JP2009299581A - Fuel tank device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately adjust pressure of gas phase in a plurality of storage tanks. <P>SOLUTION: A fuel tank device has: a high vapor pressure tank 12 storing fuel with high saturated vapor pressure; and a low vapor pressure tank 14 storing fuel with low saturated vapor pressure. A communicating pipe 18 is disposed between the tanks 12, 14 to connect between gas phase spaces 16 of both tanks 12, 14. An ECU 40 controls a fuel selector valve 36 depending on operating statuses, and supplies fuel of any one of the tanks 12, 14 to an internal combustion engine 10. The ECU 40 detects pressure P of the gas phase space 16 by the pressure sensor 38. When the pressure P becomes a lower limit determination value L or lower, fuel supply from the high vapor pressure tank 12 to the internal combustion engine 10 is prohibited and only the fuel in the low vapor pressure tank 14 is used. Therefore, concentration of evaporated fuel in the tanks 12, 14 can be maintained to be concentration higher than an ignitable concentration range. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel tank apparatus suitably used for supplying fuel to equipment such as an internal combustion engine, and more particularly to a fuel tank apparatus having a plurality of tanks.

  As a prior art, for example, as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2008-8278), for example, a fuel tank device including two tanks is known. This type of conventional fuel tank apparatus is mounted on a vehicle that uses, for example, low-octane gasoline and high-octane gasoline as needed. For this reason, the fuel tank device of the prior art includes a high vapor pressure tank and a low vapor pressure tank.

  In the high vapor pressure tank, fuel having a low octane number and a high saturated vapor pressure is stored, such as regular gasoline. In the case of fuel having a sufficiently high saturated vapor pressure, the concentration of fuel that evaporates in the tank at room temperature is higher than the ignitable concentration range (generally, about 0.6 to 8.0 vol%). Therefore, there is no possibility that this fuel will ignite in the tank.

  On the other hand, a fuel having a relatively high octane number and a relatively low saturated vapor pressure is stored in the low vapor pressure tank, such as high-octane gasoline. In the case of a fuel with a low saturated vapor pressure, the volatility of the fuel is low. For this reason, the fuel vapor concentration in the fuel tank at room temperature may fall within the ignitable concentration range.

  For this reason, in a prior art, it is set as the structure which connects a high vapor pressure tank and a low vapor pressure tank by communication piping. Thereby, the fuel evaporated in the high vapor pressure tank is introduced into the low vapor pressure tank through the communication pipe. Therefore, the fuel vapor concentration in the low vapor pressure tank can be kept higher than the ignitable concentration range.

JP 2008-8278 A

  By the way, in the prior art mentioned above, it is set as the structure which connects a high vapor pressure tank and a low vapor pressure tank, and makes the vaporized fuel density | concentration in both tanks higher than the ignition possible concentration range. However, there may be a relatively large difference between the remaining fuel levels in the two tanks depending on the operating state of the internal combustion engine, the refueling situation, and the like. For example, regular gasoline in the high vapor pressure tank is greatly reduced, and high-octane gasoline in the low vapor pressure tank is sufficiently remaining.

  In such a case, even if the two fuel tanks are communicated with each other, the evaporated fuel in the high vapor pressure tank is not sufficiently supplied to the low vapor pressure tank. For this reason, in the prior art, when the fuel in the high vapor pressure tank is greatly reduced, the vaporized fuel concentration in the low vapor pressure tank may fall within the ignitable concentration range, which is not preferable in terms of system design. is there.

  Further, when the pressure in the tank rises more than usual due to, for example, a high temperature, an extra load is applied to the peripheral wall of each tank, which is not preferable from the viewpoint of durability.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a plurality of storage tanks in consideration of the volatility of fuel, the load on the tank, and the like. An object of the present invention is to provide a fuel tank device capable of appropriately adjusting the pressure of the gas phase and realizing high reliability.

The first invention comprises a plurality of storage tanks each storing different types of fuel,
A communication path communicating the gas phase space in each storage tank;
When supplying fuel from the storage tank to the outside, a tank switching mechanism capable of switching the storage tank used for the fuel supply to any of the storage tanks;
Pressure detecting means for detecting the pressure of the gas phase space;
Switching control means for switching the storage tank used for the fuel supply to one of the storage tanks according to the pressure of the gas phase space by controlling the tank switching mechanism;
It is characterized by providing.

