CN214707374U - Brushless motor and unmanned aerial vehicle - Google Patents

Abstract

The utility model discloses a brushless motor and an unmanned aerial vehicle, wherein the brushless motor comprises a rotating shaft, a stator bracket, a supporting piece, a bearing, an elastic piece and a sealing piece, and the stator bracket is provided with a middle hole; the support piece is sleeved on the rotating shaft, a boss is arranged at the end part of the support piece and located outside the middle hole, and the boss covers the middle hole in the axis direction of the rotating shaft. According to the utility model discloses a brushless motor, the mesopore can be hidden to the boss to play waterproof dirt-proof effect, improve brushless motor's life, guaranteed brushless motor's stability and reliability. Meanwhile, the boss is positioned outside the middle hole, so that the covering area of the boss can be conveniently increased, and the waterproof and dustproof effects are further ensured. The supporting part can also play a role in supporting, so that the supporting part has a multi-purpose effect. The elastic part can compensate the play influence of the bearing. The sealing member may further prevent impurities from entering the interior of the brushless motor through the central hole.

Description

Brushless motor and unmanned aerial vehicle

Technical Field

The utility model belongs to the technical field of the motor technique and specifically relates to a brushless motor and unmanned aerial vehicle are related to.

Background

The brushless motor has the characteristics of small volume, light weight, high efficiency, low noise, good reliability and the like. Therefore, brushless motors have been used in many industries and mass production applications have been implemented. Brushless motor can be applied to fields such as car, medical equipment, unmanned aerial vehicle, domestic appliance.

Among the correlation technique, brushless motor generally includes rotation axis and stator support, and the rotation axis is generally located in stator support's mesopore, and like this, when brushless motor located external environment, impurity such as rainwater or dust got into brushless motor's inside through the mesopore easily, very big influence brushless motor's life and moving stability. Therefore, how to facilitate the waterproof and dustproof of the brushless motor becomes a problem to be solved urgently. In addition, it is important to adjust the play of the bearing conveniently while ensuring the waterproof and dustproof performance of the brushless motor.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at solving one of the technical problem that exists among the prior art at least. Therefore, the utility model provides a brushless motor, brushless motor's waterproof dustproof effectual, long service life.

The utility model also provides an unmanned aerial vehicle, unmanned aerial vehicle includes above-mentioned brushless motor.

According to the utility model discloses brushless motor, include: a rotating shaft; a stator frame having a central bore; the support piece is sleeved on the rotating shaft and provided with a boss and a support part which are connected, the support part is positioned in the middle hole, the boss is positioned outside the middle hole, and in the axial direction of the rotating shaft, the boss covers the middle hole; the bearing is positioned in the central hole, the rotating shaft penetrates through the bearing, and the support piece is positioned on one side of the bearing in the axial direction; the elastic piece is sleeved on the rotating shaft and abuts against the supporting piece and the inner ring of the bearing in the axis direction of the rotating shaft; a seal clamped between the central bore and the support.

According to the utility model discloses brushless motor through setting up the boss, can cover the mesopore to play waterproof dirt-proof effect, prevent that impurity such as ponding, rainwater, dust from getting into brushless motor's inside, improve brushless motor's life, guaranteed brushless motor's reliability. Meanwhile, the boss is positioned outside the middle hole, so that the covering area of the boss can be conveniently increased, and the waterproof and dustproof effects are further ensured. Meanwhile, the supporting piece can also play a role in supporting, so that the supporting piece has a multi-purpose effect, the structure of the brushless motor is simplified, the assembly is convenient, and the assembly efficiency is high. In addition, through setting up the elastic component, the elastic component can compensate the play influence of bearing to improve brushless motor's the stability of operation and life. In addition, through the setting of sealing member, can further prevent that impurity from getting into brushless motor's inside through the mesopore, improved brushless motor's life.

In some embodiments, the inner race of the bearing is clearance fit with the rotating shaft.

In some embodiments, the brushless motor further comprises: the retainer ring is positioned on the other side of the bearing in the axial direction, the retainer ring is connected with the rotating shaft, and the inner ring of the bearing is abutted between the retainer ring and the elastic piece.

