CN112340037B - Double-cavity fuel system suitable for diving flight of unmanned aerial vehicle and design method thereof - Google Patents
Double-cavity fuel system suitable for diving flight of unmanned aerial vehicle and design method thereof Download PDFInfo
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- CN112340037B CN112340037B CN202011233628.8A CN202011233628A CN112340037B CN 112340037 B CN112340037 B CN 112340037B CN 202011233628 A CN202011233628 A CN 202011233628A CN 112340037 B CN112340037 B CN 112340037B
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- 239000000446 fuel Substances 0.000 title claims abstract description 66
- 230000009189 diving Effects 0.000 title claims abstract description 40
- 238000013461 design Methods 0.000 title claims abstract description 19
- 238000000034 method Methods 0.000 title claims abstract description 8
- 239000003921 oil Substances 0.000 claims abstract description 114
- 239000007788 liquid Substances 0.000 claims abstract description 16
- 239000010705 motor oil Substances 0.000 claims abstract description 3
- 239000002828 fuel tank Substances 0.000 claims description 13
- 239000000295 fuel oil Substances 0.000 claims description 12
- 238000012360 testing method Methods 0.000 claims description 4
- 238000005086 pumping Methods 0.000 claims description 3
- 230000002411 adverse Effects 0.000 abstract description 2
- 230000009977 dual effect Effects 0.000 abstract 2
- 230000009194 climbing Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000013507 mapping Methods 0.000 description 2
- 230000003471 anti-radiation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000000306 component Substances 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000012938 design process Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000003502 gasoline Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 239000003350 kerosene Substances 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- B64D37/00—Arrangements in connection with fuel supply for power plant
- B64D37/02—Tanks
- B64D37/04—Arrangement thereof in or on aircraft
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- B64D37/00—Arrangements in connection with fuel supply for power plant
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- B64D37/00—Arrangements in connection with fuel supply for power plant
- B64D37/02—Tanks
- B64D37/06—Constructional adaptations thereof
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64U—UNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR
- B64U50/00—Propulsion; Power supply
- B64U50/10—Propulsion
- B64U50/11—Propulsion using internal combustion piston engines
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T50/00—Aeronautics or air transport
- Y02T50/40—Weight reduction
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- Aviation & Aerospace Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
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- Cooling, Air Intake And Gas Exhaust, And Fuel Tank Arrangements In Propulsion Units (AREA)
Abstract
The utility model provides a be suitable for unmanned aerial vehicle diving and fly's dual cavity fuel system and design method thereof, the export of flexible tank in the dual cavity fuel system communicates through the oil pump with the oil inlet of oil and gas separator upper end, and the oil-out of this oil and gas separator lower extreme passes through the external engine oil inlet of check valve. An oil inlet and an exhaust port are formed in an upper end cover of the oil-gas separator; an oil outlet is arranged at the lower part of the side wall of the oil-gas separator; a liquid level sensor is arranged on a side wall plate of the upper cavity. The oil-gas separator is divided into an upper cavity and a lower cavity. The utility model can not only meet the reliable oil supply of the unmanned aerial vehicle in normal flight, but also adapt to the influence of severe shaking of the fuel liquid level on the oil supply reliability of the oil outlet caused by adverse factors such as yaw, overload, gust and the like of the unmanned aerial vehicle in flight under the large maneuvering flight attitude, especially in the case of diving flight and pulling up and flying back, and the fuel system can stably and reliably supply pure fuel to the engine, thereby ensuring the normal operation of the engine.
Description
Technical Field
The utility model relates to the field of unmanned aerial vehicle fuel systems, in particular to a fuel system with a double-cavity structure, which is suitable for the diving flight of an unmanned aerial vehicle in a large-angle posture and can still reliably work after being pulled up.
