Fuel Supply Processing Device

Abstract

To suppress the generation of vapor in a fuel tank.SOLUTION: A control device valve-closes a sealing valve at a high-density determination in which the generation of high-density vapor in a fuel tank is determined, after that, when fuel pressure reaches target fuel pressure or higher, valve-opens the sealing valve, also, when the fuel pressure reaches a lower-limit fuel pressure or lower in a state that the sealing valve is valve-opened at the high-density determination, valve-closes the sealing valve, and after that, when the fuel pressure reaches the target fuel pressure or higher, valve-opens the sealing valve. Also, when valve-opening the sealing valve, the control device valve-opens so that a pressure reduction speed of the inner pressure of the fuel tank is lowered compared with the case that the number of times of the lowering of the fuel pressure as the number of times at which the fuel pressure reaches prescribed lower-limit fuel pressure or lower is small when the number of times of the lowering of the fuel pressure is large in a state that the sealing valve is valve-opened, and when the number of times of the lowering of the fuel pressure is equal to or larger than the prescribed number of times, or when the pressure reduction speed is within a prescribed low-speed range including a value 0, the control device prohibits the valve-opening of the sealing valve.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a fuel supply processing device, and more particularly to a fuel supply processing device including a fuel supply device and a vaporized fuel processing device. [Background technology]

[0002] Conventionally, as this type of fuel supply processing device, one that includes a fuel supply device and a vaporized fuel processing device has been proposed (for example, see Patent Document 1). The fuel supply processing device includes a fuel pump that supplies fuel in a fuel tank to a fuel passage (fuel piping). The vaporized fuel processing device includes a shutoff valve (control valve) and a surge tank. The shutoff valve is provided in a vapor passage (vapor conduit) that is connected to the fuel tank and the canister. The surge tank temporarily stores vapor (vaporized fuel) generated in the fuel tank. In this device, when a vehicle equipped with the fuel supply processing device is traveling at high altitude, the shutoff valve of the vaporized fuel processing device is closed. This is said to suppress decompression in the fuel tank when traveling at high altitude, and suppress the fuel in the fuel tank from vaporizing and generating vapor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 6-31576 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned fuel supply processing device, when the shutoff valve is closed, the pressure in the fuel tank may rise excessively. In this case, it is possible to open the shutoff valve to reduce the pressure in the fuel tank. At this time, if the opening speed of the shutoff valve is fast, the pressure in the fuel tank may be suddenly reduced, and a large amount of vapor may be generated in the fuel pump or fuel passage, causing the fuel pressure to decrease. As a method for dealing with such a decrease in fuel pressure, a method is conceivable in which the opening speed of the shutoff valve is slowed down as the frequency of fuel pressure decreases increases, thereby suppressing the sudden reduction in pressure in the fuel tank and suppressing the generation of vapor. However, when the fuel is in a state in which vapor is highly likely to be generated, such as when the fuel contains a large amount of light components or when the atmospheric pressure is suddenly decreasing, the generation of vapor may not be suppressed even if the opening speed of the shutoff valve is slowed down.

[0005] The main object of the fuel supply processing device of the present invention is to suppress the generation of vapor. [Means for solving the problem]

[0006] In order to achieve the above-mentioned main object, the fuel supply processing device of the present invention employs the following means.

[0007] The fuel supply processing device of the present invention comprises: a fuel supply device having a fuel pump for supplying fuel in a fuel tank to a fuel passage; a fuel vapor processing device having a shutoff valve disposed in a vapor passage connected to the fuel tank and the canister; a control device that controls the fuel pump so that a fuel pressure as a pressure of the fuel becomes a target fuel pressure and also controls the shutoff valve; A fuel supply processing device comprising: The control device includes: When it is determined that the concentration of vapor in the fuel tank is high, the shutoff valve is closed, and thereafter, when the fuel pressure becomes equal to or higher than the target fuel pressure, the shutoff valve is opened; When the fuel pressure becomes equal to or lower than a predetermined lower limit fuel pressure with the shut-off valve open during the high concentration determination, the shut-off valve is closed, and thereafter, when the fuel pressure becomes equal to or higher than the target fuel pressure, the shut-off valve is opened; Furthermore, the control device When the shutoff valve is opened, the shutoff valve is opened so that the rate at which the internal pressure of the fuel tank is reduced is slower when the number of fuel pressure drops, which is the number of times that the fuel pressure has become equal to or lower than the predetermined lower limit fuel pressure while the shutoff valve is open, is large compared to when the number of fuel pressure drops is small. When the number of times the fuel pressure decreases is equal to or greater than a predetermined number, or when the reduction speed is within a predetermined low speed range including a value of 0, the closing valve is prohibited from opening. The gist of the present invention is as follows.