In some embodiments, the end of the rotating shaft has a mounting groove, and the retainer ring is mounted to the mounting groove.

In some embodiments, the peripheral wall of the central bore has a sealing groove, and the seal is disposed within the sealing groove.

In some embodiments, the slot of the seal groove opens toward the rotational shaft.

In some embodiments, the stator support has a water receiving groove on its periphery, and the end of the stator support has a plurality of overflow grooves arranged at intervals for guiding water flow to the water receiving groove.

In some embodiments, the brushless motor further includes an upper end cap, the upper end cap is connected to the rotating shaft and rotates synchronously, one of the rotating shaft and the upper end cap has a rivet column, and the other has a rivet hole, and the rivet column is in riveting fit with the rivet hole.

In some embodiments, the brushless motor further includes a lower end cap and a circuit substrate, the lower end cap is fixedly connected with the stator support, and the circuit substrate is sealed in the lower end cap through a pouring sealant.

In some embodiments, the middle hole includes a first hole section, a second hole section and a third hole section which are connected in sequence, the inner diameter of the first hole section is smaller than that of the second hole section to form a first step portion,

the inner diameter of the third hole section is smaller than that of the second hole section so as to form a second step part, and the outer ring of the bearing is stopped between the first step part and the second step part; or

The inner diameter of the third hole section is larger than or equal to that of the second hole section, a blocking cover is arranged in the third hole section, and the outer ring of the bearing is stopped against the first step part and the blocking cover.

In some embodiments, the resilient member is a spring or washer or a rubber tube.

According to the utility model discloses unmanned aerial vehicle, include as above brushless motor. According to the utility model discloses unmanned aerial vehicle through setting up the boss, can cover the mesopore to play waterproof dirt-proof effect, prevent that impurity such as ponding, rainwater, dust from getting into brushless motor's inside, improve brushless motor's life, guaranteed brushless motor's reliability. Simultaneously, the boss is located the outside of mesopore, can be convenient for improve the area that covers of boss to further guarantee waterproof dirt-proof effect, and then can improve unmanned aerial vehicle's life and stability. Meanwhile, the supporting piece can also play a role in supporting, so that the supporting piece has a multi-purpose effect. In addition, the elastic part can compensate the play influence of the bearing so as to improve the running stability and the service life of the brushless motor. In addition, the sealing member can further prevent that impurity from getting into brushless motor's inside through the mesopore, has improved unmanned aerial vehicle's life.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic structural diagram of a brushless motor according to an embodiment of the present invention;

fig. 2 is a sectional view of a brushless motor according to an embodiment of the present invention, taken along an axial direction of a rotating shaft;

fig. 3 is an exploded view of a brushless motor according to an embodiment of the present invention;

fig. 4 is an exploded view of a rotating shaft and an upper end cap according to an embodiment of the present invention;

fig. 5 is a sectional view of a brushless motor according to another embodiment of the present invention, taken along an axial direction of a rotating shaft;

fig. 6 is a schematic structural diagram of a stator frame according to an embodiment of the present invention.

Reference numerals:

a brushless motor 100; a rotating shaft 10; riveting columns 11; a mounting groove 12;

a stator holder 20; a central bore 21; a first bore section 211; a second bore section 212; a third bore segment 213; a first step portion 214; a seal groove 22; a notch 221; a water receiving tank 23; an overflow tank 24; a plug-in cover 25;

a support member 30; a boss 31; support portion 32

A bearing 40; the inner race 41 of the bearing; the outer race 42 of the bearing;

an elastic member 50; a retainer ring 60; a seal 70; an upper end cap 80; riveting holes 81;

a lower end cap 91; a circuit substrate 92, a wire harness assembly 93; a housing 94; a retainer ring 95; an iron core 96; a winding 97; a magnetic shoe 98;

a fastener 110.

Detailed Description

Embodiments of the present invention are described in detail below, and the embodiments described with reference to the drawings are exemplary.

A brushless motor 100 according to an embodiment of the present invention is described below with reference to fig. 1 to 6, and the brushless motor 100 includes a rotating shaft 10, a stator bracket 20, a support member 30, a bearing 40, an elastic member 50, and a sealing member 70.

