by the fuel pump 17. In this embodiment, when it is determined that the vapor concentration in the fuel tank 10 is not high, the target lower limit fuel pressure Ptag is set to, for example, any one of 300 kPa, 400 kPa, and 500 kPa depending on the operating state of the engine 2, etc.

[0033] The engine ECU 200 detects the atmospheric pressure P atm When the atmospheric pressure P atm is equal to or lower than a predetermined pressure, the intake air temperature Ta is equal to or higher than a predetermined temperature, and the fuel pressure P FL is lower than the target lower limit fuel pressure Ptag by a predetermined value or more and is not sufficiently close to the target lower limit fuel pressure Ptag, the engine ECU 200 also determines that the vapor concentration in the fuel tank 10 is high (step S220: YES). Furthermore, in other cases, the engine ECU 200 determines that the vapor concentration in the fuel tank 10 is not high (step S220: NO). When it is determined in step S220 that the vapor concentration in the fuel tank 10 is not high (step S220: NO), the engine ECU 200 sets the high vapor concentration flag Fvh described above to "0", sets the valve opening threshold Pop to the above-mentioned constant value Pref, and starts the timer and the fuel pressure drop counter C described below. L is reset (step S225), and the routine of FIG. 5 is temporarily terminated.

[0034] On the other hand, if it is determined in step S220 that the vapor concentration in the fuel tank 10 is high (step S220: YES), the engine ECU 200 turns on a timer that measures the elapsed time t since it was determined that the vapor concentration in the fuel tank 10 is high (step S230), and sets the high vapor concentration flag Fvh to "1" (step S240). atm In step S250, the engine ECU 200 sets the valve opening threshold Pop taking into consideration the above (step S250). atm The map used in step S250 is a map for determining whether a value corresponding to the atmospheric pressure Pt is greater than the value derived from the map or the internal pressure Pt of the fuel tank 10 obtained in step S200. atm The engine ECU 200 specifies a value that can be the valve opening threshold Pop adapted through experiments, analyses, etc. for each tank. The engine ECU 200 sets the value of the valve opening threshold Pop set in step S250 as the initial target internal pressure Pint when the shutoff valve 30 is opened in a state where the vapor concentration in the fuel tank 10 is high, and stores the value in the RAM or non-volatile memory (step S260). Furthermore, the engine ECU 200 sets the value of the atmospheric pressure P atm Reference atmospheric pressure P0 atm The result is stored in the RAM or non-volatile memory (step S270).

[0035] Next, engine ECU 200 increases the target lower limit fuel pressure Ptag (step S280). That is, if it is determined in step S220 that the vapor concentration in fuel tank 10 is high, then in step S280, the target lower limit fuel pressure Ptag is increased from the previous value (e.g., 300, 400, or 500 kPa) to a predetermined value (e.g., a value around 650 kPa). This increases the discharge pressure (rotation speed) of fuel pump 17 to increase fuel pressure P in low-pressure fuel passage 16L. FLSince the fuel pressure can be increased, it is possible to suppress the occurrence of vapor lock in the low-pressure fuel passage 16L. Furthermore, the engine ECU 200 sets a fuel pressure drop determination threshold P L In step S290, engine ECU 200 sets a fuel pressure drop determination threshold P as a value (e.g., Ptag-200 kPa) obtained by subtracting a predetermined value α (e.g., a value around 200 kPa) from the target lower limit fuel pressure Ptag (e.g., 300, 400, or 500 kPa) before it was changed (raised) in step S280. L Set to.

[0036] After the process of step S290, engine ECU 200 calculates the fuel pressure P FL The fuel pressure drop determination threshold P set in step S290 L It is determined whether the fuel pressure P FL is the fuel pressure drop threshold P L If it is determined that the fuel pressure is equal to or less than the fuel pressure decrease counter C L (step S310). Furthermore, the engine ECU 200 increments the In order to prohibit the valve from being opened, the shutoff valve open flag Fop is set to "0" (step S320), and the routine of FIG. 5 is temporarily terminated. FL is the fuel pressure drop threshold P L If it is determined that the value exceeds the previous value (step S300: NO), engine ECU 200 skips the processes of steps S310 and S320 and temporarily ends the routine of FIG. 5 so that the value of the shutoff valve open flag Fop is maintained at the previous value.