[0008] In the fuel supply processing device of the present invention, when it is determined that the concentration of vapor in the fuel tank is high, the shutoff valve is closed. This increases the internal pressure of the fuel tank to suppress the generation of vapor. Thereafter, when the fuel pressure becomes equal to or higher than the target fuel pressure, the shutoff valve is opened. This suppresses an excessive increase in the internal pressure of the fuel tank. Then, when the fuel pressure becomes equal to or lower than a predetermined lower limit fuel pressure with the shutoff valve open during the high concentration determination, the shutoff valve is closed. When the fuel pressure becomes equal to or lower than the predetermined lower limit fuel pressure with the shutoff valve open, it is considered that a vapor lock has occurred in which fuel cannot be supplied to the fuel passage with sufficient pressure due to the generation of vapor in the fuel pump or the fuel passage. Therefore, when the fuel pressure becomes equal to or lower than the predetermined lower limit fuel pressure with the shutoff valve open, the shutoff valve is closed to increase the internal pressure of the fuel tank, suppressing the generation of vapor and eliminating the vapor lock. Then, when the fuel pressure becomes equal to or higher than the target fuel pressure, the shutoff valve is opened. This makes it possible to suppress an excessive increase in the internal pressure of the fuel tank. Furthermore, when the shut-off valve is opened, the shut-off valve is opened so that the rate at which the internal pressure of the fuel tank is reduced is slower when the number of fuel pressure drops, which is the number of times the fuel pressure falls below a predetermined lower limit fuel pressure with the shut-off valve open, is large than when it is small. It is considered that the fuel is in a state where vapor is more likely to be generated when the number of fuel pressure drops is large than when it is small. Therefore, by opening the shut-off valve so that the rate at which the internal pressure of the fuel tank is reduced is slower when the number of fuel pressure drops is large than when it is small, the generation of vapor can be suppressed. Furthermore, when the number of fuel pressure drops is equal to or greater than a predetermined number, or when the rate of reduction is within a predetermined low-speed range including the value 0, the shut-off valve is prohibited from opening. When the number of fuel pressure drops is equal to or greater than a predetermined number, or when the decompression rate is within a predetermined low-speed range including the value 0, the fuel is in a state where it is highly likely to generate vapor, such as when the fuel contains a large amount of light components or when the atmospheric pressure drops rapidly, and it is considered that when the shut-off valve is opened, a large amount of vapor is generated even with a slight reduction in pressure inside the fuel tank. Therefore, when the number of fuel pressure drops is equal to or greater than a predetermined number, or when the decompression rate is within a predetermined low-speed range including the value 0, the shut-off valve is prohibited from opening, thereby suppressing the decompression inside the fuel tank. As a result, the generation of vapor can be suppressed.

[0009] In the fuel supply processing device of the present invention, when the control device prohibits the closing valve from opening when the number of fuel pressure drops is equal to or greater than the predetermined number, the control device may permit the closing valve to open and reset the number of fuel pressure drops to a value of 0 when a system stop command is issued. When a system stop command is issued for the fuel supply processing device, the fuel is in a state in which vapor is unlikely to be generated, such as when the fuel temperature has dropped during system stop or the fuel tank has lost light components due to the reduced pressure in the fuel tank before the system stop command was issued, and it is highly likely that the closing valve can be opened at the next system startup. Therefore, when a system stop command is issued for the fuel supply processing device, the closing valve can be permitted to open and the number of fuel pressure drops can be reset to a value of 0, thereby ensuring an opportunity to open the closing valve and reduce the pressure in the fuel tank after the next system startup.

[0010] Furthermore, in the fuel supply processing device of the present invention, the control device may permit the shut-off valve to open and reset the number of fuel pressure drops to a value of 0 when the high concentration is not determined. When the high concentration is not determined, the fuel is considered to be in a state in which it is difficult for vapor to be generated. Therefore, by permitting the shut-off valve to open and resetting the number of fuel pressure drops to a value of 0 when the high concentration is not determined, an opportunity to open the shut-off valve and reduce the pressure inside the fuel tank can be secured at the next high concentration determination. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing the configuration of an automobile 10 equipped with a fuel supply processing device according to an embodiment of the present invention. [Diagram 2] 4 is a flowchart showing an example of an opening / closing control routine executed by an electronic control unit 70. [Diagram 3] 4 is a flowchart showing an example of an opening / closing control routine executed by an electronic control unit 70. [Figure 4] 4 is a flowchart showing an example of a valve opening permission processing routine executed by an electronic control unit 70. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Next, an embodiment of the present invention will be described with reference to the accompanying drawings. EXAMPLES

[0013] 1 is a schematic diagram showing the configuration of an automobile 10 equipped with a fuel supply processing device as an embodiment of the present invention. As shown in the figure, the automobile 10 of the embodiment includes an engine 12, a fuel supply device 42, a vaporized fuel processing device 50, a transmission 60 connected to a crankshaft 14 of the engine 12 and connected to driving wheels 64a, 64b via a differential gear 62, a starter (not shown) for starting the engine 12, and an electronic control unit 70 for controlling the entire vehicle. The fuel supply processing device of the embodiment mainly includes the fuel supply device 42, the vaporized fuel processing device 50, and the electronic control unit 70.

[0014] The engine 12 is configured as an internal combustion engine that outputs power through four strokes: intake, compression, expansion, and exhaust, using fuel such as gasoline or diesel from a fuel tank 40. The engine 12 draws air purified by an air cleaner 22 into an intake pipe 23 and passes it through a throttle valve 24, while injecting fuel from a fuel injection valve 26 downstream of the throttle valve 24 of the intake pipe 23 to mix the air and fuel. The mixture is then drawn into a combustion chamber 29 via an intake valve 28, where it is explosively combusted by an electric spark from an ignition plug 30, and the reciprocating motion of a piston 32 pushed down by the energy of the explosive combustion is converted into the rotational motion of the crankshaft 14. The exhaust gas discharged from the combustion chamber 29 into an exhaust pipe 34 via an exhaust valve 33 is discharged into the outside air via a purification device 35. The purification device 35 has a catalyst (three-way catalyst) 35a that purifies harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx).

