Structural energy integrated device for unmanned aerial vehicle

Abstract

The invention provides a structure and energy integrated device for an unmanned aerial vehicle, and belongs to the technical field of structure and energy integrated devices. The metal anode of the metal-air battery with certain mechanical strength is used as an electrode active material and a mechanical supporting profile, so that on one hand, the proportion of the metal anode in the battery is increased, and the battery is endowed with high energy density, and on the other hand, the structural proportion of a traditional structural part in the whole unmanned aerial vehicle is reduced, and the mass of the whole unmanned aerial vehicle is reduced; and the endurance of the whole machine is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of unmanned aerial vehicle devices, and in particular relates to a structural energy integrated device for unmanned aerial vehicles. Background Art

[0002] The demand for energy systems for fully electrified micro-UAV equipment is constantly increasing, including high energy density, high integration, high safety, high flexibility, and meeting distributed energy storage needs. There are currently two ways to improve the endurance of UAVs: the first is to develop high-energy-density battery technology to increase the amount of energy carried by UAVs; the second is to reduce the weight of the fuselage and reduce the functional burden. In order to fully improve the endurance of UAVs, the two methods can be combined to develop high-energy-density structural energy storage integrated batteries, combining energy storage components and structural components into one, so as to increase the amount of power stored by the UAV while reducing the weight of the structural components.

[0003] Drones generally use various batteries as power sources, such as metal lithium batteries, metal air batteries, etc. Among them, metal air batteries are batteries that use the redox reaction between metals and oxygen to convert chemical energy into electrical energy. They have the advantages of high specific energy, fast reaction kinetics, stable performance, and low price. They are high energy density (taking zinc metal air batteries as an example, the theoretical specific energy density can reach 1086Wh kg -1 ), energy storage devices with high power density. Metal-air batteries are mainly composed of three parts: metal electrode, alkaline electrolyte, and air electrode. During the discharge process, oxygen in the air reaches the air electrode and is catalyzed by the catalyst loaded on it to undergo a reduction reaction, while metal oxidation occurs on the metal electrode. Ionic conduction in the alkaline electrolyte relies on hydroxide ions, thereby forming a discharge current in the external circuit.

[0004] At present, small drones generally use batteries as power sources alone. The weight of the drone includes not only the weight of its own structure but also the weight of the power source, which reduces the endurance of the drone. Therefore, how to design a structure and energy integrated device for drones based on metal-air batteries so that drones based on the integrated device can have better endurance than conventional drones with independent power sources has become a focus of attention. Summary of the invention

[0005] In view of the problems existing in the background technology, the purpose of the present invention is to provide a structural energy integrated device for drones. The device uses the metal anode of the metal-air battery as the support part of the drone, which provides energy and serves as the mechanical structure of the drone, realizing the integrated design of structure and energy, and achieving the goal of increasing the amount of power stored in the drone while reducing the weight of the structural parts.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A structural energy integrated device for a drone, the device comprising a bracket and a metal air battery; the bracket comprises a cylindrical frame 1, a cantilever beam 2 fixedly connected to the wall of the cylindrical frame 1, and the other end of the cantilever beam 2 is fixedly connected to a connecting plate 3;

[0008] Among them, the cylindrical frame 1 is used to fix the power device of the drone, the cantilever beam is the anode of the metal air battery; the connecting plate is used to be fixedly connected to the main fuselage of the drone;

[0009] The cantilever beam is sequentially covered with an alkaline gel electrolyte layer, an air electrode layer, a breathable water-blocking membrane and a fixed shell, and a cathode lead is also arranged between the alkaline gel electrolyte and the air electrode layer; the fixed shell is used to make the cantilever beam anode, the alkaline gel electrolyte, the air electrode layer, and the breathable water-blocking membrane fit closely to form a complete metal-air battery;

[0010] A plurality of through holes are provided on the fixed shell, and air enters the metal-air battery through the through holes and reacts with the air electrode layer to generate current.

[0011] Furthermore, the bracket is prepared by integrated metal casting; the metal is zinc alloy or aluminum alloy.

[0012] Furthermore, the cylindrical frame and the cantilever beam are hollowed out or not hollowed out, and the hollowing out facilitates reducing the dead weight, thereby increasing the endurance of the UAV.

