阅读说明：本技术 飞机辅助油箱的通气装置、通气控制系统以及飞机燃油供给系统 (Ventilation device of aircraft auxiliary fuel tank, ventilation control system and aircraft fuel supply system ) 是由 姚莉君 刘亦林 何昌升 管天麟 刘德刚 于 2021-09-30 设计创作，主要内容包括：一种飞机辅助油箱的通气装置,用于维持所述辅助油箱内的无油空间的气体压力,其特征在于,包括：辅助油箱用通气管,所述辅助油箱用通气管连接在所述辅助油箱与设置于飞机机翼的机翼油箱之间,使得所述辅助油箱内的无油空间与所述机翼油箱内的无油空间流体连通；以及通气阀,所述通气阀设置于所述辅助油箱用通气管的中途,根据所述辅助油箱内的无油空间与机外环境的压力差的大小打开、关闭或者调节开度。(An aircraft auxiliary fuel tank vent apparatus for maintaining gas pressure in an oil free space within the auxiliary fuel tank, comprising: the breather pipe for the auxiliary oil tank is connected between the auxiliary oil tank and a wing oil tank arranged on the wing of the airplane, so that an oil-free space in the auxiliary oil tank is communicated with an oil-free space in the wing oil tank in a fluid manner; and a vent valve provided midway in the vent pipe for the auxiliary oil tank, and opening, closing, or adjusting the opening degree according to the magnitude of the pressure difference between the oil-free space in the auxiliary oil tank and the environment outside the machine.)

1. An aircraft auxiliary fuel tank vent apparatus for maintaining gas pressure in an oil free space within the auxiliary fuel tank, comprising:

the breather pipe for the auxiliary oil tank is connected between the auxiliary oil tank and a wing oil tank arranged on the wing of the airplane, so that an oil-free space in the auxiliary oil tank is communicated with an oil-free space in the wing oil tank in a fluid manner; and

and the vent valve is arranged in the middle of the vent pipe for the auxiliary oil tank and is opened, closed or opened according to the pressure difference between the oil-free space in the auxiliary oil tank and the environment outside the machine.

2. An aircraft auxiliary fuel tank venting device as defined in claim 1 wherein said vent valve is a safety valve.

3. An aircraft auxiliary fuel tank venting device as defined in claim 1, further comprising:

the quick-pressure vent pipe is connected to the middle of the auxiliary oil tank vent pipe and used for introducing external environment gas; and

and a check valve provided in a middle of the quick pressure vent pipe and allowing only the introduced external ambient gas to flow into the auxiliary tank.

4. An aircraft fuel supply system comprising:

the ventilation oil tank is communicated with the fluid of the external environment through a ventilation pipe for the ventilation oil tank, one end of the ventilation oil tank is arranged outside the machine;

a wing tank storing fuel to be delivered to an engine of an aircraft;

the ventilation pipe for the wing oil tank is connected with an oil-free space in the wing oil tank and an oil-free space in the ventilation oil tank; and

an auxiliary fuel tank that stores fuel to be supplied to the wing fuel tank,

it is characterized in that the preparation method is characterized in that,

an aircraft auxiliary fuel tank ventilation device as claimed in any one of claims 1 to 3.

5. A ventilation control system for an aircraft auxiliary fuel tank for controlling a ventilation device for an aircraft auxiliary fuel tank as claimed in any one of claims 1 to 3, comprising:

a differential pressure sensor that detects a pressure difference between an oil-free space in the auxiliary oil tank and the environment outside the engine; and

an auxiliary fuel control unit that receives a detection result of the pressure difference detected by the pressure difference sensor and opens and closes the vent valve according to the detection result of the pressure difference.

6. An aircraft auxiliary fuel tank ventilation control system as claimed in claim 5, further comprising:

a differential pressure switch sensing a pressure difference between an oil-free space in the auxiliary oil tank and the environment outside the engine and opening and closing according to a sensing result of the pressure difference,

the auxiliary fuel control unit receives a sensing result from the pressure difference switch, compares the detection result with the sensing result, and judges that the detection result of the pressure difference is correct when the comparison result is consistent.

Technical Field

The invention relates to a ventilation device of an aircraft auxiliary fuel tank, a ventilation control system and an aircraft fuel supply system.