According to the second invention, in the first invention,
The plurality of storage tanks include a high vapor pressure tank that stores fuel having a high saturation vapor pressure, and a low vapor pressure tank that stores fuel having a saturation vapor pressure lower than that of the high vapor pressure tank,
The switching control means supplies the fuel in the low vapor pressure tank to the outside and supplies the fuel in the high vapor pressure tank to the outside when the pressure in the gas phase space becomes equal to or lower than a lower limit determination value. Is prohibited.

According to the third invention, in the first or second invention,
The plurality of storage tanks include a high vapor pressure tank that stores fuel having a high saturation vapor pressure, and a low vapor pressure tank that stores fuel having a saturation vapor pressure lower than that of the high vapor pressure tank,
The switching control means supplies the fuel in the high vapor pressure tank to the outside and supplies the fuel in the low vapor pressure tank to the outside when the pressure in the gas phase space exceeds the upper limit determination value. Is prohibited.

According to the fourth invention, in the second or third invention,
The tank switching mechanism is a three-way valve that connects one of a pipe connected to the high vapor pressure tank and a pipe connected to the low vapor pressure tank to an external fuel supply target. .

  According to the first aspect of the present invention, the switching control means controls the tank switching mechanism according to the pressure in the gas phase space in the tank, thereby supplying fuel from an appropriate tank among the plurality of storage tanks to the outside. Can do. Thereby, for example, the fuel in a specific tank can be preferentially used in consideration of the volatility of the fuel, the load on the tank, etc., or the fuel supply from the specific tank can be prohibited. Therefore, the gas phase pressure in the storage tank can be adjusted appropriately, and the reliability of the fuel tank device can be improved.

  According to the second invention, the switching control means can prohibit the fuel supply from the high vapor pressure tank to the outside when the pressure in the gas phase space falls below the lower limit determination value. Thereby, fuel with a high saturated vapor pressure can be left in the high vapor pressure tank as much as possible. For this reason, it is possible to prevent the pressure in the gas phase space from falling below the allowable range, and it is possible to maintain the concentration of the evaporated fuel in the tank at a concentration higher than the ignitable concentration range.

  According to the third invention, the switching control means can preferentially use the fuel in the high vapor pressure tank having a high saturated vapor pressure when the pressure in the gas phase space rises to the upper limit determination value or more. . Thereby, the pressure rise of gas-phase space can be suppressed as much as possible, and the pressure of gas-phase space can be maintained within an allowable range. Therefore, it is possible to prevent an extra load due to the pressure increase from being applied to the storage tank, thereby protecting the storage tank.

  According to the fourth invention, by using the three-way valve, the switching connection between the plurality of storage tanks and the fuel supply target can be easily performed even with a small number of parts, and the piping connection structure can be simplified. .

Embodiment 1 FIG.
[Configuration of Embodiment 1]
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is an overall configuration diagram for explaining a system configuration according to the first embodiment of the present invention. As shown in this figure, the system of the present embodiment includes an internal combustion engine 10 constituted by, for example, a gasoline engine. The internal combustion engine 10 is provided with, for example, two storage tanks 12 and 14 for storing fuels having different saturation vapor pressures.

  The fuel stored in one of the storage tanks 12 and 14 is selectively supplied to the internal combustion engine 10. The internal combustion engine 10 operates by injecting this fuel into a cylinder from a fuel injection valve and combusting it together with intake air. In the present invention, the number of storage tanks is not limited to two.

  Here, one of the storage tanks 12 and 14 is used as a high vapor pressure tank that stores fuel having a high saturated vapor pressure (hereinafter referred to as a high vapor pressure tank 12). The other storage tank 14 is used as a low vapor pressure tank that stores fuel having a saturated vapor pressure lower than that of the high vapor pressure tank 12 (hereinafter referred to as a low vapor pressure tank 14). Here, the fuel having a high saturated vapor pressure is a fuel having a relatively low octane number, such as regular gasoline. A fuel with a low saturated vapor pressure is a fuel with a relatively high octane number, such as high-octane gasoline.

  These tanks 12 and 14 are provided with a communication pipe 18 as a communication path for communicating the gas phase space 16 existing in each tank. The low vapor pressure tank 14 is provided with a purge mechanism including a purge pipe 20, a check valve 22 and a canister 24. According to this purge mechanism, the purge gas containing the evaporated fuel in the tank 14 can be purified and escaped to the outside.

