JP7655256B2 - Fuel Supply Processing Device - Google Patents

Description

The present invention relates to a fuel supply processing device, and more specifically, to a fuel supply processing device that includes a fuel supply device, a vaporized fuel processing device, and a fuel pressure sensor.

Conventionally, this type of fuel supply processing device has been proposed to include a fuel supply device and a fuel vapor processing device (see, for example, 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 fuel vapor processing device includes a shutoff valve (control valve) and a surge tank. The shutoff valve is provided in a vapor passage (vapor conduit) connected to the fuel tank and the canister. The surge tank temporarily stores vapor 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 is closed. This is said to suppress a drop in pressure in the fuel tank when traveling at high altitude, and to suppress the fuel in the fuel tank from vaporizing and generating vapor.

Special Publication No. 6-31576

In the above-mentioned fuel supply processing device, the pressure in the fuel tank may rise excessively by closing the shutoff valve. In this case, it is possible to open the shutoff valve to lower the pressure in the fuel tank, but if the pressure in the fuel tank drops due to the opening of the shutoff valve, the fuel vaporization in the fuel tank cannot be sufficiently suppressed, and vapor in the fuel pump or fuel passage may cause a vapor lock in which the fuel pump cannot pump fuel at the target fuel pressure. Therefore, if the fuel pressure detected by the fuel pressure sensor that detects the fuel pressure drops while the shutoff valve is open, the shutoff valve is closed again to increase the pressure in the fuel tank, suppressing fuel vaporization and suppressing the occurrence of vapor lock. However, since the detected pressure from the fuel pressure sensor may temporarily drop due to some error even when vapor lock does not actually occur, closing the shutoff valve only because the detected fuel pressure has dropped may not close at the appropriate time.

The main purpose of the fuel supply processing device of the present invention is to close the shutoff valve at a more appropriate timing.

The fuel supply processing device of the present invention employs the following means to achieve the above-mentioned main objective.

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 installed in a vapor passage connected to the fuel tank and the canister;
a fuel pressure sensor for detecting the pressure of the fuel;
a control device that controls the fuel pump and the shutoff valve so that a detected fuel pressure, which is the pressure of the fuel detected by the fuel pressure sensor, becomes a target fuel pressure;
A fuel supply processing device comprising:
The control device includes:
When it is determined that a high concentration of vapor is generated in the fuel tank, a first control is executed to close the shutoff valve,
when the detected fuel pressure becomes equal to or higher than the target fuel pressure as a result of the execution of the first control, a second control is executed to open the blocking valve;
When a predetermined time has elapsed since the start of execution of the second control and the detected fuel pressure is lower than the target fuel pressure, a third control is executed to close the stop valve.

In the fuel supply processing device of the present invention, when it is determined that a high concentration of vapor has been generated in the fuel tank, a first control is executed to close the shutoff valve. The first control increases the pressure in the fuel tank to suppress fuel vaporization and suppress the generation of vapor. This suppresses the occurrence of vapor lock, in which the fuel pump cannot pump fuel at the target fuel pressure due to vapor in the fuel tank or fuel passage. Then, when the first control is executed and the detected fuel pressure becomes equal to or higher than the target fuel pressure, a second control is executed to open the shutoff valve. The second control suppresses an excessive increase in the internal pressure of the fuel tank. Then, when a predetermined time has elapsed since the start of execution of the second control and the detected fuel pressure is equal to or lower than the threshold value, a third control is executed to close the shutoff valve. When the shutoff valve is opened, the pressure in the fuel tank decreases, making it impossible to sufficiently suppress fuel vaporization, which may cause vapor lock to occur and reduce the fuel pressure. The drop in fuel pressure due to vapor lock occurs after a certain amount of time has elapsed since the second control was started, i.e., after the shutoff valve was opened. Therefore, if the fuel pressure starts to drop immediately after the shutoff valve is opened, it is believed that an error has occurred in the detection value from the fuel pressure sensor due to some factor. Therefore, when a predetermined time has elapsed since the second control was started and the detected fuel pressure is equal to or lower than the threshold, the shutoff valve can be closed at a more appropriate timing by executing the third control to close the shutoff valve. Note that the "predetermined time" may be a time determined in advance by experiment, analysis, machine learning, etc., as the time from the start of the second control to open the shutoff valve to the time when vapor lock occurs due to the drop in pressure in the fuel tank caused by the shutoff valve being opened.

