JP3163442B2 - Fuel supply system with fuel leak detection function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system which is installed in, for example, a school, a hospital, a high-rise house, etc. and distributes and supplies fuel from one oil storage tank to a large number of combustors. The present invention relates to a fuel supply system having a fuel leak detection function capable of detecting a minute leak of fuel in a fuel supply system.

[0002]

2. Description of the Related Art Heretofore, when a fuel leak has occurred in this type of fuel supply system, it is extremely difficult to identify the location of the leak due to the long fuel passage, and the fuel leak cannot be noticed. The use of equipment in is extremely dangerous. Therefore, a technique for detecting fuel leakage in the fuel flow path has been proposed. For example, Tokiko 7-18
No. 546 discloses an on-off valve controlled by a combustion control circuit at an outlet of a fuel tank connected via a fuel supply pipe to a combustor provided with a device plug at a fuel inflow port. An auxiliary tank is provided downstream of the valve, and a liquid level detection sensor for detecting a liquid level position of the auxiliary tank when the instrument stopper and the on-off valve are closed is provided in the auxiliary tank. A liquid fuel leak detecting device for an oil combustor, characterized in that the on-off valve is kept closed by the combustion control circuit after detecting a decrease in the fuel pressure.

In Japanese Utility Model Laid-Open Publication No. 6-40640,
A relay tank that temporarily stores kerosene from the storage tank, a plurality of air conditioning terminals that use kerosene supplied from the relay tank as fuel, and a pump provided in a communication passage between the storage tank and the relay tank. Liquid level detecting means for detecting whether the liquid level of kerosene stored in the relay tank has reached an upper limit and a lower limit, and detecting the flow rate of kerosene flowing through the communication passage, A flow meter that outputs a detection signal when the detected flow rate reaches or exceeds the set flow rate from the lower limit to the upper limit of the liquid level, and the liquid level detecting means at the time when the detection signal is output from the flow meter. And a kerosene leak detecting means for detecting whether or not the level of kerosene in the relay tank has reached an upper limit via an interface, and controlling the operation of the pump based on the detection result. Air conditioning system Oil leakage detecting device Yes discloses a,
In addition, the relay tank and multiple air conditioning terminals are connected via a door-to-door tank, and the total amount of kerosene supplied based on the number of operating air conditioners and the actual flow rate are compared. Is disclosed.

[0004]

However, according to the prior art described in Japanese Patent Publication No. Hei 7-18546, once the operation of the combustor is started, the auxiliary tank is continuously supplied with fuel from the fuel tank. Therefore, there is a disadvantage that even if there is a fuel leak between the auxiliary tank and the combustor, it cannot be detected. Further, according to the technology according to Japanese Utility Model Application Laid-Open No. 6-40640, the detected flow rate of the kerosene in the relay tank reaches or exceeds the set flow rate from the lower limit to the upper limit, and the kerosene liquid level in the relay tank increases. When the upper limit has been reached, the pump continues to operate assuming that there is no kerosene leakage in the communication passage.Therefore, the pump operates between the underground tank and the relay tank via the piping as the communication passage and the piping as the return path. And there is a drawback that it cannot cope with a case where the kerosene consumption fluctuates. Further, there is a problem that the method of summing up the kerosene consumption at a plurality of air conditioning terminals and determining the required flow rate based on the total value is not practical because each device has an error.

Further, when the operation of the fuel supply system is suspended for a long period of time, such as in summer, the fuel remains in the relay tank in the prior art, so that fuel leakage may occur, and the system may be damaged. There is a drawback in that it is not detected that leakage has occurred due to the pause.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and it is possible to detect fuel leakage in any part of a fuel flow path from an oil storage tank to a terminal combustor, and the fuel consumption varies. Even if leaks can be detected reliably,
It is another object of the present invention to provide a fuel supply system having a fuel leak detection function that is excellent in safety and reliability because a fuel leak can be detected while the combustor is operating or stopped.