Background
The unmanned aerial vehicle fuel system is used for storing fuel required by an onboard engine and continuously supplying fuel with specified pressure and flow to the engine according to a certain sequence under all flight states and working conditions allowed by the unmanned aerial vehicle. With the rapid development of the unmanned aerial vehicle industry, unmanned aerial vehicles are widely applied to military fields such as technical reconnaissance, patrol monitoring, target attack and the like and civil fields such as geological mapping, mineral exploration and the like. For most unmanned aerial vehicles for investigation, patrol, surveying and mapping and exploration, strong maneuverability is not needed, and flight states such as large-angle dive do not exist, so that the fuel system of the unmanned aerial vehicle mostly adopts a hard flexible fuel tank which is normally communicated with the atmosphere, and the fuel flexible fuel tank is directly communicated with the atmosphere during operation and supplies fuel through an oil supply hole at the bottom of the flexible fuel tank. For unmanned aerial vehicles with strong maneuverability requirements such as various target attack unmanned aerial vehicles and anti-radiation unmanned aerial vehicles, the fuel system of the unmanned aerial vehicle needs to be specifically designed according to different combat mission requirements, so that the problems of oil spilling or unsmooth oil supply of the aircraft during diving are avoided. At present, an unmanned aerial vehicle oil supply system is disclosed in the utility model patent with publication number CN205366088U, wherein the top of a flexible oil tank is provided with an air inlet and an oil inlet, the flexible oil tank is communicated with a carburetor through an oil pipe, and the tail end of the oil pipe arranged in the flexible oil tank is provided with an oil hammer. The utility model has the advantages that the piston rod is pushed to drive the sliding block to move, so that the purpose of reducing the storage space of the fuel in the flexible fuel tank is realized, the fuel hammer is always immersed in the fuel, the flexible fuel tank is ensured to supply the fuel to the carburetor continuously and stably, but the fuel system cannot meet the requirement of large overload diving flight of the unmanned aerial vehicle.
The utility model discloses an external pressurizing oil supply system in the utility model patent with the publication number of CN209719944U, which adopts an auxiliary oil tank to externally pressurize a main oil tank, so as to realize negative pressure oil supply of the main oil tank and ensure high-altitude oil supply of an airplane and oil supply of a large maneuvering flight; however, this method requires a great deal of space and weight requirements and requires the introduction of engine compressed gas, which is not possible with piston or rotary engines.
The unmanned aerial vehicle in the form of a propeller in the current market mostly adopts a conventional piston engine or rotor engine, fuel oil is volatile gasoline or aviation kerosene, and the conventional hard atmospheric fuel oil system can not meet the requirement of the unmanned aerial vehicle on large-angle diving flight at present.
Disclosure of Invention
In order to overcome the defect that the fuel system in the prior art cannot meet the normal fuel supply requirement when the unmanned aerial vehicle is in large-angle diving flight, the utility model provides a double-cavity fuel system suitable for the unmanned aerial vehicle diving flight and a design method thereof.
The utility model provides a double-cavity fuel system suitable for the diving flight of an unmanned aerial vehicle, which comprises a flexible fuel tank, an oil pump, an exhaust electromagnetic valve, a one-way valve and an oil-gas separator; wherein: the outlet of the soft oil tank is communicated with the oil inlet at the upper end of the oil-gas separator through a pipeline; an oil pump is connected to the pipeline; an oil outlet at the lower end of the oil-gas separator is externally connected with an oil inlet of an engine through a pipeline; and the pipeline is connected with a one-way valve, and an outlet of the one-way valve is communicated with the engine oil inlet. The exhaust port at the upper end of the oil-gas separator is communicated with the outside atmosphere through a pipeline; an exhaust solenoid valve is connected to the pipe.
The oil-gas separator is divided into an upper cavity and a lower cavity; the lower panel of the upper cavity is an inclined plane, and the upper panel of the lower cavity is also an inclined plane, so that a V-shaped opening is formed between the lower panel of the upper cavity and the upper panel of the lower cavity; the root of the V-shaped opening is positioned at one side of the machine head, the mouth of the V-shaped opening is positioned at one side of the machine tail, and the upper cavity is communicated with the lower cavity at the root of the V-shaped opening.
The included angle between the lower panel of the upper cavity and the horizontal plane is a; the included angle between the upper panel of the lower cavity and the horizontal plane is b; the included angle between the lower panel of the lower cavity and the horizontal plane is c; a=18 to 22 °, b=0 to-5 °, c=18 to 22 °; the distance between one side wall plate of the head of the oil-gas separator and one side wall plate of the tail of the oil-gas separator is L; the horizontal distance between the bottom of the V-shaped opening and the opening part of the V-shaped opening is L1; l1: l=0.65 to 0.9.
An oil inlet and an exhaust port are formed in an upper end cover of the oil-gas separator; an oil outlet is arranged at the lower part of the side wall of the oil-gas separator; a liquid level sensor is arranged on a side wall plate of the upper cavity.