In the fuel supply processing device of the present invention, the control device controls the fuel pump by setting a target discharge flow rate of the fuel pump using feedback control with a proportional term and an integral term based on the difference between the detected fuel pressure and the target fuel pressure, and the control device may determine that a high concentration of vapor has been generated in the fuel tank when the fuel in the fuel tank is in a predetermined state in which it is easy to vaporize and the time change amount of the integral term in the feedback control of the fuel pump is equal to or greater than a predetermined change amount. In this way, it is possible to properly determine that a high concentration of vapor has been generated in the fuel tank. Note that the "predetermined state" can be when the atmospheric pressure is low and the fuel temperature is high, for example, when the vehicle is in a high-temperature environment at high altitude. The "predetermined change amount" can be a threshold value for determining whether the integral term has increased significantly because the fuel pressure does not increase even though the fuel pump is driven.

In this case, the vaporized fuel processing device has a purge passage that connects the canister and the intake pipe of the engine, and the control device may determine that a high concentration of vapor has been generated in the fuel tank when the predetermined state is reached and the amount of change over time of the integral term is equal to or greater than the predetermined amount of change, or when the predetermined state is reached and a purge concentration, which is the ratio of vaporized fuel (vapor) to the amount of gas supplied to the intake pipe, is equal to or greater than a predetermined concentration.

The fuel supply processing device of the present invention also includes a drive motor that drives the shutoff valve, and the control device controls the drive motor in the first control so that the shutoff valve closes at a first speed, and in the third control so that the control device controls the drive motor so that the shutoff valve closes at a second speed that is faster than the first speed. In the third control, by controlling the drive motor so that the shutoff valve closes at the second speed that is faster than the first speed, the pressure in the fuel tank can be increased more quickly and the generation of vapor can be suppressed.

In this case, the second speed may be a maximum speed that is predetermined as the fastest speed at which the shut-off valve closes. In this way, the shut-off valve is closed quickly, and vapor generation can be quickly suppressed. After the third control is executed, an initialization process may be executed to learn the reference position of the shut-off valve. In this way, even if the drive motor loses step-out due to the execution of the third control, the initialization process learns the reference position of the shut-off valve, and the subsequent control of the shut-off valve can be executed appropriately.

Furthermore, in the fuel supply processing device of the present invention, the control device may set the target fuel pressure higher when executing the first to third controls compared to when executing a control different from the first to third controls. In this way, more vapor can be crushed in the fuel pump and fuel passages using fuel pressure, further suppressing the occurrence of vapor lock.

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; 4 is a flowchart showing an example of a high vapor processing routine executed by an electronic control unit 70.

Next, we will explain how to implement the present invention using examples.

Figure 1 is a schematic diagram showing the configuration of an automobile 10 equipped with a fuel supply processing device as one embodiment of the present invention. As shown in the figure, the automobile 10 of the embodiment is equipped with an engine 12, a fuel supply device 42, a vaporized fuel processing device 50, a transmission 60 connected to the crankshaft 14 of the engine 12 and connected to drive 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.

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 cleaned by an air cleaner 22 into an intake pipe 23, passes it through a throttle valve 24, and injects 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 a 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).

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

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 fuel pressure (fuel pressure Pf) in the fuel passage 43 is less than the valve opening pressure Pfrv of the relief valve 46, and opens when the fuel pressure 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 fuel pressure in the fuel passage 43 is prevented from becoming excessive.

The vaporized fuel processing device 50 is configured to perform a purge that supplies vaporized fuel gas (purge gas) containing vaporized fuel generated in the fuel tank 40 to the intake pipe 23. The 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.

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

The shutoff valve 52 is a flow rate control valve that, in a closed state, shuts off the introduction passage (vapor passage) 51 to block 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 freely 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 the 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 the 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 the electronic control unit 70.