Background

As is known, a civil aircraft is generally provided with an auxiliary fuel tank system on the basis of an original aircraft model to increase the fuel loading of the aircraft, thereby improving the cruising ability of the aircraft. In addition, the auxiliary oil tank system is generally designed, produced, manufactured and installed after the original machine type is designed and proved.

The main function of the auxiliary fuel tank system is to supplement fuel to the original wing fuel tank (basic fuel tank) of the airplane, and the fuel in the auxiliary fuel tank is usually not directly supplied to the engine for consumption, but is firstly transferred to the basic fuel tank and supplied to the engine for consumption through the fuel pump of the basic fuel tank. The auxiliary oil tank system is in the process of refueling or in the process of transferring fuel oil, and in order to ensure that the internal pressure of the auxiliary oil tank meets the structural strength requirement, namely the difference between the gas pressure of an oil-free space in the oil tank and the external environment gas pressure is maintained, the auxiliary oil tank is required to be ventilated and the pressure in the oil tank is monitored.

Currently, regarding a conventional ventilation method for an auxiliary fuel tank, patent document 1 (chinese patent CN103057714B) proposes an auxiliary fuel system in which a new ventilation system (including an independent ventilation fuel tank) is separately provided for the auxiliary fuel tank, so as to maintain the gas pressure in an oil-free space in the auxiliary fuel tank. Also, the independent venting system is often an open venting system, i.e., the auxiliary tank is in direct communication with the external environment via a vented tank. Because the independent ventilation system is an open ventilation system, when the aircraft flies at high altitude, the fuel in the auxiliary fuel tank is difficult to supply to the wing fuel tank in a mode of pressurizing the inside of the auxiliary fuel tank by the gas in the cabin or the gas in the environment outside the aircraft. In view of the above, in order to replenish the fuel in the auxiliary fuel tank to the wing fuel tank, technical means such as adding a fuel delivery pump in the auxiliary fuel tank or adding an oil pump in the wing fuel tank are generally adopted. Therefore, the fuel in the auxiliary fuel tank can be supplied to the wing fuel tank under the condition that the auxiliary fuel tank is not pressurized, and the open type ventilation system can meet the ventilation requirement of the auxiliary fuel tank.

Disclosure of Invention

Technical problem to be solved by the invention

However, in the case of separately setting up a ventilation system dedicated to the auxiliary tank as described above, additional new equipment (for example, a transfer pump or an oil pump, or even a separate ventilation tank) and associated cables are required, increasing the risk of ignition sources, and also additional ventilation system management, increasing the weight of the aircraft and the development costs.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a breather device, a breather control system, and an aircraft fuel supply system for an auxiliary fuel tank of an aircraft, which can control the inside of the auxiliary fuel tank accurately without adding new equipment, such as a transfer pump or an oil pump, which may become a potential ignition source, and which have excellent safety and high reliability, while making full use of the breather system of the original type.

Technical scheme for solving technical problem

The invention provides a breather device for an aircraft auxiliary fuel tank, which is used for maintaining the gas pressure of an oil-free space in the auxiliary fuel tank, and is characterized by comprising: the breather pipe for the auxiliary oil tank is connected between the auxiliary oil tank and a wing oil tank arranged on the wing of the airplane, so that an oil-free space in the auxiliary oil tank is communicated with an oil-free space in the wing oil tank in a fluid manner; and a vent valve provided midway in the vent pipe for the auxiliary oil tank, and opening, closing, or adjusting the opening degree according to the magnitude of the pressure difference between the oil-free space in the auxiliary oil tank and the environment outside the machine.

According to the ventilating device of the auxiliary oil tank of the airplane, a set of new ventilating system is not independently arranged for the auxiliary oil tank, but the auxiliary oil tank is connected with the original ventilating system of the airplane wing through the ventilating pipe, and the ventilating oil tank is used for ventilating. The reason for this is that the auxiliary tanks are usually under pressure, no venting is normally required during flight, and the auxiliary tanks and wing tanks are not refueled simultaneously, so that less venting is required. Therefore, the auxiliary oil tank and the ventilation system of the original wing oil tank are connected and share the ventilation oil tank, so that the structure can be simplified, and the weight of the airplane can be reduced. In addition, the breather pipe for the auxiliary oil tank is provided with the breather valve which can be opened, closed or adjusted in opening degree according to the pressure difference between the oil-free space in the auxiliary oil tank and the environment outside the aircraft, so that the breather device of the auxiliary oil tank is formed into a closed device. Thus, it is not necessary to provide a device which may be a potential ignition source such as a transfer pump or an oil pump, and safety can be improved.