The design process of the double-cavity fuel system suitable for the diving flight of the unmanned aerial vehicle provided by the utility model is as follows:
step 1, determining the volume V of the flexible fuel tank 1 ：
The cruise flight time t and the average engine fuel consumption Q of the unmanned aerial vehicle are proposed according to the design 0 By formula V 1 ＝n 1 Q 0 t determines the volume V of the flexible tank 1 Wherein n is 1 As a safety factor, n 1 ＝1.2；
Step 2, determining the maximum dive time T of the unmanned plane:
the maximum flying height H of the unmanned aerial vehicle and the minimum diving speed v of the unmanned aerial vehicle are proposed according to the design Diving down By the formula t=h/v Diving down Determining the maximum diving time T of the unmanned aerial vehicle;
step 3, determining the pump oil flow Q of the pump 2 ：
The pump is selected to be pumping oil flow Q 2 Must be greater than the maximum oil consumption flow Q of the engine 1 I.e. Q 2 ＞Q 1 To realize reliable and stable fuel supply of the fuel system; maximum oil consumption flow Q of the engine 1 Is determined in the unmanned aerial vehicle design;
in order to enable the oil-gas separator to smoothly exhaust, the pump oil flow Q 2 ＝kQ 1 Wherein k is the supercharging coefficient of the oil-gas separator; k=2 to 4; the larger the allowable volume pressure value of the oil-gas separator is, the larger the value of k is;
step 4, determining the opening pressure F of the check valve 3 ：
By formula F 1 ≤F 2 +F 3min And formula F 3 ＝n 2 F 3min Obtaining the opening pressure F of the one-way valve 3 ；
In the formula, F 1 The resistance of gas in the oil-gas separator to be discharged out of the unmanned aerial vehicle body when the exhaust electromagnetic valve is opened; f (F) 2 When the engine works, a one-way valve is not arranged between the oil outlet of the oil-gas separator and the engine, and the exhaust electromagnetic valve is openedResistance of fuel oil in the oil-gas separator to the engine; n is n 2 As a safety factor, n 2 ＝1.5～3.0；
The F is 1 Is the pressure at the exhaust port of the oil-gas separator when the exhaust solenoid valve is opened;
the F is 2 When the one-way valve is not arranged between the oil outlet and the engine pipeline, the exhaust electromagnetic valve is opened, and the engine stably works, the pressure at the oil outlet of the oil-gas separator is obtained through testing;
when F 1 And F is equal to 2 After determination, by formula F 1 ≤F 2 +F 3min Obtaining F 3min ；
According to F obtained 3min By the formula F 3 ＝n 2 F 3min Determination of F 3 ；
Step 5, determining the volume V of the upper cavity 11 ：
Maximum oil consumption flow Q of engine according to design 1 And in the step 2, determining the maximum diving time T of the unmanned aerial vehicle, and passing through a formula V 11 ＝n 3 Q 1 T is obtained to obtain the volume V of the upper cavity in the oil-gas separator 11 Wherein n is 3 As a safety factor, n 3 ＝2；
Step 6, determining the volume V of the lower cavity 12 ：
By formula V 12 ＝0.5V 11 Determining the volume V of the lower cavity 12 ；
Step 7, determining an included angle a between the lower panel of the upper cavity and the horizontal plane:
by the formula a=θ 1 +2° determines an included angle a between the lower panel of the upper cavity and the horizontal plane; wherein θ 1 The maximum attitude angle is the maximum attitude angle when the unmanned aerial vehicle climbs;
step 8, determining an included angle b between the upper panel of the cavity and the horizontal plane:
through the formula b=θ 2 -2 ° determining the angle b between the upper panel of the cavity and the horizontal plane; wherein θ 2 The minimum attitude angle is the minimum attitude angle when the unmanned aerial vehicle slides down;
step 9, determining an included angle c between the lower panel of the lower cavity and the horizontal plane:
through formula c=θ 1 +2° determines an included angle c between the lower panel of the lower cavity and the horizontal plane; wherein θ 1 The maximum attitude angle is the maximum attitude angle when the unmanned aerial vehicle climbs;
step 10, determining the ratio of L1 to L:
the ratio of L1 to L is the ratio of the horizontal distance L1 between the bottom of the V-shaped opening and the opening part of the V-shaped opening to the distance L between the wall plate on one side of the head of the oil-gas separator and one side of the tail of the oil-gas separator;
l1: l=0.65 to 0.9; the smaller the viscosity of the fuel medium is, the larger the value of the ratio is;
thus, the design of the double-cavity fuel system is completed.
By adopting the technical scheme of the utility model, when the aircraft flies normally, the oil pump sucks the fuel oil in the flexible fuel tank into the upper cavity of the oil-gas separator through the oil inlet. The lower surface of the upper cavity is an inclined plane, and oil can further flow into the lower cavity. The inclined angle a of the inclined plane is larger than the maximum pitch angle of the aircraft during normal flat flight climbing. The upper surface of the lower cavity is also an inclined surface, and the gas can further reach the upper cavity; the inclination angle b of the inclined plane is smaller than the minimum pitch angle of the aircraft during normal flat flight and downslide.
