JP4172167B2 - Oil supply control device for closed tank system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oil supply control device for a closed tank system, and more particularly to an oil supply control device that prevents excessive oil supply to the closed tank system.
[0002]
[Prior art]
In order to prevent the evaporated fuel from being released into the atmosphere from the fuel tank of an internal combustion engine, particularly an automobile engine, the fuel tank is sealed to prevent the evaporated fuel (fuel vapor) from leaking out of the tank. A so-called sealed fuel tank system is known.
[0003]
In the closed fuel tank system, when fuel is injected into the tank at the time of refueling, the gas in the upper space of the liquid surface (the mixture of fuel vapor and air) is compressed due to the rise of the liquid level in the tank, and the tank internal pressure rises. When the tank internal pressure becomes high to some extent, the fuel supplied from the tank oil supply pipe cannot flow into the tank and the fuel supply becomes impossible. For this reason, in the sealed fuel tank system, the upper surface of the liquid level in the fuel tank is connected to the canister that stores the fuel vapor adsorbent via the breather pipe, and an electromagnetic on-off valve (vent valve) is provided on the breather pipe to supply the fuel. Sometimes the vent valve is opened to exhaust the gas in the tank to the canister.
[0004]
As described above, when the gas in the tank is exhausted to the canister during refueling, the valve is opened when the fuel is excessively refilled and an amount of fuel exceeding the design capacity (so-called full fuel amount) is injected into the tank. The fuel may enter the canister from the vent valve via the breather pipe. When liquid fuel reaches the canister, the adsorbent in the canister saturates with the adsorbed fuel, so that fuel vapor cannot be adsorbed, and fuel that has entered the canister or breather piping leaks to the outside. .
[0005]
For example, Japanese Patent Application Laid-Open No. 6-235346 discloses a configuration for preventing refueling (excessive refueling) exceeding the design capacity of the tank as described above.
In the apparatus of the publication, a vent valve is arranged on a vent passage (breather piping) that connects the upper liquid level space in the tank to the canister, and when refueling, the vent valve is opened to allow gas in the tank to pass through the vent passage. By exhausting to the canister, the tank internal pressure rise during refueling is prevented. In addition, the apparatus of the same publication is provided with a liquid level detection sensor for detecting the liquid level (liquid level) in the fuel tank, and when the liquid level in the tank becomes a predetermined height or higher during refueling. The vent valve is closed.
[0006]
Normally, fuel supply is performed by inserting a fuel supply nozzle into a fuel supply pipe of a fuel tank and injecting fuel from the fuel supply nozzle through the fuel supply pipe. The fuel supply nozzle is provided with an auto-stop mechanism. The auto-stop mechanism is a mechanism that stops oil supply when the liquid level in the oil supply pipe rises and reaches a liquid level detection hole provided in the nozzle. In the apparatus disclosed in the above publication, the vent valve is closed when the liquid level in the fuel tank becomes equal to or higher than a predetermined level, and therefore the tank internal pressure rises when refueling is continued. For this reason, the liquid level in the oil supply pipe also rises according to the tank internal pressure, and when the tank internal pressure reaches a certain pressure, the auto-stop mechanism is activated to automatically stop the oil supply. In the apparatus of the publication, this prevents excessive fuel supply to the tank.
[0007]
[Problems to be solved by the invention]
However, if the vent valve is closed when the detected liquid level reaches a predetermined height as in the device disclosed in Japanese Patent Laid-Open No. 8-235346, there may be a problem at the end of refueling.
For example, in the apparatus of the above publication, when the liquid level in the tank reaches a predetermined height and the vent valve closes, the liquid level continues to rise further by the fuel injected from the fueling nozzle, and the tank internal pressure rises accordingly. . This pressure rise speed is a speed corresponding to the liquid level rise speed, that is, the oil supply flow rate from the oil supply nozzle.
[0008]
In the apparatus of the above publication, after the vent valve is closed, when the tank internal pressure rises and reaches a predetermined pressure, the auto stop of the oil supply nozzle is activated and the oil supply is stopped, but when the oil supply flow rate from the nozzle is large, the internal pressure Ascending speed also increases. On the other hand, when the vent valve is opened, a gas with the same volume as the fuel flowing in due to the fuel flow rate flows out of the tank from the vent valve, so the gas flow rate flowing from the vent valve through the breather pipe to the canister is almost the same as the fuel flow rate. .
[0009]
In this case, the pressure loss of the gas when the vent valve is opened and when passing through the canister increases as the flow rate increases. That is, as the oil supply flow rate increases, the pressure loss of the exhausted gas increases and the tank internal pressure increases. For this reason, when the oil supply flow rate is large, the tank internal pressure when the vent valve is closed is also high. Moreover, when the oil supply flow rate is large as described above, the tank internal pressure increase rate after the vent valve is closed also increases. For this reason, after the tank internal pressure reaches the pressure at which the automatic stop mechanism operates and the actual refueling is stopped, an overshoot of the tank internal pressure may occur and the tank internal pressure may increase greatly. Thus, when the tank internal pressure rises greatly after the end of refueling, there is a problem that so-called blowback (spit back) occurs in which the fuel in the oil supply pipe is pushed out from the fuel filler port due to the tank internal pressure.
[0010]
Further, in this case, the fuel liquid level in the tank when the fuel supply is stopped varies, and there may be an excessive fuel supply in which fuel is injected beyond the design capacity.
In view of the above problems, an object of the present invention is to provide an oil supply control device for a closed tank system that can accurately control an oil supply amount without causing blow-back or excessive oil supply at the end of oil supply.