[0013] Furthermore, the bracket is regarded as a single cantilever with one end fixed and the other end hanging the load. According to the deflection formula:

[0014]

[0015] Where f is the deflection, P is the stress, l is the length of the cantilever beam, E is the Young's modulus of the cantilever beam material, and I is the moment of inertia of the cantilever beam section;

[0016] The formula for calculating the moment of inertia of a rectangular section is,

[0017]

[0018] Where a is the width of the cantilever beam section, and b is the height of the cantilever beam section;

[0019] Combining formulas (1) and (2), based on actual engineering experience, and taking the deflection of the cantilever beam of the UAV not exceeding 0.1 as the standard, we can obtain:

[0020] a 3 bE>6.4×10 -6 (3)

[0021] Based on formula (3), once the material of the bracket is determined, the size of the cantilever beam can be determined based on the Young's modulus of the material.

[0022] Furthermore, when the cantilever beam is hollowed out, the hollowed out portion is filled with metal active slurry, wherein the metal active slurry is formed by mixing metal powder, electrolyte and adhesive.

[0023] Furthermore, the air electrode layer is obtained by attaching a catalyst to a cathode current collector, the cathode current collector is nickel foam, and the catalyst is Pt@C; the air-permeable and water-blocking membrane is polyurethane (PU), polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE), etc.; the alkaline gel electrolyte layer is a composite material layer generated by the reaction of an alkaline electrolyte and a polymer gel organism, wherein the polymer gel organism is polyvinyl alcohol (PVA) and the alkaline electrolyte is potassium hydroxide (KOH); the fixed shell is a resin generated by 3D printing.

[0024] Furthermore, the shell is divided into an upper shell and a lower shell, which are connected by a snap-fit, and an opening is arranged on the shell.

[0025] Furthermore, the opening can be covered with PI tape to ensure air isolation. When in use, it can be removed and used normally. When not in use, the opening can continue to be covered with PI tape. This method can extend the battery life.

[0026] The present invention also provides a UAV, which includes a main body, a structural energy integration device and a power device;

[0027] The power device includes a motor and a propeller electrically connected to the motor; wherein the structural energy integration device is symmetrically and fixedly arranged on the main body, the motor is fixedly arranged in a cylindrical frame of the structural energy integration device, and a control unit is arranged on the main body for controlling the output of the electrode, thereby controlling the flight of the UAV.

[0028] Furthermore, the UAV is a quad-rotor UAV or a two-rotor UAV.

[0029] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0030] 1. The present invention adopts the metal anode of the metal-air battery with certain mechanical strength as the electrode active material and mechanical support profile, which, on the one hand, increases the proportion of the metal anode in the battery, thereby increasing the energy density of the battery; on the other hand, reduces the structural proportion of traditional structural parts in the UAV, reduces the weight of the whole machine, and improves the endurance of the whole machine.

[0031] 2. The metal-air battery of the present invention adopts a gel electrolyte to improve the safety and stability of the energy storage system and can adapt to complex flight conditions; the air electrode is obtained by rolling a catalyst, a conductive substrate, and nickel foam, so that the contact area between the air electrode and the electrolyte is large and there are many electron transmission paths, which is beneficial to the transfer, reaction and electron transmission of the reactants, and improves the power density of the battery. At the same time, nickel foam can easily meet different shape design requirements and can make full use of the fuselage space of small unmanned aerial vehicle equipment; an oxygen-permeable and water-resistant elastic material is used as the packaging layer to ensure that moisture is retained in the electrolyte, so that the battery can operate normally for a long time, and a 3D-printed shell is used to extrude the battery core to achieve good contact between the layers of the structural energy integrated device for unmanned aerial vehicles, and excellent electrochemical properties and mechanical properties can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the structure of the structural energy integration device of the present invention.

[0033] Figure 2 Schematic diagram of the structure of the support of the present invention.

[0034] Figure 3 Schematic diagram of the structure of the metal-air battery of the present invention.

[0035] Figure 4 It is a schematic structural diagram of the fixed housing of the present invention.

[0036] Figure 5 This is a physical picture of the structural energy integration device of Example 1 of the present invention.

[0037] Figure 6 This is a physical picture of a UAV constructed based on the structural energy integration device of Example 1 of the present invention.