Preferably, the ventilation valve is a safety valve on the basis of the ventilation device of the auxiliary mailbox of the aircraft.

By using the vent valve as a safety valve, the opening degree can be automatically adjusted according to the actual pressure when the vent valve is opened. Therefore, the gas pressure in the auxiliary fuel tank can be controlled more accurately, and the safety is good.

On the basis of the air vent device for the auxiliary fuel tank of the aircraft, the air vent device preferably further comprises: the quick-pressure vent pipe is connected to the middle of the auxiliary oil tank vent pipe and used for introducing external environment gas; and a check valve provided in the middle of the quick pressure vent pipe and allowing only the introduced external environmental gas to flow into the auxiliary tank.

Because the ventilating device also comprises the quick-pressure ventilating pipe and the one-way valve arranged on the quick-pressure ventilating pipe, when the aircraft is steeply pitched and the outside air pressure is rapidly increased, part of the outside environment gas is introduced through the quick-pressure ventilating pipe and the one-way valve, and the auxiliary oil tank can be prevented from being crushed in the process of steeply pitching the aircraft.

In addition, the present invention also provides an aircraft fuel supply system comprising: the ventilation oil tank is communicated with the fluid of the external environment through a ventilation pipe for the ventilation oil tank, one end of the ventilation oil tank is arranged outside the machine; a wing tank storing fuel to be delivered to an engine of an aircraft; the ventilation pipe for the wing oil tank is connected with an oil-free space in the wing oil tank and an oil-free space in the ventilation oil tank; and an auxiliary fuel tank for storing fuel to be supplied to the wing fuel tank, wherein the aircraft further comprises a breather device of the aircraft auxiliary fuel tank.

Generally, the auxiliary fuel tanks of an aircraft are capable of withstanding a certain pressure without venting in the air, and the auxiliary fuel tanks and wing fuel tanks are generally not refueled at the same time, so that there is less need for venting. In view of the above, the auxiliary fuel tank is connected to the wing fuel tank through the breather device so as to share a set of breather system and a breather fuel tank with the wing fuel tank, thereby not only simplifying the structure of a breather subsystem in the fuel supply system, but also reducing the overall weight of the aircraft.

In another aspect, the present invention provides a ventilation control system for an aircraft auxiliary fuel tank, for controlling a ventilation device, comprising: a differential pressure sensor that detects a pressure difference between an oil-free space in the auxiliary oil tank and the environment outside the engine; and an auxiliary fuel control unit that receives a detection result of the pressure difference detected by the pressure difference sensor and opens and closes the vent valve according to the detection result of the pressure difference.

According to the ventilation control system of the auxiliary fuel tank of the airplane, the pressure difference between the oil-free space in the auxiliary fuel tank and the environment outside the airplane is detected through the pressure difference sensor, the detected pressure difference is transmitted to the auxiliary fuel control unit, and then the auxiliary fuel control unit opens and closes the ventilation valve according to the detection result of the pressure difference. Thus, the gas pressure in the auxiliary oil tank can be accurately controlled.

On the basis of the ventilation control system for the auxiliary fuel tank of the aircraft, preferably, the ventilation control system further comprises: the auxiliary fuel control unit receives a sensing result from the pressure difference switch, compares the detection result with the sensing result, and judges that the detection result of the pressure difference is correct when the comparison result is consistent.

According to the ventilation control system, by adopting a non-similar design of pressure measurement, namely comparing whether a sensing result of the differential pressure switch is consistent with a detection result of the differential pressure sensor, the accuracy of gas pressure measurement in the auxiliary oil tank can be improved, and the reliability of the ventilation control system can be improved.

Effects of the invention

According to the ventilating device of the auxiliary oil tank of the airplane, the inside of the auxiliary oil tank can be accurately controlled without adding new equipment which can become a potential ignition source, such as a transfer pump or an oil well pump, and the ventilating device has good safety and high reliability.

Drawings

Figure 1 is a schematic view of an aircraft fuel supply system according to an embodiment of the invention, showing the venting means of the auxiliary fuel tank according to the invention.

Fig. 2 is a schematic view of a ventilation control system for an auxiliary fuel tank according to an embodiment of the present invention.

Fig. 3 is an architecture diagram of an auxiliary fuel control unit in the vent control system of fig. 2.