[0011]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a fuel supply control device for a sealed fuel tank system that adjusts the tank internal pressure when supplying fuel to the sealed fuel tank and prevents excessive fuel supply to the tank, the pressure detecting the tank internal pressure. Detection means, exhaust means for exhausting the gas in the upper liquid level space in the tank to a predetermined location outside the tank during refueling, refueling flow estimation means for estimating the refueling flow based on the tank internal pressure during refueling, and A fuel amount detecting means for determining whether or not the fuel amount in the fuel tank has reached a predetermined reference amount, and a target value of the tank internal pressure increase rate is set based on the fuel supply flow rate estimated by the fuel supply flow rate estimating means. After the target pressure change setting means and the fuel amount detection means detect that the fuel amount in the tank has reached the reference amount, the rate of increase in the tank internal pressure detected by the pressure detection means is Lubrication control system for closed tank system comprising a pressure control means for controlling operation of said exhaust means to match the target value, is provided.
[0012]
That is, in the first aspect of the invention, after the fuel amount in the tank reaches a predetermined reference amount (that is, the reference liquid level) by refueling, the tank pressure increase rate is controlled to the target value by the pressure control means. For example, in the case where a vent valve is provided as an exhaust means, the pressure control is performed by opening and closing the vent valve to exhaust the gas in the tank to the canister. Further, the target value of the tank internal pressure increase speed is set based on the actual oil supply flow rate estimated by the oil supply flow rate estimating means.
As a result, the tank internal pressure increase speed is controlled to the target value, so that the internal pressure increase speed is excessively prevented and the tank internal pressure overshoot is prevented at the end of refueling, and the occurrence of blow-back at the end of refueling is reliably prevented. The
In addition, since the target value of the tank internal pressure increase speed is set according to the actual oil supply flow rate, it is possible to accurately control the liquid level in the tank when the oil supply is stopped.
[0013]
According to a second aspect of the present invention, the target pressure change setting means is calculated based on the fuel supply flow rate estimated by the fuel supply flow rate estimation means, and after the fuel amount in the tank reaches the reference amount. Based on the time required to reach a predetermined target amount and the tank internal pressure when the fuel in the tank reaches the reference amount, the tank internal pressure is predetermined when the fuel amount in the tank reaches the target amount. The oil supply control device for a closed tank system according to claim 1, wherein a target value of the tank internal pressure increase rate is set so as to be equal to the target pressure.
[0014]
That is, in the invention of claim 2, the target value of the tank internal pressure increase rate is set so as to become a predetermined target pressure when the fuel amount in the tank reaches a target amount larger than the reference amount. In this case, since the actual fuel supply flow rate is estimated by the fuel supply flow rate estimation means, the time until the fuel amount in the tank reaches the target amount from the reference amount can be calculated based on the fuel supply amount. In addition, since the tank internal pressure when the reference amount is reached is detected by the pressure detection means, when the fuel amount reaches the target amount (for example, the tank design capacity), the tank internal pressure is set to the target pressure (for example, the auto stop mechanism of the fueling nozzle is activated). The tank internal pressure increase speed (target speed) required to obtain the target pressure can be calculated by dividing the difference between the target pressure and the tank internal pressure when the reference amount is reached by the time until the target amount is reached. In the present invention, by setting the target value of the tank pressure increase rate as described above, when the fuel amount in the tank reaches the target amount (for example, the design capacity, that is, the so-called full tank capacity), the auto stop mechanism is accurately operated. Therefore, it is possible to stop refueling, and it is possible to reliably prevent excessive refueling.
[0015]
According to the third aspect of the present invention, the additional fuel supply detecting means for detecting that the additional fuel supply is started again after the fuel amount in the tank reaches the target amount and the fuel supply is completed, and the additional fuel supply. An additional oil supply target pressure change setting means for setting a target value of the tank internal pressure increase speed when the pressure is started, and the pressure control means detects the tank internal pressure increase speed detected by the pressure detection means during the additional oil supply. The oil supply control device for the closed tank system according to claim 1 or 2, wherein the operation of the exhaust means is controlled so as to match a target value at the time of the additional oil supply.
[0016]
That is, in the third aspect of the invention, for example, when the amount of fuel in the tank reaches the target amount and the refueling is once stopped and then the additional refueling is performed again, the tank internal pressure increasing speed is A target value different from the target value at the time of refueling is set, and the same operation is performed. Thereby, it is possible to reliably prevent the blow-back at the end of the refueling even during the additional refueling.
[0017]
According to the fourth aspect of the present invention, the additional oil supply target pressure change setting means is based on the oil supply flow rate estimated by the oil supply flow rate estimation means before the fuel amount in the tank reaches the target amount. Based on the calculated time required for the amount of fuel in the tank to reach a predetermined allowable maximum amount from the target amount, and the pressure in the tank when the additional fueling is started, the amount of fuel in the tank is The oil supply control device for a closed tank system according to claim 3, wherein a target value of a tank internal pressure increase rate at the time of additional oil supply is set so that the tank internal pressure becomes the target pressure when an allowable maximum amount is reached.
[0018]
That is, in the invention of claim 4, the tank internal pressure is set to the target pressure when the fuel amount in the tank reaches the allowable maximum amount at the time of additional fueling. In addition, as the oil supply flow rate when calculating the target value of the tank pressure increase rate, the oil supply flow rate estimated before reaching the target value is used. In the additional fuel supply after the fuel in the tank reaches the target amount (full tank capacity) and the fuel supply is once stopped, it is usual to reduce the fuel supply flow rate and supply the fuel little by little. For this reason, by setting the target value of the tank internal pressure increase speed using the refueling flow rate at the time of refueling before reaching the target amount, the tank internal pressure actually reaches the target value before the fuel amount in the tank reaches the allowable maximum amount. (For example, the pressure at which the auto-stop mechanism operates) is reached. For this reason, it is reliably prevented that the amount of fuel in the tank exceeds the allowable maximum amount by refueling at the time of additional refueling.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram showing a schematic configuration of an embodiment in which the present invention is applied to an automobile fuel tank. In FIG. 1, reference numeral 100 denotes an internal combustion engine main body, 1 denotes an intake passage of the internal combustion engine 100, and 3 denotes an air cleaner disposed in the intake passage 1. The intake passage 1 is provided with a throttle valve 6 having an opening degree corresponding to the driver's operation of an accelerator pedal (not shown).