In the utility model, whether gas exists in the upper cavity of the oil-gas separator or not is sensed by the liquid level sensor: when gas exists, the exhaust electromagnetic valve is opened, the gas in the upper cavity of the oil-gas separator is discharged through the exhaust port until the liquid level of the fuel is higher than the liquid level sensor, and the exhaust electromagnetic valve is closed. When the fuel oil in the lower cavity of the oil-gas separator generates gas due to vibration or volatilization, the gas can float to the upper surface of the upper cavity due to gravity.
Only fuel oil in the lower cavity of the oil-gas separator is led to the engine through the oil outlet. When the aircraft is in large-angle diving flight, gas existing in the flexible oil tank enters an upper cavity of the oil-gas separator; the oil-gas separator blocks the gas entering into the upper cavity by utilizing the self structural characteristics and the exhaust function, and continuously discharges the gas through the exhaust port; when enough gas can not be discharged in time, the upper cavity is gradually filled with the gas.
When the liquid level in the upper cavity is lower than the communication port between the upper cavity and the lower cavity, gas enters the lower cavity. The designed distance between one side wall plate of the oil-gas separator head and one side wall plate of the tail is L; the horizontal distance between the bottom of the V-shaped opening and the opening part of the V-shaped opening is L1; when L1: and when l=0.65-0.9, the utilization rate of fuel in the upper cavity can be effectively improved.
The utility model relates to the aircraft diving time T and the maximum fuel consumption flow Q of the engine 1 Volume V of upper cavity of designed oil-gas separator 11 ＝2Q 1 The safety coefficient is 2, so that gas cannot enter the lower cavity of the oil-gas separator in the aircraft diving stage; volume V of designed lower cavity of oil-gas separator 12 ＝0.5V 11 The engine is prevented from being entered after a small amount of gas enters the lower cavity in the nose down stage of the aircraft.
When the aircraft is pushed up after the end of diving, only fuel oil in the flexible fuel tank enters the upper cavity of the oil-gas separator.
The utility model can not only meet the reliable oil supply of the unmanned aerial vehicle during normal flight, but also adapt to the unmanned aerial vehicle under the large maneuvering flight attitude, especially during the diving flight and the pull-up and fly-down, can supply pure fuel oil for the engine stably and reliably, and ensures the normal operation of the engine.
Compared with the prior art, the utility model has the beneficial effects that:
1. the double-cavity fuel system provided by the utility model mainly utilizes the structural characteristics of the upper cavity and the lower cavity of the oil-gas separator, oil-gas separation is carried out on fuel which is led to the engine, liquid fuel is supplied to the engine, and the gas is discharged out of the engine, so that the fuel system can continuously supply fuel with specified flow when the unmanned aerial vehicle is pushed down and pulled up to fly.
2. According to the double-cavity oil-gas separator provided by the utility model, the fuel oil liquid level is kept in the upper cavity, so that the influence of severe shaking of the fuel oil liquid level on the oil supply reliability at the oil outlet caused by adverse factors such as yaw, overload and gust of an unmanned aerial vehicle in flight can be effectively avoided.
3. The included angle a=θ between the lower panel of the upper cavity and the horizontal plane 1 +2°, the angle b=θ between the upper panel of the lower cavity and the horizontal plane 2 -2 °, the angle c=θ between the lower panel of the lower cavity and the horizontal plane 1 +2°, where θ 1 For the maximum attitude angle theta during climbing of the unmanned aerial vehicle 2 Is the minimum attitude angle when the unmanned aerial vehicle slides down. Through the angle of each cavity panel in the reasonable setting double-cavity oil-gas separator, when making unmanned aerial vehicle fly at the level, climb, the flight gesture such as gliding, neither can keep gas in the oil-gas separator, also can not form dead oil region, guaranteed the long-time stable fuel feeding of fuel system. The flight verification data curve is shown in fig. 3. In fig. 3, the abscissa is the time axis; the ordinate is the engine fuel flow axis, unit: ml/min. The 101 curve is a curve of the fuel flow supplied by an engine along with the time change when the unmanned aerial vehicle adopting the fuel system of the utility model is in the diving and pulling flight; 102 is a curve of the change of the engine supply fuel flow with time when the unmanned aerial vehicle adopting a conventional atmospheric fuel system is in a diving pull-up flight; the curve 201 is the flying height over time.