[0007]

According to a first aspect of the present invention, there is provided a fuel supply system comprising: a fuel supply tank configured to transfer fuel supplied from an oil storage tank via an oil supply passage to a relay tank; In the fuel supply system, fuel is supplied from the relay tank 2 to the combustor 6 through the oil supply path 7, and the oil supply path 4 is provided with a pumping flow meter 11 and an oil supply pump 5. The relay tank 2 is provided with a liquid level detector 3 for detecting the upper limit of the liquid storage amount. When the liquid level detector 3 detects the upper limit of the liquid storage amount, the measured supply amount of the oil pump flow meter 11 is controlled by the control panel 23. The relay tank 2 stored in advance in
The supply pump 5 is stopped when the amount of liquid stored in the storage tank 1 exceeds
And a normally closed discharge on-off valve 13
When the refueling pump 5 is stopped, the discharge on-off valve 1
3 to open the fuel in the relay tank 2
It is configured to return to the oil storage tank 1 via the oil drainage passage 12 .

A main on-off valve 15, a refueling flow meter 16, and an intermittent on-off valve 20 are provided in the oil supply passage 7 from the upstream side, respectively, and are located between the intermittent on-off valve 20 and the combustor 6. A small amount relay tank 17 is provided in the oil supply passage 7 so that when the intermittent on-off valve 20 is closed while the combustor 6 is operating, the leakage of the oil supply passage 7 is detected from the metering operation of the oil supply flow meter 16. Good to do.

Further, according to a third aspect of the present invention, which is configured to solve the above-described problem, the fuel supplied from the oil storage tank 1 via the oil supply path 4 is stored in the oil server 31. Combustion machine 6 from oil server 31 via oil supply path 7
In the fuel supply system configured to supply fuel to the oil supply passage, an oil supply flow meter 11 is provided in the oil supply passage 4, and an oil supply flow meter 16 is provided in the oil supply passage 7. When the measured flow rate of the flow meter 16 is exceeded, the operation of the oil server 31 is stopped ,
And located in the refueling passage 7 upstream of the refueling flow meter 16
And the main on-off valve 15 is located on the downstream side and the intermittent on-off valve 2
0 is provided for each of the intermittent on-off valve 20 and the combustor 6.
A small relay tank 17 is installed in the oil supply passage 7
The intermittent on-off valve 2 during operation of the combustor 6
0 when the refueling flow meter 16 measures the
It is configured to detect leakage of the oil passage 7 .

When the amount of liquid stored in the small amount relay tank 17 is a predetermined amount, a normally closed liquid amount control valve 18 is provided, and when the main on-off valve 15 and the intermittent on-off valve 20 are closed, the refueling is performed. It is preferable to detect a leak from the road 7.

Further, in the above invention, when the amount of liquid stored in the small amount relay tank 17 is a predetermined amount, a normally closed liquid storage amount control valve 18 and a liquid level detector 19 for detecting the state of the predetermined amount of liquid storage.
The intermittent on-off valve 20 is closed, and the operation of the combustor 6 is stopped, and the liquid level detector 19 detects a decrease in the amount of liquid stored in the small amount relay tank 17 so that the liquid level is detected. It is preferable to detect fuel leakage between the intermittent on-off valve 20 and the combustor 6.

Further, the relay tank 2 is located between the refueling flow meter 16 and the intermittent on-off valve 20 and is connected to the refueling passage 7.
It is preferable to provide a leak detector 21 to which fuel is supplied from the fuel cell system, and to detect a leak from the oil supply passage 7 when the main on-off valve 15 and the intermittent on-off valve 20 are closed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. In FIGS. 1 and 2, 1
Is an oil storage tank buried underground or the like for storing fuel, 2 is a high-altitude relay tank installed at a high place of a building such as a school building, a high-rise house, etc., for supplying fuel by a head, and the high-altitude relay tank. 2 is provided with a liquid level detector 3 having an upper limit liquid level sensor 3A for detecting the upper limit of the liquid storage amount and a lower limit liquid level sensor 3B for detecting the lower limit. And high-altitude relay tank 2
Is connected to the oil storage tank 1 via an oil supply pipe 4 forming an oil supply path, and fuel is supplied from the oil storage tank 1 by an oil supply pump 5 provided in the middle of the oil supply pipe 4.
Are a plurality of combustors constituting an air conditioning terminal for heating or cooling a room on each floor of a high-rise house. Each of the combustors 6 forms a refueling passage, and the downstream side is branched. Tubes 7A, 7
B and 7C, which are in communication with the high-altitude relay tank 2 via the oil supply pipe 7, and are connected to the oil storage tank 1, the high-altitude relay tank 2, the oil supply pump 5, the combustor 6, and the oil supply pipe 4 for communicating these oils and The pipe 7 forms the basis of the fuel supply system.