Specifically, as shown in fig. 1 to 4, the stator holder 20 has a central hole 21, the support 30 is fitted over the rotary shaft 10, the support 30 has a boss 31 and a support portion 32 connected, the boss 31 is located outside the central hole 21, and the boss 31 blocks the central hole 21 in the axial direction of the rotary shaft 10.

In the related art, the stator bracket has a center hole for mounting a structure such as a rotating shaft, and if the center hole cannot be shielded, impurities such as rainwater and dust easily enter the interior of the brushless motor through the center hole. And in the brushless motor 100 of the embodiment of the present invention, the center hole 21 can be covered by the boss 31, for example, in the axis direction (for example, the up-down direction shown in fig. 2) of the rotating shaft 10, the orthographic projection of the center hole 21 falls into the orthographic projection of the boss 31, so as to ensure the effect that the boss 31 blocks rainwater and dust, and the waterproof and dustproof effects are good. Meanwhile, the boss 31 is located outside the middle hole 21, so that the shielding area of the boss 31 can be increased conveniently, and further, the waterproof and dustproof effects of the boss 31 can be further improved. Of course, the boss 31 may abut against the central hole 21, or the boss 31 may be spaced apart from the central hole 21, which is not limited herein.

As shown in fig. 1, for example, the elastic member 50 may be provided at an upper end of the bearing 40, such as shown in fig. 2. The support 30 is located on one side of the bearing 40 in the axial direction, the bearing 40 is located in the central hole 21, the rotating shaft 10 is inserted into the bearing 40, the elastic element 50 is sleeved on the rotating shaft 10, the support 30 has a support portion 32, the support portion 32 is located in the central hole 21, and the elastic element 50 abuts between the support 30 and the inner ring 41 of the bearing in the axial direction of the rotating shaft 10.

Therefore, the elastic member 50 has an elastic force, the play of the bearing 40 in the axial direction can be compensated and eliminated by the elastic force of the elastic member 50, and the elastic member 50 can apply an elastic force to the inner ring 41, the retainer ring 60 and the support 30 of the bearing, so as to compensate the play influence of the bearing 40, prevent the bearing 40 from shaking during the rotation process, and prolong the service life of the bearing 40. Meanwhile, the supporting member 30 can support the elastic member 50 at the upper end of the bearing 40, for example, fig. 2, to ensure that the elastic member 50 compensates for the reliability of the play of the bearing 40, and the supporting member 30 thus provided not only has the waterproof and dustproof functions, but also can play a supporting role, so that the supporting member 30 has a multi-purpose effect, the structure of the brushless motor 100 is simplified, the assembly is convenient, and the assembly efficiency is high. For example, the outer race 42 of the bearing may have an interference or transition fit with the inner wall of the central bore 21 of the stator frame 20.

Referring to fig. 2 and 3, the brushless motor 100 may further include a sealing member 70, and the sealing member 70 is clamped between the central hole 21 and the support member 30. By the arrangement of the sealing member 70, water or dust can be further prevented from entering the interior of the brushless motor, and impurities such as water or dust can be prevented from affecting the operation of the bearing, so as to improve the service life of the brushless motor 100. For example, the sealing member 70 may be a Y-shaped sealing ring, the sealing member 70 may be sleeved on the supporting member 30, and an inner lip of the Y-shaped sealing ring may abut against the supporting member 30 to further prevent water or dust from flowing along the rotating shaft 10 toward the inside of the brushless motor 100. Of course, the sealing member 70 may be transition fit or interference fit with the support member 30, and is not limited thereto.