[0037] When the shutoff valve open flag Fop is set to "0" in step S320 and the shutoff valve 30 is open to release the pressure in the fuel tank 10, the engine ECU 200 operates the stepping motor 34 at a low speed (e.g., 30 msec / step) that makes the above-mentioned initialization unnecessary, to close the shutoff valve 30. As a result, at least the atmospheric pressure P atm Based on the above, it is determined that the vapor concentration in the fuel tank 10 is high, and the fuel pressure P FL When it is determined that the pressure has decreased (step S220: YES, step S300: YES), the stop valve 30 is forcibly closed.

[0038] That is, when the vapor concentration in the fuel tank 10 is high, if the shutoff valve 30 is opened in response to an increase in the internal pressure Pt of the fuel tank 10, a large amount of vapor may be generated in the fuel tank 10 in response to a decrease in the internal pressure Pt caused by the opening of the shutoff valve 30. In addition, if a large amount of vapor is generated in the fuel tank 10, the fuel pressure P in the low-pressure fuel passage 16L may increase due to the vapor being mixed in by the fuel pump 17. FL In consideration of this, the engine ECU 200, which is a control device for the engine 2, controls the engine 2 so that at least the atmospheric pressure P atm Based on the above, it is determined that the vapor concentration in the fuel tank 10 is high, and the fuel pressure P FL When it is determined that the pressure has decreased (step S220: YES, step S300: YES), the shutoff valve open flag Fop is set to "0" to close the shutoff valve 30 (step S320).

[0039] As a result, the closing of the shutoff valve 30 suppresses the decrease in the internal pressure Pt of the fuel tank 10 and the generation of vapor, so that the fuel pressure P FL In addition, the fuel pressure P in the low pressure fuel passage 16L can be reduced. FLWhen the pressure Pt in the fuel tank 10 has not decreased (step S220: YES, step S300: NO), the shutoff valve 30 is allowed to open, and the increase in the internal pressure Pt in the fuel tank 10 can be suppressed. As a result, in the engine 2, the increase in the internal pressure Pt in the fuel tank 10 can be suppressed while the occurrence of vapor lock in the low-pressure fuel passage 16L can be effectively suppressed.

[0040] When it is determined that the vapor concentration in the fuel tank 10 is high (step S220: YES), the engine ECU 200 atm In other words, when the engine ECU 200 determines that the vapor concentration in the fuel tank 10 is high, the engine ECU 200 uses the atmospheric pressure P atm or the internal pressure Pt of the fuel tank 10, whichever is larger. In this way, when the vapor concentration in the fuel tank 10 is high, the valve opening threshold Pop is set appropriately and the surrounding atmospheric pressure P atm Even if the internal pressure Pt of the fuel tank 10 is low, the internal pressure Pt of the fuel tank 10 is not suddenly reduced when the shutoff valve 30 opens, thereby preventing a large amount of vapor from being generated in the fuel tank 10.

[0041] Here, when the shutoff valve 30 is open and the shutoff valve open flag Fop is set to "0" in step S320 of Fig. 5, the shutoff valve 30 is closed. In this case, it is preferable to keep the shutoff valve 30 open and continue depressurizing the fuel tank 10. For this reason, when the shutoff valve 30 is closed in response to the shutoff valve open flag Fop being set to "0" in step S320, the engine ECU 200 executes the routine of Fig. 6 at predetermined time intervals (very short time) to determine whether or not to open the shutoff valve 30, i.e., whether or not to resume depressurizing the fuel tank 10. The routine of Fig. 6 is also executed when the shutoff valve 30 is opened in response to the processing of step S615 of Fig. 4 after it is determined in step S220 of Fig. 5 that the vapor concentration in the fuel tank 10 is high.

[0042] When the routine of FIG. 6 starts, engine ECU 200 detects fuel pressure P FL and the above-mentioned elapsed time t, data necessary for the judgment are acquired (step S400). Next, the engine ECU 200 judges whether the elapsed time t acquired in step S400 is longer than a predetermined valve opening restriction time tref0 (step S410). In this embodiment, the valve opening restriction time tref0 is, for example, a value of about 200 msec. If it is determined in step S410 that the elapsed time t is equal to or shorter than the valve opening restriction time tref0 (step S410: NO), the engine ECU 200 temporarily ends the routine in FIG. 6 at that point in time, and executes the processing from step S400 onwards when the next execution timing arrives.

