KR102694353B1 - Apparatus for Driving Propeller and Vehicle Using the Same - Google Patents

Abstract

The present invention relates to a propeller drive device having excellent heat dissipation effect and an aircraft using the same by forming an insulator (or bobbin) that insulates between a stator core and a coil with an insulating heat-dissipating composite material having both heat dissipation and insulation performance.
A propeller driving device according to the present invention comprises: a BLDC motor of a single rotor-single stator type; and a propeller installation bracket for mounting a propeller on a rotational shaft of the motor; wherein the motor has a stator, a rotor, and a rotational shaft sequentially arranged inside a housing in which an upper cover and a lower cover are respectively joined to the upper and lower portions of a cylindrical case, and wherein the stator comprises: an annular back yoke having a predetermined width to form a magnetic circuit; and a stator core having a plurality of teeth extending toward the center from the back yoke; an insulator formed to surround an outer surface on which a coil is wound around each of the plurality of teeth; and a stator coil wound on an outer surface of the insulator around each of the plurality of teeth; wherein the insulator is characterized in that it is formed of an insulating heat-dissipating composite material having both heat dissipation performance and insulation performance.

Description

{Apparatus for Driving Propeller and Vehicle Using the Same}

The present invention relates to a propeller drive device and an aircraft using the same, and more specifically, to a propeller drive device having excellent heat dissipation effect and an aircraft using the same by forming an insulator (or bobbin) that insulates between a stator core and a coil with an insulating heat-dissipating composite material having both heat dissipation and insulation performance.

Typically, brushless electric motors used in aircraft consist of a stator to which a battery is connected, a rotor, and a case in which a propeller is mounted.

In this case, in the case of an aircraft electric motor, the case acts as a rotor, so the case itself rotates to rotate the propeller, thereby generating propulsion for the aircraft.

In addition, in the case of electric motors for aircraft, since the case itself rotates, they are characterized by high torque, and can directly rotate large propellers without a reducer, and since there is no need for accessories such as reducers, the electric motor can be made lighter.

However, in the case of an electric motor, since the case itself rotates as a rotor, a lot of heat is generated from the stator placed inside the case. In this case, if the speed of the aircraft is fast, the electric motor is cooled by the air flow, but in the case of a helicopter that mainly hovers, there is almost no air flow, so the electric motor overheats, so it is necessary to cool the electric motor.

For this purpose, in the case of electric motors used in aircraft, the upper plate of the case is usually provided with a number of cooling holes formed by being perforated or cut to a certain area. Accordingly, when the electric motor is driven, air is drawn into the cooling holes of the case through the air flow caused by the rotation of the propeller, thereby cooling the electric motor.

However, when the electric motor is driven and the case rotates at a constant speed, there is no concern that rain, moisture, or other foreign substances will be introduced due to the rotational force of the case. However, when the aircraft is stopped and located outside, rainwater, moisture, or foreign substances such as dust may be introduced through the cooling holes of the case.

Foreign substances such as rainwater, moisture, or dust that enter in this way can cause electrical shorts or fires due to short circuits.

Therefore, to solve these problems, measures such as covering the electric motor with a waterproof sheet such as vinyl were taken in the past, but these measures are only temporary and cumbersome, and do not solve the fundamental problem.

Korean Patent Publication No. 10-2017-0090037 (Patent Document 1) discloses an aircraft power transmission device equipped with moisture penetration prevention and overheating prevention functions, which introduces an opening/closing control means capable of opening and closing a cooling hole of a case formed to cool an electric motor, so that when the aircraft is stopped, the opening/closing control means automatically closes the cooling hole of the case to prevent moisture or foreign substances from entering the electric motor, and when the aircraft is in operation, the opening/closing control means adjusts the opening amount of the cooling hole of the case according to the rotational force of the case, thereby effectively implementing the cooling function of the electric motor.

In general, electric motors generate more heat in the stator, where the motor driving current is applied to the coil, than in the rotor. If the heat generated in this way cannot be discharged to the outside of the electric motor, it can act as a factor that reduces the efficiency and lifespan of the motor.

The electric motor of the above patent document 1 has a structure in which the stator (stator) is located in the center in an outer rotor manner. In patent document 1, cooling holes are provided on the front and rear of the cylindrical case that functions as the rotor, through which air cooling wind is introduced and discharged.

Patent Document 1 discloses a technology that introduces an opening/closing control means capable of opening and closing a cooling hole of a case formed to cool an electric motor, and when the aircraft stops, the opening/closing control means automatically closes the cooling hole of the case to block moisture or foreign substances from entering the inside of the electric motor.

Meanwhile, unmanned aerial vehicles (UAVs), or drones, are being used for a variety of purposes, including logistics for delivering parcels, surveillance/reconnaissance/search, quarantine/disinfection/spraying, broadcasting/performance, environmental surveying, and rescue.

Motors for propeller drives employed in two-seater light aircraft or large drones carrying heavy loads, especially BLDC motors, require drive motors of several tens of kilowatts, and in this case, an outer rotor type motor (Patent Document 1) in which a stator with coils wound around a core is arranged on the inside has limitations in effectively cooling the large amount of heat generated from the stator.