The canister 53 is connected to the introduction passage (vapor passage) 51 and the purge passage 55, and is open to the atmosphere via the atmosphere release 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 release passage 54 is provided with an air filter (not shown).

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. This purge valve 56 is controlled by the electronic control unit 70.

This vaporized fuel processing device 50 performs purging by adjusting the opening of the 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 with the flow rate adjusted via the introduction passage (vapor passage) 51, the canister 53, and the purge passage 55 by utilizing the negative pressure in the intake pipe 23. 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.

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.

Examples of signals input to the electronic control unit 70 include the crank angle θcr from the crank position sensor 14a that detects the rotational position of the crankshaft 14 of the engine 12, and the cooling water temperature Tw from the water temperature sensor 15 that detects the temperature of the cooling water of the engine 12. Other examples include the throttle opening TH from the throttle position sensor 24a that detects the opening (position) of the throttle valve 24, and the cam angles θci and θco from the cam position sensor 16 that detects the rotational positions of the intake camshaft that opens and closes the intake valve 28 and the exhaust camshaft that opens and closes the exhaust valve 33. Other examples of the intake air quantity Qa from an air flow meter 23a attached upstream of the throttle valve 24 of the intake pipe 23, the 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 purifier 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 purifier 35 of the exhaust pipe 34. Other examples of the intake air quantity Qa from an air flow meter 23a ... Tank internal pressure Pt, which is the pressure inside the fuel tank 40, from a pressure sensor 40a attached to the fuel tank 40, fuel pressure Pf, which is the pressure of the fuel inside the fuel passage 43, from a fuel pressure sensor 43p attached near the fuel injection valve 26 of the fuel passage 43 (for example, a delivery pipe), and the rotation speed Np of the fuel pump 44 from a rotation speed sensor 44b attached to the fuel pump 44 can also be mentioned. Examples of the opening degree Osv of the shutoff valve 52 from the shutoff valve position sensor 52a that detects the opening degree (position) of the shutoff valve 52, and the opening degree Opv of the purge valve 56 from the purge valve position sensor 56a that detects the opening degree (position) of the purge valve 56 can also be mentioned. Examples of the opening degree Osv of the shutoff valve 52 from the shutoff valve position sensor 52 ...

Various control signals are output from the electronic control unit 70 via the 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).

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 the 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 volume Qa from the air flow meter 23a and the rotation speed Ne of the engine 12. Furthermore, the electronic control unit 70 calculates the consumption flow rate Qfr of the engine 12 based on the fuel injection amount Qf from the fuel injection valve 26.

In the automobile 10 of the embodiment thus configured, the electronic control unit 70 performs operation control of the engine 12 based on the required load rate KL* of the engine 12, which is based on the accelerator opening Acc and the vehicle speed V, specifically, intake air amount control that controls the opening of the throttle valve 24, fuel injection control that controls the amount of fuel injected from the fuel injection valve 26, and ignition control that controls the ignition timing of the spark plug 30. 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.

In the operation control of the engine 12, in the intake air amount control, the electronic control unit 70 sets the target opening TH* of the throttle valve 24 based on the required load rate 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 the target ignition timing Ti* of the spark plug 30 based on the rotation speed Ne and load rate 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 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*, and the fuel pump 44 is controlled. In controlling the shutoff 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 shutoff valve 52 is controlled to be in a closed state, and when the tank internal pressure Pt is higher than the threshold Ptref, the shutoff 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 so that the above-mentioned purge is performed, 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, the operation control of the engine 12 (fuel injection control, etc.) is being performed, and the shutoff valve 52 is in an open state, is used.

Next, the operation of the automobile 10 of the embodiment thus configured will be described, particularly the operation when the vapor in the fuel tank 40 is at a high concentration. FIG. 2 is a flow chart showing an example of a high vapor processing routine executed by the electronic control unit 70. This routine is executed when the shutoff valve 52 and the purge valve 56 are open and a high vapor condition occurs in which the vaporized fuel in the fuel tank 40 is at a high concentration.