[0015] Fuel supply device 42 is configured to be able to supply fuel in fuel tank 40 to fuel injection valve 26. Fuel supply device 42 includes a fuel passage 43, a fuel pump 44, a relief passage 45, and a relief valve 46. Fuel passage 43 is connected to fuel injection valve 26. Fuel pump 44 supplies fuel in fuel tank 40 to fuel passage 43. Fuel pump 44 is formed with discharge hole 44a for discharging vaporized fuel generated in fuel tank 40 (fuel vaporized by evaporation or boiling) by driving fuel pump 44 when the vaporized fuel is sucked in.

[0016] The relief passage 45 is connected to the fuel passage 43 and the fuel tank 40. The relief valve 46 is provided in the relief passage 45, and closes when the pressure of the fuel in the fuel passage 43 (fuel pressure Pf) is less than the valve opening pressure Pfrv of the relief valve 46, and opens when the pressure of the fuel in the fuel passage 43 is equal to or greater than the valve opening pressure Pfrv. When the relief valve 46 opens, a portion of the fuel in the fuel passage 43 is returned to the fuel tank 40 via the relief passage 45. In this way, the pressure of the fuel in the fuel passage 43 is prevented from becoming excessive.

[0017] Vaporized fuel processing device 50 is configured to be capable of purging, supplying vaporized fuel gas (purge gas) containing vaporized fuel generated in fuel tank 40 to intake pipe 23. Vaporized fuel processing device 50 includes an introduction passage (vapor passage) 51, a shutoff valve 52, a canister 53, a purge passage 55, and a purge valve 56.

[0018] The introduction passage (vapor passage) 51 is connected to the fuel tank 40 and a canister 53. The shutoff valve 52 is provided in the introduction passage (vapor passage) 51, and is configured as a normally closed type electromagnetic valve.

[0019] The shutoff valve 52 is a flow rate adjustment valve, which in a closed state shuts off the introduction passage (vapor passage) 51 to cut off communication between the fuel tank 40 and the canister 53, and in an open state adjusts the flow rate of gas flowing through the introduction passage (vapor passage) 51. The shutoff valve 52 includes a valve seat (not shown) formed in the casing, a valve body (not shown) arranged in the casing so as to be movable in the axial direction, and a stepping motor 52b arranged in the casing and connected to the valve body via a valve guide (not shown). The stepping motor 52b moves the valve body back and forth in the axial direction relative to the valve seat. The valve body approaches the valve seat with the operation of the stepping motor 52b, and a seal member (not shown) of the valve body abuts against the valve seat, thereby closing the shutoff valve 52. The valve body moves away from the valve seat with the operation of the stepping motor 52b, and a seal member (not shown) of the valve body moves away from the valve seat, thereby opening the shutoff valve 52. The stepping motor 52b is controlled by an electronic control unit 70.

[0020] The canister 53 is connected to the introduction passage (vapor passage) 51 and the purge passage 55, and is open to the atmosphere via an atmosphere vent passage 54. The inside of the canister 53 is filled with an adsorbent, such as activated carbon, capable of adsorbing vaporized fuel from the fuel tank 40. The atmosphere vent passage 54 is provided with an air filter (not shown).

[0021] The purge passage 55 is connected to the canister 53 and the intake pipe 23 downstream of the throttle valve 24. The purge valve 56 is provided in the purge passage 55 and is configured as a normally closed type electromagnetic valve. The purge valve 56 is controlled by an electronic control unit 70.

[0022] This vaporized fuel processing device 50 performs purging by adjusting the opening of a purge valve 56 when the shutoff valve 52 is open. Specifically, vaporized fuel gas (purge gas) containing vaporized fuel generated in the fuel tank 40 is supplied to the intake pipe 23 through an introduction passage (vapor passage) 51, a canister 53, and a purge passage 55 by utilizing the negative pressure in the intake pipe 23, with the flow rate being adjusted. Therefore, the engine 12 can draw a mixture of air and fuel (fuel from the fuel injection valve 26 and vaporized fuel from the vaporized fuel processing device 50) into the combustion chamber 29.

[0023] The electronic control unit 70 is configured as a microprocessor with a CPU at its core, and in addition to the CPU, it is equipped with a ROM for storing processing programs, a RAM for temporarily storing data, a flash memory for storing and holding data, and input / output ports. Signals from various sensors are input to the electronic control unit 70 via the input ports.

[0024] Examples of signals input to the electronic control unit 70 include a crank angle θcr from a crank position sensor 14a that detects the rotational position of the crankshaft 14 of the engine 12, and a coolant temperature Tw from a water temperature sensor 15 that detects the temperature of the coolant for the engine 12. Other examples include a throttle opening TH from a throttle position sensor 24a that detects the opening (position) of the throttle valve 24, and cam angles θci, θco from a cam position sensor 16 that detects the rotational positions of an intake camshaft that opens and closes the intake valve 28 and an exhaust camshaft that opens and closes the exhaust valve 33. Other examples of the intake air amount Qa from an air flow meter 23a attached upstream of the throttle valve 24 of the intake pipe 23, an intake air temperature Ta from a temperature sensor 23b attached upstream of the throttle valve 24 of the intake pipe 23, a front air-fuel ratio AF1 from a front air-fuel ratio sensor 37 attached upstream of the purification device 35 of the exhaust pipe 34, and a rear air-fuel ratio AF2 from a rear air-fuel ratio sensor 38 attached downstream of the purification device 35 of the exhaust pipe 34. Other examples of the intake air amount Qa from an air flow meter 23a .... Other examples of the intake air amount Qa from an air flow meter 23a attached upstream of the throttle valve 24 of the intake pipe 23. Other examples include the opening Osv of the shut-off valve 52 from the shut-off valve position sensor 52a that detects the opening (position) of the shut-off valve 52, and the opening Opv of the purge valve 56 from the purge valve position sensor 56a that detects the opening (position) of the purge valve 56. Other examples include an ignition signal IG from an ignition switch 80, and a shift position SP from a shift position sensor 82 that detects the operating position of the shift lever 81.Other examples include the accelerator opening Acc from an accelerator pedal position sensor 84 that detects the amount of depression of an accelerator pedal 83, a brake pedal position BP from a brake pedal position sensor 86 that detects the amount of depression of a brake pedal 85, a vehicle speed V from a vehicle speed sensor 88, and an atmospheric pressure Pout from an atmospheric pressure sensor 89.

