A method for preparing a low wind resistance coil

Abstract

The present invention relates to a coil and a preparation method thereof. In order to solve the technical problems in the prior art that the air resistance coefficient of the wireless charging transceiver coil of an aircraft is large, which affects the attitude control stability and flight performance of the aircraft, and the use of large-diameter copper Litz wire greatly increases the curb weight of the aircraft, seriously affecting the performance of the aircraft, the present invention provides a low-drag coil and a preparation method thereof, and an aircraft using the low-drag coil. The low-drag coil is in the shape of a torus as a whole, the cross-section of the torus is elliptical, the short axis of the ellipse is arranged axially along the torus, and the torus is a hollow structure formed by winding the Litz wire; in the aircraft using the low-drag coil, the low-drag coil is installed as a receiving coil on a bracket of the aircraft; the preparation method of the coil is to first wind a planar coil, use two molds to make the planar coil into a curved coil, and then bond the two curved coils and connect them to form a complete low-drag coil.

Description

Technical Field

[0001] The present invention relates to a coil and a preparation method thereof, and in particular to a low-drag coil and a preparation method thereof, and an aircraft using the low-drag coil. Background Art

[0002] The aircraft's wireless charging receiving coil completes energy reception during the aircraft's charging process and also needs to conform to the aerodynamic low-resistance characteristics so as not to reduce the aircraft's flight performance.

[0003] In existing technologies, the transceiver coils used in wireless charging systems often only consider electrical performance. Therefore, the design of the transceiver coils is based on high efficiency, low cost, and mature technology as the main design inputs, and aerodynamic effects are rarely considered. As a result, the air resistance coefficient of the transceiver coil is relatively large, which to a certain extent affects the attitude control stability and flight performance of the aircraft.

[0004] In addition, when designing the transceiver coil, in order to reduce copper loss and increase the current value in the transceiver coil, the internal resistance is made smaller, and large-diameter copper Litz wire is usually used. However, the density of copper is high (8.9 grams / cubic centimeter), so it will significantly increase the curb weight of the aircraft and seriously affect the aircraft performance. Summary of the Invention

[0005] The present invention aims to solve the technical problems in the prior art that the air resistance coefficient of the wireless charging transceiver coil of an aircraft is large, which affects the attitude control stability and flight performance of the aircraft, and the use of large-diameter copper Litz wire greatly increases the curb weight of the aircraft, seriously affecting the performance of the aircraft. The present invention provides a low-drag coil and a preparation method thereof, and an aircraft using the low-drag coil.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A low-drag coil, which is special in that the low-drag coil is in the shape of a torus as a whole, and the cross-section of the torus is elliptical;

[0008] The minor axis of the ellipse is arranged along the axial direction of the torus, and the major axis is arranged perpendicular to the axial direction of the torus;

[0009] The torus is a hollow structure formed by winding Litz wire.

[0010] Furthermore, the litz wire is an aluminum litz wire.

[0011] At the same time, the present invention also provides an aircraft using the low-drag coil, the special feature of which is that the low-drag coil is installed as a receiving coil on a bracket of the aircraft.

[0012] In addition, the present invention also provides a method for preparing the low-wind resistance coil, which is special in that it comprises the following steps:

[0013] S1, wound planar coil

[0014] Litz wire is wound into a flat coil in the shape of a torus;

[0015] S2, prepare the mold

[0016] Take a first mold and a second mold;

[0017] The first mold is in the shape of a circular cylinder, matching the shape and size of the planar coil, and has a circumferential groove with an arc-shaped cross-section on one end surface;

[0018] The second mold is in the shape of a circular cylinder, matching the shape and size of the planar coil, and has a circumferential protrusion with an arc-shaped cross-sectional profile on one end surface;

[0019] The circumferential groove and the circumferential protrusion are adapted to each other, and the depth of the circumferential groove and the height of the circumferential protrusion are adapted to the elliptical curvature of the cross section of the low-drag coil to be manufactured;

[0020] S3, pressed bent coil

[0021] The planar coil is concentrically placed between the circumferential groove of the first mold and the circumferential protrusion of the second mold, and pressure is applied to the first mold or the second mold to form the planar coil into a curved coil with a semi-elliptical cross-sectional profile;

[0022] S4, preparation of low wind resistance coil

[0023] Place two curved coils opposite to each other, bond the inner and outer edges together, and connect the end point of the Litz wire of the first curved coil and the starting point of the Litz wire of the second curved coil through a lead wire to form a torus-shaped low-wind resistance coil.

[0024] Furthermore, step S1 specifically includes covering the surface of the aluminum litz wire with adhesive and winding the aluminum litz wire into a circular planar coil.

[0025] Furthermore, in step S3, placing the planar coil between the circumferential groove of the first mold and the circumferential protrusion of the second mold is specifically performed by applying release liquid in the circumferential groove of the first mold and the circumferential protrusion of the second mold, and then placing the planar coil between the circumferential groove of the first mold and the circumferential protrusion of the second mold.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The low-drag coil of the present invention adopts a toroidal design as the entire coil, which can effectively reduce the wind resistance during use. In particular, the elliptical cross-section makes the coil surface shape smoother, further effectively reducing the wind resistance of the coil. The hollow structure of the coil can also reduce the overall mass of the coil; while ensuring the electrical performance, the air resistance coefficient of the coil is effectively reduced, thereby improving the working performance of the coil.