The high vapor condition can be when the first condition is satisfied and at least one of the second and third conditions is satisfied. The first condition can 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 fuel's saturated vapor pressure curve, that is, 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 location. In the first condition, if a fuel temperature sensor that detects the temperature of the fuel in the fuel tank 40 is provided, 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 can 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, that is, the vaporized fuel in the fuel tank 40 is highly concentrated. 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 injection valve 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 time change amount of the integral term in the feedback control of the fuel pump 44 is equal to or greater than a predetermined change amount, that is, the integral term is in a state where the fuel pressure does not increase even though the fuel pump 44 is driven. The predetermined change amount 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 even though the fuel pump 44 is driven.

When this routine is executed, the CPU (not shown) of the electronic control unit 70 executes the first control of steps S100 to S130. In step S100, the stepping motor 52b is controlled so that the shutoff valve 52 is closed at a closing speed Sc1 (step S100). The closing speed Sc1 is set based on the characteristics of the stepping motor 52b as a speed slower than the closing speed corresponding to the lower limit of the rotation speed at which the stepping motor 52b steps out. By closing the shutoff valve 52 in this manner, the pressure in the fuel tank 40 is increased to suppress fuel evaporation and the generation of vapor. This makes it possible to suppress the occurrence of vapor lock, in which the fuel pump 44 is unable to pump fuel at the target fuel pressure Pf* due to vapor in the fuel pump 44 or the fuel passage 43.

Next, the target fuel pressure Pfn* is set by adding a predetermined fuel pressure Pfref to the target fuel pressure Pfn*, which is set when the high vapor condition is not satisfied and a process different from this routine is being performed, and the 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 fuel pressure Pfn* is obtained by previously determining the relationship between the required air amount Qa* based on the accelerator opening Acc and the engine speed Ne of the engine 12, the engine speed Ne of the engine 12, and the target fuel pressure Pfn*, and storing it as a target fuel pressure setting map. When the required air amount Qa* and the engine speed Ne are given, the corresponding target fuel pressure Pfn* is derived from the map. The predetermined fuel pressure Pfref is determined in advance through experiments, analysis, machine learning, etc. as an increase amount that, when added to the target fuel pressure Pfn*, increases the target fuel pressure Pfn* to a pressure that can crush bubbles in the fuel pump 44 and the fuel passage 43. By increasing the fuel pressure Pf in this way, it is possible to crush bubbles in the fuel pump 44 and the fuel passage 43, and the occurrence of vapor lock can be suppressed.

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 vapor lock has occurred in the fuel pump 44 and that the fuel pump 44 is not generating sufficient fuel pressure, and the system waits until the fuel pressure Pf becomes equal to or greater than the target fuel pressure Pf* (steps S120, S130).

When the fuel pressure Pf is equal to or greater than the target fuel pressure Pf* in step S130, it is determined that vapor lock has not occurred in the fuel pump 44 and that sufficient fuel pressure is being generated by the fuel pump 44, and a second control is executed to control the stepping motor 52b so that the shutoff valve 52 opens at the opening speed So (step S140). This allows the pressure in the fuel tank 40 to be reduced. Here, the opening speed So is a speed that is determined in advance through experiments, analysis, machine learning, etc. as the speed at which the pressure in the fuel tank 40 slowly decreases. By opening the shutoff valve 52 in this way, the pressure in the fuel tank 40 is reduced. This makes it possible to prevent the pressure in the fuel tank 40 from becoming excessively high.

Next, the process waits until the elapsed time to from the start of opening the shutoff valve 52 in step S140 reaches a predetermined time toref (step S150). When the elapsed time to reaches the predetermined time toref, the fuel pressure Pf is input in the same process as in step S120 (step S160), and it is determined whether the fuel pressure Pf is equal to or greater than the target fuel pressure Pf* (step S170). The predetermined time toref in step S150 is a time determined in advance by experiment, analysis, machine learning, etc. as the time from the start of execution of the second control for opening the shutoff valve 52 in step S140 to the occurrence of vapor lock due to a decrease in pressure in the fuel tank 40 caused by opening the shutoff valve 52, and is set to, for example, 18 msec, 20 msec, 22 msec, etc.