Numeral 11 denotes an oil-lifting flow meter which is provided on the oil feed pipe 4 at an upstream side of the oil supply pump 5 and detects the supply amount of fuel supplied from the oil storage tank 1 to the high-altitude relay tank 2. When the amount of liquid stored in the high-altitude relay tank 2 decreases and the lower limit liquid level sensor 3B is turned on, the counter of the flow meter 11 is reset to zero. Reference numeral 12 denotes a fuel return pipe provided between the high-altitude relay tank 2 and the oil storage tank 1, and a normally-closed electromagnetic oil drain valve 13 is provided in the fuel return pipe 12.
Numeral 14 denotes a high-altitude relay tank 2 which bypasses the electromagnetic oil drain valve 13.
And an overflow pipe connected between the fuel return pipe 12.

Thus, a predetermined amount of fuel is stored in the high-altitude relay tank 2.
When the fuel is supplied and the upper limit liquid level switch 3A is ON, the refueling flow meter 16 described later is reset to zero, the amount of liquid stored in the high-altitude relay tank 2 decreases, and the lower limit liquid level sensor 3B turns ON.
, The oil flow meter 11 is reset to zero, the oil supply pump 5 is driven, and the difference between the two flow meters 11, 16 when the upper limit liquid level switch 3A detects that the storage amount has reached the predetermined amount again. Is determined by the control panel 23 so that the oil storage tank 1 and the high-altitude relay tank 2 can be operated while the combustor 6 is operating.
Can be detected.

Next, reference numeral 15 denotes an electromagnetic main on-off valve which is provided in the fuel supply pipe 7 and collectively controls the supply of fuel from the high-altitude relay tank 2 to all the combustors 6. A refueling flow meter that is provided on the refueling pipe 7 and that detects the total amount of fuel supplied from the high-altitude relay tank 2 to all the combustors 6. The counter is reset to zero when the volume reaches a predetermined volume. The refueling flow meter 16 is of a type having a high measurement accuracy, so that even a small amount of leakage can be detected with high accuracy. Reference numerals 17, 17, 17 denote small relay tanks located downstream of the refueling flow meter 16 and connected to the branch pipes 7 </ b> A to 7 </ b> C of the refueling pipe 7, respectively. Each of the small relay tanks 17 has a capacity to store the fuel consumed by the combustor 6 in a short time, for example, for one minute.
A float valve 18 is provided for maintaining a predetermined storage volume.

Reference numeral 19 denotes a small relay tank 1 in a state where the operation of the combustor 6 is stopped and the intermittent on-off valve 20 is closed.
5 shows a distal leak detector that detects a leak of fuel on the distal side between the fuel cell 7 and the combustor 6. The end-side leak detector 19 has a predetermined amount of liquid stored in the relay tank 17 and a float valve 18.
Is closed, the liquid level sensor 19A is in the ON state, and when the liquid level drops and turns OFF, a liquid level drop signal is sent to the control unit 23 to detect fuel leakage. . When a leak is detected by the end-side leak detector 19, an alarm device 25, which will be described later, issues an alarm according to an alarm signal from the control unit 23, and the intermittent on-off valve 20 stops operating.

Further, 20, 20, 20 are located on the upstream side of the small amount relay tanks 17, 17, 17 and each branch pipe 7A, 7
B and 7C show an electromagnetic intermittent on-off valve provided in 7C. Each of the intermittent on-off valves 20 is intermittently opened at intervals of one minute, for example, by rotating or reciprocating the valve element at a constant cycle, and feeds fuel from the high-altitude relay tank 2 at regular intervals, for example, one minute. The small amount is intermittently supplied to the relay tank 17 at intervals.