  Next, the fuel supply system will be described. First, in the two tanks 12 and 14, fuel pumps 26 and 28 for respectively taking in the fuel in the tanks and discharging them to the outside are arranged. On the discharge side of the fuel pumps 26 and 28, tank pipes 30 and 32 on the high vapor pressure side and the low vapor pressure side are connected, respectively. These tank pipes 30 and 32 are connected in parallel to an engine side pipe 34 provided in the internal combustion engine 10. A fuel switching valve 36 is provided at the junction of the three pipes 30 to 34.

  The fuel switching valve 36 is composed of, for example, an electromagnetically driven three-way valve or the like, and constitutes the tank switching mechanism of the present embodiment. The fuel switching valve 36 connects either one of the tank pipes 30 and 32 to the engine side pipe 34 in accordance with a control signal input from the ECU 40 described later. Thus, the fuel switching valve 36 switches the tank used for fuel supply to the internal combustion engine 10 to either the high vapor pressure tank 12 or the low vapor pressure tank 14.

  That is, when the fuel switching valve 36 is switched to the valve position on the high vapor pressure side, the fuel in the high vapor pressure tank 12 is supplied to the internal combustion engine 10 via the pipes 30 and 34. At this time, the low vapor pressure tank 14 is disconnected from the internal combustion engine 10. When the fuel switching valve 36 is switched to the low vapor pressure side valve position, the fuel in the low vapor pressure tank 14 is supplied to the internal combustion engine 10 via the pipes 32 and 34. At this time, the high vapor pressure tank 12 is cut off from the internal combustion engine 10.

  Furthermore, the system of the present embodiment includes a sensor system including a pressure sensor 38 and an ECU (Electronic Control Unit) 40 that controls the operation of the internal combustion engine 10. The pressure sensor 38 is a pressure detection means of the present embodiment, and detects the pressure of the gas phase space 16 in the tanks 12 and 14. 1 illustrates the case where the pressure sensor 38 is disposed in the high vapor pressure tank 12, the pressure sensor 38 may be disposed on the low vapor pressure tank 14 side.

  In addition to the pressure sensor 38, the sensor system described above includes a crank angle sensor that detects the crank angle of the internal combustion engine 10, an air flow meter that detects the intake air amount, and an A / F sensor that detects the air-fuel ratio of the exhaust gas. A water temperature sensor for detecting the temperature of the cooling water of the internal combustion engine is included. On the other hand, the internal combustion engine 10 includes various actuators including a fuel injection valve and a spark plug.

  The ECU 40 controls each actuator while detecting the operating state of the internal combustion engine using the sensor system. Further, the ECU 40 performs fuel selection control in parallel with the operation control of the internal combustion engine. In this fuel selection control, for example, regular gasoline in the high vapor pressure tank 12 and high-octane gasoline in the low vapor pressure tank 14 are selectively used by controlling the fuel switching valve 36 according to, for example, the operating state of the internal combustion engine. It is.

  Here, the low vapor pressure tank 14 is provided with a purge pipe 20 and the like for discharging the purge gas to the outside. For this reason, when fuel with a high saturated vapor pressure evaporates in the high vapor pressure tank 12, this fuel also flows into the low vapor pressure tank 14 through the communication pipe 18. Thereby, in the low vapor pressure tank 14, even if the volatility of the fuel is low, the concentration of the evaporated fuel is maintained at a concentration value higher than the ignitable concentration range.

  However, depending on the operating state of the internal combustion engine, the refueling situation, etc., for example, sufficient fuel may be stored in the low vapor pressure tank 14 while the fuel in the high vapor pressure tank 12 may be greatly reduced. In such a case, even if the communication pipe 18 exists, the vaporized fuel in the high vapor pressure tank 12 is not sufficiently supplied to the low vapor pressure tank 14, and the vaporized fuel concentration in the low vapor pressure tank 14 is ignited. There is a risk of entering the possible concentration range. For this reason, in this Embodiment, the pressure monitoring control described below is implemented.

(Pressure monitoring control)
In the pressure monitoring control, the storage tank that supplies fuel to the internal combustion engine 10 is switched to one of the tanks 12 and 14 according to the pressure in the gas phase space 16. FIG. 2 is a flowchart of pressure monitoring control executed by the ECU 40 in the first embodiment of the present invention. Note that the routine shown in FIG. 2 is repeatedly executed during operation of the internal combustion engine.

  In the routine shown in FIG. 2, first, the pressure P in the gas phase space 16 in the tanks 12 and 14 is detected by the pressure sensor 38 (step 100). Next, it is determined whether or not the pressure P is equal to or lower than the lower limit determination value L by comparing the detected value of the pressure P with a lower limit determination value L stored in the ECU 40 in advance (step 102).