4. The core component in the utility model is an oil-gas separator, and the component is simple, convenient to maintain and high in reliability.
In order to verify the effect of the utility model, the technical scheme of the utility model is experimentally verified. In the experiment, according to the flight requirement of an unmanned plane, the maximum climbing attitude angle of the plane is 18 degrees, the minimum downslide attitude angle is-1 degrees, the diving time T of the plane is less than or equal to 120s, and the maximum oil consumption flow Q of an engine 1 =200 ml/min, designed to give the physical parameters as follows: the volume of the upper cavity 11 is 1000ml, the volume of the lower cavity 12 is 500ml, an included angle a between the upper cavity lower panel and the horizontal plane in the upper cavity 11 is 20 degrees, an included angle b between the lower cavity upper panel and the horizontal plane in the lower cavity 12 is-3 degrees, an included angle c between the lower cavity lower panel and the horizontal plane is 20 degrees, and L1: l is 0.85, and the opening pressure of the one-way valve is 18KPa. When the flat flight test is carried out, the fuel system can stably work for a long time, and the phenomenon of unsmooth oil supply or interruption does not occur; when the diving flight test is carried out, the diving angle is in a state of minus 90 degrees, at the moment, the fuel system can dive for 360 seconds at least, and after the diving flight, the fuel system is pulled up to fly, and the fuel system is not supplied with oil or is not supplied with oil smoothlyInterruption phenomenon.
Drawings
FIG. 1 is a schematic diagram of a fuel system according to the present utility model;
FIG. 2 is a schematic diagram of the structure of the dual-cavity oil-gas separator of the utility model;
FIG. 3 is a graph of fuel supply flow over time for an unmanned aerial vehicle using the present utility model for a nose-down pull-up maneuver;
fig. 1 and 2: 1. a flexible oil tank; 2. an oil pump; 3. an exhaust electromagnetic valve; 4. a one-way valve; 5. an oil-gas separator; 6. an oil-gas separator; 7. a liquid level sensor; 8. an oil inlet; 9. an oil outlet; 10. an exhaust port; 11. an upper cavity; 12. a lower cavity.
Detailed Description
The fuel system capable of adapting to the diving flight of the unmanned aerial vehicle provided in the embodiment comprises a flexible fuel tank 1, an oil pump 2, an exhaust electromagnetic valve 3, a one-way valve 4 and an oil-gas separator 5. Wherein: the outlet of the soft oil tank is communicated with the oil inlet at the upper end of the oil-gas separator through a pipeline; an oil pump 2 is connected to the pipe. An oil outlet 9 at the lower end of the oil-gas separator is externally connected with an oil inlet of an engine through a pipeline; a check valve 4 is connected to the pipe. The exhaust port 10 at the upper end of the oil-gas separator is communicated with the outside atmosphere through a pipeline; an exhaust electromagnetic valve 3 is connected to the pipe.
The flexible oil tank 1, the oil pump 2, the exhaust electromagnetic valve 3 and the one-way valve 4 are all of the prior art.
The oil-gas separator 5 includes an oil-gas separator 6 and a liquid level sensor 7. The oil-gas separator 6 is divided into an upper cavity 11 and a lower cavity 12; the lower panel of the upper cavity 11 is an inclined plane, and the upper panel of the lower cavity 12 is also an inclined plane, so that a V-shaped opening is formed between the lower panel of the upper cavity and the upper panel of the lower cavity; the root of the V-shaped opening is positioned at one side of the machine head, the mouth of the V-shaped opening is positioned at one side of the machine tail, and the upper cavity is communicated with the lower cavity at the root of the V-shaped opening. The included angle between the lower panel of the upper cavity and the horizontal plane is a; the included angle between the upper panel of the lower cavity and the horizontal plane is b; the included angle between the lower panel of the lower cavity and the horizontal plane is c; a=18 to 22 °, b=0 to-5 °, c=18 to 22 °. The distance between one side wall plate of the head of the oil-gas separator 6 and one side wall plate of the tail of the oil-gas separator is L; the horizontal distance between the bottom of the V-shaped opening and the opening part of the V-shaped opening is L1; l1: l=0.65 to 0.9.