[0043] In addition, when it is determined in step S410 that the elapsed time t is longer than the valve opening restriction time tref0 (step S410: YES), the engine ECU 200 FL is the predetermined valve opening permission pressure (valve opening permission threshold) P H It is determined whether the valve opening permission pressure P H is a pressure that can prevent the occurrence of vapor lock in the low pressure fuel passage 16L, and in this embodiment, is set to a value (e.g., a value of about 620 kPa) slightly lower than the target lower limit fuel pressure Ptag (e.g., a value of about 650 kPa) raised in step S280 of FIG. 5. FL is the valve opening pressure P H If it is determined that the difference is less than the predetermined value (step S420: NO), engine ECU 200 temporarily ends the routine in FIG. 6 at that point in time, and executes the processes in and after step S400 when the next execution timing arrives.

[0044] In response to this, in step S420, the fuel pressure P FL is the valve opening pressure P HIf it is determined that this is the case (step S420: YES), the engine ECU 200 sets the shutoff valve open flag Fop to "1" to permit the shutoff valve 30 to open (step S430), and temporarily ends the routine of Fig. 6. When the shutoff valve open flag Fop is set to "1" in step S430, the engine ECU 200 operates the stepping motor 34 at a low speed (e.g., 30 msec / step) that does not require the above-mentioned initialization, to open the shutoff valve 30.

[0045] That is, in the vehicle 1, as shown in FIG. 7, from the time t1 when it is determined that the vapor concentration in the fuel tank 10 is high until the predetermined valve opening restriction time tref0 has elapsed, the stop valve 30 that was once closed is kept open to prevent the fuel pressure P FL As a result, the fuel pressure P in the low pressure fuel passage 16L is prohibited from being opened based on the target lower limit fuel pressure Ptag being set high in step S280 of FIG. FL Before the fuel pressure P becomes sufficiently high, a temporary fuel pressure P caused by, for example, fuel pulsation generated by the mechanical pump 19 of the high-pressure fuel passage 16H may occur. FL In the vehicle 1, the fuel pressure P in the low pressure fuel passage 16L is effectively prevented from being opened in response to a rise in the vapor concentration in the fuel tank 10 (see part A in FIG. 7). FL The valve opening permission pressure P based on the target lower limit fuel pressure Ptag increased in step S280 H When the target lower limit fuel pressure Ptag is equal to or higher than the target lower limit fuel pressure Ptag (time t2 in FIG. 7), the shutoff valve 30 is permitted to open. FL Once the pressure in the fuel tank 10 has risen sufficiently to avoid vapor lock, the shutoff valve 30 can be opened and depressurization of the fuel tank 10 can be resumed.

[0046] Now, when the processes of steps S310 and S320 in FIG. 5 are skipped and the shutoff valve 30 is closed, the shutoff valve 30 is maintained in a closed state. When the processes of steps S310 and S320 are skipped and the shutoff valve 30 is open, the shutoff valve 30 is maintained in an open state. In this case, the shutoff valve 30 is controlled to open at an opening degree corresponding to, for example, the estimated vapor concentration Cv, until it is determined that the vapor concentration in the fuel tank 10 is high. Then, after determining that the vapor concentration in the fuel tank 10 is high (step S220: YES, step S300: NO), the engine ECU 200 sets the target internal pressure P* of the fuel tank 10 so as to gradually decrease with time, and controls the shutoff valve 30 so that the internal pressure Pt becomes the target internal pressure P*. More specifically, the engine ECU 200 converts the target internal pressure P* into a flow rate, and controls the stepping motor 34 so that the vapor at the flow rate passes through the shutoff valve 30.

[0047] Fig. 8 is a flowchart showing a routine repeatedly executed by the engine ECU 200 at predetermined time intervals (very short time intervals) in order to set the target internal pressure P* of the fuel tank 10 after it is determined that the vapor concentration in the fuel tank 10 is high. The routine of Fig. 8 is also repeatedly executed at predetermined time intervals (very short time intervals) after it is determined in step S220 of Fig. 5 that the vapor concentration in the fuel tank 10 is high and after the shutoff valve 30 is opened in response to the processing of step S615 of Fig. 4.