According to the utility model discloses brushless motor 100 through setting up boss 31, can cover mesopore 21 to play waterproof dirt-proof effect, prevent that impurity such as ponding, rainwater, dust from getting into brushless motor 100's inside, improve brushless motor 100's life, guaranteed brushless motor 100's stability and reliability. Meanwhile, the boss 31 is located outside the middle hole 21, so that the covering area of the boss 31 can be increased conveniently, and the waterproof and dustproof effects are further ensured. Meanwhile, the supporting member 30 can also play a role in supporting, so that the supporting member 30 has a multi-purpose effect, the structure of the brushless motor 100 is simplified, the assembly is convenient, and the assembly efficiency is high. In addition, by providing the elastic member 50, the elastic member may compensate for the play influence of the bearing 40 to improve the stability of the operation and the lifespan of the brushless motor 100. In addition, by the provision of the sealing member 70, it is possible to further prevent impurities from entering the interior of the brushless motor 100 through the central hole 21, improving the life span of the brushless motor 100.

Further, the inner race 41 of the bearing is clearance-fitted with the rotary shaft 10. Here, "clearance fit" means that the rotating shaft 10 and the bearing 40 are in a loose fit state. So configured, the elastic member 50 can be facilitated to compensate for the play of the bearing 40. For example, the number of the bearings 40 may be plural, and the plural bearings 40 are blocked by a blocking ring. In the description of the present invention, "a plurality" means two or more.

In some embodiments, referring to fig. 2 and 3, brushless motor 100 may further comprise a retaining ring 60, and retaining ring 60 may be located, for example, at a lower end as shown in fig. 2. The retainer ring 60 is located on the other side in the axial direction of the bearing 40, the retainer ring 60 is connected to the rotary shaft 10, and the inner race 41 of the bearing is stopped between the retainer ring 60 and the elastic member 50. The retainer ring 60 may function to support the inner race 41 of the bearing. Further, as shown in fig. 3 and 4, the end of the rotating shaft 10 may have a mounting groove 12, and the retainer ring 60 is mounted to the mounting groove 12, so that the reliability of mounting the retainer ring 60 may be ensured. For example, the mounting groove 12 is an annular groove to ensure the reliability of the installation of the retainer ring 60.

Thus, the supporting member 30, the elastic member 50, the bearing 40, and the retainer ring 60 are sequentially disposed, the elastic member 50 is stopped against between the supporting member 30 and the bearing 40 to compensate for the play of the bearing 40, and the supporting member 30 and the retainer ring 60 are respectively disposed on two opposite sides of the bearing 40 in the axial direction to support. Of course, in other embodiments, the elastic element 50 may also be stopped between the inner ring 41 of the bearing and the retainer ring 60.

For example, the elastic member 50 may be a spring. Alternatively, the elastic member 50 may be an elastic washer. Alternatively, the elastic member 50 may be a rubber tube. The elastic members 50 thus provided may each have good elasticity to ensure the effect of compensating for the elimination of the play of the bearing 40.

In some embodiments, as shown in fig. 2, the peripheral wall of the central hole 21 has a sealing groove 22, and the sealing member 70 is disposed in the sealing groove 22 to ensure the stability of the installation of the sealing member 70 and ensure the waterproof and dustproof effects. Further, the notch 221 of the seal groove 22 is opened toward the rotary shaft 10. Thus, the seal groove 22, while functioning to mount the seal 70, may stroke the sealing surface, for example, above FIG. 2, to prevent standing water or dust from entering the seal groove 22. Of course, in other examples, the notch 221 of the sealing groove 22 may also be open in a direction away from the rotating shaft 10, and is not limited herein.

In some embodiments, as shown in fig. 6, the periphery of the stator frame 20 has a water receiving groove 23, for example, the upper end of the stator frame 20 has the water receiving groove 23. The stator frame 20 has a plurality of overflow grooves 24 provided at intervals at, for example, an end in the circumferential direction, and the overflow grooves 24 are used for guiding water to flow to the water receiving groove 23. Accordingly, water may be prevented from entering the center hole 21, reliability of components inside the center hole 21 may be improved, and operation stability and lifespan of the brushless motor 100 may be improved. For example, the water receiving tank 23 may be provided in plurality, the overflow tank 24 may be provided in plurality, and each overflow tank 24 may be provided corresponding to one water receiving tank 23. The bottom (e.g., lower end as shown in fig. 2) of the overflow trough 24 may be slightly higher than the bottom (e.g., lower end as shown in fig. 2) of the sealing member 70 to ensure that water can be effectively guided out of the overflow trough 24 to prevent water from being stored.