Description of the symbols

O fuel supply system

LF aircraft left wing

RF aircraft right wing

1 ventilating oil tank

2 wing oil tank

3 auxiliary oil tank

4 ventilation control system

5 differential pressure sensor

6 auxiliary fuel control unit

7 pressure difference switch

8 auxiliary fuel isolation unit

P1 breather pipe for wing fuel tank

P2 breather pipe for auxiliary oil tank

P3 vent pipe for quick pressure

V-shaped vent valve

V1 one-way valve

Detailed Description

First, a fuel supply system and a breather device of an auxiliary tank according to an embodiment of the present invention will be described with reference to fig. 1.

Fig. 1 is a schematic view of an aircraft fuel supply system O according to an embodiment of the invention. As shown in fig. 1, the fuel supply system O includes a breather tank 1 and a wing tank 2 provided to a left wing LF and a right wing RF of the aircraft (here, for simplicity, only the breather tank 1 and the wing tank 2 of the left wing are shown), and an auxiliary tank 3 provided in a cabin of the fuselage on the rear side of the wings. The ventilation tank 1 is a tank for communicating the fuel supply system O with the environment outside the engine, and is in fluid communication with the environment outside the engine through a ventilation pipe (not shown) having one end provided outside the engine and the other end provided in an oil-free space of the ventilation tank 1. In the present embodiment, the ventilation oil tank 1 is provided at the tip of the left wing LF and the right wing RF. The wing oil tank 2 is provided in the left wing LF and the right wing RF on the body side of the aircraft relative to the ventilation oil tank 1, and is connected to the ventilation oil tank 1 via a wing oil tank ventilation pipe P1, so that the oil-free space in the ventilation oil tank 1 is in fluid communication with the oil-free space in the wing oil tank 2. In the present embodiment, fuel to be supplied to an engine (not shown) of an aircraft is stored in the wing tank 2 as a basic tank (also referred to as a main tank or a consumable tank). The auxiliary oil tank 3 is an oil tank in which the wing oil tanks 2 are replenished, and is connected to the wing oil tank 2 that is disposed closer to the auxiliary oil tank 3, of the two wing oil tanks 2 of the left wing LF and the right wing RF, via an auxiliary oil tank vent pipe P2, so that the oil-free space in the auxiliary oil tank 3 is in fluid communication with the oil-free space in the wing oil tank 2. When the fuel in the wing tank 2 decreases to a certain extent, specifically, when the liquid level of the fuel in the wing tank 2 decreases to a certain level, a fuel delivery valve (not shown) provided in the wing tank 2 is opened, and the fuel stored in the auxiliary tank 3 is supplied to the wing tank 2 through a fuel delivery pipe (not shown) to replenish the fuel in the wing tank 2.

In the present embodiment, the aircraft fuel supply system O comprises a breather device for the auxiliary fuel tank 3. The breather device includes the auxiliary tank breather pipe P2 and a breather valve V provided in the middle of the auxiliary tank breather pipe P2. The vent valve V is a valve that opens, closes, or adjusts the opening degree according to the magnitude of the pressure difference between the oil-free space in the auxiliary tank 3 and the environment outside the aircraft, and is, for example, a spring-type safety valve. The breather device further includes a quick pressure vent pipe P3 and a check valve V1. One end of the quick pressure vent pipe P3 is connected to a middle portion of the auxiliary tank vent pipe P2, and the other end is communicated with the outside ambient atmosphere, and the check valve V1 is provided at a middle portion of the quick pressure vent pipe P3 and allows only the outside ambient gas to flow from the outside of the machine to the inside of the auxiliary tank 3.

Next, the ventilation control system 4 of the auxiliary tank 3 in the present embodiment will be described with reference to fig. 2.