Reference numeral 21 denotes a refueling flow meter 16 and an intermittent on-off valve 20.
And a leak detector which is provided in the supply pipe 7 and communicates with the high-altitude relay tank 2 through the ventilation pipe 22. The leak detector 21 is a container 21A having a capacity of about 20 to 30 cc.
And a liquid level sensor 21B provided in the container 21A for detecting whether or not the liquid is at a predetermined storage amount. Then, the leak detector 21 stops the operation of all the combustors 6 and accordingly stops or suspends the system in which the main on-off valve 15 is closed, and the refueling flow meter 16 and the intermittent on-off valve A hydraulic pressure is applied to the supply pipe 7 between the supply pipe 20 and the liquid supply pipe 20 to detect a drop in the liquid level, thereby detecting the presence or absence of leakage. In this case, even if the combustor 6 attempts to start operation, the main opening / closing valve 15 is not opened until a reset signal is sent from the control panel 23 and reset.

Reference numeral 23 denotes a control panel constituted by a microcomputer. The control panel 23 is a storage unit for storing a predetermined amount of liquid stored in the high-altitude relay tank 2 and the like, and the amount of liquid supplied to the oil flow meter 11 and the oil flow meter 16. And a judgment unit for judging the presence or absence of fuel leakage. And control panel 2
Reference numeral 3 denotes a liquid level detector 3 through a signal line 24A and a signal line 24B.
Oil pump 5 and each combustor 6 by signal line 24C.
The first flow meter 11 is connected to the signal line 24D through the signal line 24D.
E for the second flowmeter 12 and the signal line 24F for the electromagnetic type
A discharge valve 13, an electromagnetic main on-off valve by a signal line 24G 15
, A terminal leak detector 19 via a signal line 24H, an intermittent on / off valve 20 via a signal line 24J, and a signal line 24
K is connected to each of the leak detectors 21. 2
Reference numeral 5 denotes an alarm which is electrically connected to the control panel 23. The alarm 25 is provided when the fuel leak is detected.
A warning is issued by a signal from

The apparatus according to the present embodiment is configured as described above. Next, the operation thereof will be described. First, when the system according to the present embodiment is stopped, the discharge on-off valve 13 is in the open state, the main on-off valve 15 is in the closed state, and the high-altitude relay tank 2 is empty. When the operation of the combustor 6 is started, first, the discharge on-off valve 13 is closed, the pumping flow meter 11 is reset to zero, and the fuel pump 5
To supply fuel to the high-altitude relay tank 2. The liquid level in the high-altitude relay tank 2 rises and the upper limit liquid level sensor 3A turns ON.
Is reached, a stop signal is sent from the control panel 23 to the refueling pump 5 to stop the refueling pump 5 and the refueling flow meter 16
Resets to zero. If the supply amount measured by the pumping flow meter 11 before the refueling pump 5 stops exceeds the predetermined storage amount of the high-altitude relay tank 2 stored in the control panel 23, the control panel 23 Determines that there is a fuel leak between the oil storage tank 1 and the high-altitude relay tank 2, stops the operation of the refueling pump 5, and issues an alarm by the alarm 25. In addition,
If the refueling pump 5 does not stop due to a malfunction of the liquid level detector 3 or an erroneous determination of the control panel 23, excess fuel in the high-altitude relay tank 2 is transferred to the fuel return pipe 1 via the overflow pipe 14.
2 returns to the oil storage tank 1.

Next, when the operation of any of the combustors 6 is started, the main opening / closing valve 15 is opened by a valve opening signal from the control panel 23, and the intermittent on / off valve 20 is opened by a starting signal from the control panel 23. Is started, fuel is supplied to the combustor 6, and the refueling flow meter 16 measures the flow rate of the fuel from the high-altitude relay tank 2 to the combustor 6. The intermittent on-off valve 20 that repeats the open state and the closed state at regular intervals.
If the refueling flow meter 16 is measuring the fuel flow rate even when the valve is closed, it is determined that there is a leak in the refueling pipe 7 between the refueling flow meter 16 and the intermittent on-off valve 20, and the alarm 25 An alarm is issued by. As described above, the leakage of the fuel can be detected even during the operation of the combustor 6.

Even when the operation of the combustor 6 is stopped, the float valve 1 becomes
The intermittent on-off valve 20 repeats the on-off operation until the valve 8 closes, and the inside of the small amount relay tank 17 is always kept full. When the liquid level in the end-side leak detector 19 drops and the liquid level sensor 19A is turned off even while the combustor 6 is stopped, the control panel 23 sends the small amount of the relay tank 1
It is determined that there is a fuel leak between the fuel cell 7 and the combustor 6, and an alarm is issued from the alarm device 25. In this case, even if the control panel 23 receives a start signal from the combustor 6, it does not send an operation signal to the intermittent on-off valve 20.