[0025] Various control signals are output from the electronic control unit 70 via an output port. Examples of signals output from the electronic control unit 70 include a control signal to the throttle valve 24, a control signal to the fuel injector 26, a control signal to the spark plug 30, a control signal to the fuel pump 44, a control signal to the shutoff valve 52, and a control signal to the purge valve 56. Other examples include a control signal to the transmission 60 and a control signal to a starter (not shown).

[0026] The electronic control unit 70 calculates the rotation speed Ne of the engine 12 based on the crank angle θcr from the crank position sensor 14a. The electronic control unit 70 also calculates a load factor KL (the ratio of the volume of air actually taken in one cycle to the stroke volume per cycle of the engine 12) based on the intake air amount Qa from the air flow meter 23a and the rotation speed Ne of the engine 12. Furthermore, the electronic control unit 70 calculates a consumption flow rate Qfr of the engine 12 based on the fuel injection amount Qf from the fuel injection valve 26.

[0027] In the automobile 10 of the embodiment thus configured, the electronic control unit 70 performs operation control of the engine 12, specifically, intake air amount control for controlling the opening of the throttle valve 24, fuel injection control for controlling the amount of fuel injected from the fuel injection valve 26, and ignition control for controlling the ignition timing of the spark plug 30, based on the required load rate KL* of the engine 12 which is based on the accelerator opening Acc and the vehicle speed V. The electronic control unit 70 also controls the fuel pump 44 of the fuel supply device 42, and the shutoff valve 52 and purge valve 56 of the vaporized fuel processing device 50.

[0028] In the operation control of the engine 12, in the intake air amount control, the electronic control unit 70 sets a target opening TH* of the throttle valve 24 based on the required load factor KL* of the engine 12, and controls the throttle valve 24 using the set target opening TH*. In the ignition control, the electronic control unit 70 sets a target ignition timing Ti* of the spark plug 30 based on the rotation speed Ne and the load factor KL of the engine 12, and controls the spark plug 30 using the set target ignition timing Ti*. In the control of the fuel pump 44, the electronic control unit 70 sets a target discharge flow rate of the fuel pump 44 using feedback control with a proportional term and an integral term based on the difference between the fuel pressure Pf detected by the fuel pressure sensor 43p and the target fuel pressure Pf*, and controls the fuel pump 44. In the control of the stop valve 52, when the tank internal pressure Pt (gauge pressure) is equal to or lower than a threshold Ptref that is slightly higher than 0 kPa, the stop valve 52 is controlled to be in a closed state, and when the tank internal pressure Pt is higher than the threshold Ptref, the stop valve 52 is controlled to be in an open state. In controlling the purge valve 56, when the purge condition is satisfied, the purge valve 56 is controlled to be in an open state to perform the above-mentioned purge, and when the purge condition is not satisfied, the purge valve 56 is controlled to be in a closed state. As the purge condition, for example, a condition that the cooling water temperature Tw is equal to or higher than a threshold value, operation control of the engine 12 (fuel injection control, etc.) is being performed, and the shutoff valve 52 is in an open state, etc., is used.

[0029] Next, the operation of the automobile 10 of the embodiment thus configured, particularly the operation when the vapor concentration in the fuel tank 40 is high, will be described. Figures 2 and 3 are flowcharts showing an example of an opening / closing control routine executed by the electronic control unit 70. The opening / closing control routine is executed at the time of high concentration determination that the vapor concentration (vaporized fuel) in the fuel tank 40 is high when the shutoff valve 52 and the purge valve 56 are open. In the embodiment, the vapor concentration in the fuel tank 40 is determined to be high when the following high vapor condition is established.

[0030] The high vapor condition may be when the first condition is satisfied and at least one of the two conditions, the second condition and the third condition, is satisfied. The first condition may be when the intake air temperature Ta from the temperature sensor 23b corresponds to the temperature of the fuel, and the fuel state determined from the intake air temperature Ta and the atmospheric pressure Pout from the atmospheric pressure sensor 89 is on the high temperature / low pressure side of the saturated vapor pressure curve of the fuel, that is, when the fuel in the fuel tank 40 is in an environment where it is easy to vaporize. The first condition is satisfied, for example, when the automobile 10 is traveling in a high altitude and high temperature place. In the first condition, if the automobile 10 is provided with a fuel temperature sensor that detects the temperature of the fuel in the fuel tank 40, the fuel temperature from the fuel temperature sensor may be used instead of the intake air temperature Ta from the temperature sensor 23b. The second condition may be when the purge concentration, which is the ratio of vaporized fuel to the amount of gas supplied to the intake pipe 23, is equal to or higher than a predetermined concentration. The purge concentration is estimated based on the front air-fuel ratio AF1 from the front air-fuel ratio sensor 37 and the amount of fuel injected from the fuel injector 26. The predetermined concentration is a value determined in advance through experiments, analysis, machine learning, etc. as a threshold value for determining whether or not a high concentration of vapor is generated in the fuel tank 40. The third condition is that the amount of change over time of the integral term in the feedback control of the fuel pump 44 is equal to or greater than a predetermined amount of change, that is, the fuel pump 44 is driven but the fuel pressure does not increase, so that the integral term is greatly increased. The predetermined amount of change is a value determined in advance through experiments, analysis, machine learning, etc. as a threshold value for determining whether or not the fuel pressure does not increase despite the fuel pump 44 being driven.