Fig. 2 shows a ventilation control system 4 of the auxiliary fuel tank 3 according to the present embodiment. For convenience of understanding, the quick pressure vent pipe P3 and the check valve V1 are omitted in fig. 2. The ventilation control system 4 is a control system for opening and closing a ventilation valve V provided in the middle of the auxiliary tank ventilation pipe P2, and includes a differential pressure sensor 5, an auxiliary fuel control unit 6, a differential pressure switch 7, and an auxiliary fuel isolation unit 8. The differential pressure sensor 5 is a sensor for detecting a pressure difference between the gas in the oil-free space in the auxiliary oil tank 3 and the external ambient gas, and the differential pressure switch 7 is a switch for sensing the pressure difference between the gas in the oil-free space in the auxiliary oil tank 3 and the external ambient gas and is turned on or off according to the sensing result of the pressure difference. The auxiliary fuel isolation unit 8 is a signal processing unit which receives the sensed value of the pressure difference sensed by the pressure difference switch 7, converts the signal type of the sensed value and sends the converted value to the auxiliary fuel control unit 6. The auxiliary fuel control unit 6 is a comprehensive control unit, which draws a wheel-mounted signal of the aircraft from an avionics system control unit 9 of the aircraft, acquires a button state signal (fuel supply state signal) of an auxiliary fuel control panel, reads a detection value of a pressure difference detected by the pressure difference sensor 5, receives a switched on/off state signal of the pressure difference switch 7 transmitted from the auxiliary fuel isolation unit 8, and determines whether the vent valve V needs to be opened or closed by a combinational logic circuit shown in fig. 3. Further, the auxiliary fuel control unit 6 reads a detection value of the pressure difference detected by the pressure difference sensor 5, compares the detection value with a preset design value, and acquires a comparison result signal. The auxiliary fuel control means 6 receives the switching state signal of the differential pressure switch 7 transmitted from the auxiliary fuel isolation means 8, and then compares the switching state signal with the comparison result signal to generate the operation state signal of the differential pressure sensor 5.

As for the control structure of the auxiliary fuel control unit 6, as shown in fig. 3, the fuel supply state signal and the wheel load signal are simultaneously inputted to an or gate circuit, and at the same time, the detection signal of the pressure difference detected by the pressure difference sensor 5 and the operation state signal of the pressure difference sensor 5 are simultaneously inputted to an nand gate circuit, and the or gate circuit and the nand gate circuit are connected in parallel and then connected to an and gate circuit, through which the opening and closing control signal of the vent valve V is outputted. In the present embodiment, the fuel supply state signal, the wheel load signal, the comparison result signal, the operation state signal of the differential pressure sensor 5, and the control signal of the vent valve V as the output signals are all one-bit binary signals (including a high level signal, i.e., 1, and a low level signal, i.e., 0).

As an example of the logic determination, if the fuel supply state signal is a low level signal, that is, 0 (not in the refueling state or the fuel replenishment state), the wheel load signal is a high level signal, that is, 1 (the aircraft is in the flying state), the result of comparing the detected value of the differential pressure sensor 5 with the design value is 0 (the detected value is larger than the design value), and the operation state signal of the differential pressure sensor 5 is a low level signal, that is, 0 (the differential pressure sensor 5 is not in a failure and is in a normal operation state), the output result of the combinational logic circuit is 1, which indicates that the vent valve V needs to be opened. On the other hand, if the output result of the combinational logic circuit is 0, it indicates that the ventilation valve V needs to be closed.

Next, the opening/closing control of the ventilation valve V by the ventilation control system 4 according to the present embodiment will be described in detail based on the above description.

First, the differential pressure sensor 5 detects the gas pressure in the oil-free space in the auxiliary oil tank 3 and the external ambient gas pressure, respectively, to thereby obtain the pressure difference between the gas in the oil-free space in the auxiliary oil tank 3 and the external ambient gas. Meanwhile, the differential pressure switch 7 senses and detects the pressure difference between the gas in the oil-free space in the auxiliary fuel tank 3 and the gas in the environment outside the engine, and opens and closes according to the magnitude of the pressure difference, and simultaneously sends a discrete quantity signal indicating the opening or closing of the differential pressure switch 7 to the auxiliary fuel isolation unit 8. In the present embodiment, for example, when the sensed value of the pressure difference is larger than a design value set in advance, the pressure difference switch 7 is closed and generates a discrete quantity signal equivalent to a low level signal, and when the sensed value is smaller than the design value, the pressure difference switch 7 is opened and generates a discrete quantity signal equivalent to a high level signal.

Then, the auxiliary fuel isolation unit 8 receives the discrete magnitude signal from the differential pressure switch 7, and after signal type conversion is performed on the discrete magnitude signal, the converted switching state signal of the differential pressure switch 7 is sent to the auxiliary fuel control unit 8.