[0038] Figure 7 The open circuit voltage and LSV curve of the metal-air battery prepared in Example 1 of the present invention.

[0039] Figure 8 This is a graph showing the constant current test results of the metal-air batteries prepared in Examples 1 and 2 of the present invention.

[0040] Fig. 9 This is a test diagram of the mechanical properties of the stent obtained in Example 1 of the present invention;

[0041] Among them, (a) is a schematic diagram of the bracket compression loading, and (b) is the test result data curve.

[0042] Reference numerals: 1 is a cylindrical frame, 2 is a cantilever beam, and 3 is a connecting plate. DETAILED DESCRIPTION

[0043] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the implementation modes and the accompanying drawings.

[0044] A structural energy integrated device for unmanned aerial vehicles, the structural schematic diagram of the device is as follows Figure 1 As shown, it includes a bracket and a metal-air battery; the structural schematic diagram of the bracket is as shown Figure 2 As shown, it includes a cylindrical frame, a cantilever beam and a connecting plate connected in sequence; wherein the cylindrical frame is used to place the power device of the UAV, and the connecting plate is used to connect the energy integration device with the UAV body; the bracket can be hollowed out ( Figure 2 Right) or not hollowed out ( Figure 2 Left), both can realize the design concept of the present invention of integrated structure and energy; the non-hollow bracket has better mechanical strength and battery performance, and the hollow bracket has lighter weight and better endurance; two screw holes are reserved on the connecting plate for fixing the device to the drone body, and the connecting plate also has the functions of anode current collector and part of the lead;

[0045] The bracket is prepared by integrally casting a metal material, and the metal is a zinc alloy or an aluminum alloy.

[0046] The schematic diagram of the metal-air battery structure is shown in Figure 2. Figure 3 As shown, the cantilever beam is the anode of the metal-air battery, which is located inside the metal-air battery. The cantilever beam is sequentially covered with an alkaline gel electrolyte layer, an air electrode layer, a breathable water-blocking membrane and a fixed shell. A cathode lead is also arranged between the alkaline gel electrolyte and the air electrode layer. The fixed shell is used to make the anode, the alkaline gel electrolyte, the cathode lead, the air electrode layer and the breathable water-blocking membrane fit tightly to form a complete metal-air battery. A plurality of openings are provided on the fixed shell, and air enters the metal-air battery from the openings to generate current.

[0047] The opening can be covered with PI tape to ensure air isolation. When in use, remove it and use it normally. When not in use, continue to cover the opening with PI tape. This method can extend the battery life.

[0048] The air electrode layer is a catalyst attached to a conductive substrate and rolled with a cathode current collector, wherein the cathode current collector is nickel foam and the catalyst is Pt@C; the conductive substrate is carbon paper; the air-permeable and water-blocking membrane is polyurethane (PU), polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE), etc.; the alkaline gel electrolyte layer is a composite material layer generated by the reaction of an alkaline electrolyte and a polymer gel organism, wherein the polymer gel organism is polyvinyl alcohol (PVA) and the alkaline electrolyte is potassium hydroxide (KOH); the fixed shell is a resin generated by 3D printing.

[0049] Example 1

[0050] A method for preparing a structure and energy integrated device for a drone, comprising the following steps:

[0051] Step 1. According to Figure 2 Draw the CAD model of the structure of the right bracket, write the corresponding CAM program, and process it in the CNC machine tool to obtain the required zinc alloy bracket;

[0052] Step 2. Prepare an alkaline gel electrolyte: dissolve 4.22 g of polyvinyl alcohol (PVA) in 40 mL of water at 90°C, stir for 2 h, and then evenly pour the solution into a petri dish and repeatedly freeze-dry to obtain a PVA film with uniform texture and good mechanical strength; finally, soak the prepared PVA film in 6 M KOH to obtain an alkaline gel electrolyte;

[0053] Step 3. Prepare the air electrode layer: nickel foam is used as the cathode current collector; Pt@C is used as a catalyst to directly participate in the electrochemical reaction of the cathode; carbon paper is used as a conductive substrate and catalyst carrier to provide conductive function and structural support. The catalyst is evenly coated on the surface of the conductive carbon paper (1 mg cm -2 ), and then rolling the carbon paper and nickel foam to a thickness of 0.9 mm to obtain an air electrode layer;