[0031] When the opening / closing control routine is executed, the CPU (not shown) of the electronic control unit 70 controls the stepping motor 52b to close the shutoff valve 52 (step S100). By closing the shutoff valve 52 in this manner, the internal pressure of the fuel tank 40 is increased, thereby suppressing the generation of vapor.

[0032] Next, a target fuel pressure Pf* is set by adding a predetermined fuel pressure Pfref to the target value Pfn of the fuel pressure when the high vapor condition is not satisfied, and a target discharge flow rate of the fuel pump 44 is set using feedback control with a proportional term and an integral term based on the difference between the fuel pressure Pf detected by the fuel pressure sensor 43p and the target fuel pressure Pf* to control the fuel pump 44 (step S110). The target value Pfn is obtained by previously determining the relationship between the required air amount Qa* based on the accelerator opening Acc and the rotation speed Ne of the engine 12, the rotation speed Ne of the engine 12, and the target value Pfn, and storing it as a target value setting map, and when the accelerator opening Acc, the required air amount Qa*, and the rotation speed Ne are given, the corresponding target value Pfn is derived from the map. The predetermined fuel pressure Pfref is determined in advance by experiments, analysis, machine learning, etc., as an increase amount that increases the fuel pressure to a pressure that can crush bubbles in the fuel pump 44 and the fuel passage 43 when added to the target value Pfn. Increasing the fuel pressure in this manner breaks down air bubbles in the fuel pump 44 and the fuel passage 43. This suppresses the occurrence of vapor lock, in which fuel cannot be supplied to the fuel passage 43 with sufficient pressure due to vapor generation in the fuel pump 44 or the fuel passage 43. Thereafter, while the opening / closing control routine is being executed, the fuel pump 44 is continuously controlled so that the fuel pressure Pf becomes the target fuel pressure Pf*, which is the sum of the target value Pfn and the predetermined fuel pressure Pfref.

[0033] Next, the fuel pressure Pf is input from the fuel pressure sensor 43p (step S120), and it is determined whether the fuel pressure Pf is equal to or greater than the target fuel pressure Pf* (step S130). If the fuel pressure Pf is less than the target fuel pressure Pf*, it is determined that the fuel pump 44 is in a state where it cannot generate sufficient fuel pressure due to vapor lock, and the shutoff valve 52 is closed and the fuel pump 44 is controlled so that the fuel pressure Pf becomes the target value Pfn while waiting for the fuel pressure Pf to become equal to or greater than the target fuel pressure Pf*.

[0034] When the fuel pressure Pf is equal to or greater than the target fuel pressure Pf* in step S130, it is determined that the fuel pump 44 is generating sufficient fuel pressure, and the stepping motor 52b is controlled so that the closing valve 52 opens at a valve opening speed So at which the pressure reduction speed Sr in the fuel tank 40 becomes the normal speed Sn (step S140). The normal speed Sn is a value determined in advance by experiment, analysis, or machine learning as a pressure reduction speed at which a large amount of vapor is not generated due to pressure reduction in the fuel tank 40 when the content of light components in the fuel in the fuel tank 40 is a predetermined content. This prevents the internal pressure of the fuel tank 40 from rising excessively.

[0035] Next, the fuel pressure Pf is input from the fuel pressure sensor 43p (step S150), and it is determined whether the fuel pressure Pf is equal to or lower than a lower limit fuel pressure (predetermined lower limit fuel pressure) Pfmin (step S160). The lower limit fuel pressure Pfmin is a threshold value for determining whether or not a sufficient amount of fuel cannot be sent to the fuel passage 43 due to vapor lock, and is a fuel pressure that is determined in advance by experiment, analysis, machine learning, or the like. Therefore, step S160 is a process for determining whether or not an engine stall is likely to occur.

[0036] When the fuel pressure Pf is greater than the lower limit fuel pressure Pfmin, it is determined that there is no possibility of engine stall occurring, and the process returns to step S150. With the shut-off valve 52 open, steps S150 and S160 are repeated to input the fuel pressure Pf and determine whether the fuel pressure Pf is equal to or less than the lower limit fuel pressure Pfmin.

[0037] When the fuel pressure Pf is equal to or lower than the lower limit fuel pressure Pfmin, it is determined that if the shutoff valve 52 is continued to be open, vapor lock may occur, causing the engine to stall. The number of fuel pressure drops Npd, which indicates the number of times the fuel pressure Pf has become equal to or lower than the lower limit fuel pressure Pfmin by opening the shutoff valve 52, is increased by 1 (step S170), and the stepping motor 52b is controlled to close the shutoff valve 52 (step S180). This increases the internal pressure of the fuel tank 40, suppressing the generation of vapor in the fuel tank 40. The reason for counting the number of fuel pressure drops Npd in step S170 is as follows. If the fuel pressure drops in steps S150 and S160 despite the shutoff valve 52 being closed and opened once in steps S100 to S140 to suppress the generation of vapor, it can be said that the fuel in the current fuel tank 40 is in a state in which vapor is very likely to be generated. It is considered that the greater the number of fuel pressure drops Npd, the more likely the fuel in the fuel tank 40 is to generate vapor. Therefore, in order to recognize the state of the fuel in the fuel tank 40, the number of fuel pressure drops Npd is counted.