Reference numeral 11 in FIG. 1 denotes an engine fuel tank. The fuel oil in the tank 11 is boosted by the fuel pump 70 and is pumped to the fuel injection valve 101 of each cylinder of the engine 100 via the feed pipe 71.
[0020]
The fuel tank 11 is provided with an oil supply pipe 111 for supplying oil into the tank. In the present embodiment, the vicinity of the inlet (fuel supply port) 114 of the fuel supply pipe 111 communicates with the liquid level upper space in the fuel tank 11 through the circulation passage (circulation line) 111a. The circulation line 111a has a function of supplying gas in the fuel tank 11 to the vicinity of the fuel filler port 114 when fuel is supplied from the fuel filler port 114 and preventing the inside of the fuel filler pipe 111 from becoming negative pressure.
In FIG. 1, reference numeral 115 denotes a lid that covers the oil supply port 114 of the oil supply pipe 111. In this embodiment, in order to supply oil into the tank from the oil supply pipe 111, it is necessary to open the lid 115 and remove the cap 113 provided at the oil supply port 114 of the oil supply pipe. The lid 115 includes an actuator of an appropriate type such as a solenoid actuator, and is provided with a lid opener 115a that opens the lid 115 by a drive signal from an electronic control unit (ECU) 30 described later.
[0021]
A breather pipe 13 is connected to the upper part of the tank 11 to connect a space above the fuel oil level in the tank 11 to a canister 10 described later.
A vent valve 131 made of a solenoid valve or the like, a COV (CUT OFF VALVE) 132 and a ROV (ROLL OVER VALVE) 133 each made of a float valve are provided at a connection portion between the breather pipe 13 and the tank 11. As will be described later, the vent valve 131 is opened and closed by a drive signal from the ECU 30 and has a function of discharging the fuel paper in the fuel tank 11 to the canister 10 through the breather pipe 13.
[0022]
In the present embodiment, the vent valve 131 is always closed, and the fuel tank 11 is maintained in a sealed state. As a result, the fuel vapor generated by the evaporation of the fuel in the fuel tank 11 is sealed in the fuel tank 11 and does not leak outside. For this reason, the diffusion of the fuel vapor to the atmosphere is completely prevented.
However, as a result of sealing the fuel tank 11, for example, when high-temperature return fuel from the fuel injection valve 101 flows into the fuel tank 11 during engine operation and the fuel temperature in the tank rises, the fuel vapor pressure increases accordingly. Tank internal pressure rises. In the present embodiment, the fuel tank 11 is provided with a pressure sensor 120 that detects the pressure in the space above the liquid level in the tank, and the tank internal pressure exceeds an allowable value (for example, the design pressure of the fuel tank) during engine operation. When the pressure rises, the vent valve 131 is opened, and the fuel vapor in the tank is released to the canister 10 via the breather pipe 13 so as to lower the tank internal pressure.
[0023]
The valve is closed when the liquid level of the ROV 133 provided in the tank 11 rises during refueling, and the connection between the vent valve 131 and the fuel tank 11 is cut off. The ROV 133 also has a function of closing a connection portion between the vent valve 131 and the tank 11 when the vehicle falls or the like and preventing a large amount of fuel oil from leaking to the outside via the breather pipe 13.
The COV 132 is arranged in parallel with the ROV 133 and shuts off the communication between the vent valve 131 and the tank 11 when the liquid level rises further than the ROV 133. When the liquid level rises during refueling, the COV 132 is opened even after the ROV 133 is closed, and the tank 11 and the vent valve 131 are communicated with each other. When the surface has reached, or when the vehicle falls, etc., the valve is closed and has a function of preventing fuel oil from entering the breather pipe 13 through the vent valve 131.
[0024]
Reference numeral 30 in FIG. 1 denotes an engine electronic control unit (ECU). The ECU 30 includes a microcomputer having a known configuration in which a ROM (read only memory), a RAM (random access memory), a CPU (microprocessor), and an input / output port are connected to each other via a bidirectional bus. In addition to the above basic control, in this embodiment, as will be described later, a tank internal pressure control operation is performed to adjust the tank internal pressure during refueling to prevent excessive refueling and blowback at the end of refueling.
[0025]
For the above control, the output port of the ECU 30 is connected to the fuel injection valve 101 of the engine 100 via a drive circuit (not shown), and is connected to the vent valve 131 in addition to controlling the fuel injection amount from the fuel injection valve. Open / close control of the vent valve 131 is performed. In the present embodiment, the vent valve 131 is a solenoid valve, and repeats the opening / closing operation in accordance with ON / OFF of the drive pulse signal from the ECU 30 input to the solenoid actuator. The flow rate of the gas passing through the vent valve 131 increases in proportion to the ratio (duty ratio) that the ON time of the drive pulse signal (vent valve open) occupies in one cycle of the pulse signal. Therefore, the duty ratio has the same meaning as the valve opening in a normal control valve. For this reason, in this specification, the duty ratio of the drive pulse signal of the vent valve 131 may be referred to as the opening degree of the vent valve for convenience. In this case, the fully opened state of the vent valve 131 corresponds to a state where the duty ratio of the drive pulse signal is 100%, and the fully closed state corresponds to a state where the duty ratio is 0. Further, when a normal control valve is used as the vent valve 131, the following description is applied as it is by replacing the duty ratio with the valve opening.