Heat generated from the above stator and accumulated internally without being dissipated to the outside may shorten the operating life and reduce operating efficiency. To prevent this, heat dissipation components or heat dissipation devices such as heat sinks and heat exchangers are used together with devices that generate heat.

Recently, heat-radiating members manufactured using injection-molded or extrudable polymer resins have been proposed, and much research is being conducted on them due to their advantages, such as lightness and low unit cost due to the material properties of the polymer resin itself.

However, heat dissipation members manufactured using polymer resins exhibit heat dissipation properties through thermally conductive fillers. However, thermally conductive fillers with excellent heat dissipation performance usually also exhibit electrical conductivity. Therefore, heat dissipation members implemented using such fillers exhibit electrical conductivity, and thus are highly unsuitable for use in electronic devices requiring insulation.

In particular, in the case of aircraft motors, it is required to have insulation performance that can avoid lightning strikes.

Additionally, AC motors are larger and heavier than BLDC motors, making them unsuitable as aircraft motors.

: Korean Patent Publication No. 10-2017-0090037

The inventor of the present invention has found that while arranging the stator, which generates more heat than the rotor, on the outside, external air cooling is achieved through natural side casings during flight, and internal air cooling is achieved simultaneously by forming a plurality of through holes between a plurality of bridges connecting the upper and lower covers and the rotor body and the rotating shaft, and that the problem of electrical short circuits occurring due to moisture or foreign substances entering the motor due to internal air cooling can be solved by isolating and blocking the stator by insert molding using an insulating heat-dissipating composite.

Accordingly, the present invention has been proposed to solve the problems of the above-mentioned prior art, and its purpose is to provide a propeller drive device having excellent heat dissipation effect and an aircraft using the same by forming an insulator (or bobbin) that insulates between the stator core and the coil with an insulating heat-dissipating composite material having both heat dissipation and insulation performance.

Another object of the present invention is to provide a propeller drive device and an aircraft using the same, which can solve the problem of electrical short-circuiting caused by moisture or foreign substances flowing into the motor due to internal air cooling, by insert molding an insulating heat-dissipating composite material having both heat dissipation and insulation performance to surround a coil wound on an insulator (or bobbin) of a stator and insulate between the coils, while providing a heat dissipation effect.

Another object of the present invention is to provide a propeller drive device and an aircraft using the same in which heat dissipation performance is maximized by varying the composition of a first insulating heat-dissipating composite material used to form an insulator (or bobbin) that insulates between a stator core and a coil, and a second insulating heat-dissipating composite material that surrounds a coil wound on the insulator (or bobbin) and is covered by insert molding to insulate between the coils.

Another object of the present invention is to provide a propeller driving device capable of effectively dissipating heat by a water cooling method by having a water jacket having a refrigerant circulation circuit capable of circulating refrigerant between the outer periphery of a stator core and a casing, and an aircraft using the same.

Another object of the present invention is to provide a propeller driving device capable of effectively cooling the rotor and stator by external air cooling and internal air cooling using a BLDC motor of the inner rotor-outer stator type, and an aircraft using the same.

Another object of the present invention is to provide a propeller drive device and an aircraft using the same, which can effectively cool by internal air cooling by forming a plurality of through holes in upper and lower covers and connecting a rotor body and a rotating shaft through a plurality of bridges at the same time.

Another object of the present invention is to provide a propeller driving device in which a plurality of through holes are formed by connecting a rotor body and a rotating shaft through a plurality of bridges, thereby enabling internal air cooling to be achieved together with a plurality of through holes formed in upper and lower covers.

In order to achieve the above object, a propeller driving device according to one embodiment of the present invention comprises: a BLDC motor of a single rotor-single stator type; and a propeller installation bracket for mounting a propeller on a rotational shaft of the motor; wherein the motor has a stator, a rotor, and a rotational shaft sequentially arranged inside a housing in which an upper cover and a lower cover are respectively coupled to the upper and lower portions of a cylindrical case, and the stator comprises: an annular back yoke having a predetermined width to form a magnetic circuit; and a stator core having a plurality of teeth extending toward the center from the back yoke; an insulator formed to surround an outer surface on which a coil is wound around each of the plurality of teeth; and a stator coil wound on an outer surface of the insulator around each of the plurality of teeth; wherein the insulator is characterized in that it is formed of an insulating heat-dissipating composite material having both heat dissipation performance and insulation performance.

The above insulator may include upper and lower insulators each wrapping half of the outer surface of the teeth on which the coil is to be wound, and the upper and lower insulators may each include an annular base frame having a predetermined width; and a plurality of tooth receiving portions protruding from the base frame and receiving half of the winding area of the teeth at the upper and lower portions, respectively.

The above insulator may include upper and lower insulators each wrapping half of the outer surface of the teeth on which the coil is to be wound, and the upper and lower insulators may each include an annular base frame having a predetermined width; and a plurality of tooth receiving portions protruding from the base frame and receiving half of the winding area of the teeth at the upper and lower portions, respectively.