[0028] 2. The coil in the present invention uses aluminum Litz wire, which is lighter and reduces the impact on the flight performance of the aircraft.

[0029] 3. The present invention uses an aircraft with a low-drag coil, which is mounted on an aircraft bracket and used as a receiving coil. It has all the technical effects of the aforementioned coils. While ensuring the coil's receiving performance, the coil's air resistance is low during aircraft operation, avoiding any impact on the aircraft's stability and safety. It also has very little impact on the aircraft's load capacity and flight control. Practical verification has shown outstanding performance.

[0030] 4. The preparation method of the low wind resistance coil of the present invention is to first wind a flat coil, use two molds to make the flat coil into a curved coil, and then bond the two curved coils and connect them to form a complete low wind resistance coil. The process is simple and easy to operate, and is convenient for industrial promotion. The molds used are all simple rotating bodies, which are simple to process and easy to form. In addition, the preparation method of the present invention does not involve many process parameter limitations and processing environment requirements, and there are fewer human factors. Therefore, the preparation has high stability and repeatability, and the cross-sectional contour shape of the coil can be controlled by mold processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of a planar coil in an embodiment of a method for preparing a low wind resistance coil of the present invention;

[0032] Figure 2 Schematic diagram of a method for preparing a low-drag coil according to an embodiment of the present invention, wherein a coil is bent by pressing using a first mold and a second mold (only a portion of the first mold and the second mold along the circumferential direction is shown);

[0033] Figure 3 For the present invention Figure 2 A partial schematic diagram of the middle part;

[0034] Figure 4 For the present invention Figure 3 Schematic cross-section diagram;

[0035] Figure 5 Schematic diagram of a bent coil in an embodiment of a method for preparing a low-wind resistance coil of the present invention (only a portion of the bent coil along the circumferential direction is shown);

[0036] Figure 6This is a cross-sectional schematic diagram of two bent coils placed opposite to each other in an embodiment of a method for preparing a low wind resistance coil of the present invention;

[0037] Figure 7 This is a schematic cross-sectional view of the inner and outer sides of two curved coils bonded together in an embodiment of a method for preparing a low wind resistance coil of the present invention;

[0038] Figure 8 Schematic diagram of a toroidal low-drag coil prepared in an embodiment of a method for preparing a low-drag coil of the present invention;

[0039] Figure 9 This is a schematic structural diagram of an aircraft embodiment of the present invention that uses a low-drag coil.

[0040] Among them, 1-low wind resistance coil, 2-bracket, 3-planar coil, 4-first mold, 5-second mold, 6-circumferential groove, 7-circumferential protrusion, 8-bent coil, 9-ground transmitting coil. DETAILED DESCRIPTION

[0041] The technical solutions of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are not intended to limit the present invention.

[0042] The purpose of the present invention is to design a low-air-drag conformal coil to solve the problem in the prior art that coils often only consider electrical performance and ignore aerodynamic effects. At the same time, when used as an aircraft receiving coil, the coil's large air drag coefficient affects the aircraft's attitude control stability and flight performance.

[0043] The present invention provides a low-wind resistance coil 1, which is in the shape of a torus as a whole, and the cross-section of the torus is elliptical. The short axis of the ellipse is arranged along the axial direction of the torus, and the long axis is arranged perpendicular to the axial direction of the torus. The overall external shape is streamlined, conforming to aerodynamic characteristics, and effectively reducing wind resistance during application. The torus of the coil as a whole is a hollow structure formed by winding Litz wire, which is light in weight and has excellent electrical performance.

[0044] like Figure 9 As shown, the low-drag coil 1 of the present invention can be used as a receiving coil for an aircraft. Figure 9Figure 2 shows an embodiment of an aircraft employing a low-drag coil 1 according to the present invention. The low-drag coil 1 is mounted on a quadcopter's frame 2, opposite a ground-mounted transmitting coil 9. This minimizes the impact on the aircraft's flight stability and attitude control sensitivity. Furthermore, to further reduce the weight of the low-drag coil 1, aluminum Litz wire is used as the Litz wire wound around it. Because aluminum Litz wire weighs only one-third of a coil made from traditional copper Litz wire, even though the coil is located below the quadcopter's center of mass, the gravitational eccentric moment generated by its mass is minimal, minimizing the impact on the aircraft's load capacity and flight control, achieving ideal results.

[0045] In wireless charging systems, considering the interference with other wireless transceiver devices and the biological effects on organisms, an operating frequency of tens to hundreds of kilohertz is generally selected. This frequency range will not have a significant impact on communication broadcasting, nor will it harm the human body. However, at this frequency, the current has a relatively serious skin effect. Therefore, the transceiver coil for wireless energy transmission generally uses copper Litz wire (a high-current wire composed of multiple thin enameled wires). However, copper has a high density and heavy weight. Using it on an aircraft will reduce the load capacity and shorten the airborne time. Therefore, it is necessary to use the preferred aluminum Litz wire in combination with the low wind resistance coil 1 of the present invention, which is lightweight and has a low air resistance coefficient. It can significantly reduce the weight of the coil, so as to increase the load capacity and extend the airborne time.