[0026]
The output port of the ECU 30 is connected to an actuator of a purge control valve 15 and an actuator of a CCV (CANISTER CLOSEURE VALVE) 17 to be described later via a drive circuit (not shown), and controls the operation of these valves. It is connected to the lid opener 115a through the drive circuit, and the lid 115 is opened.
[0027]
On the other hand, signals representing the engine speed, the intake air amount, the engine coolant temperature, the vehicle running speed, etc. are input to the input port of the ECU 30 from sensors (not shown), and in response to the driver's switch operation. A lid opening switch (oil supply switch) 140 for outputting an oil supply signal is connected. The output of the pressure sensor 120 provided in the fuel tank 11 for detecting the pressure in the tank is supplied to the input port of the ECU 30 via an AD converter (not shown).
[0028]
A canister for adsorbing fuel vapor in the fuel tank is indicated by 10 in FIG. The canister 10 includes a breather pipe 13 through a vent valve 131 and a fuel liquid level upper space of the fuel tank 11, a purge pipe 14 through a purge control valve 15, and an air communication pipe 18. , CCV 17 and filter 19 are connected to the atmosphere portion in the vicinity of refueling port 114, respectively.
The purge control valve 15 includes an actuator of an appropriate type such as a solenoid actuator, and is opened by a signal from the ECU 30, and the canister 10 and the intake passage 1 are communicated to purge the canister 10.
[0029]
The air communication pipe 18 is provided with an air filter 19 and a CCV 17. The air filter 19 removes foreign substances in the air flowing into the canister 10 from the atmosphere communication pipe 18 when purging, which will be described later. The CCV 17 includes an appropriate type of actuator such as a solenoid actuator, and blocks communication between the atmosphere communication pipe 18 and the canister 11 in accordance with a control signal from the ECU 30.
[0030]
When the vent valve 131 and the CCV 17 are opened while the purge control valve 15 is closed, the mixture of fuel vapor and air enters the canister 10 from the upper liquid level space of the fuel tank 11 through the breather pipe 13. Inflow. The canister is filled with an evaporative fuel adsorbent 50 such as activated carbon. When the pressure in the fuel tank 11 is higher than the atmospheric pressure, the gas containing the fuel vapor in the fuel tank 11 passes through the adsorbent 50 in the canister 10 and then is released to the atmosphere through the CCV 17 and the atmosphere communication pipe 18. Become so. As a result, only air after the fuel vapor is removed by the adsorbent 50 in the canister is released from the atmosphere communication pipe 18, and the fuel tank 11 is prevented from being released into the atmosphere. The internal pressure can be reduced.
[0031]
Further, when the purge control valve 15 and the CCV 17 are opened while the engine is in operation and negative pressure is generated in the intake passage 1, the negative pressure of the intake passage 1 is introduced into the canister 10 via the purge passage 14. Acts, and the canister internal pressure becomes lower than the atmospheric pressure. For this reason, when the purge control valve 15 is opened, clean air from which foreign matter has been removed by the filter 19 flows from the atmospheric communication pipe 18 into the canister 10. This air separates the fuel vapor adsorbed from the adsorbent 50, becomes a mixed gas (purge gas) of the fuel vapor and air, flows into the engine intake passage 1 from the purge passage 14, and burns in the engine combustion chamber. This prevents the adsorbent 50 from being saturated with fuel vapor.
[0032]
In the present embodiment, as described above, the vent valve 131 is normally kept closed, and is opened only when the tank internal pressure exceeds the allowable limit and when refueling is performed as described later. The fuel vapor in the tank is adsorbed by the canister 10. For this reason, the capacity of the canister 10 is set to be relatively small compared to the case of a normal open type fuel tank that constantly supplies fuel vapor to the canister.
[0033]
Next, fuel tank pressure control during refueling will be described.
In the embodiment described below, refueling is performed by inserting a fueling nozzle (not shown) into the fueling tube 111 of the fuel tank 11 and supplying fuel from the nozzle into the fueling tube 111. The fuel supplied into the fuel supply pipe 111 flows into the fuel tank 11 from the fuel supply pipe 111.
At this time, when the internal pressure of the fuel tank 11 is equal to or higher than the atmospheric pressure, a liquid column having a height corresponding to the difference between the tank internal pressure and the atmospheric pressure is formed in the fuel supply pipe 11. Therefore, for example, when the liquid level in the fuel tank 11 has risen to a liquid level height, the liquid level height in the fuel supply pipe 11 corresponds to the above-described pressure difference in the liquid level height in the tank. It becomes the height which added the height of the liquid column.
[0034]
In general, an oil stop nozzle is provided with an auto-stop mechanism that automatically stops fuel supply. The auto-stop mechanism is a mechanism that stops refueling by detecting that the fuel level formed in the refueling pipe 111 has reached a predetermined height during refueling. That is, a liquid level detection hole is provided on the side surface of the oil supply nozzle, and the oil supply is stopped when the liquid level in the oil supply pipe 111 rises and reaches the liquid level detection hole.
In the embodiment described below, the fuel supply to the fuel tank 11 is stopped by operating an auto-stop mechanism provided in the fuel supply nozzle.
[0035]
In the present embodiment, the vent valve 131 is fully opened prior to the start of refueling, and the gas in the tank is released to the atmosphere via the canister 10 to reduce the internal pressure of the tank 11 to near atmospheric pressure. Thereby, when the cap 113 of the fuel filler port 114 is removed for fueling, the gas containing the fuel vapor in the tank is prevented from being released from the fuel filler port 114 to the atmosphere.