The above insulator may be manufactured in advance as upper and lower insulators and then assembled to the stator core, or may be integrally formed by insert molding using an insulating heat-dissipating composite material having heat dissipation and insulation performance.

A propeller driving device according to one embodiment of the present invention further includes a stator support having heat dissipation properties while surrounding the stator coils wound on the insulator and insulating between adjacent coils, and the stator support can be integrally formed by insert molding with an insulating heat-dissipation composite material having heat dissipation performance and insulation performance.

In this case, the diametrically outer surface of the heat-dissipating stator support is in contact with a water jacket installed on the outer side of the stator, and the water jacket can be cooled by a water-cooling method.

In addition, the insulating heat-dissipating composite may include a polymer matrix having a continuous use temperature of 150°C or higher and acting as a binder; an insulating heat-dissipating filler made of ceramic added and dispersed in the polymer matrix to improve thermal conductivity; and reinforcing fibers added to the polymer matrix to reinforce strength.

The above insulating heat-dissipating composite material can have an insulating performance of at least 10Kv or more and a thermal conductivity of at least 3W/mK.

In addition, in a propeller driving device according to one embodiment of the present invention, the motor can be internally cooled by using airflow discharged through a plurality of through holes provided in the upper cover from the outside, a plurality of spaces formed between a plurality of bridges connecting the rotating shaft and the rotor, and a plurality of through holes provided in the lower cover.

Furthermore, the propeller installation bracket is formed in a ring shape with a central through hole formed in the central portion, and an annular protrusion is positioned on the lower side of the central through hole for coupling with the rotation shaft of the motor, and the upper end of the rotation shaft and the lower surface of the protrusion that receives and faces the upper end can be coupled in a step structure.

According to another embodiment of the present invention, an aircraft is characterized by including: a fuselage; a control box arranged at a forward end of the fuselage; and a propeller driving device installed at a spaced distance in front of the control box and driving a propeller.

As described above, in the present invention, the insulator (or bobbin) that insulates between the stator core and the coil is formed of an insulating heat-dissipating composite material having both heat dissipation and insulation performance, thereby achieving excellent heat dissipation effects and improving motor efficiency. Furthermore, by forming the insulator (or bobbin) of an insulating heat-dissipating composite material, it is possible to provide an aviation motor that not only has heat dissipation and insulation performance, but also mechanical strength such as tensile strength and flexural modulus that can withstand external force.

In addition, in the present invention, by insert molding with an insulating heat-dissipating composite material having both heat dissipation and insulation performance to surround a coil wound on an insulator (or bobbin) of a stator and insulate between coils, the problem of moisture or foreign substances flowing into the motor during internal air cooling, causing an electrical short circuit, can be solved simultaneously with the heat dissipation effect. When insert molding with the insulating heat-dissipating composite material, the stator is formed to cover all parts exposed to the outside except for the shoe portion of the stator core facing the magnet of the rotor.

Furthermore, in the present invention, the composition of the first insulating heat-dissipating composite material used to form an insulator (or bobbin) that insulates between the stator core and the coil and the second insulating heat-dissipating composite material that surrounds the coil wound on the insulator (or bobbin) and is coated by insert molding to insulate between the coils can be varied to maximize the heat dissipation performance.

In the propeller driving device of the present invention, a BLDC motor of the inner rotor-outer stator type is used, and effective cooling can be achieved through external air cooling and internal air cooling of the rotor and stator.

In addition, in the present invention, a plurality of through holes are formed in the upper and lower covers, and at the same time, a plurality of bridges are connected between the rotor body and the rotating shaft, thereby forming a plurality of through holes, so that effective cooling can be achieved through internal air cooling.

Furthermore, in the present invention, effective heat dissipation can be achieved through water cooling by providing a water jacket having a refrigerant circulation circuit that can circulate refrigerant between the outer peripheral portion of the stator core and the casing.

FIGS. 1A to 1C are a perspective view showing a propeller light aircraft to which a propeller drive device according to the present invention is applied, a photograph showing the propeller drive device installed in a control box, and an enlarged side view showing a propeller coupled to the propeller drive device, respectively.
FIG. 2a and FIG. 2b are a plan view and a cross-sectional view taken along line AA of FIG. 2a, respectively, showing a propeller driving device according to the present invention.
Figure 3 is a partially cut-away perspective view of a propeller drive device according to the present invention.
Figure 4 is an exploded perspective view of a propeller driving device according to the present invention.
Figure 5 is an exploded perspective view of a rotor of a propeller driving device according to the present invention.
Figure 6 is an exploded perspective view of a stator of a propeller driving device according to the present invention.
Figure 7 is a graph showing the temperature of each phase of an example in which an insulator (or bobbin) is formed with an insulating heat-dissipating composite according to the present invention and a comparative example in which a heat-dissipating plastic is not applied.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the attached drawings.

In this process, the size and shape of the components depicted in the drawings may be exaggerated for clarity and convenience of explanation. In addition, terms specifically defined in consideration of the configuration and operation of the present invention may vary depending on the intention or custom of the user or operator. The definitions of these terms should be made based on the contents throughout this specification.