[0046] At the same time, the present invention also provides a method for preparing the low-drag coil 1, which is described using the above-mentioned aluminum Litz wire preparation as an example:

[0047] (1) Aluminum Litz wire is wound into Figure 1 The planar coil 3 shown has an aluminum litz wire with glue on the surface;

[0048] (2) Based on the geometric parameters of the planar coil 3 and the low-drag coil 1 to be manufactured, a first mold 4 and a second mold 5 are designed and manufactured. The first mold 4 is in the shape of a circular cylinder, and a circumferential groove 6 with an arc-shaped cross-sectional profile is provided on one end surface. The second mold 5 is in the shape of a circular cylinder, and a circumferential protrusion 7 with an arc-shaped cross-sectional profile is provided on one end surface. The circumferential groove 6 and the circumferential protrusion 7 are adapted to each other, and the depth of the circumferential groove 6 and the height of the circumferential protrusion 7 are adapted to the elliptical curvature of the cross-sectional profile of the low-drag coil to be manufactured.

[0049] (3) Figures 2 to 4 As shown, when the glue on the surface of the aluminum Litz wire is about to dry, the planar coil 3 is concentrically placed between the first mold 4 and the second mold 5 coated with release fluid, and the planar coil 3 is located between the circumferential groove 6 and the circumferential protrusion 7;

[0050] (4) Press the first mold 4 up and down to fit the planar coil 3 between the circumferential groove 6 and the circumferential protrusion 7. Apply external force to the planar coil 3 through the circumferential groove 6 and the circumferential protrusion 7. After demolding, the planar coil 3 is fully solidified to form a curved coil 8 with a semi-elliptical cross-sectional profile. The curved coil 8 is as shown in FIG. Figure 5 As shown, the curvature of the semi-ellipse is consistent with the curvature of the circumferential groove 6 of the first mold 4 and the curvature of the circumferential protrusion 7 of the second mold 5 .

[0051] (5) Press the two bending coils 8 Figure 6 As shown, place them opposite to each other, apply glue on the inner and outer edges, and bend the two coils 8 as shown. Figure 7 As shown, press them together lightly, and after the glue is completely cured, the end point of the Litz wire of the first curved coil 8 is connected to the starting point of the Litz wire of the second curved coil 8 by a lead wire in a desired manner to form a Figure 8 The toroidal low wind resistance coil 1 is shown.

[0052] In the above embodiment, the low-drag coil 1 of the present invention is shown as an installation structure of a receiving coil in an aircraft. However, this does not mean that the low-drag coil 1 of the present invention can only be used as a receiving coil for an aircraft. It can be used in any scenario where wind resistance may exist.

[0053] The above descriptions are merely embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any equivalent structural transformations made using the contents of the present invention's description and drawings, or directly or indirectly applied to other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a low-drag coil, characterized in that: The following steps are involved: S1, Winding Planar Coil (3) The Litz wire is wound into a planar coil in a circular shape (3); S2, prepare the mold Take a first mold (4) and a second mold (5); The first mold (4) is in the shape of a circular cylinder, matching the shape and size of the planar coil (3), and has a circumferential groove (6) with an arc-shaped cross-sectional profile on one end surface; The second mold (5) is in the shape of a circular cylinder, matching the shape and size of the planar coil (3), and one end face is provided with a circumferential protrusion (7) with an arc-shaped cross-sectional profile; The circumferential groove (6) and the circumferential protrusion (7) are adapted to each other, and the depth of the circumferential groove (6) and the height of the circumferential protrusion (7) are adapted to the elliptical curvature of the cross section of the low-drag coil to be manufactured; S3, Pressed Bend Coil (8) The planar coil (3) is concentrically placed between the circumferential groove (6) of the first mold (4) and the circumferential protrusion (7) of the second mold (5), and pressure is applied to the first mold (4) or the second mold (5) to form the planar coil (3) into a curved coil (8) having a semi-elliptical cross-sectional profile; S4, preparation of low wind resistance coil (1) Two curved coils (8) are placed opposite to each other, the inner and outer edges are bonded, and the end point of the Litz wire of the first curved coil (8) is connected to the start point of the Litz wire of the second curved coil (8) through a lead wire to form a torus-shaped low-windage coil (1).

2. The method for preparing a low-drag coil according to claim 1, wherein: Step S1 specifically includes covering the surface of the aluminum Litz wire with adhesive and winding the aluminum Litz wire into a circular planar coil (3).

3. A method for preparing a low-drag coil according to claim 1 or 2, characterized in that: In step S3, placing the planar coil (3) between the circumferential groove (6) of the first mold (4) and the circumferential protrusion (7) of the second mold (5) is specifically performed by applying a release liquid in the circumferential groove (6) of the first mold (4) and the circumferential protrusion (7) of the second mold (5), and then placing the planar coil (3) between the circumferential groove (6) of the first mold (4) and the circumferential protrusion (7) of the second mold (5).

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