An oil inlet 8 and an exhaust port 10 are formed in the upper end cover of the oil-gas separator 6; the center of the exhaust port 10 is 10mm away from the outer surface of a side wall plate of the tail of the oil-gas separator 6. An oil outlet 9 is arranged at the lower part of the side wall of the oil-gas separator, and the distance between the center of the oil outlet and the upper surface of the bottom plate of the oil-gas separator is 12mm. The liquid level sensor 7 is arranged on the side wall plate of the upper cavity 11, the distance from the center of the liquid level sensor to the outer surface of the side wall plate of the tail of the oil-gas separator 6 is 12mm, and the distance from the center of the liquid level sensor to the upper surface of the oil-gas separator 6 is 10mm.
In this embodiment, the volume of the upper cavity 11 is 1000ml, and the volume of the lower cavity 12 is 500ml; the included angle a between the lower panel of the upper cavity and the horizontal plane is 20 degrees; the included angle b between the upper panel of the lower cavity and the horizontal plane is-3 degrees; the included angle c between the lower panel of the lower cavity and the horizontal plane is 20 degrees; the distance between one side wall plate of the head of the oil-gas separator 6 and one side wall plate of the tail of the oil-gas separator is L; the horizontal distance between the bottom of the V-shaped opening and the opening part of the V-shaped opening is L1; the L1: l=0.85. In order to meet the requirement that the oil-gas separator can smoothly exhaust, the opening pressure of the one-way valve 4 is 18KPa.
An oil outlet of the flexible oil tank 1 is connected with an oil inlet of the oil pump 2 through an oil pipe; the oil outlet of the oil pump 2 is connected with the oil inlet 8 of the oil-gas separator through an oil pipe; a one-way valve 4 is arranged on an oil pipe between an oil outlet 9 of the oil-gas separator and an oil inlet of the engine, an outlet of the one-way valve 4 is communicated with the oil inlet of the engine, and oil is supplied to the engine through the one-way valve 4; the exhaust port 10 of the oil-gas separator is connected to the exhaust solenoid valve 3 through a gas pipe, and the gas is exhausted through the other end of the exhaust solenoid valve 3. In this embodiment, the inner diameter of the oil pipe is 8mm, and the inner diameter of the gas pipe is 6mm.
The utility model also provides a design method of the double-cavity fuel system, which comprises the following specific processes:
step 1, determining the volume V of the flexible fuel tank 1 1 ：
The cruise flight time t and the average engine fuel consumption Q of the unmanned aerial vehicle are proposed according to the design 0 By formula V 1 ＝n 1 Q 0 t determines the volume V of the flexible tank 1 1 Wherein n is 1 As a safety factor, n 1 ＝1.2。
Step 2, determining the maximum dive time T of the unmanned plane:
according to the designed maximum flying height H of the unmanned aerial vehicle and the minimum diving speed v of the unmanned aerial vehicle Diving down By the formula t=h/v Diving down And determining the maximum dive time T of the unmanned aerial vehicle.
Step 3, determining the pump oil flow Q of the pump 2
The pump is selected to be pumping oil flow Q 2 Must be greater than the maximum oil consumption flow Q of the engine 1 I.e. Q 2 ＞Q 1 So as to realize reliable and stable fuel supply of the fuel system. Maximum oil consumption flow Q of the engine 1 Is determined in the unmanned aerial vehicle design.
In order to enable the oil-gas separator to smoothly exhaust, the pump oil flow Q 2 ＝kQ 1 Wherein k is the supercharging coefficient of the oil-gas separator; k=2 to 4. The larger the allowable volume pressure value of the oil separator 5 is, the larger the value of k is.
Step 4, determining the opening pressure F of the check valve 3 ：
By formula F 1 ≤F 2 +F 3min And formula F 3 ＝n 2 F 3min To obtain the opening pressure F of the check valve 4 3 。
In the formula, F 1 The resistance of gas in the oil-gas separator to be discharged out of the unmanned aerial vehicle body when the exhaust electromagnetic valve is opened; f (F) 2 When the engine works, the resistance of the fuel oil in the oil-gas separator to the engine is not caused by the fact that a one-way valve is not arranged between the oil outlet of the oil-gas separator and the engine and the exhaust electromagnetic valve 3 is opened; n is n 2 As a safety factor, n 2 ＝1.5～3.0。
The F is 1 Is the pressure at the gas-oil separator exhaust port 10 when the exhaust solenoid valve 3 is opened.
The F is 2 When the one-way valve 4 is not arranged between the oil outlet and the engine pipeline, the exhaust electromagnetic valve 3 is opened, and the engine stably works, the pressure of the oil outlet 9 of the oil-gas separator is tested.