[0048] When the routine of FIG. 8 starts, engine ECU 200 detects atmospheric pressure (current atmospheric pressure) P atm , the above-mentioned reference atmospheric pressure P0 atm , Fuel pressure drop counter C LThe engine ECU 200 acquires data necessary for setting the target internal pressure P*, such as the value of the fuel pressure reduction amount ρ (step S500). Next, the engine ECU 200 calculates the reduction amount ρ of the target internal pressure P* per execution cycle (predetermined time) of the routine of FIG. 8 (step S510). In step S510, the engine ECU 200 calculates a predetermined change amount Δρ from a predetermined reference reduction amount ρref and a fuel pressure reduction counter C according to the following formula (1): L and subtracting the product of the value of the reference pressure reduction amount ρref from the target internal pressure P*. In this embodiment, the reference pressure reduction amount ρref is set so that the target internal pressure P* is reduced at a rate of, for example, 2 kPa / min while it is determined that the vapor concentration in the fuel tank 10 is high, and is expressed as ρref=2 kPa×execution cycle / 60 sec. The change amount Δρ is a fixed value (for example, a value around Δρ=0.5 kPa×execution cycle / 60 sec) that is adapted through experiments and analyses so as to be smaller than the reference pressure reduction amount ρref.

[0049] ρ=ρref-Δρ×C L …(1)

[0050] Furthermore, the engine ECU 200 determines the reference atmospheric pressure P0 atm from atmospheric pressure (current atmospheric pressure) P atm Subtract the atmospheric pressure correction amount ΔP atm (Step S520). atm is the current atmospheric pressure P atm and the reference atmospheric pressure P0, which is the atmospheric pressure when it is determined that the vapor concentration in the fuel tank 10 is high. atm The engine ECU 200 then subtracts the pressure reduction amount ρ from the target internal pressure (previous target internal pressure) P* that was set the previous time the routine in FIG. 8 was executed, to obtain the atmospheric pressure correction amount ΔP. atm The target internal pressure P* is set by adding the above (step S530), and the routine of Fig. 8 is temporarily terminated. Note that immediately after the start of the routine of Fig. 8, the initial target internal pressure Pint set in step S260 of Fig. 5 becomes the previous target internal pressure in step S530.

[0051] In this way, when the engine ECU 200 serving as the pressure control device for the fuel tank 10 opens the shutoff valve 30 to release the pressure in the fuel tank 10 in a state in which the vapor concentration in the fuel tank 10 is high, the engine ECU 200 reduces the target internal pressure P* by a predetermined reduction amount ρ at predetermined time intervals and adjusts the atmospheric pressure correction amount ΔP atm (steps S500-S530). As a result, the internal pressure Pt of the fuel tank 10 is corrected based on the surrounding atmospheric pressure P atm In this way, it is possible to suppress both the increase in internal pressure of the fuel tank 10 and the occurrence of vapor lock.

[0052] In addition, the fuel pressure reduction counter C which is incremented in step S310 of FIG. L As described later, the fuel pressure P in the low pressure fuel passage 16L while the shutoff valve 30 is open corresponds to the vapor concentration in the fuel tank 10. FL Therefore, by the process of step S510 in FIG. 8, the reduction amount ρ of the target internal pressure P* is incremented by the fuel pressure P in the low-pressure fuel passage 16L. FL Fuel pressure drop counter C indicates the number of times that the fuel pressure has dropped. L As the value of the fuel pressure P FL Each time it is determined that the internal pressure Pt of the fuel tank 10 has decreased, the amount of reduction ρ of the target internal pressure P* is reduced, thereby making it possible to gradually reduce the internal pressure Pt of the fuel tank 10 while suppressing the generation of vapor.

[0053] However, if the vehicle 1 is traveling at high altitude or if the fuel tank 10 contains, for example, highly volatile fuel for winter use, there is a risk that a large amount of vapor will be generated in the fuel tank 10 in response to a sudden decrease in the internal pressure Pt caused by the opening of the shut-off valve 30 due to changes in atmospheric pressure, fuel properties, etc. In consideration of this, while the shut-off valve 30 is opened to release the pressure of the fuel tank 10 in a state where the vapor concentration in the fuel tank 10 is high, the engine ECU 200 repeatedly executes the routine of FIG 9 at predetermined time intervals (very short time intervals) in parallel with the routine of FIG 8 in order to suppress a sudden decrease in the internal pressure Pt.