[0038] After closing the shutoff valve 52 in this manner, the fuel pressure Pf is input from the fuel pressure sensor 43p (step S190), and it is determined whether the fuel pressure Pf is equal to or greater than the target fuel pressure Pf* (step S200). If the fuel pressure Pf is less than the target fuel pressure Pf*, it is determined that the fuel pressure has not risen sufficiently, and the shutoff valve 52 is closed and the fuel pump 44 is controlled so that the fuel pressure Pf becomes equal to the target value Pfn while waiting for the fuel pressure Pf to become equal to or greater than the target fuel pressure Pf*.

[0039] When the fuel pressure Pf is equal to or greater than the target fuel pressure Pf* in step S200, it is determined that the fuel pump 44 is generating sufficient fuel pressure, and then it is determined whether the number of fuel pressure drops Npd is less than the threshold value Npref (step S210). The threshold value Npref is a threshold value for determining whether the fuel currently in the fuel tank 40 is in a state in which a fuel pressure drop is likely to occur even if the shutoff valve 52 is opened slightly, and is set to, for example, 5 times, 6 times, 7 times, etc. This is based on the fact that, as described above, the greater the number of fuel pressure drops Npd, the more likely the fuel currently in the fuel tank 40 is to generate vapor.

[0040] When the number of fuel pressure drops Npd is less than the threshold value Npref, it is determined that the fuel is in a state where vapor is likely to be generated, but the state is not such that a fuel pressure drop will occur even if the shut-off valve 52 is opened slightly, and a target pressure reduction speed Sr* is set by the following formula (1) using the normal speed Sn, the number of fuel pressure drops Npd, and the pressure reduction amount ΔSr used in step S140 so that the target pressure reduction speed Sr* is slower when the number of fuel pressure drops Npd is large than when it is small, within a range that does not fall below the value 0 (step S220). The pressure reduction amount ΔSr is a value determined in advance by experiments, analysis, machine learning, etc. as the amount of pressure reduction at which a large amount of vapor is not generated in the fuel tank 40.

[0041] Sr*=max(Sn-Npd·ΔSr,0) ···(1)

[0042] Once the target pressure reduction speed Sr* is set in this manner, the stepping motor 52b is controlled so that the closing valve 52 opens at a valve opening speed So at which the pressure reduction speed Sr in the fuel tank 40 becomes the target pressure reduction speed Sr* (step S230). Then, the process returns to step S150, and steps S150 to S230 are repeated. Through these processes, when the fuel pressure Pf becomes equal to or lower than the lower limit fuel pressure Pfmin while the closing valve 52 is open, the closing valve 52 is closed (steps S150 to S180), and when the fuel pressure Pf becomes equal to or higher than the target fuel pressure Pf*, the closing valve 52 opens so that the pressure reduction speed Sr of the fuel tank 40 becomes slower when the number of fuel pressure reductions Npd is large than when the number of fuel pressure reductions Npd is small (steps S190 to S230). It is considered that the fuel currently in the fuel tank 40 is in a state in which vapor is more likely to be generated when the number of fuel pressure drop Npd is large compared to when the number of fuel pressure drop Npd is small. Therefore, the generation of vapor can be suppressed by opening the shut-off valve 52 so that the pressure reduction rate Sr of the fuel tank 40 is slower when the number of fuel pressure drop Npd is large compared to when the number of fuel pressure drop Npd is small.

[0043] If the number of fuel pressure drops Npd is equal to or greater than the threshold value Npref in step 210, it is determined that the fuel in the current fuel tank 40 is in a state in which vapor is likely to be generated and vapor lock is likely to occur even if the shut-off valve 52 is opened slightly, and the shut-off valve 52 is prohibited from opening (step S240), and this routine is terminated. In this way, when the fuel in the current fuel tank 40 is in a state in which vapor is likely to be generated and vapor lock is likely to occur even if the shut-off valve 52 is opened slightly, the opening of the shut-off valve 52 is prohibited, thereby suppressing the generation of vapor and suppressing the occurrence of vapor lock. This makes it possible to suppress engine stall of the engine 12.

[0044] In addition, when the high vapor condition is no longer satisfied during the execution of the opening / closing control routine, or when an instruction to stop the system of the automobile 10 is given, such as when the ignition switch 80 is turned off, the execution of the opening / closing control routine is immediately terminated. When the processing of step S240 is not being executed at the time of the completion of the execution of the opening / closing control routine, the opening of the shutoff valve 25 is not prohibited, so that when the tank internal pressure Pt (gauge pressure) is equal to or lower than a threshold value Ptref slightly higher than 0 kPa, the shutoff valve 52 is controlled to be in a closed state, and when the tank internal pressure Pt is higher than the threshold value Ptref, the shutoff valve 52 is controlled to be in an open state. When the processing of step S240 is executed at the time of the completion of the execution of the opening / closing control routine and the opening of the shutoff valve 25 is prohibited, the shutoff valve 52 is maintained in a closed state until the opening of the shutoff valve 52 is permitted in a valve opening permission processing routine described later.