When F 1 And F is equal to 2 After determination, by formula F 1 ≤F 2 +F 3min Obtaining F 3min 。
According to F obtained 3min By the formula F 3 ＝n 2 F 3min Determination of F 3 。
In the present embodiment, F 1 ＝3KPa；F 2 -15KPa. The resulting minimum opening pressure F of the non-return valve 4 3min Opening pressure F of check valve 4 =12 KPa 3 ＝n 2 F 3min ＝18KPa，n 2 Taking 1.5.
Step 5, determining the volume V of the upper cavity 11
Maximum oil consumption flow Q of engine according to design 1 And in the step 2, determining the maximum diving time T of the unmanned aerial vehicle, and passing through a formula V 11 ＝n 3 Q 1 T is obtained to obtain the volume V of the upper cavity of the oil-gas separator 6 11 Wherein n is 3 As a safety factor, n 3 ＝2。
Step 6, determining the volume V of the lower cavity 12
By formula V 12 ＝0.5V 11 Determining the volume V of the lower cavity 12 。
Step 7, determining an included angle a between the lower panel of the upper cavity and the horizontal plane
By the formula a=θ 1 The angle a between the upper cavity lower panel and the horizontal plane is determined by +2°. Wherein θ 1 The maximum attitude angle is the maximum attitude angle when the unmanned aerial vehicle climbs.
Step 8, determining an included angle b between the upper panel of the cavity and the horizontal plane
Through the formula b=θ 2 -2 ° determines the angle b between the upper panel of the cavity and the horizontal plane. Wherein θ 2 Is the minimum attitude angle when the unmanned aerial vehicle slides down.
Step 9, determining an included angle c between the lower panel of the lower cavity 12 and the horizontal plane
Through formula c=θ 1 +2° determines the angle c between the lower panel of the lower chamber 12 and the horizontal. Wherein θ 1 The maximum attitude angle is the maximum attitude angle when the unmanned aerial vehicle climbs.
Step 10, determining the ratio of L1 to L:
the ratio of L1 to L is the ratio of the horizontal distance L1 between the bottom of the V-shaped opening and the opening part of the V-shaped opening to the distance L between the side wall plate of the head of the oil-gas separator and the side of the tail of the oil-gas separator.
L1: l=0.65 to 0.9; the smaller the viscosity of the fuel medium, the larger the value of the ratio.
Thus, the design of the double-cavity fuel system is completed.
Claims (2)
1. The double-cavity fuel system suitable for the diving flight of the unmanned aerial vehicle is characterized by comprising a flexible fuel tank, an oil pump, an exhaust electromagnetic valve, a one-way valve and an oil-gas separator; wherein: the outlet of the soft oil tank is communicated with the oil inlet at the upper end of the oil-gas separator through a pipeline; an oil pump is connected to the pipeline; an oil outlet at the lower end of the oil-gas separator is externally connected with an oil inlet of an engine through a pipeline; a one-way valve is connected to the pipeline; the exhaust port at the upper end of the oil-gas separator is communicated with the outside atmosphere through a pipeline; an exhaust electromagnetic valve is connected to the pipeline;
the oil-gas separator is divided into an upper cavity and a lower cavity; the lower panel of the upper cavity is an inclined plane, and the upper panel of the lower cavity is also an inclined plane, so that a V-shaped opening is formed between the lower panel of the upper cavity and the upper panel of the lower cavity; the root of the V-shaped opening is positioned at one side of the machine head, the mouth of the V-shaped opening is positioned at one side of the machine tail, and the upper cavity and the lower cavity are communicated at the root of the V-shaped opening;
the included angle between the lower panel of the upper cavity and the horizontal plane is a; the included angle between the upper panel of the lower cavity and the horizontal plane is b; the included angle between the lower panel of the lower cavity and the horizontal plane is c; a=18 to 22 °, b=0 to-5 °, c=18 to 22 °; the distance between one side wall plate of the head of the oil-gas separator and one side wall plate of the tail of the oil-gas separator is L; the horizontal distance between the bottom of the V-shaped opening and the opening part of the V-shaped opening is L1; l1: l=0.65 to 0.9;
the lower plate surfaces of the upper cavity and the lower cavity are inclined planes, the inclined angles of the inclined planes are larger than the maximum pitch angle when the aircraft normally flies flat and climbs, and the upper surface of the lower cavity is also inclined plane, and the inclined angles of the inclined planes are smaller than the minimum pitch angle when the aircraft normally flies flat and slides down;
an oil inlet and an exhaust port are formed in an upper end cover of the oil-gas separator; an oil outlet is arranged at the lower part of the side wall of the oil-gas separator; a liquid level sensor is arranged on a side wall plate of the upper cavity;
and an outlet of the one-way valve is communicated with the engine oil inlet.