[0054] Step 4. Prepare a breathable and water-blocking membrane. Polyurethane (PU), polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE), etc. can be used as the base material. This embodiment takes polytetrafluoroethylene (PTFE) as an example and uses a phase transfer method to prepare the membrane material;

[0055] First, PTFE powder and foaming agent were mixed at a ratio of 5%, then preheated at 150°C for 5 minutes and kept at 10MPa pressure for 5 minutes to form bubbles; then, the temperature was raised to 300°C and kept for 30 minutes for thermal curing; after cooling, the membrane was washed with ethanol and deionized water, and finally dried at 60°C for 12 hours to obtain a membrane with good air permeability and water barrier properties;

[0056] Step 5. Use high-performance plastic ABS and 3D printing technology to manufacture a fixed shell. The structural diagram of the shell is as follows: Figure 4 As shown;

[0057] Step 6. Fill the hollow part of the cantilever beam with metal powder active slurry, and then cover the four sides of the cantilever beam with alkaline gel electrolyte, air electrode layer and breathable water-blocking membrane in turn. At the same time, place the cathode lead between the alkaline gel electrolyte and the air electrode layer. Finally, fix the metal-air battery with a fixed shell to obtain the required structure and energy integrated device.

[0058] The actual picture of the structure and energy integration device prepared in this embodiment is as follows Figure 5 As shown, the actual picture of the drone based on the structure energy integration device of this embodiment is as follows Figure 6 shown.

[0059] Example 2

[0060] The only difference between this embodiment and embodiment 1 is that aluminum alloy is selected as the metal anode material, and other conditions and parameters are exactly the same as those in embodiment 1.

[0061] Example 3

[0062] The difference between this embodiment and embodiment 1 is that the support structure is selected Figure 2 The structure shown on the left, other conditions and parameters are exactly the same as those in Example 1.

[0063] Comparative Example 1

[0064] The only difference between this embodiment and the first embodiment is that no outer shell is assembled outside the packaging layer, and other conditions and parameters are exactly the same as those in the first embodiment.

[0065] Figure 7 The open circuit voltage and LSV curve of the metal-air battery prepared in Example 1 of the present invention (LSV test was performed between 0.2V and 1.6V). It can be seen from the left figure that the open circuit voltage of the battery is greater than 1.4V; it can be seen from the right figure that a significant current can be observed from 0.2V to 1.62V, indicating that the structural energy storage integrated battery can be practically applied.

[0066] Figure 8 This is a constant current test result diagram of the metal-air battery prepared in Example 1 of the present invention. The left figure shows the discharge voltage curve of the zinc alloy-air battery prepared in Example 1 at two constant current values ​​of 1mA and 10mA, indicating that the voltage of the battery is stable under different load conditions. The right figure shows the discharge voltage curve of the zinc alloy-air battery prepared in Example 1 and the aluminum alloy-air battery prepared in Example 2 at a constant current of 10mA. The figure compares the voltage stability of the zinc alloy-air battery and the aluminum alloy-air battery in the initial discharge, indicating that the discharge voltage stability of the aluminum alloy-air battery is poorer than that of the zinc alloy-air battery under the same discharge conditions, but it is still relatively stable. The left and right figures together illustrate that under different currents, both zinc alloy-air and aluminum alloy-air batteries can maintain an operating voltage of 1.3-1.4V, and can ensure that the output power can be used for practical applications.

[0067] Fig. 9 This is a test diagram of the mechanical properties of the stent obtained in Example 1 of the present invention; Fig. 9 (a) is a schematic diagram of the bracket compression loading. Fig. 9(b) is the stress-strain test result diagram. As shown in the figure, the battery anode can withstand a stress of 30MPa. According to the stress area of ​​40mm 2 To convert, the anode can bear 1200N pressure when used as a bracket, and its Young's modulus reaches 618MPa. Through theoretical calculation and flight test, the design of Example 1 is fully capable of supporting the overall 80g mass of the UAV for stable flight.

[0068] The structural components prepared in all embodiments and control examples were integrated into a complete UAV, and then actual flight tests were carried out. The actual flight test results are shown in Table 1. As can be seen from Table 1, the use of the specific structural function integration device of the present invention can increase the maximum flight time of the UAV.