[0054] At the start of the routine of FIG. 9, engine ECU 200 detects fuel pressure P FL In step S600, the engine ECU 200 acquires data necessary for the judgment, such as the above-mentioned elapsed time t, and the like. Next, the engine ECU 200 judges whether the elapsed time t acquired in step S600 exceeds a predetermined first duration (predetermined time) tref1 (step S610). In this embodiment, the first duration tref1 is, for example, a value of about 200 msec. If it is determined in step S610 that the elapsed time t is equal to or less than the first duration tref1 (step S610: NO), the engine ECU 200 acquires the fuel pressure P acquired in step S600. FL is the fuel pressure drop threshold P L While it is determined in step S610 that the elapsed time t is equal to or less than the first duration tref1, the fuel pressure drop determination threshold P L is a relatively small value set in step S290 of FIG.

[0055] When the engine ECU 200 determines that the elapsed time t is longer than the first duration tref1 (step S610: YES), it determines whether the elapsed time t is equal to or shorter than a second duration tref2 that is longer than the first duration tref1 (step S620). When the engine ECU 200 determines that the elapsed time t is equal to or shorter than the second duration tref2 in step S620 (step S620: YES), it determines the fuel pressure drop determination threshold P L In step S630, engine ECU 200 sets a fuel pressure drop determination threshold P L That is, the fuel pressure drop determination threshold value P LWhen the elapsed time t exceeds the first duration tref1, the fuel pressure P FL The fuel pressure drop determination threshold P L It is determined whether or not it is equal to or less (step S650).

[0056] Furthermore, when it is determined in step S620 that the elapsed time t is longer than the second duration tref2 (step S620: NO), engine ECU 200 sets the fuel pressure drop determination threshold P as a value obtained by subtracting a predetermined value β (β<α, for example, a value of approximately 140 kPa) from the target lower limit fuel pressure Ptag (for example, a value of approximately 650 kPa) raised in step S280 of FIG. L (step S640). As a result, the fuel pressure drop determination threshold value P L When the elapsed time t exceeds the second duration tref2, the fuel pressure drop determination threshold P L is set to a higher value in stages as the elapsed time t increases. FL The fuel pressure drop determination threshold P L It is determined whether or not it is equal to or less (step S650).

[0057] The fuel pressure P obtained in step S600 FL The fuel pressure drop determination threshold P L If it is determined that the fuel pressure P obtained in step S600 is greater than the fuel pressure P (step S650: NO), the engine ECU 200 temporarily ends the routine of FIG. FL The fuel pressure drop determination threshold P LIf it is determined that the fuel pressure is equal to or less than the fuel pressure decrease counter C L (step S660), and the fuel pressure drop counter C L It is determined whether the value is equal to or greater than "2" (step S670).

[0058] Fuel pressure drop counter C L If it is determined that the value of the fuel pressure reduction counter C is less than "2" (step S670: YES), the engine ECU 200 sets the shutoff valve open flag Fop to "0" and specifies closing at a low speed (e.g., 30 msec / step) (step S680) in order to suppress a decrease in the internal pressure of the fuel tank 10 due to the closing of the shutoff valve 30, and then ends the routine of FIG. 9. L If it is determined that the value is equal to or greater than "2" (step S670: NO), the engine ECU 200 sets the shut-off valve open flag Fop to "0" and specifies high-speed (e.g., 4 msec / step) closing of the shut-off valve 30 in order to suppress a drop in the internal pressure of the fuel tank 10 due to the closing of the shut-off valve 30 (step S690), and then temporarily terminates the routine in FIG. 9.

[0059] As described above, when the engine ECU 200 determines that the vapor concentration in the fuel tank 10 is high (step S220: YES), it sets the target lower limit fuel pressure Ptag in the low pressure fuel passage 16L to be higher than when it is determined that the vapor concentration in the fuel tank 10 is not high (step S280 in FIG. 5). Furthermore, while the elapsed time t after it is determined that the vapor concentration in the fuel tank 10 is high is equal to or less than the first duration (predetermined time) tref1, the engine ECU 200 sets the fuel pressure drop determination threshold P L is maintained at a relatively small value based on the target lower limit fuel pressure Ptag before it was raised as described above, and when the elapsed time t exceeds the first duration tref1, the fuel pressure drop determination threshold P Lis changed to a relatively high value based on the increased target lower limit fuel pressure Ptag as described above (steps S610-S640). This increases the discharge pressure (rotation speed) of the fuel pump 17 and increases the fuel pressure PFL in the low-pressure fuel passage 16L, making it possible to effectively prevent vapor lock in the low-pressure fuel passage 16L. In addition, as can be seen from FIG. 10, the fuel pressure PFL in the low-pressure fuel passage 16L is increased. FL Even though the fuel pressure P FL It is possible to prevent the system from determining that the power consumption has decreased (see part B in the figure).