When the refueling nozzle is inserted into the refueling pipe 111 and refueling is started in this state, the liquid level in the tank 11 rises due to the inflowing fuel and is replaced with the inflowing fuel from the vent valve 131 that is being opened. The gas in the upper surface of the liquid level in the tank passes through the breather pipe 13 and the canister 10 and the fuel vapor is removed and then released to the atmosphere.
[0036]
In this state, the tank internal pressure becomes higher than the atmospheric pressure by the pressure loss of the exhaust path that is released from the vent valve 131 to the atmosphere via the canister. The pressure loss of the exhaust path is determined by the flow rate of the gas flowing through the exhaust path, and the flow rate of the gas flowing through the exhaust path is an amount corresponding to the flow rate of the fuel flowing into the tank 11, that is, the refueling flow rate. Accordingly, during refueling when the vent valve 131 is fully opened, the tank internal pressure is a pressure corresponding to the refueling flow rate.
When the liquid level rises due to refueling and reaches the position of the ROV 133, the float of the ROV 133 closes the connection port with the vent valve 131. As a result, the tank 11 and the vent valve 131 communicate with each other only through the small diameter COV 132. For this reason, when the ROV 133 is closed, the flow path resistance of the exhaust path from the vent valve 131 through the breather pipe 13 and the canister 10 to the atmosphere communication pipe 18 is greatly increased, so that the internal pressure of the tank 11 rapidly increases. become.
[0037]
In the tank internal pressure control operation of the present embodiment, the fuel amount (liquid level height) in the tank when the ROV 133 is closed is referred to as a reference amount.
If fueling is continued after the fuel in the tank reaches the reference amount, the liquid level in the tank rises and the tank internal pressure rises at the same time. When the liquid level further rises as the refueling is continued, the liquid level in the tank eventually reaches the position of the COV 132 and the float of the COV 132 closes the connection port of the vent valve 131. In this state, the exhaust path is completely closed, and the fuel tank 11 is sealed even if the vent valve 131 is open.
[0038]
In the present embodiment, the design capacity of the fuel tank 11 is set larger than the fuel amount (reference amount) that the ROV 133 closes and smaller than the fuel amount that the COV 132 closes. The design capacity of this fuel tank is a so-called full fuel amount. In this embodiment, as will be described later, the design capacity in the tank is set as the target fuel amount, and the fuel amount in the tank reaches this target fuel amount. When this happens, the automatic stop mechanism of the oil supply nozzle is activated to stop the oil supply.
[0039]
2 and 3 are flowcharts for explaining the tank internal pressure control operation of the present embodiment. This operation is executed by the ECU 30.
Step 201 in FIG. 2 is an operation for detecting whether or not the lid opening switch 140 (FIG. 1) is turned on by the vehicle driver. When the lid opening switch 140 is turned on and a fueling signal is output, the ECU 30 operates the lid opener 115a to open the fueling port lid 115, so that the operator removes the fueling port cap 113 and performs fueling. Is possible. Therefore, when the lid opening switch 140 is turned on (when a fueling signal is input), the driver has a willingness to fuel, and it is expected that fueling will be started following the operation of the switch 140.
[0040]
Therefore, in this embodiment, when the lid opening switch 140 is turned on in step 201, the vent valve 131 is fully opened in step 203. As a result, the internal pressure of the fuel tank 11 decreases to near atmospheric pressure, so that even when the operator removes the fuel filler cap 113 to refuel, the gas containing the fuel vapor in the fuel tank 11 enters the atmosphere from the fuel filler opening. It is prevented from being released.
[0041]
Steps 205 and 207 are a refueling start detection operation from the refueling nozzle. In the present embodiment, it is determined whether refueling has been started based on the pressure increase rate in the fuel tank when the vent valve is fully opened. When refueling is started with the vent valve fully open, the gas in the tank is exhausted from the vent valve 131 as the liquid level in the tank rises. For this reason, the pressure loss of the exhaust path is caused by the flow of the gas flowing through the exhaust path from the vent valve 131 to the atmosphere through the breather pipe 13 and the canister 10 to the atmosphere, and the tank internal pressure rises. Therefore, in the present embodiment, the tank internal pressure increase rate ΔPT is a certain value ΔPT. ₁ If it exceeds, it is determined that refueling has started.
[0042]
That is, in step 205, based on the detection value of the pressure sensor 120, a tank pressure increase width within a predetermined time is calculated and stored as a tank pressure increase rate ΔPT. In step 207, the calculated ΔPT is a predetermined value ΔPT. ₁ It is determined whether or not the number is exceeded. In step 205 and step 207, ΔPT> ΔPT in step 207 ₁ Repeat until.
[0043]
After the start of refueling, it is determined in steps 209 and 211 whether or not the refueling flow rate is stable and substantially constant. As described above, when refueling when the vent valve 131 is fully closed, the fuel tank internal pressure converges to a substantially constant pressure corresponding to the refueling flow rate. In the present embodiment, after the start of refueling is detected (step 207), the tank pressure increase rate is a predetermined value ΔPT. ₂ When it becomes smaller, that is, when the tank internal pressure has converged to a certain value, it is determined that the fuel supply is stable. ΔPT ₂ Is a relatively small positive value.
[0044]
That is, in step 209, the tank internal pressure increase rate ΔPT is calculated as a change width of the detection value of the pressure sensor 120 within a predetermined time, and in step 211, the internal pressure increase rate ΔPT calculated in step 209 is the predetermined value ΔPT. ₂ It is determined whether or not it has become smaller. In steps 211 and 211, ΔPT <ΔPT in step 211 ₂ Until it is detected, that is, until it is detected that the fuel supply is stable.