[0069] Table 1

[0070]

[0071]

[0072] The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other alternative features that are equivalent or have similar purposes; all the disclosed features, or all the steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A structural energy integrated device for unmanned aerial vehicles, characterized in that: The device comprises a bracket and a metal-air battery; the bracket comprises a cylindrical frame, a cantilever beam fixedly connected to the cylindrical frame wall, and the other end of the cantilever beam is fixedly connected to the connecting plate; Among them, the cylindrical frame is used to fix the power device of the drone, the cantilever beam is the anode of the metal air battery; the connecting plate is used to fix the main fuselage of the drone; The cantilever beam is sequentially covered with an alkaline gel electrolyte layer, an air electrode layer, a breathable water-blocking membrane and a fixed shell, and a cathode lead is also arranged between the alkaline gel electrolyte and the air electrode layer; the fixed shell is used to make the cantilever beam anode, the alkaline gel electrolyte, the air electrode layer, and the breathable water-blocking membrane fit closely to form a complete metal-air battery; A plurality of through holes are provided on the fixed shell, and air enters the metal-air battery through the through holes and reacts with the air electrode layer to generate current.

2. The structural energy integrated device for unmanned aerial vehicles according to claim 1, characterized in that: The bracket is prepared by integrated metal casting; the metal is zinc alloy or aluminum alloy.

3. The structural energy integrated device for unmanned aerial vehicles according to claim 1, characterized in that: The cylindrical frame and the cantilever beam are hollowed out or not hollowed out.

4. The structural energy integrated device for unmanned aerial vehicles according to claim 1, characterized in that: The bracket is regarded as a single cantilever with one end fixed and the other end hanging a load. According to the deflection formula: Where f is the deflection, P is the stress, l is the length of the cantilever beam, E is the Young's modulus of the cantilever beam material, and I is the moment of inertia of the cantilever beam section; The formula for calculating the moment of inertia of a rectangular section is, Where a is the width of the cantilever beam section, and b is the height of the cantilever beam section; Combining formulas (1) and (2), and based on actual engineering experience, taking the deflection of the cantilever beam of the UAV not exceeding 0.1 as the standard, we can obtain: a 3 bE>6.4×10 -6 (3) Based on formula (3), once the material of the bracket is determined, the size of the cantilever beam can be determined based on the Young's modulus of the material.

5. The structural energy integrated device for unmanned aerial vehicles according to claim 3, characterized in that: When the cantilever beam is hollowed out, the hollowed out part is filled with metal active slurry, wherein the metal active slurry is formed by mixing metal powder, electrolyte and adhesive.

6. The structural energy integrated device for unmanned aerial vehicles according to claim 1, characterized in that: The air electrode layer is obtained by attaching a catalyst to a cathode current collector, the cathode current collector is nickel foam, and the catalyst is Pt@C; the air-permeable and water-blocking membrane is polyurethane, polydimethylsiloxane or polytetrafluoroethylene; the alkaline gel electrolyte layer is a composite material layer generated by the reaction of an alkaline electrolyte and a polymer gel organism, wherein the polymer gel organism is polyvinyl alcohol and the alkaline electrolyte is potassium hydroxide; the fixed shell is a resin generated by 3D printing.

7. The structural energy integrated device for unmanned aerial vehicles according to claim 1, characterized in that: The shell is divided into an upper shell and a lower shell, which are connected by buckles, and an opening is arranged on the shell.

8. The structural energy integrated device for unmanned aerial vehicles according to claim 7, characterized in that: Cover the opening with PI tape to ensure air isolation. When in use, remove it and use it normally. When not in use, continue to cover the opening with PI tape. This method can extend the battery life.

9. A drone, characterized in that: The drone comprises a main body, a structural energy integration device as described in any one of claims 1 to 8, and a power device; The power device includes a motor and a propeller electrically connected to the motor; wherein the structural energy integration device is symmetrically and fixedly arranged on the main body, the motor is fixedly arranged in a cylindrical frame of the structural energy integration device, and a control unit is arranged on the main body for controlling the output of the electrode, thereby controlling the flight of the UAV.

10. The drone according to claim 9, characterized in that: The UAV is a quad-rotor UAV or a bi-rotor UAV.

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