  Here, when the pressure in the gas phase space 16 decreases, the concentration of the evaporated fuel in the low vapor pressure tank 14 also decreases accordingly. When the pressure drops below the lower limit determination value L, the evaporated fuel concentration in the low vapor pressure tank 14 may fall within the ignitable concentration range. That is, the lower limit determination value L is a pressure value in the gas phase space when the concentration of the evaporated fuel in the low vapor pressure tank 14 is reduced to the upper limit value of the ignitable concentration range, or a certain margin with respect to the pressure value. It is defined as the pressure value with the allowance added.

  When the determination in step 102 is established, the valve position of the fuel switching valve 36 is switched to the low vapor pressure side. That is, in order to suppress the pressure drop in the gas phase space 16, the fuel in the high vapor pressure tank 12 having a high saturated vapor pressure is prohibited from being supplied to the internal combustion engine, and the fuel in the low vapor pressure tank 14 is used as the internal combustion engine. (Step 104).

  On the other hand, when the determination in step 102 is not established, the fuel selection control described above is performed because the pressure in the gas phase space 16 is in a normal state sufficiently high (step 106).

  According to the above configuration, when the pressure in the tanks 12, 14 falls below the lower limit determination value L, fuel supply from the high vapor pressure tank 12 to the internal combustion engine 10 can be prohibited. Thereby, fuel such as regular gasoline having a high saturated vapor pressure can be left in the high vapor pressure tank 12 as much as possible. For this reason, it is possible to prevent the pressure in the tanks 12 and 14 from falling below the allowable range, and to maintain the concentration of the evaporated fuel in the tank at a concentration higher than the ignitable concentration range. .

  Therefore, according to the present embodiment, the fuel in the low vapor pressure tank 14 can be preferentially used in consideration of the volatility of the fuel, or the fuel supply from the high vapor pressure tank 12 can be prohibited. Thereby, the pressure of the gas phase space 16 can be adjusted appropriately, and the reliability of the fuel tank device can be improved. Further, by using the fuel switching valve 36 composed of a three-way valve, the switching connection between the plurality of storage tanks 12 and 14 and the internal combustion engine 10 can be easily performed with a small number of parts, and the piping 30, 32, 34, etc. The connection structure can be simplified.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. Although the system according to the present embodiment employs a configuration (FIG. 1) that is substantially the same as that of the first embodiment, the control described below is different from the first embodiment.

[Features of Embodiment 2]
FIG. 3 is a flowchart of pressure monitoring control executed by the ECU 40 in the second embodiment of the present invention. Note that the routine shown in FIG. 3 is repeatedly executed during operation of the internal combustion engine. In this routine, first, as in the first embodiment, the pressure P in the gas phase space 16 is detected (step 200). Next, it is determined whether or not the pressure P is equal to or higher than the upper limit determination value H by comparing the detected value of the pressure P with the upper limit determination value H stored in advance in the ECU 40 (step 202).

  Here, when the pressure in the gas phase space 16 rises more than usual due to, for example, a high temperature, there is a possibility that an extra load is applied to the tanks 12 and 14. For this reason, the upper limit determination value H is defined as, for example, the maximum value of the internal pressure applied to the tank in a normal use environment, or a pressure value obtained by subtracting a certain margin from the maximum value. That is, when the pressure P becomes equal to or higher than the upper limit determination value H, it can be determined that the load applied to the tanks 12 and 14 exceeds the allowable range.

  Therefore, when the determination in step 202 is satisfied, the valve position of the fuel switching valve 36 is switched to the high vapor pressure side. That is, in order to suppress the pressure rise in the gas phase space 16, the fuel in the high vapor pressure tank 12 having a high saturated vapor pressure is supplied to the internal combustion engine as much as possible, and the fuel in the low vapor pressure tank 14 is supplied to the internal combustion engine. Is prohibited (step 204).

  On the other hand, when the determination in step 202 is not established, the pressure in the gas phase space 16 is at a normal level, so that the fuel selection control described above is performed (step 206).