The propeller drive device according to the present invention can be applied to, for example, a two-person light aircraft or a large drone carrying a heavy load, and a motor equipped in the propeller drive device is required to be a large BLDC drive motor of several tens of kW.

When a large BLDC drive motor of several tens of kilowatts used in the above propeller drive device generates a lot of heat from the stator, if proper cooling and heat dissipation are not achieved, the motor efficiency may decrease and failure may occur.

In the present invention, a BLDC motor of the inner rotor-outer stator type, in which a stator that generates a lot of heat is placed on the outside of the rotor, is used, and its application to driving a propeller of a light aircraft is explained as an example.

The above embodiment can be applied to cases where the rotation axis of the propeller drive device is arranged horizontally or vertically. In this case, a reducer may be coupled to the output of the motor to increase torque.

The attached FIGS. 1a to 1c are a perspective view showing a propeller light aircraft to which a propeller drive device according to the present invention is applied, a photograph showing the propeller drive device installed in a control box, and an enlarged side view showing a propeller coupled to the propeller drive device, respectively. In addition, FIGS. 2a and 2b are a plan view showing the propeller drive device according to the present invention and a cross-sectional view taken along line A-A of FIG. 2a, respectively.

Referring to FIGS. 1A to 1C, a propeller drive device (10) according to the present invention is installed at a distance from the front of a control box (220) positioned at the front end of a fuselage (210) of a light aircraft (200), a propeller (70) is coupled to the front end of a rotational shaft to rotate the propeller (70), and the rotational shaft of the propeller drive device (10) is positioned in a horizontal direction.

The above control box (220) may include a control unit for controlling various electronic devices for controlling the operation of a light aircraft (200) and a motor drive device for driving a BLDC motor (100) equipped in a propeller drive device (10).

In this case, the propeller drive device (10) according to the present invention is not limited to a light aircraft (200), and can be applied not only to a multicopter type drone that drives multiple propellers, but also to a drone that drives a single propeller.

Referring to FIGS. 2a to 3, a propeller driving device (10) according to the present invention includes a single rotor-single stator type motor (100) and a propeller installation bracket (20) for mounting a propeller (70) on the rotation shaft (50) of the motor (100).

The above propeller installation bracket (20) is largely formed in a ring shape, and a large-diameter central through hole (21) is formed in the center. In addition, a plurality of large-diameter peripheral through holes (23) and a plurality of small-diameter peripheral through holes (24) are arranged on the same circumference around the central through hole (21). The plurality of large-diameter peripheral through holes (23) and the plurality of small-diameter peripheral through holes (24) are arranged for slimming purposes to reduce weight.

The rotation shaft (50) of the above motor (100) is also formed in a hollow shape at the center (50a) to reduce weight, and its outer diameter is set to a size corresponding to the center through-hole (21) of the propeller installation bracket (20).

A ring-shaped protrusion (25) is positioned on the lower side of the central through hole (21) of the propeller installation bracket (20) for coupling with the rotation shaft (50) of the motor (100). In addition, a plurality of screw fastening through holes are formed in the ring-shaped protrusion (25) for fastening a plurality of fixing screws (22) to the rotation shaft (50) of the motor (100).

The upper end (50b) of the above-mentioned rotation shaft (50) and the bottom surface of the annular projection (25) that receives and faces the upper end (50b) of the above-mentioned rotation shaft (50) are joined in a step structure. This step structure joining of the upper end (50b) of the above-mentioned rotation shaft (50) and the bottom surface of the projection (25) is intended to prevent twisting that occurs when the propeller (70) rotates.

The above single rotor-single stator type motor (100) includes a cylindrical case (12), and an upper cover (16) and a lower cover (18) which are respectively connected to the upper and lower portions of the cylindrical case (12). As a result, the cylindrical case (12), the upper cover (16), and the lower cover (18) serve as a housing for the motor (100).

Inside the cylindrical case (12) above, a water jacket (46), a stator (40), a rotor (30), and a rotation shaft (50) for cooling the motor (100) by water cooling are sequentially arranged. The rotation shaft (50) is rotatably supported by an upper bearing (51) and a lower bearing (52) installed in upper and lower bearing housings (16c, 18c) located at the center of the upper cover (16) and the lower cover (18), respectively.

In this case, the upper bearing (51) may be, for example, a double-row angular ball bearing capable of supporting a radial load and one large axial load simultaneously, and the lower bearing (52) may be a single-row angular ball bearing.

As shown in Fig. 6, the water jacket (46) has a spiral projection (46a) formed on the outer periphery of the cylindrical body to form a spiral passage, and the spiral projection (46a) comes into contact with the inner surface of the cylindrical case (12). As a result, a spiral passage (46b) can be formed between the spiral projections (46a) through which a coolant for cooling the motor (100) by water cooling is circulated. In this case, water or aircraft cooling oil can be used as the coolant.