[0045]
If it is detected in step 211 that the oil supply is stable, in step 213, the tank internal pressure PT after the oil supply is stabilized is detected by the pressure sensor 120, and in step 215, this value is used as a parameter PV representing the oil supply speed. Remember. PV is used when calculating the target value of the tank internal pressure increase rate in step 225 (FIG. 3) described later.
[0046]
When PV is stored in step 215, next, in step 217 of FIG. 3, the tank internal pressure increase rate ΔPT is calculated again.
In step 219, this ΔPT is a negative predetermined value −ΔPT. _Three Whether or not the pressure has become smaller (that is, whether or not the internal pressure of the tank is decreasing at a predetermined speed or more), and in step 221, ΔPT is the above-mentioned predetermined value ΔPT. ₂ (FIG. 2, step 211) It is determined whether it became more than this. Step 219 is an operation for determining whether or not the refueling is intentionally stopped before the refueling amount reaches the reference amount. Step 221 is a step for determining whether the fuel amount in the tank is the reference amount (the liquid level at which the ROV 133 is closed). The operation of determining whether or not the amount corresponding to the above has been reached is shown.
[0047]
If the operator intends to refuel only a certain amount of fuel, refueling may be stopped before the fuel in the tank reaches the reference amount. In this case, since the fuel supply is stopped with the vent valve 131 fully open, the tank internal pressure starts to decrease after the fuel supply is stopped. In step 219, the tank pressure starts to decrease for the first time, and the decreasing speed is a predetermined value ΔPT. _Three When it becomes larger, it is determined that the fuel supply is stopped before the fuel amount reaches the reference amount. In this case, the process proceeds to step 237 and the vent valve 131 is fully closed, and then the tank internal pressure control operation is terminated.
[0048]
On the other hand, in step 221, the tank internal pressure increase rate ΔPT is a predetermined value ΔPT. ₂ When it becomes above, it determines with the amount of fuel in a tank reaching the reference amount, and ROV133 having closed. The operations from step 217 to 221 are repeated until refueling is completed in step 219 or until the fuel amount in the tank reaches the reference amount in step 221.
[0049]
When the fuel amount in the tank reaches the reference amount in step 221, the control of the tank pressure increase rate in steps 223 to 233 is performed next.
The operations in steps 223 to 233 are operations for reliably operating the auto-stop mechanism of the fueling nozzle and stopping the fueling when the fuel amount in the tank reaches the target amount by fueling.
[0050]
In the operations from step 223 to 233, first, the current tank internal pressure PT is read from the pressure sensor 120 in step 223. This internal pressure PT is a pressure when the ROV 133 is closed.
Next, at step 225, the target value ΔPS of the tank internal pressure increase rate ₁ Is calculated.
Target rise speed ΔPS of tank internal pressure ₁ Uses the fuel supply flow rate QF, the tank target fuel amount VT, the reference fuel amount VS, the tank internal pressure PT when the reference fuel amount is reached (step 223), and the tank internal pressure (target pressure) PTR when the target fuel amount is reached. It is calculated by the following procedure.
[0051]
That is, first, the fuel supply flow rate QF is calculated from the tank internal pressure PV stored in step 215 (FIG. 2) based on a predetermined relationship. In this embodiment, an experiment is performed in advance using an actual fuel tank 11 and an exhaust path (a flow path constituted by a vent valve 131, a breather pipe 13, a canister 10, a CCV 17, a filter 19, and an atmosphere communication pipe 18), and fueling is performed. The relationship between the flow rate QF and the tank internal pressure PV when the vent valve 131 is fully opened is obtained, and this relationship is stored in the ROM of the ECU 30. The actual fuel supply flow rate QF is obtained from the relationship stored in the ECU 30 using the tank internal pressure PV stored in step 215.
[0052]
After calculating the flow rate QF, the time T until the fuel amount in the tank reaches the target amount VT after reaching the reference amount VS when refueling is continued at this flow rate. ₀ Is calculated. Time T ₀ T ₀ = (VT-VS) / QF.
In order to increase the tank internal pressure PT when the reference fuel amount is reached to the PTR when the target fuel amount is reached, the time T ₀ During this time, it is necessary to increase the pressure by (PTR-PT). Therefore, the target value ΔPS of the tank internal pressure increase rate ₁ Is ΔPS ₁ = (PTR-PT) / T ₀ Is calculated as
[0053]
The target pressure PTR is a tank internal pressure required to raise the liquid level in the oil supply pipe 111 to the position of the liquid level detection hole of the oil supply nozzle.
That is, after the tank fuel amount reaches the reference value, the tank pressure increase rate is calculated by ΔPS calculated above. ₁ When the fuel amount in the tank reaches the target amount, the automatic stop mechanism of the fueling nozzle always operates and the fueling is stopped, so that excessive fueling exceeding the target fuel amount is prevented. .
[0054]
The tank internal pressure increase speed target value ΔPS ₁ May be calculated using PV and PT each time as described above, but once the fuel tank system is determined, VT, VS, and PTR have constant values. Normally, the tank internal pressure PV stored in step 215 and the tank internal pressure PT detected in step 223 are substantially the same value.
[0055]
For this reason, in the actual fuel tank system, if the PV value is determined in step 215, the above calculation can be performed based only on the PV value. Accordingly, the above calculation is performed by changing the PV value in advance, and the target pressure increase rate ΔPS of the internal pressure is calculated. ₁ It is also possible to ask for. FIG. 4 shows PV and ΔPS obtained in advance by the above. ₁ FIG. In step 225, the relationship shown in FIG. 4 is stored in advance in the ROM of the ECU 30, for example, and ΔPS each time using PV and PT. ₁ 4 instead of directly calculating ΔPS from the relationship of FIG. 4 based on the PV value stored in step 215. ₁ It is also possible to ask for.