When all the combustors 6 are stopped, the main on-off valve 15 is closed. When there is a fuel leak between the main on-off valve 15 and the combustor 6, the normally closed leak detector 21 turns off the liquid level sensor 21B and sends an alarm signal from the control panel 23 to the alarm 25. In addition, even when the refueling system is stopped, a leak between the main on-off valve 15 and the intermittent on-off valve 20 in the refueling pipe 7 can be detected. Note that the main on-off valve 15 is kept closed until reset.

As described above, when the high-altitude relay tank 2 reaches a predetermined liquid storage amount, the refueling flow meter 16 is reset to zero.
The total amount of fuel consumed by the combustor 6 in the operating state is measured by the refueling flow meter 16. The operation of the combustor 6 causes the liquid level in the high-altitude relay tank 2 to drop, and the lower limit liquid level sensor 3
When B is turned on, the control panel 23 resets the oil flow meter 11 to zero and then starts the oil supply pump 5. When the refueling pump 5 is started, the control panel 23 displays the integrated value M of the oil flow meter 11 until the upper limit liquid level sensor 3A of the liquid level detector 3 is turned on.
₁ is compared with the integrated value M ₂ of the refueling flow meter 16. Integrated value M
If _1> integrated value M _2, control panel 23 as there is leakage of the fuel between the oil storage tank 1 and the high place relay tank 2 an alarm by sending an alarm signal to the alarm device 25, the oil supply pump 5 By sending a stop signal and a valve opening signal to the electromagnetic oil drain valve 13, respectively, the inside of the high-altitude relay tank 2 is emptied. The control panel 23 sends a stop signal to all the combustors 6 and also sends a stop signal to each intermittent on-off valve 20. In this way, even during the operation of the refueling system, the leakage of fuel between the oil storage tank 1 and the high-altitude relay tank 2 can be detected.

Next, FIG. 3 shows a second embodiment. In the present embodiment, the same components as those of the first embodiment are denoted by the same reference numerals , and the description thereof is omitted. The feature of the present embodiment lies in that an oil server 31 is used in place of the high relay tank 2 in the first embodiment. That is, in the figure, 3
Reference numeral 1 denotes an automatic oil server having a built-in high level switch 31A and a low level switch 31A. The oil server 31 is connected to the oil storage tank 1 through an oil feed pipe 4 provided with a pumping flow meter 11, and has a main outlet. An oil supply pipe 7 provided with an on-off valve 15 and an oil supply flow meter 16 is connected. The fuel return pipe 12 is connected to the oil server 31, but the discharge on-off valve 13 is not provided.

This embodiment is characterized by the above-described configuration, and other components are the same as the first configuration. With this configuration, the oil supply system using the oil server 31 can also have the fuel leak detection function of the present invention.

[0028]

The present invention has the following advantages because it is constructed as described above. (1) Since the type of the combustor and the individual fuel consumption of the combustor are not used as the information of the fuel leakage, high-precision leakage detection can be performed without being affected by the operating condition of the individual combustor. it can. (2) Leakage of fuel that occurs between the oil storage tank and the combustor can be detected during operation and at rest, so that safety and reliability are excellent. (3) According to the first aspect of the invention, from the oil storage tank to the relay tank
If the amount of oil supplied to the tank exceeds the
Stop the operation of the refueling pump and open / close for discharge
Open valve to return fuel from relay tank to oil storage tank
Fuel leakage between the oil storage tank and the relay tank
Crab can be prevented. (4) According to the invention of claim 3, the oil is supplied from the oil storage tank.
Change fuel to relay tank, store in oil server and burn
Fuel leaks in the fuel supply system
Can be detected.

[Brief description of the drawings]

FIG. 1 is a partial configuration diagram of a fuel supply system having a fuel leak detection function according to a first embodiment of the present invention.

FIG. 2 is a partial configuration diagram of a fuel supply system having a fuel leak detection function shown after FIG.