[0045] Next, the valve opening permission processing routine will be described. Fig. 4 is a flowchart showing an example of the valve opening permission processing routine executed by the electronic control unit 70. This routine is executed at predetermined time intervals (e.g., every few msec) when the opening of the stop valve 52 is prohibited by the execution of the opening / closing control routine.

[0046] When the valve opening permission processing routine is executed, the CPU of the electronic control unit 70 determines whether or not the high vapor condition is established (step S300), and whether or not the ignition switch 80 has been turned off and an instruction to stop the system of the automobile 10 has been issued (step S310). When the system of the automobile 10 is stopped, the fuel supply device 42 and the vaporized fuel processing device 50 are also stopped, so the processing of step S310 is processing to determine whether or not an instruction to stop the systems of the fuel supply device 42 and the vaporized fuel processing device 50 has been issued.

[0047] If the high vapor condition is not established in step S300, it is determined that the fuel currently in the fuel tank 40 is not in a state that is likely to generate vapor, and the shut-off valve 52 is permitted to open (step S320), the number of fuel pressure drops Npd is reset to a value of 0 (step S330), and the valve open permission processing routine is terminated. As a result, the next time the high vapor condition is established, the shut-off valve 52 can be opened, ensuring an opportunity to reduce the pressure inside the fuel tank 40.

[0048] If the high vapor condition is met in step S300 but a system stop command has not been issued in step S310, the valve opening permission processing routine is terminated without resetting the number of fuel pressure drops Npd and the closing valve 52 continues to be prohibited from opening. If the high vapor condition is met while the closing valve 52 is prohibited from opening, the current fuel is in a state that is highly likely to generate vapor, and therefore the internal pressure of the fuel tank 40 is increased by continuing to close the closing valve 52, thereby suppressing the generation of vapor.

[0049] If the high vapor condition is met in step S300, but a system stop command is issued in step S310, the shutoff valve 52 is permitted to open (step S320), and the number of fuel pressure drops Npd is reset to a value of 0 (step S330), and the valve open permission processing routine ends. As a result, the next time the system of the automobile 20 is turned on, the shutoff valve 52 can be opened, ensuring an opportunity to reduce the pressure inside the fuel tank 40.

[0050] According to the automobile 10 equipped with the fuel supply processing device of the embodiment described above, when a high concentration is determined, the shut-off valve 52 is closed, and then, when the fuel pressure Pf becomes equal to or higher than the target fuel pressure Pf*, the shut-off valve 52 is opened. When the fuel pressure Pf becomes equal to or lower than the lower limit fuel pressure (predetermined lower limit fuel pressure) Pfmin with the shut-off valve 52 open during a high concentration determination, the shut-off valve 52 is closed, and then, when the fuel pressure Pf becomes equal to or higher than the target fuel pressure Pf*, the shut-off valve 52 is opened. Furthermore, when the shut-off valve 52 is opened, the shut-off valve 52 is opened so that the reduction rate Sr of the internal pressure of the fuel tank 40 is slower when the number of fuel pressure drops Npd, which is the number of times that the fuel pressure Pf becomes equal to or lower than the lower limit fuel pressure Pfmin with the shut-off valve 52 open, is high compared to when it is low. When the number of fuel pressure drops Npd is equal to or higher than a predetermined number Npdref, the opening of the shut-off valve 52 is prohibited, thereby suppressing the generation of vapor.

[0051] In addition, when an instruction to stop the system of the automobile 10 is given, the shut-off valve 52 is permitted to open and the number of fuel pressure drops Npd is reset to a value of 0, thereby ensuring an opportunity to open the shut-off valve 52 and reduce the pressure inside the fuel tank 40 after the next system startup.

[0052] In the automobile 10 equipped with the fuel supply processing device of the embodiment, in the process of step S210, it is determined whether or not the number of fuel pressure drops Npd is less than the threshold value Npref. However, instead of whether or not the number of fuel pressure drops Npd is less than the threshold value Npref, it may be determined whether or not the pressure reduction rate Sr is within a predetermined low speed range including the value 0. Here, the predetermined low speed range may be a range of pressure reduction rates that can be determined to be equivalent to maintaining the pressure in the fuel tank 40. In this case, if the pressure reduction rate Sr is not within the predetermined low speed range including the value 0, it is determined that there is a possibility that the generation of vapor can be suppressed by further slowing down the pressure reduction rate Sr, and the process proceeds to step S220, and if the pressure reduction rate Sr is within the predetermined low speed range including the value 0, the process proceeds to step S240.

[0053] In the automobile 10 equipped with the fuel supply processing device of the embodiment, in step S220 of the opening / closing control routine, the target decompression speed Sr* is set by the above-mentioned formula (1) using the normal speed Sn, the number of fuel pressure drops Npd, and the decompression amount ΔSr so that it is slower when the number of fuel pressure drops Npd is large than when it is small, within a range that does not fall below the value 0. However, since the target decompression speed Sr* may be set to be slower when the number of fuel pressure drops Npd is large than when it is small, the relationship between the number of fuel pressure drops Npd and the target decompression speed Sr* may be determined in advance and stored as a map so that the target decompression speed Sr* is slower when the number of fuel pressure drops Npd is large than when it is small, and when the number of fuel pressure drops Npd is given, the corresponding target decompression speed Sr* may be derived and set from the map.

[0054] In the automobile 10 equipped with the fuel supply processing device of the embodiment, the determinations of steps S300 and S310 are executed in the valve opening permission processing routine. However, it is also possible to execute only the determination of step S310 without executing the determination of step S300.