[0056]
Steps 227 to 233 are operations for controlling the tank internal pressure increase rate.
That is, in step 227, the current tank pressure increase rate ΔPT is calculated based on the detected value of the pressure sensor 120. In step 229, this ΔPT is calculated as the target speed ΔPS. ₁ In step 231, the vent valve 131 is fully opened to decrease the internal pressure increasing speed. Conversely, ΔPT is the target speed ΔPS. ₁ In the case of the following, in step 233, the vent valve 131 is fully closed to increase the internal pressure increasing speed. As a result, the tank internal pressure increase rate becomes the target value ΔPS. ₁ Will be maintained. Thereby, when the fuel amount in the tank reaches the target amount VT, the tank internal pressure becomes a pressure at which the auto-stop mechanism of the fuel nozzle is operated, and the fuel supply is stopped.
[0057]
Step 235 is an operation for determining whether or not refueling is completed. When the fuel amount in the tank reaches the target value and the auto-stop mechanism is activated and the refueling is stopped, and when the refueling is stopped artificially, the increase rate of the tank internal pressure will decrease. In steps 229 and 233, the vent valve 131 is fully closed. For this reason, the rising speed of the tank internal pressure is only due to the evaporation of the fuel, and becomes an extremely small value. In step 235, the tank internal pressure increase rate ΔPT is a relatively small positive value ΔPT. _Four When it becomes smaller, it determines with refueling having been complete | finished and complete | finishes tank internal pressure control operation.
The operations from step 227 to 235 are repeated until it is determined in step 235 that refueling has been completed.
[0058]
As described above, according to the present embodiment, when the fuel amount in the tank reaches the target fuel amount, it is possible to reliably stop the fuel supply by operating the auto-stop mechanism of the fuel nozzle, so that the target fuel amount is exceeded. Thus, it is possible to prevent excessive refueling. Further, since the tank internal pressure after the stop of fueling does not rise above the pressure for operating the auto stop mechanism, the occurrence of blow-back after the stop of fueling is prevented.
[0059]
Next, another embodiment of the tank internal pressure control operation will be described.
The present embodiment includes a tank internal pressure control operation in a case where additional fueling is performed after fueling up to the target fuel amount by the operations of FIGS. 2 and 3.
In the present embodiment, refueling that is resumed after the auto-stop mechanism once operates to stop refueling is referred to as additional refueling.
[0060]
In actual refueling work, after the fuel is refueled up to the target fuel amount in the fuel tank and the fuel tank is in a so-called full tank condition, it is necessary to continue refueling and supply fuel above the target fuel amount to the tank. May be. However, even in this case, it is necessary to prevent the fuel from being supplied beyond the maximum allowable amount into the tank.
[0061]
When the additional fueling is performed, the fuel tank liquid level further rises from the liquid level at the target fuel amount, reaches the COV 132, and closes the COV 132. In the present embodiment, the allowable maximum amount of fuel in the tank is set to a capacity that is slightly smaller than the amount of fuel that the COV 132 closes, so that the fuel amount in the tank is not more than the maximum allowable amount even when additional fuel is supplied. The tank internal pressure control operation for operating the auto stop mechanism is performed. This prevents refueling from exceeding the allowable maximum amount in the tank.
[0062]
FIG. 5 is a flowchart for explaining the main part of the tank internal pressure control operation of the present embodiment. Also in this embodiment, the tank internal pressure control operation of FIGS. 2 and 3 is performed in the refueling operation other than the additional refueling. The operation of FIG. 5 is continuously performed when refueling is completed by the operation of step 235 of FIG. The flowchart of FIG. 5 does not show the operations of FIGS. 2 and 3.
[0063]
The operation of FIG. 5 will be explained. When the refueling is finished in step 235, the process proceeds to step 501 and the vent valve 131 is fully opened, and the operations of steps 503 to 507 are repeated to start additional refueling. Wait for Steps 503 and 505 are operations for determining whether or not refueling is started based on the pressure increase rate ΔPT of the tank, and are the same operations as steps 205 and 207 in FIG. If refueling has not started in step 505, the time T has elapsed since the last refueling in step 507. ₁ Whether or not T has passed, and T ₁ If has elapsed, the process proceeds to step 525, the vent valve 131 is fully closed, and the operation is terminated. That is, in this embodiment, after it is determined in step 235 that refueling has been completed, a certain time T ₁ Within (for example, T ₁ If the additional oil supply is not started within a period of about 15 seconds, it is determined that the possibility of the additional oil supply is low, and the tank internal pressure control operation is terminated.
[0064]
A certain time T since the last refueling ₁ If it is detected in step 505 that additional refueling has been started before the time elapses, the process proceeds to step 509, where the current tank internal pressure PT is read from the pressure sensor 120 and stored as PTA in step 511. PTA is the tank internal pressure at the start of additional refueling.
Next, at step 513, the target value ΔPS of the tank internal pressure increase rate at the time of additional refueling ₂ Is calculated. In step 513, ΔPS is performed in the same procedure as in step 225 in FIG. ₂ Is calculated. However, in this case, the value of PTA stored in step 511 is used instead of the PT in step 223, and the value stored in step 215 is used as PV.
[0065]
The tank internal pressure PV stored in step 215 corresponds to the oil supply flow rate during steady state oil supply. Normally, when performing additional refueling, the operator reduces the refueling flow rate and gradually refuels, so that the refueling flow rate becomes smaller than the steady refueling flow rate.