The auxiliary fuel control unit 8 draws an on-wheel signal of the aircraft from the avionics system control unit 9 of the aircraft, collects a button state signal (i.e., a fuel supply state signal) from the auxiliary fuel control panel, receives a switch state signal transmitted from the auxiliary fuel isolation unit 8, and reads a detected value of the pressure difference detected by the pressure difference sensor 5. After reading the detection value of the pressure difference detected by the pressure difference sensor 5, the auxiliary fuel control unit 8 compares the detection value with a preset design value of the pressure difference and generates a comparison result signal. Specifically, when the detection value is larger than the design value, the generated comparison result signal is a low level signal, i.e., 0, and when the detection value is smaller than the design value, the generated comparison result signal is a high level signal, i.e., 1. Then, upon receiving the switching state signal transmitted from the auxiliary fuel isolation unit 6, the auxiliary fuel control unit 8 compares the comparison result signal with the switching state signal and generates an operation state signal of the differential pressure sensor 5. Specifically, if the comparison result signal and the switch state signal are signals of the same state (for example, both are low level signals), it is determined that the differential pressure sensor 5 is not in a failure state and is in a normal operation state, and the auxiliary fuel control unit 8 generates a low level operation state signal. If the comparison result signal and the switch state signal are signals of different states (for example, one is a high level signal and the other is a low level signal), it is determined that the differential pressure sensor 5 is malfunctioning, and the auxiliary fuel control unit 8 generates an operating state signal of a high level. That is, in the present embodiment, the auxiliary fuel control unit 8 determines whether or not the differential pressure sensor 5 is malfunctioning by means of a non-similar design of pressure measurement.

Then, the fuel supply state signal, the wheel load signal, the comparison result signal, and the operation state signal, which are input signals, are input to a combinational logic circuit shown in fig. 3, and a switching control signal of the vent valve V is output after calculation by the logic circuit. The assist control unit 6 then sends the on-off control signal to the vent valve V, thereby opening and closing the vent valve V.

(technical Effect of the embodiment)

The ventilation device according to the above embodiment of the present invention is a closed ventilation device, and is connected to the ventilation system of the original wing fuel tank 2. Generally, the auxiliary fuel tanks of an aircraft are capable of withstanding a certain pressure without venting in the air, and the auxiliary fuel tanks and wing fuel tanks are generally not refueled at the same time, so that there is less need for venting. In view of the above, the auxiliary fuel tank is connected to the wing fuel tank through the breather device so as to share a set of breather system and a breather fuel tank with the wing fuel tank, thereby not only simplifying the structure of a breather subsystem in the fuel supply system, but also reducing the overall weight of the aircraft. In addition, because this breather is closed breather, can carry out accurate control to the oil tank internal pressure, when pressure differential is in reasonable scope, can guarantee auxiliary fuel oil system and normally work, can not lead to the oil tank structure to damage because of the pressure is too big again.

The ventilation control system of the above embodiment of the present invention is a control system based on a non-similar design, and by providing a differential pressure switch and a differential pressure sensor, the differential pressure switch and the differential pressure sensor can simultaneously detect the pressure difference between the oil-free space in the auxiliary oil tank 3 and the external environment, and compare the detection results of the two to ensure the accuracy of pressure measurement, thereby improving the safety of the oil tank structure and the reliability of the system.

(other embodiments)

In the above embodiment, the case where the breather device includes the auxiliary tank breather pipe P2, the breather valve V provided in the auxiliary tank breather pipe P2, the quick pressure breather pipe P3 connected to the auxiliary tank breather pipe P2, and the check valve V1 provided in the quick pressure breather pipe P3 has been described, but the breather device is not limited to this. For example, the breather device of the auxiliary tank 3 may include only the auxiliary tank breather pipe P2 and the breather valve V provided in the auxiliary tank breather pipe P2, instead of the quick pressure breather pipe P3 and the check valve V1.

Further, in the above-described embodiment, the ventilation control system 4 of the auxiliary fuel tank 3 includes, but is not limited to, the differential pressure sensor 5, the auxiliary fuel control unit 6, the differential pressure switch 7, and the auxiliary fuel isolation unit 8 based on the concept of a non-similar design. For example, the ventilation control system 4 may include only the differential pressure sensor 5 and the auxiliary fuel control unit 6, instead of the dissimilar design, thereby enabling the opening and closing control of the ventilation valve V.

In addition, the present invention can freely combine the respective embodiments, or appropriately modify or omit the respective embodiments within the scope thereof.