[0060] As shown in FIG. 10, the engine ECU 200 determines the fuel pressure drop determination threshold P based on the target lower limit fuel pressure Ptag while the vapor concentration in the fuel tank 10 is high. L is gradually increased over time (steps S610-S640). FL It is therefore possible to effectively suppress erroneous determination of a decrease in the concentration of the charged particle.

[0061] Furthermore, when the vapor concentration in the fuel tank 10 is high, the engine ECU 200 controls the fuel pressure P FL In response to the first determination that the fuel pressure P in the low-pressure fuel passage 16L is decreasing (step S670: YES, time t10 in FIG. 10), the engine ECU 200 sets the shutoff valve open flag Fop to "0" and specifies closing at a low speed (step S680). In this case, as shown in FIG. 10, the engine ECU 200 closes the shutoff valve 30 at a low speed (e.g., 30 msec / step) that makes the above initialization unnecessary. As a result, after the shutoff valve 30 is closed, the fuel pressure P in the low-pressure fuel passage 16L is FL The pressure increases and the valve opening pressure P H When this occurs (time t20 in FIG. 10), the shutoff valve 30 can be opened promptly without executing initialization.

[0062] In this embodiment, after the shutoff valve 30 is closed, the fuel pressure P FL The pressure increases and the valve opening pressure PH When this occurs (time t20 in FIG. 10), the engine ECU 200 operates the stepping motor 34 at a low speed (e.g., 30 msec / step) that makes the above-mentioned initialization unnecessary, to open the shutoff valve 30. In this way, by opening the shutoff valve 30 at a low speed that makes initialization unnecessary in response to the establishment of the opening condition after the shutoff valve 30 is closed, the fuel pressure P FL In response to the decrease in the pressure, the shutoff valve 30 can be quickly opened without executing initialization.

[0063] In addition, when the vapor concentration in the fuel tank 10 is high, the engine ECU 200 controls the fuel pressure P FL In response to the second determination that the fuel pressure P is decreasing (step S670: NO, time t20 in FIG. 10), in order to suppress a decrease in the internal pressure of the fuel tank 10 by closing the shutoff valve 30, the shutoff valve open flag Fop is set to "0" and high-speed valve closing is specified (step S690). In this case, after it is determined that the vapor concentration in the fuel tank 10 is high, the fuel pressure P FL Despite the decrease and increase in the fuel properties and atmospheric pressure P atm Due to the effects of these factors, the fuel pressure P FL Since it is assumed that the internal pressure Pt of the fuel tank 10 is decreasing, the engine ECU 200 closes the stop valve 30 at the maximum speed (for example, 4 msec / step). This makes it possible to suppress a sudden decrease in the internal pressure Pt of the fuel tank 10 and suppress the occurrence of vapor lock in the low-pressure fuel passage 16L.

[0064] In the above embodiment, when it is determined that the vapor concentration in the fuel tank 10 is high and the fuel pressure P FL is the fuel pressure drop threshold P L The shutoff valve 30 is closed when it is determined that the fuel pressure is equal to or lower than the fuel pressure drop determination threshold P L is set to an extremely large value, and when it is determined that the vapor concentration in the fuel tank 10 is high, the fuel pressure PFL The shutoff valve 30 may be forcibly closed when it is determined that the vapor concentration is high. That is, when the vapor concentration in the fuel tank 10 is high, there is a risk of vapor lock occurring, so the shutoff valve 30 may be uniformly prohibited from opening at the point in time when it is determined that the vapor concentration is high. This makes it possible to effectively suppress the occurrence of vapor lock in the low-pressure fuel passage 16L. In addition, the invention of the present disclosure is useful for the vehicle 1, which is a hybrid vehicle in which the vapor concentration in the fuel tank 10 tends to be high due to the intermittent operation of the engine 2, but a vehicle equipped with the engine 2 to which the invention of the present disclosure is applied may have only the engine 2 as a power source that outputs power for traveling.