In some examples, as shown in fig. 1-4, brushless motor 100 may further include an upper end cap 80. An upper end cap 80 may be provided to cover an upper end of the stator frame 20, for example, of fig. 2, and may further allow dust and water to enter the center hole 21. The upper end cover 80 is connected with the rotating shaft 10 and synchronously rotates, one of the rotating shaft 10 and the upper end cover 80 is provided with a riveting column 11, the other one is provided with a riveting hole 81, and the riveting column 11 is in riveting fit with the riveting hole 81. With this arrangement, the rotary shaft 10 can be subjected to a large torque without being loosened from the upper end cap 80, and the reliability of the assembly of the rotary shaft 10 and the upper end cap 80 is improved. For example, the rotating shaft 10 has a rivet stud 11, the upper end cap 80 has a rivet hole 81, one end of the rotating shaft 10 away from the upper end cap 80 may have an annular protrusion protruding in a circumferential direction of the rotating shaft 10, and the rivet stud 11 may be provided on a side of the annular protrusion facing the upper end cap 80. The rivet hole 81 may be a through hole or a blind hole, and when the rivet hole 81 is a blind hole, the rivet stud 11 may abut against the blind hole. The rivet columns 11 and the rivet holes 81 may be provided in plurality at intervals, and each rivet column 11 and each rivet hole 81 are provided in one-to-one correspondence. Meanwhile, the rotating shaft 10 and the upper end cap 80 may be further connected by a fastener to further improve the mounting stability of the two.

In some embodiments, as shown in fig. 1 and 3, the brushless motor 100 may further include a lower cover 91 and a circuit substrate 92, and the lower cover 91 may be covered on a lower end of the stator frame 20, for example, as shown in fig. 2, so that water and dust may be further prevented from entering the central hole 21 from the lower end of the central hole 21. The lower end cover 91 is fixedly connected with the stator bracket 20, and the circuit substrate 92 is sealed in the lower end cover 91 through pouring sealant. The potting adhesive can guide heat generated by components on the circuit substrate 92 to the lower end cover 91 and radiate the heat to the outside, and can isolate water and dust and prevent damage to water or dust components.

In some embodiments, as shown in fig. 2 and 5, the middle hole 21 includes a first hole section 211, a second hole section 212, and a third hole section 213 connected in sequence, an inner diameter of the first hole section 211 is smaller than an inner diameter of the second hole section 212 to form a first step 214, an inner diameter of the third hole section 213 is smaller than an inner diameter of the second hole section 212 to form a second step, and the outer ring 42 of the bearing is prevented from abutting between the first step 214 and the second step, so that the first step 214 and the second step can respectively prevent the outer ring 42 of the bearing from abutting, so as to prevent the outer ring 42 of the bearing from loosening. Or, the inner diameter of the third hole section 213 is greater than or equal to the inner diameter of the second hole section 212, a blocking cover 25 is arranged in the third hole section 213, and the outer ring 42 of the bearing is stopped between the first step portion 214 and the blocking cover 25. Thereby, the first stepped portion 214 and the cap 25 can respectively prevent the outer ring 42 of the bearing from abutting, to prevent the outer ring 42 of the bearing from loosening. A cap 25 may close one end of the central hole 21 to prevent water flow or dust from entering the central hole 21. For example, the cap 25 may have an interference or transition fit with the central bore 21.

According to the utility model discloses unmanned aerial vehicle, its characterized in that includes brushless motor 100 as above. The unmanned aerial vehicle can be an unmanned aerial vehicle, an unmanned ship, an unmanned vehicle and the like. For example, the upper end of brushless motor 100, e.g., as shown in fig. 2, may be mounted to a fan blade of the unmanned aircraft, and the lower end of brushless motor 100, e.g., as shown in fig. 2, may be mounted to the body of the unmanned aircraft. According to the utility model discloses unmanned aerial vehicle through the boss 31 that sets up support piece 30, can play waterproof dirt-proof effect, prevents that impurity such as ponding, rainwater, dust from getting into brushless motor 100's inside, improves brushless motor 100's life, has guaranteed brushless motor 100's reliability. Simultaneously, boss 31 is located mesopore 21's outside, can be convenient for improve the area that covers of boss 31 to further guarantee waterproof dirt-proof effect, in order to improve unmanned aerial vehicle's life and reliability. Meanwhile, the supporting member 30 can also play a role in supporting, so that the supporting member 30 has a multi-purpose effect, the structure of the brushless motor 100 is simplified, the assembly is convenient, and the assembly efficiency is high. In addition, by providing the elastic member 50, the elastic member may compensate for the play influence of the bearing 40 to improve the stability of the operation and the lifespan of the brushless motor 100. In addition, through the setting of sealing member 70, can further prevent that impurity from getting into brushless motor 100's inside through mesopore 21, improved unmanned aerial vehicle's life.