In addition, as shown in Fig. 2b, an inlet or outlet (47a, 47b) connected to a spiral passage (46b) is formed at the upper and lower portions of the cylindrical case (12), respectively, and the inlet or outlet (47a, 47b) is connected to a pump for circulating the refrigerant.

O-rings (48a, 48b) for sealing are inserted into the upper and lower portions of the water jacket (46) and the cylindrical case (12), respectively, to prevent leakage of the spiral passage (46b).

Between the above cylindrical case (12) and the upper cover (16) and the lower cover (18), a protrusion is provided in which a plurality of through holes (19) are formed in the upper cover (16) and the lower cover (18) for mutual connection, and a fixing screw (19a) is fastened to the plurality of through holes (19) to secure them.

The upper cover (16) and the lower cover (18) are formed with a plurality of through holes (16e, 18e) that serve as air flow passages for cooling. To this end, the upper cover (16) and the lower cover (18) are provided with an intermediate ring (16b, 18b) that is formed in a concentric shape between the upper and lower bearing housings (16c, 18c) that are positioned on the inside and serve as hubs and the outer rings (16a, 18a) that are arranged on the outside, and a plurality of bridges (16d, 18d) extend radially to connect the upper and lower bearing housings (16c, 18c) and the intermediate rings (16b, 18b) and the outer rings (16a, 18a). Accordingly, a plurality of through holes (16e, 18e) are formed between the upper and lower bearing housings (16c, 18c), the middle ring (16b, 18b), the outer ring (16a, 18a), and the plurality of bridges (16d, 18d).

The above intermediate rings (16b, 18b) may be omitted or added as needed for strength reinforcement, and the network structure for forming a plurality of through holes (16e, 18e) formed in the upper cover (16) and the lower cover (18) may be changed differently.

The above plurality of through holes (16e, 18e) form an air flow passage for cooling air that introduces relatively low temperature outside air from the outside into the inside of the motor (100), then exchanges heat with the heat generated from the stator (40) and then discharges it to the outside of the motor.

The motor (100) according to the present invention has an inner rotor structure in which a rotor (30) is arranged inside a stator (40). In addition, the motor (100) constitutes a radial gap type electric motor in which a rotor (30) is arranged concentrically inside a stator (40).

As shown in FIGS. 2A to 5, the above rotor (30) has a plurality of bridges (34) extending radially from a hollow rotation shaft (50) arranged at the center, and the tip ends of the plurality of bridges (34) are connected to an annular rim (33). In addition, an annular hub (35) is reinforced at the connection portion between the plurality of bridges (34) and the rotation shaft (50) to enhance strength.

The above-mentioned rotation shaft (50) and the annular rim (33) connected through a plurality of bridges (34) are formed integrally and may be made of a metal material that is lightweight and provides strength, such as an aluminum alloy or duralumin.

A back yoke (31) that functions as a magnetic circuit is slidably coupled to the outer periphery of the above-mentioned annular rim (33). To this end, a plurality of coupling grooves (33a) are formed on the outer periphery of the rim (33), and a plurality of coupling projections (31b) that are coupled to the plurality of coupling grooves (33a) are protruded from the inner periphery of the back yoke (31).

The above back yoke (31) may be made of an electrical steel plate (silicon steel plate) to form a magnetic circuit together with a plurality of magnets (32) attached to the outer surface, and a plurality of coupling protrusions (31a) for attaching a plurality of magnets (32) protrude from the outer surface.

The plurality of coupling protrusions (31a) of the above back yoke (31) support the magnet (32) by receiving it between two adjacent coupling protrusions (31a) in a sliding coupling manner. In this case, the shape of the magnet (32) is formed as a trapezoidal shape, and the space formed between the two coupling protrusions (31a) is formed with a longer inner width so that the trapezoidal magnet (32) can be coupled. Accordingly, the coupling protrusions (31a) can prevent the magnet (32) coupled between the coupling protrusions (31a) from flying away or coming off.

The above plurality of magnets (32) are made of permanent magnets, and a plurality of N-pole and S-pole magnets are arranged alternately.

The above rotor (30) has a plurality of magnets (32) attached to the outer surface of the back yoke (31), and then a rotor support (36) is coupled to it.

The above rotor support (36) includes an annular upper plate (36a) and a lower plate (36b) covering the upper and lower portions of the magnet (32), and a plurality of connecting portions (36c) arranged between the magnets (32) and having both ends connected to the upper plate (36a) and the lower plate (36b). Accordingly, the rotor support (36) covers the outer surface except for the outer surface of each magnet (32) facing the shoe portion of the stator core.

A plurality of blades (37a, 37b) are protruded from the upper plate (36a) and the lower plate (36b) to generate wind when the rotor (30) rotates and cool the stator (40). In this case, the shapes of the plurality of blades (37a, 37b) may be formed as a straight shape, a round shape, etc.