The reason for waiting until the elapsed time to reaches the predetermined time toref in step S150 is as follows. When the shut-off valve 52 is opened in step S140, the pressure in the fuel tank 40 drops. Then, more fuel vaporizes in the fuel tank 40, the vapor concentration increases, vapor lock occurs in the fuel pump 44, and the fuel pressure Pf drops. This drop in fuel pressure Pf does not occur immediately after the shut-off valve 52 starts to open (execution of the second control), but occurs after a certain amount of time (the predetermined time toref) has passed. Therefore, if the fuel pressure Pf drops immediately after the shut-off valve 52 is opened, it is considered that an error has occurred in the detection value (fuel pressure Pf) of the fuel pressure sensor 43p due to some factor. In steps S150 to S170, the system determines whether the fuel pressure Pf is equal to or greater than the target fuel pressure Pf* after the elapsed time to has exceeded a predetermined time toref in order to prevent an error in the detection value (fuel pressure Pf) of the fuel pressure sensor 43p from being mistakenly determined to mean that the fuel pressure is actually decreasing.

When the elapsed time to has exceeded the predetermined time toref in step S150, and the fuel pressure Pf is equal to or greater than the target fuel pressure Pf* in steps S160 and S170, it is determined that vapor lock has not occurred and this routine ends.

In step S150, when the elapsed time to has exceeded the predetermined time toref but the fuel pressure Pf is less than the target fuel pressure Pf*, it is determined that vapor lock has occurred and the fuel pressure has dropped, and a third control is executed to control the stepping motor 52b so that the shutoff valve 52 is closed at the closing speed Sc2 (step S180). The closing speed Sc2 is the fastest closing speed corresponding to the maximum rotation speed allowed for the stepping motor 52b, and is set based on the characteristics of the stepping motor 52b as a speed faster than the closing speed Sc1. Here, the reason for closing the shutoff valve 52 at the fastest closing speed will be explained. When the fuel pressure Pf drops despite once becoming equal to or greater than the target fuel pressure Pf* in steps S100 to S130, it is considered that the fuel is very likely to vaporize and vapor lock is likely to occur. In this case, if the pressure in the fuel tank 40 is not quickly increased by quickly closing the shutoff valve 52, the fuel injection valve 26 will not be able to inject a sufficient amount of fuel due to the drop in fuel pressure, and the engine 12 may stall. Therefore, by closing the shutoff valve 52 as quickly as possible, the pressure in the fuel tank 40 is quickly increased to suppress fuel vaporization and the generation of vapor in the fuel tank 40 and the fuel passage 43. This suppresses engine stall. In addition, when the elapsed time to from when the shutoff valve 52 starts to open in step S150 has exceeded the predetermined time toref and the fuel pressure Pf is less than the target fuel pressure Pf*, the shutoff valve 52 is closed. This prevents the shutoff valve 52 from being closed due to an error in the detection value (fuel pressure Pf) of the fuel pressure sensor 43p being erroneously determined to be the occurrence of vapor lock, and the shutoff valve 52 can be closed at a more appropriate timing.

After closing the shutoff valve 52 at the closing speed Sc2 in this way, an initialization process is executed (step S190), and this routine is terminated. The initialization process is a process in which the stepping motor 52b is controlled to open the shutoff valve 52 slightly enough to maintain the closed state, and then close until it hits a bump, and the bumping position is learned as a reference position. If the shutoff valve 52 is closed at the fastest speed in step S180, the stepping motor 52b may lose synchronism. The initialization process is a process in which the reference position is learned when the stepping motor 52b loses synchronism. By executing the initialization process in this way, it becomes possible to appropriately control the opening and closing of the shutoff valve 52 after this routine is terminated. After this routine is completed, when the tank internal pressure Pt (gauge pressure) is equal to or lower than a threshold value Ptref that is 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.