Other configurations of the brushless motor 100 according to an embodiment of the present invention, such as the wire harness assembly 93, the housing 94, the baffle ring 95, the core 96, the windings 97, the magnetic shoes 98, etc., and operations are known to those of ordinary skill in the art and will not be described in detail herein.

In the description of the present invention, it is to be understood that the terms "central," "upper," "lower," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," and the like are used in the orientation or positional relationship shown in the drawings for convenience in describing the present invention and for simplicity in description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the present invention.

In the description of the present invention, "a plurality" means two or more.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example.

While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims (12)

1. A brushless motor, comprising:

a rotating shaft;

a stator frame having a central bore;

the support piece is sleeved on the rotating shaft and provided with a boss and a support part which are connected, the support part is positioned in the middle hole, the boss is positioned outside the middle hole, and in the axial direction of the rotating shaft, the boss covers the middle hole;

the bearing is positioned in the central hole, the rotating shaft penetrates through the bearing, and the support piece is positioned on one side of the bearing in the axial direction;

the elastic piece is sleeved on the rotating shaft and abuts against the supporting piece and the inner ring of the bearing in the axis direction of the rotating shaft;

a seal clamped between the central bore and the support.

2. The brushless electric machine of claim 1, wherein the inner race of the bearing is clearance fit with the rotating shaft.

3. The brushless electric machine of claim 1, further comprising: the retainer ring is positioned on the other side of the bearing in the axial direction, the retainer ring is connected with the rotating shaft, and the inner ring of the bearing is abutted between the retainer ring and the elastic piece.

4. The brushless motor of claim 3, wherein an end of the rotation shaft has a mounting groove, and the retaining ring is mounted to the mounting groove.

5. The brushless electric machine of claim 1, wherein the elastic member is a spring or a washer or a rubber tube.

6. The brushless electric machine of claim 1, wherein a peripheral wall of the central bore has a sealing groove, the seal being disposed within the sealing groove.

7. The brushless motor of claim 6, wherein the notch of the sealing groove opens toward the rotation shaft.

8. The brushless electric motor of claim 1, wherein the stator frame has a water receiving groove formed in an outer circumference thereof, and a plurality of water overflowing grooves formed at intervals at an end portion thereof for guiding water to flow toward the water receiving groove.

9. The brushless motor of claim 1, further comprising an upper cover connected to the rotation shaft and rotating synchronously, wherein one of the rotation shaft and the upper cover has a rivet stud, and the other has a rivet hole, and the rivet stud is in riveting fit with the rivet hole.

10. The brushless electric machine of claim 1, further comprising a bottom cap and a circuit substrate, wherein the bottom cap is fixedly connected to the stator frame, and the circuit substrate is sealed in the bottom cap by a potting compound.

11. The brushless motor of claim 1, wherein the middle hole includes a first hole section, a second hole section, and a third hole section connected in sequence, the first hole section having an inner diameter smaller than that of the second hole section to form a first stepped portion,

the inner diameter of the third hole section is smaller than that of the second hole section so as to form a second step part, and the outer ring of the bearing is stopped between the first step part and the second step part; or

The inner diameter of the third hole section is larger than or equal to that of the second hole section, a blocking cover is arranged in the third hole section, and the outer ring of the bearing is stopped against the first step part and the blocking cover.

12. An unmanned aerial vehicle comprising a brushless motor as claimed in any one of claims 1 to 11.

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