As described above, the wind generated by the plurality of blades (37a, 37b) according to the rotation of the rotor (30) follows the circumferential direction, and this circumferential wind collides with the air flow for cooling passing through the plurality of through holes (16e) of the upper cover (16), the plurality of spaces (33c) formed between the plurality of bridges (34), and the plurality of through holes (18e) formed in the lower cover (18) to generate a vortex. The vortex generated in this way reaches even the corners of the inside of the motor (100), so that heat exchange can be effectively performed with the stator (40) where the greatest amount of heat is generated.

In addition, the upper plate (36a) and the lower plate (36b) are provided with protrusions having a plurality of through holes (36d) formed therein for connection with the back yoke (31), and the back yoke (31) is also provided with a plurality of connecting holes (33b) so that it can be fastened with a fixing screw or the like.

The above rotor (30) is connected between the rotation shaft (50) and the annular rim (33) through a plurality of bridges (34). As a result, a plurality of spaces (33c) formed between the plurality of bridges (34) form an air flow passage through which relatively low temperature external air, which is introduced from the outside of the motor into the inside through a plurality of through holes (16e, 18e) provided in the upper cover (16) and the lower cover (18), is discharged to the outside of the motor.

The above stator (40) includes, as shown in FIGS. 2a to 4 and 6, a stator core (41) having a ring-shaped back yoke (41a) having a predetermined width to form a magnetic circuit, a plurality of teeth (41b) extending radially inward from the back yoke (41a), an insulator (or bobbin) (42a, 42b) made of an insulating material integrally formed to surround an outer surface on which coils of each of the teeth (41b) are wound, and a stator coil (43) wound on the outer surface of the insulator (42a, 42b) of each of the plurality of teeth (41b).

The above plurality of teeth (41b) are each formed in a “T” shape and have a winding area in which a coil (43) is wound between a shoe portion facing the magnet (32) of the rotor (30) and an annular back yoke (41a).

The insulator (or bobbin) (42a, 42b) may be manufactured in advance as upper and lower insulators (42a, 42b) and then assembled to the stator core (41) or formed integrally using an insert molding method with insulating plastic (resin).

In this case, the upper and lower insulators (42a, 42b) are formed on an annular base frame (420) having a predetermined width, and a plurality of tooth receiving portions (422) that receive half of the winding area of the teeth (41b) at the upper and lower portions, excluding the shoe portion facing the magnet (32) of the rotor (30), protrude at intervals.

The upper and lower insulators (42a, 42b) may preferably be formed of an insulating heat-dissipating composite material having both heat dissipation and insulation performance. When the motor (100) is employed in an aircraft, it is required to have an insulation performance of at least 10Kv or higher to ensure safety from lightning, and considering the heat dissipation characteristics, it is preferable that the thermal conductivity be 3W/mK or higher.

Considering the above points, the insulating heat-dissipating composite used in the present invention has a continuous use temperature of 150°C or higher and includes a polymer matrix acting as a binder, an insulating heat-dissipating filler made of ceramic added and dispersed to improve thermal conductivity, and reinforcing fibers added to reinforce strength.

The above polymer matrix may include one compound selected from the group consisting of polyamide, polyester, polyketone, liquid crystal polymer, polyolefin, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyphenylene oxide (PPO), polyether sulfone (PES), polyether imide (PEI), and polyimide, or a mixture or copolymer of two or more compounds.

In this case, it is preferable that the polymer matrix have a continuous use temperature of 150°C or higher, and for example, polyphenylene sulfide (PPS) can be used.

Additionally, the insulating heat-dissipating filler may be provided in an amount of 75 to 100 parts by weight per 100 parts by weight of the polymer matrix.

In addition, the insulating heat-dissipating filler may include at least one selected from the group consisting of magnesium oxide, talc, titanium dioxide, aluminum nitride, silicon nitride, boron nitride, aluminum oxide, silica, zinc oxide, barium titanate, strontium titanate, beryllium oxide, silicon carbide, and manganese oxide.

The average particle diameter of the above insulating heat-dissipating filler may be 10 nm to 600 μm.

Furthermore, the reinforcing fibers may be provided in an amount of about 30 parts by weight per 100 parts by weight of the polymer matrix, and for example, glass fibers may be used.

Additionally, the insulating composite may further include one or more additives selected from the group consisting of dispersants, antioxidants, workability improvers, coupling agents, stabilizers, flame retardants, pigments, and impact improvers.

The BLDC motor (100) of the inner rotor-outer stator type applied to the propeller driving device (10) of the present invention is composed of a single rotor (30) and a single stator (40). The stator (40) has a three-phase (U, V, W) coil (43) wound around the teeth (41b) of the stator core (41), and is connected via a cable (45) to apply a driving signal to the three-phase (U, V, W) coil (43) from a motor driving device installed outside the motor.

Figure 7 is a graph showing the temperature of each phase of an example in which an insulator (or bobbin) is formed with an insulating heat-dissipating composite according to the present invention and a comparative example in which a heat-dissipating plastic is not applied.

In the present invention, by forming an insulator (or bobbin) with an insulating heat-dissipating composite material, an aircraft motor can be provided that not only has heat dissipation and insulation performance, but also mechanical strength such as tensile strength and flexural modulus that can withstand external force.