  According to the said structure, when the pressure in the tanks 12 and 14 rises more than the upper limit judgment value H, fuel, such as regular gasoline with a high saturated vapor pressure, can be used preferentially. Thereby, the pressure rise of the gas phase space 16 can be suppressed as much as possible. For this reason, the pressure in the tanks 12 and 14 can be maintained within an allowable range, and an extra load due to the pressure increase can be prevented from being applied to the tanks 12 and 14 in advance. Therefore, according to the present embodiment, it is possible to appropriately adjust the pressure in the gas phase space 16 in consideration of the load applied to the tank. And the tanks 12 and 14 can be protected from high pressure, and the reliability of an apparatus can be improved.

  In the above embodiment, steps 102 and 202 in FIGS. 2 and 3 show specific examples of the switching control means.

  In the first embodiment, the tank is switched in accordance with the magnitude relationship between the pressure P of the gas phase space 16 and the lower limit determination value L. In the second embodiment, the magnitude relationship between the pressure P and the upper limit judgment value H. The tank is switched according to the conditions. However, the present invention is not limited to this, and the first and second embodiments may be combined. That is, the pressure P and the two determination values H and L may be compared, and the tanks 12 and 14 to be used may be switched according to the results.

  Further, in the embodiment, the case where regular gasoline and high-octane gasoline are stored in the two tanks 12 and 14 respectively is illustrated. However, the present invention is not limited to this, and any two types of fuel may be stored in the tanks 12 and 14 as long as the fuels have different saturated vapor pressures. Furthermore, the present invention can be widely applied to any fuel, even if the fuel does not have a large difference in saturated vapor pressure, as long as it is necessary to control the fuel to be used in accordance with the pressure in the tank.

  In the embodiment, the pressure sensor 38 is provided in the high vapor pressure tank 12. However, the present invention is not limited to this. For example, the pressure sensor 38 may be disposed in the low vapor pressure tank 14, the communication pipe 18, the purge pipe 20, and the like.

  In the embodiment, the case where there are two storage tanks 12 and 14 has been described as an example. However, the present invention is not limited to this, and may be applied to a fuel tank apparatus including three or more storage tanks.

  Furthermore, in the embodiment, the fuel tank device that supplies fuel to the internal combustion engine 10 has been described as an example. can do.

It is a whole block diagram for demonstrating the system configuration | structure of Embodiment 1 of this invention. In Embodiment 1 of this invention, it is a flowchart of the pressure monitoring control performed by ECU. In Embodiment 2 of this invention, it is a flowchart of the pressure monitoring control performed by ECU.

Explanation of symbols

10 Internal combustion engine 12 High vapor pressure tank (storage tank)
14 Low vapor pressure tank (storage tank)
16 Gas phase space 18 Communication piping (communication passage)
20 Purge piping 22 Check valve 24 Canisters 26, 28 Fuel pump 30, 32 Tank piping 34 Engine side piping 36 Fuel switching valve (tank switching mechanism)
38 Pressure sensor (pressure detection means)
40 ECU

Claims (4)

A plurality of storage tanks each storing different types of fuel;
A communication path communicating the gas phase space in each storage tank;
When supplying fuel from the storage tank to the outside, a tank switching mechanism capable of switching the storage tank used for the fuel supply to any of the storage tanks;
Pressure detecting means for detecting the pressure of the gas phase space;
Switching control means for switching the storage tank used for the fuel supply to one of the storage tanks according to the pressure of the gas phase space by controlling the tank switching mechanism;
A fuel tank apparatus comprising: The plurality of storage tanks include a high vapor pressure tank that stores fuel having a high saturation vapor pressure, and a low vapor pressure tank that stores fuel having a saturation vapor pressure lower than that of the high vapor pressure tank,
The switching control means supplies the fuel in the low vapor pressure tank to the outside and supplies the fuel in the high vapor pressure tank to the outside when the pressure in the gas phase space becomes equal to or lower than a lower limit determination value. The fuel tank apparatus according to claim 1, wherein the fuel tank apparatus is configured to prohibit the operation. The plurality of storage tanks include a high vapor pressure tank that stores fuel having a high saturation vapor pressure, and a low vapor pressure tank that stores fuel having a saturation vapor pressure lower than that of the high vapor pressure tank,
The switching control means supplies the fuel in the high vapor pressure tank to the outside and supplies the fuel in the low vapor pressure tank to the outside when the pressure in the gas phase space exceeds the upper limit determination value. The fuel tank device according to claim 1, wherein the fuel tank device is configured to prohibit the operation of the fuel tank.   The tank switching mechanism is a three-way valve that connects one of a pipe connected to the high vapor pressure tank and a pipe connected to the low vapor pressure tank to an external fuel supply target. Or the fuel tank apparatus of 3.

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