[0055] In the automobile 10 equipped with the fuel supply processing device of the embodiment, in step S110, a value obtained by adding a predetermined fuel pressure Pfref to the target value Pfn set when the high vapor condition is not satisfied is set as the target fuel pressure Pf*, and a target discharge flow rate of the fuel pump 44 is set using feedback control with a proportional term and an integral term based on the difference between the fuel pressure Pf detected by the fuel pressure sensor 43p and the target fuel pressure Pf* to control the fuel pump 44. However, the target value Pfn set when the high vapor condition is not satisfied may be set as the target fuel pressure Pf*, and the target discharge flow rate of the fuel pump 44 may be set using feedback control with a proportional term and an integral term based on the difference between the fuel pressure Pf detected by the fuel pressure sensor 43p and the target fuel pressure Pf* to control the fuel pump 44.

[0056] In the automobile 10 equipped with the fuel supply processing device of the embodiment, the engine 12 is equipped with a fuel injection valve 26 (in-cylinder injection valve) that injects fuel into a cylinder. However, instead of or in addition to the fuel injection valve 26, a port injection valve that injects fuel into an intake port may be provided.

[0057] In the embodiment, the fuel supply processing device is provided in an automobile 10 that runs using power from an engine 12. However, the fuel supply processing device may be provided in a hybrid automobile that has a motor in addition to an engine, or in a mobile body other than an automobile or in equipment installed in a factory. Also, the fuel supply processing device may be provided in a device that operates using a fuel other than an engine.

[0058] The relationship between the main elements of the embodiment and the main elements of the invention described in the section on Means for Solving the Problems will be described below. In the embodiment, the fuel supply device 42 corresponds to the "fuel supply device", the vaporized fuel processing device 50 corresponds to the "vaporized fuel processing device", and the electronic control unit 70 corresponds to the "control device".

[0059] The correspondence between the main elements of the Examples and the main elements of the invention described in the Summary of the Problem column does not limit the elements of the invention described in the Summary of the Problem column, since the Examples are examples for specifically explaining the mode for implementing the invention described in the Summary of the Problem column. In other words, the interpretation of the invention described in the Summary of the Problem column should be based on the description in that column, and the Examples are merely a specific example of the invention described in the Summary of the Problem column.

[0060] Although the form for carrying out the present invention has been described above using examples, the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms without departing from the scope of the gist of the present invention. [Industrial Applicability]

[0061] The present invention can be used in the manufacturing industry of fuel supply processing devices, etc. [Explanation of symbols]

[0062] 10 automobile, 12 engine, 14 crankshaft, 14a crank position sensor, 15 water temperature sensor, 16 cam position sensor, 22 air cleaner, 23 intake pipe, 23a air flow meter, 23b temperature sensor, 24 throttle valve, 24a throttle position sensor, 26 fuel injector, 28 intake valve, 29 combustion chamber, 30 spark plug, 32 piston, 33 exhaust valve, 34 exhaust pipe, 35 purification device, 37 front air-fuel ratio sensor, 38 rear air-fuel ratio sensor, 40 fuel tank, 40a pressure sensor, 42 fuel supply device, 43 fuel passage, 43p fuel pressure sensor, 44 fuel pump, 44a discharge hole, 44b rotational speed sensor, 45 relief passage, 46 relief valve, 50 vaporized fuel treatment device, 51 introduction passage (vapor passage), 52 Shut-off valve, 52a shut-off valve position sensor, 52b stepping motor, 53 canister, 54 atmospheric release passage, 55 purge passage, 56 purge valve, 56a purge valve position sensor, 60 transmission, 62 differential gear, 64a, 64b drive wheels, 70 electronic control unit, 80 ignition switch, 81 shift lever, 82 shift position sensor, 83 accelerator pedal, 84 accelerator pedal position sensor, 85 brake pedal, 86 brake pedal position sensor, 88 vehicle speed sensor, 89 atmospheric pressure sensor.

Claims

1. a fuel supply device having a fuel pump for supplying fuel in a fuel tank to a fuel passage; a fuel vapor processing device having a shutoff valve disposed in a vapor passage connected to the fuel tank and the canister; a control device that controls the fuel pump so that a fuel pressure as a pressure of the fuel becomes a target fuel pressure and also controls the shutoff valve; A fuel supply processing device comprising: The control device includes: When it is determined that the concentration of vapor in the fuel tank is high, the shutoff valve is closed, and thereafter, when the fuel pressure becomes equal to or higher than the target fuel pressure, the shutoff valve is opened; When the fuel pressure becomes equal to or lower than a predetermined lower limit fuel pressure with the shut-off valve open during the high concentration determination, the shut-off valve is closed, and thereafter, when the fuel pressure becomes equal to or higher than the target fuel pressure, the shut-off valve is opened; Furthermore, the control device When the shutoff valve is opened, the shutoff valve is opened so that the rate at which the internal pressure of the fuel tank is reduced is slower when the number of fuel pressure drops, which is the number of times that the fuel pressure has become equal to or lower than the predetermined lower limit fuel pressure while the shutoff valve is open, is large compared to when the number of fuel pressure drops is small. When the number of times the fuel pressure decreases is equal to or greater than a predetermined number, or when the reduction speed is within a predetermined low speed range including a value of 0, the closing valve is prohibited from opening. Fuel supply processing unit.

2. 2. The fuel supply processing system of claim 1, When the control device prohibits the closing valve from opening when the number of times of fuel pressure drops is equal to or greater than the predetermined number of times, and when a system stop command is issued, the control device permits the closing valve to open and resets the number of times of fuel pressure drops to a value of 0. Fuel supply processing unit.

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