In addition, the present invention includes a heat-dissipating stator support (44) that is insert-molded with an insulating heat-dissipating composite material having both heat dissipation and insulation performance to surround a coil (43) wound on an insulator (or bobbin) (42a, 42b) of a stator (40) and insulate between adjacent coils.

In this case, the stator support (44) insert-molded with the insulating heat-dissipating composite material is formed to cover all parts exposed to the outside except for the shoe portion of the stator core (41) facing the magnet (32) of the rotor (30).

The radially outer surface of the above-mentioned heat-radiating stator support (44) is in contact with the water jacket (46). Therefore, when heat is generated from the coil (43) of the stator (40), the heat is conducted to the heat-radiating stator support (44), and then heat is exchanged with the water jacket (46) that is being cooled by a water cooling method, thereby allowing heat to be dissipated.

In this case, in the present invention, the composition of the first insulating heat-dissipating composite material used to form an insulator (or bobbin) (42a, 42b) that insulates between the stator core and the coil, and the composition of the second insulating heat-dissipating composite material used to form a stator support (44) that surrounds the stator coil (43) wound on the insulator (or bobbin) (42a, 42b) to insulate between the coils and dissipate heat generated from the coil to the outside can be varied to maximize the heat dissipation performance.

That is, the upper and lower insulators (or bobbins) (42a, 42b) formed of the first insulating heat-dissipating composite collect the generated heat into the stator core, and the upper and lower insulators (42a, 42b) are manufactured separately by an injection molding method and then assembled to the stator core (41). Therefore, it is difficult to form the upper and lower insulators (or bobbins) (42a, 42b) into a thin film structure so as to exhibit minimum impact strength characteristics, and excellent formability is required, so that the thermal conductivity characteristics are relatively poor.

That is, if the content of the heat-dissipating filler is increased to exhibit higher heat-dissipating performance (i.e., thermal conductivity) in the first insulating heat-dissipating composite, problems may arise in which the impact strength characteristics and formability deteriorate.

In contrast, the stator support (44) formed of a second insulating heat-dissipating composite material can be formed by insert molding to surround the stator coil (43) wound on an insulator (or bobbin) (42a, 42b) and insulate between the coils.

Accordingly, since the stator support (44) is formed integrally by surrounding the stator coil (43) and covering the space between the coils by insert molding instead of injection molding, the second insulating heat-dissipating composite composition used therein can have lower impact strength characteristics and moldability than the first insulating heat-dissipating composite composition, and thus it is possible to increase the content of the heat-dissipating filler so as to exhibit higher heat-dissipating performance (i.e., thermal conductivity).

As described above, in the propeller driving device (10) of the present invention, an inner rotor-outer stator type BLDC motor (100) can be used to effectively cool the rotor (30) and the stator (40) by external air cooling and internal air cooling.

In order to achieve the above-described internal cooling, the present invention forms a plurality of cooling through holes (16e, 18e) in the upper and lower covers (16, 18), and at the same time, connects a plurality of bridges (34) between an annular rim (33) supporting the main body of the rotor and a rotating shaft (50), thereby forming a plurality of spaces (33c) between the plurality of bridges (34), thereby forming an air flow passage passing through the inside of the motor.

That is, when an aircraft to which the propeller drive device (10) of the present invention is applied flies, external air that is drawn in from the outside through a plurality of through-holes (16e) provided in the upper cover (16) of the motor (100) passes through a plurality of spaces (33c) formed between a plurality of bridges (34) and is then discharged to the outside of the motor through a plurality of through-holes (18e) provided in the lower cover (18).

As a result, the internal air cooling of the motor can be achieved by the flow of air that is discharged to the outside of the motor after relatively low temperature outside air is introduced into the motor and heat is exchanged with the heat generated in the stator (40).

Furthermore, in the present invention, effective heat dissipation can be achieved through water cooling by providing a water jacket (46) having a refrigerant circulation circuit that can circulate refrigerant between the outer peripheral portion of the stator core (41) and the casing (12).

In addition, in the present invention, the insulator (or bobbin) (42a, 42b) that insulates between the stator core (41) and the coil (43) is formed of an insulating heat-dissipating composite material having both heat dissipation and insulation performance, thereby achieving an excellent heat dissipation effect and thereby improving motor efficiency. In this case, by forming the insulator (or bobbin) (42a, 42b) of the insulating heat-dissipating composite material, it is possible to provide an aviation motor that not only has heat dissipation and insulation performance, but also mechanical strength such as tensile strength and flexural modulus that can withstand external force.

In the present invention, a heat-radiating stator support (44) is provided in an insert molding made of an insulating heat-radiating composite material having both heat-radiating performance and insulation performance, which surrounds a coil (43) wound on an insulator (or bobbin) (42a, 42b) of a stator and insulates between adjacent coils.

The above-mentioned heat-dissipating stator support (44) covers all parts exposed to the outside except for the shoe part of the stator core (41) facing the magnet (32) of the rotor (30). That is, waterproof molding is performed except for the shoe part of the stator core (41) that forms a magnetic circuit path with the magnet (32) of the rotor.