2. A method for designing a double-cavity fuel system suitable for diving flight of an unmanned aerial vehicle according to claim 1, which is characterized by comprising the following specific steps:
step 1, determining the volume V of the flexible fuel tank 1 ：
The cruise flight time t and the average engine fuel consumption Q of the unmanned aerial vehicle are proposed according to the design 0 By formula V 1 ＝n 1 Q 0 t determines the volume V of the flexible tank 1 Wherein n is 1 As a safety factor, n 1 ＝1.2；
Step 2, determining the maximum dive time T of the unmanned plane:
the maximum flying height H of the unmanned aerial vehicle and the minimum diving speed v of the unmanned aerial vehicle are proposed according to the design Diving down By the formula t=h/v Diving down Determining the maximum diving time T of the unmanned aerial vehicle;
step 3, determining the pump oil flow Q of the pump 2 ：
The pump is selected to be pumping oil flow Q 2 Must be greater than the maximum oil consumption flow Q of the engine 1 I.e. Q 2 ＞Q 1 To realize reliable and stable fuel supply of the fuel system; maximum oil consumption flow Q of the engine 1 Is determined in the unmanned aerial vehicle design;
in order to enable the oil-gas separator to smoothly exhaust, the pump oil flow Q 2 ＝kQ 1 Wherein k is the supercharging coefficient of the oil-gas separator; k=2 ultra-high4, a step of; the larger the allowable volume pressure value of the oil-gas separator is, the larger the value of k is;
step 4, determining the opening pressure F of the check valve 3 ：
By formula F 1 ≤F 2 +F 3min And formula F 3 ＝n 2 F 3min Obtaining the opening pressure F of the one-way valve 3 ；
In the formula, F 1 The resistance of gas in the oil-gas separator to be discharged out of the unmanned aerial vehicle body when the exhaust electromagnetic valve is opened; f (F) 2 When the engine works, the resistance of the fuel oil in the oil-gas separator to the engine is kept; n is n 2 As a safety factor, n 2 ＝1.5～3.0；
The F is 1 Is the pressure at the exhaust port of the oil-gas separator when the exhaust solenoid valve is opened;
the F is 2 When the one-way valve is not arranged between the oil outlet and the engine pipeline, the exhaust electromagnetic valve is opened, and the engine stably works, the pressure at the oil outlet of the oil-gas separator is obtained through testing;
when F 1 And F is equal to 2 After determination, by formula F 1 ≤F 2 +F 3min Obtaining F 3min ；
According to F obtained 3min By the formula F 3 ＝n 2 F 3min Determination of F 3 ；
Step 5, determining the volume V of the upper cavity 11 ：
Maximum oil consumption flow Q of engine according to design 1 And in the step 2, determining the maximum diving time T of the unmanned aerial vehicle, and passing through a formula V 11 ＝n 3 Q 1 T is obtained to obtain the volume V of the upper cavity in the oil-gas separator 11 Wherein n is 3 As a safety factor, n 3 ＝2；
Step 6, determining the volume V of the lower cavity 12 ：
By formula V 12 ＝0.5V 11 Determining the volume V of the lower cavity 12 ；
Step 7, determining an included angle a between the lower panel of the upper cavity and the horizontal plane:
by the formula a=θ 1 +2° determines an included angle a between the lower panel of the upper cavity and the horizontal plane; wherein θ 1 The maximum attitude angle is the maximum attitude angle when the unmanned aerial vehicle climbs;
step 8, determining an included angle b between the upper panel of the cavity and the horizontal plane:
through the formula b=θ 2 -2 ° determining the angle b between the upper panel of the cavity and the horizontal plane; wherein θ 2 The minimum attitude angle is the minimum attitude angle when the unmanned aerial vehicle slides down;
step 9, determining an included angle c between the lower panel of the lower cavity and the horizontal plane:
through formula c=θ 1 +2° determines an included angle c between the lower panel of the lower cavity and the horizontal plane; wherein θ 1 The maximum attitude angle is the maximum attitude angle when the unmanned aerial vehicle climbs;
step 10, determining the ratio of L1 to L:
the ratio of L1 to L is the ratio of the horizontal distance L1 between the bottom of the V-shaped opening and the opening part of the V-shaped opening to the distance L between the wall plate on one side of the head of the oil-gas separator and one side of the tail of the oil-gas separator;
l1: l=0.65 to 0.9; the smaller the viscosity of the fuel medium is, the larger the value of the ratio is;
thus, the design of the double-cavity fuel system is completed.
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