Therefore, the tank pressure increase rate ΔPS calculated using the tank pressure PV stored in step 215. ₂ Is larger than the actual value.
[0066]
That is, ΔPS calculated in step 513 ₂ In many cases, the tank internal pressure reaches the target pressure before the fuel amount in the tank reaches the allowable maximum amount and the auto-stop mechanism of the fueling nozzle is activated.
[0067]
In the present embodiment, the tank internal pressure control is performed even when additional fueling is performed. However, the additional fueling after the fueling to the target fuel amount is not necessarily preferable in terms of tank performance, and the fuel that is fueled by the additional fueling. The amount is preferably as small as possible. For this reason, in this embodiment, the target value ΔPS of the tank internal pressure increase rate using the tank internal pressure PV corresponding to the oil supply flow rate at the time of steady oil supply. ₂ Is calculated so that the fuel amount does not actually reach the allowable maximum amount when additional fuel is supplied. Note that the tank internal pressure PTA in step 511 is usually near atmospheric pressure. Therefore, also in step 515, ΔPS each time as in step 225. ₂ Rather than calculating PV and ΔPS in advance ₂ 4 is obtained, and ΔPS is directly calculated from the PV value based on this relationship. ₂ It is also possible to ask for.
[0068]
By the above, the tank internal pressure increase rate ΔPS ₂ After the calculation, in steps 515 to 521, the tank pressure increase rate ΔPT during the additional refueling is the target value ΔPS. ₂ The vent valve 131 is controlled to open and close so as to coincide with. The operations in steps 515 to 521 are repeated until it is detected in step 523 that refueling has been completed. The operations in steps 515 to 523 are the same as the operations in steps 227 to 235 in FIG.
[0069]
If the end of refueling is detected in step 523, the vent valve 131 is fully closed in step 525, and the tank internal pressure control operation ends.
As described above, in the present embodiment, even when additional fueling is performed after the fueling is performed up to the target fuel amount and the fueling is finished, the fueling amount is surely limited to the maximum allowable amount of the tank or less and the additional fueling is performed. Blowback is prevented from occurring at the end.
[0070]
【The invention's effect】
According to the invention described in each claim, it is possible to accurately control the amount of fuel supply to prevent excessive fuel supply and to prevent the fuel from being blown back at the end of the fuel supply. .
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an embodiment in which the present invention is applied to an automobile fuel tank.
FIG. 2 is a part of a flowchart for explaining an embodiment of a fuel tank internal pressure control operation.
FIG. 3 is a part of a flowchart illustrating one embodiment of a fuel tank internal pressure control operation.
4 is a diagram illustrating an example of setting of a target value for a tank internal pressure increase speed in FIGS. 2 and 3. FIG.
FIG. 5 is a part of a flowchart for explaining an embodiment different from FIGS. 2 and 3 of the fuel tank internal pressure control operation;
[Explanation of symbols]
10 ... Canister
11 ... Fuel tank
13 ... Breather piping
30 ... Electronic control unit (ECU)
111 ... refueling pipe
120 ... Pressure sensor
131 ... Vent valve

Claims (4)

A fuel supply control device for a sealed fuel tank system that adjusts the tank internal pressure when refueling a sealed fuel tank and prevents excessive fueling to the tank,
Pressure detecting means for detecting the tank internal pressure;
Exhaust means for exhausting the gas in the upper liquid level space in the tank to a predetermined location outside the tank when refueling;
Oil supply flow rate estimation means for estimating the oil supply flow rate based on the tank internal pressure during oil supply,
Fuel amount detection means for determining whether or not the fuel amount in the fuel tank has reached a predetermined reference amount during refueling;
Target pressure change setting means for setting a target value of the tank internal pressure increase speed based on the oil supply flow rate estimated by the oil supply flow rate estimation means;
After the fuel amount detecting means detects that the fuel amount in the tank has reached the reference amount, the exhaust means is operated so that the rate of increase in the tank internal pressure detected by the pressure detecting means matches the target value. And a pressure control means for controlling the oil supply control device for the closed tank system. The target pressure change setting means is calculated based on the fuel supply flow rate estimated by the fuel supply flow rate estimation means, and the required time from when the fuel amount in the tank reaches the reference amount to the predetermined target amount. Based on the time and the tank internal pressure when the fuel in the tank reaches the reference amount, the tank internal pressure rises so that the tank internal pressure becomes a predetermined target pressure when the tank fuel amount reaches the target amount. The oil supply control device for a closed tank system according to claim 1, wherein a target value of speed is set. Furthermore, additional fuel detection means for detecting that additional fuel supply is started again after the fuel amount in the tank reaches the target amount and the fuel supply is completed, and a tank internal pressure increase rate when the additional fuel supply is started. With additional oil target pressure change setting means for setting the target value,
The said pressure control means controls the action | operation of the said exhaust means so that the tank internal pressure rise speed detected by the said pressure detection means may correspond with the target value at the time of the said additional oil supply during the said additional oil supply. The oil supply control device of the closed tank system according to 2. The additional fuel supply target pressure change setting means calculates the fuel amount in the tank calculated based on the fuel supply flow rate estimated by the fuel supply flow rate estimation means before the fuel amount in the tank reaches the target amount. Based on the time required to reach the predetermined allowable maximum amount from the amount and the tank internal pressure when the additional fueling is started, the tank internal pressure is increased when the fuel amount in the tank reaches the allowable maximum amount. The oil supply control device for a closed tank system according to claim 3, wherein a target value of a tank internal pressure increase speed at the time of additional oil supply is set so as to be a target pressure.

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