As a result, even if moisture or foreign matter flows into the motor through the airflow passage passing through the inside of the motor, an electrical short circuit does not occur.

In addition, the radial outer surface of the heat-radiating stator support (44) can be cooled by contacting the water jacket (46) through water cooling, thereby allowing heat to be dissipated through heat exchange with the water jacket (46).

In the above description of embodiments, the present invention has been exemplified as a case where a propeller drive device rotates a propeller of a light aircraft, but it can be applied to a drone in which a single propeller drive device is installed on the drone body or a multicopter-type drone in which a plurality of propeller drive devices are installed on a plurality of arms extending from the drone body.

Furthermore, although the above embodiment description exemplifies driving a propeller of a light aircraft with the rotational axis of the motor exposed to the outside, it can be changed to a drone having a fan structure with a propeller or blades built into a cylindrical casing.

In addition, the present invention can be modified for various purposes such as logistics fields, surveillance/reconnaissance/search, quarantine/disinfection/spraying, broadcasting/performance, environmental surveying, rescue, etc., by detachably installing a logistics box for delivering parcels on the lower part of the drone body.

Although the present invention has been described and illustrated with specific preferred embodiments as examples, the present invention is not limited to the above embodiments, and various changes and modifications may be made by those skilled in the art without departing from the spirit of the present invention.

The present invention relates to a propeller driving device having a heat dissipation structure in which an internal air cooling is performed using an airflow passage formed inside a motor, a water cooling is performed using a water jacket having a refrigerant circulation circuit, and an insulator (or bobbin) that insulates between a stator core and a coil is formed using an insulating heat dissipation composite material having both heat dissipation and insulation performance, and can be applied to a light aircraft or drone.

10: Propeller drive device 12: Casing
16: Top cover 16e,18e: Through hole
18: Lower cover 20: Propeller mounting bracket
30: Rotor 31: Back yoke
32: Magnet 33: Rim
34: Bridge 35: Hub
36: Rotor support 37a,37b: Blade
40: Stator 41: Stator core
42a,42b: Insulator 43: Stator coil
44: Stator support 45: Cable
46: Water jacket 50: Rotating shaft
51,52: Bearing 100: Motor
200: Light aircraft 210: Fuselage
220: Control Box

Claims (10)

A BLDC motor of single rotor-single stator type; and a propeller installation bracket for mounting a propeller on the rotation shaft of the motor;
The above motor has a stator, rotor and rotation shaft sequentially arranged inside a housing in which an upper cover and a lower cover are respectively combined at the upper and lower portions of a cylindrical case.

The above stator
A stator core having an annular back yoke having a predetermined width to form a magnetic circuit and a plurality of teeth extending toward the center from the back yoke; an insulator formed by injection molding to surround an outer surface on which a coil is wound on each of the plurality of teeth; a stator coil wound on the outer surface of the insulator on each of the plurality of teeth; and a stator support formed integrally by insert molding while surrounding the stator coil wound on the insulator and insulating between adjacent coils.

The above insulator is formed of a first insulating heat-dissipating composite material having both heat dissipation performance and insulation performance, and the stator support is formed of a second insulating heat-dissipating composite material having both heat dissipation performance and insulation performance.

The above first and second insulating heat-dissipating composites,
A polymer matrix having a continuous use temperature of 150°C or higher and acting as a binder; an insulating heat-dissipating filler made of ceramic added and dispersed in the polymer matrix to improve thermal conductivity; and reinforcing fibers added to the polymer matrix to reinforce strength;
A propeller drive device in which the second insulating heat-dissipating composite material has a higher content of heat-dissipating filler than the first insulating heat-dissipating composite material. In the first paragraph,
The above insulator includes upper and lower insulators each wrapping half of the outer surface on which the coil is wound,
The upper and lower insulators are respectively
a circular base frame having a predetermined width; and
A propeller drive device including a plurality of tooth receiving portions protruding from the base frame and receiving 1/2 of the winding area of the teeth at the upper and lower portions. In the first paragraph,
The above insulator is a propeller drive device in which the upper and lower insulators are manufactured in advance and then assembled to the stator core. delete delete In the first paragraph,
A propeller driving device in which the diametrically outer surface of the stator support is in contact with a water jacket installed on the outer side of the stator, and the water jacket is cooled by a water cooling method. delete In the first paragraph,
A propeller drive device in which the above insulating heat-dissipating composite material has an insulating performance of at least 10Kv or more and a thermal conductivity of at least 3W/mK. In the first paragraph,
The above motor is a propeller drive device in which internal air cooling is performed by using airflow discharged through a plurality of through holes provided in the upper cover from the outside, a plurality of spaces formed between a plurality of bridges connecting the rotating shaft and the rotor, and a plurality of through holes provided in the lower cover. fuselage;
A control box placed at the front end of the above fuselage; and
A propeller driving device is installed at a distance from the front of the above control box and drives the propeller;
An aircraft wherein the propeller driving device is a propeller driving device as described in any one of claims 1 to 3, 6, 8, and 9.

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