FIG. 3 is a partial configuration diagram of a fuel supply system having a fuel leak detection function according to a second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 oil storage tank 2 relay tank 3 liquid level detector 4 oil supply pipe 5 oil supply pump 6 combustor 7 oil supply pipe 11 oil flow meter 12 fuel return pipe 13 discharge on-off valve 15 main on-off valve 16 oil supply flow meter 17 small quantity relay tank 18 oil storage Volume control valve 19 Terminal leak detector 20 Intermittent on-off valve 21 Leak detector 23 Control panel 31 Oil server

Claims (6)

(57) [Claims] A fuel supplied from an oil storage tank via an oil supply path is stored in a relay tank, and fuel is supplied from the relay tank to a combustor via an oil supply path. In the fuel supply system, an oil flow meter 11 and an oil supply pump 5 are provided in the oil supply passage 4, and a liquid level detector 3 for detecting an upper limit of the liquid storage amount is provided in the relay tank 2. When the measured flow rate of the oil flow meter 11 at the time when the upper limit of the liquid storage amount is detected exceeds the liquid storage amount of the relay tank 2 stored in the control panel 23 in advance, the supply pump 5 is stopped. And the oil storage tank 1 and the middle
An oil drain 12 is provided between the relay tank 2 and the normally closed drain.
An outlet opening / closing valve 13 is provided, and when the oil supply pump 5 is stopped,
By opening the discharge on-off valve 13, the relay tank is opened.
To the oil storage tank 1 through the oil drain passage 12.
A fuel supply system having a fuel leak detection function configured to return . 2. The main on-off valve 1 is connected to the oil supply passage 7 from an upstream side.
5, a refueling flow meter 16 and an intermittent on-off valve 20 are provided, respectively. A small amount relay tank 17 is provided on the refueling passage 7 between the intermittent on-off valve 20 and the combustor 6. 2. A fuel supply system having a fuel leak detection function according to claim 1, wherein when the intermittent on-off valve (20) is closed during the operation, the leakage of the oil supply passage (7) is detected from the metering operation of the oil supply flow meter (16). . 3. The fuel supplied from the oil storage tank 1 via the oil supply passage 4 is stored in an oil server 31.
In the fuel supply system configured to supply fuel to the combustor 6 from the fuel supply line 1 through the oil supply path 7, an oil supply flow meter 11 is provided in the oil supply path 4, and the oil supply flow meter 16 is provided in the oil supply path 7.
When the flow rate measured by the oil flow meter 11 exceeds the flow rate measured by the oil flow meter 16, the oil server 3
1 is stopped , and the oil supply path 7 is
The main on-off valve 15 is located upstream of the refueling flow meter 16
The intermittent on-off valves 20 are provided on the flow side, respectively.
The oil supply passage located between the on-off valve 20 and the combustor 6
7 is provided with a small relay tank 17 so that the combustion machine 6 can be operated.
The supply oil flow rate when the valve is closed the intermittent on-off valve 20 in
The leakage of the oil supply passage 7 is detected from the weighing operation of the total 16.
The fuel supply system having a fuel leakage detecting function made by Uni. 4. A normally closed storage amount control valve 18 is provided in the small amount relay tank 17 when the storage amount is a predetermined amount, and the refueling when the main on-off valve 15 and the intermittent on-off valve 20 are closed. the fuel supply system having a fuel leakage detection function according to claim 2 or 3, wherein it has to detect leakage from the road 7. 5. A small amount relay tank 17 comprising a normally closed storage amount control valve 18 when the storage amount is a predetermined amount, and a liquid level detector 19 for detecting a state of the storage amount being a predetermined amount, The intermittent type opening / closing valve 20 is closed to detect the decrease in the amount of liquid stored in the small amount relay tank 17 when the operation of the combustor 6 is stopped. the fuel supply system having a fuel leakage detection function of way constituted claim 2 or 3 wherein detecting the leakage of fuel between the on-off valve 20 and the combustion device 6. 6. The refueling flow meter 16 and an intermittent on-off valve 20.
And a leak detector 21 for supplying fuel from the relay tank 2 to the fuel supply passage 7, and the fuel supply passage 7 when the main on-off valve 15 and the intermittent on-off valve 20 are closed.
The fuel supply system having a fuel leakage detection function according to claim 2 or 3, wherein in that to detect the leakage from.