According to the automobile 10 equipped with the fuel supply processing device of the embodiment described above, when it is determined that a high concentration of vapor has been generated in the fuel tank 40, a first control is executed to close the shutoff valve 52 until the fuel pressure Pf (detected fuel pressure) becomes equal to or greater than the target fuel pressure Pf*. When the fuel pressure Pf becomes equal to or greater than the target fuel pressure Pf* as a result of the execution of the first control, a second control is executed to open the shutoff valve 52. When the elapsed time to from the start of the execution of the second control has passed a predetermined time toref and the fuel pressure Pf is less than the target fuel pressure Pf*, a third control is executed to close the shutoff valve 52, thereby closing the shutoff valve 52 at a more appropriate timing.

In the automobile 10 equipped with the fuel supply processing device of the embodiment, in step S180, the closing speed Sc2 is set to the fastest closing speed corresponding to the maximum rotation speed allowed for the stepping motor 52b. However, the closing speed Sc2 may be any speed that quickly closes the stop valve 52, and may be a speed slightly slower than the fastest closing speed corresponding to the maximum rotation speed allowed for the stepping motor 52b, or may be the same as the closing speed Sc1.

In the automobile 10 equipped with the fuel supply processing device of the embodiment, in step S110, the target fuel pressure Pfn* set when the high vapor condition is not satisfied is added to the predetermined fuel pressure Pfref to set the target fuel pressure Pf*, and the target discharge flow rate of the fuel pump 44 is set using feedback control with proportional and integral terms 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 fuel pressure Pfn* set when the high vapor condition is not satisfied may be set to the target fuel pressure Pf*, and the target discharge flow rate of the fuel pump 44 may be set using feedback control with proportional and integral terms 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.

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 the cylinder. However, instead of or in addition to the fuel injection valve 26, a port injection valve that injects fuel into the intake port may be provided.

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. The fuel supply processing device may also be provided in a device that runs on a fuel other than an engine.

The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be explained. 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", the fuel pressure sensor 43p corresponds to the "fuel pressure sensor", and the electronic control unit 70 corresponds to the "control device".

The correspondence between the main elements of the Examples and the main elements of the invention described in the Means for Solving the Problem column does not limit the elements of the invention described in the Means for Solving the Problem column, since the Examples are examples for specifically explaining the form for implementing the invention described in the Means for Solving the Problem column. In other words, the interpretation of the invention described in the Means for Solving 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 Means for Solving the Problem column.

The above describes the form for carrying out the present invention using examples, but 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 invention.

The present invention can be used in the fuel supply processing equipment manufacturing industry, etc.

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 injection valve, 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 exhaust 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 connected to a fuel injection valve of the engine ;
a vaporized fuel processing device including a shutoff valve installed in a vapor passage connected to the fuel tank and a canister, and a purge passage connecting the canister and a downstream side of a throttle valve of an intake pipe of the engine, the vaporized fuel gas including vapor generated in the fuel tank being supplied to the intake pipe;
a fuel pressure sensor for detecting the pressure of the fuel;
a control device that feedback controls the fuel pump and controls the shutoff valve so that a detected fuel pressure, which is the pressure of the fuel detected by the fuel pressure sensor, becomes a target fuel pressure;
A fuel supply processing device comprising:
The control device includes:
determining that a high concentration of vapor has been generated in the fuel tank when a first condition is satisfied and at least one of a second condition and a third condition is satisfied;
when it is determined that a high concentration of vapor has been generated in the fuel tank, a first control is executed to close the shutoff valve until the detected fuel pressure becomes equal to or higher than the target fuel pressure;
when the detected fuel pressure becomes equal to or higher than the target fuel pressure as a result of the execution of the first control, a second control is executed to open the blocking valve;
when a predetermined time has elapsed since the start of execution of the second control and the detected fuel pressure is lower than the target fuel pressure, a third control is executed to close the blocking valve ;
the first condition is that a state of the fuel determined by an intake air temperature and an atmospheric pressure upstream of the throttle valve in the intake pipe is on a high temperature/low pressure side of a saturated vapor pressure curve of the fuel,
The second condition is that a purge concentration, which is a ratio of vapor to an amount of gas supplied to the intake pipe, is equal to or higher than a predetermined concentration,
The third condition is that a time change amount of an integral term in the feedback control of the fuel pump is equal to or greater than a predetermined change amount.
Fuel supply processing unit.

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