[0065] As described above, the fuel tank pressure control device of the present disclosure is a fuel tank pressure control device (200) that adjusts the internal pressure (Pt) of the fuel tank (10) by opening and closing the shutoff valve (30) disposed between the fuel tank (10) and the canister (22) of the vehicle (1). When the shutoff valve (30) is opened in a state in which the vapor concentration in the fuel tank (10) is high, the fuel tank pressure control device (200) adjusts the internal pressure (Pt) of the fuel tank (10) by opening and closing the shutoff valve (30). atm Taking into account fluctuations in the internal pressure (Pt), a target internal pressure (P*) of the fuel tank (10) is set (steps S500-S530), and the shutoff valve (30) is opened so that the internal pressure (Pt) becomes the target internal pressure (P*).

[0066] The fuel tank pressure control device of the present disclosure sets a target internal pressure of the fuel tank taking into consideration fluctuations in atmospheric pressure when opening the shutoff valve when the vapor concentration in the fuel tank is high. This makes it possible to appropriately reduce the internal pressure of the fuel tank even if the surrounding atmospheric pressure fluctuates due to changes in altitude, etc., by opening the shutoff valve so that the internal pressure becomes the target internal pressure, thereby making it possible to prevent a large amount of vapor from being generated in the fuel tank due to a sudden decrease in internal pressure. The fuel tank pressure control device of the present disclosure makes it possible to effectively prevent vapor lock from occurring in the fuel supply system while suppressing an increase in the internal pressure of the fuel tank.

[0067] In addition, the pressure control device (200) reduces the target internal pressure (P*) by a predetermined reduction amount (ρref) at predetermined time intervals (step S510) and simultaneously detects the current atmospheric pressure (P atm ) and the atmospheric pressure (P0 atm ) (step S520). This allows the internal pressure of the fuel tank to be gradually reduced in accordance with the surrounding atmospheric pressure, making it possible to simultaneously suppress an increase in the internal pressure of the fuel tank and suppress the occurrence of vapor lock.

[0068] However, the invention of the present disclosure is not limited to the above embodiment, and various modifications can be made within the scope of the present disclosure. Furthermore, the above embodiment is merely a specific form of the invention described in the Summary of the Invention, and does not limit the elements of the invention described in the Summary of the Invention. [Industrial Applicability]

[0069] The present disclosure is applicable to the vehicle manufacturing industry and the like. [Explanation of symbols]

[0070] 1 vehicle, 2 engine (internal combustion engine), 2a air cleaner, 2c combustion chamber, 2i intake pipe, 2jd in-cylinder injection valve, 2jp port injection valve, 2p intake port, 2s throttle valve, 3 planetary gear, 4 gear train, 5 battery, 6 power control unit (PCU), 10 fuel tank, 15 tank internal pressure sensor, 16H high-pressure fuel passage, 16L low-pressure fuel passage, 17 fuel pump, 20 evaporative fuel treatment device, 22 canister, 24 vapor passage, 26 purge passage, 27 purge valve, 28 atmospheric passage, 29 air filter, 30 shutoff valve, 31 casing, 32 valve seat, 33 valve body, 34 stepping motor, 100 hybrid electronic control unit (HVECU), 200 engine electronic control unit (engine ECU), AP atmospheric pressure sensor, LFP Low pressure fuel pressure sensor, MG1,MG2 motor generator.

Claims

[Claim 1] A pressure control device for a fuel tank that adjusts an internal pressure of the fuel tank by opening and closing a shutoff valve disposed between a fuel tank and a canister of a vehicle, comprising: A fuel tank pressure control device that, when the shut-off valve is opened while the vapor concentration in the fuel tank is high, reduces a target internal pressure of the fuel tank by a predetermined reduction amount at predetermined time intervals and corrects it by the difference between the current atmospheric pressure and the atmospheric pressure when it is determined that the vapor concentration in the fuel tank is high, thereby setting the target internal pressure taking into account fluctuations in atmospheric pressure and opening the shut-off valve so that the internal pressure becomes the target internal pressure.

Images