Brushless DC motor

Abstract

Provided is a brushless DC motor that effectively increases the space area in the winding slot and effectively improves the slot filling rate of the stator coil at the same core size. 【Solution means】 The brushless DC motor of the present invention includes a series-expanded circular stator coil assembly 1, a rotor assembly 2, and an integrally formed motor casing 3. A circular hollow inner cavity for accommodating the series-expanded circular stator coil assembly 1 is provided in the motor casing 3, and the series-expanded circular stator coil assembly 1 is fixed in the circular hollow inner cavity. A front cover is provided in the motor casing 3, and a coaxial and vertically penetrating central axis hole is provided in the front cover and the series-expanded circular stator coil assembly 1. The rotor assembly 2 penetrates through the central axis hole, and the series-expanded circular stator coil assembly 1, the rotor assembly 2, and the motor casing 3 form an integral structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of motors, and particularly relates to a brushless DC motor.

Background Art

[0002] Small or micro motors, such as high-speed permanent magnet brushless DC motors, have a series of advantages such as high power density, small size, high-speed responsiveness, and high efficiency, and are expected to have wide applications in high-speed operation scenarios. For example, high-speed permanent magnet brushless motors are used in hair dryers.

[0003] For a brushless DC motor, it is necessary to wind enameled wire around a stator core to form a stator coil. The stator coil generates a rotating magnetic field by electromagnetic induction to rotate the rotor. The stator core of a conventional brushless DC motor is usually designed in a cylindrical structure, and a winding bracket is installed inside the stator core for winding. Such a stator core is usually integrally formed and cannot be disassembled or unfolded. Since the area inside the winding slot is small and the winding space is limited, the slot filling rate of the stator coil is low. Usually, the diameter of the selected enameled wire is thin, the current density of the coil is high, and the loss is large, so there are problems such as a high temperature rise of the coil and a short life of the motor.

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to solve the above problems, an object of the present invention is to provide a brushless DC motor that effectively increases the space area in the winding slot and effectively improves the slot filling rate of the stator coil at the same core size.

[0005] Another object of the present invention is to adjust the wire diameter of the enameled wire according to the output rating of the motor, match a reasonable current density, effectively reduce the temperature rise of the stator coil, reduce the failure rate of the product, and effectively improve the service life of the product by providing a brushless DC motor.

[0006] Still another object of the present invention is to provide a brushless DC motor that realizes an assembly process in which the bearings at the upper and lower ends have good concentricity and effectively guarantees the stability during the high-speed operation of the rotor.

[0007] The last object of the present invention is to provide a brushless DC motor with a firm structure, good ventilation and heat dissipation efficiency, low cost, and easy use and popularization.

[0008] To achieve the above object, the technical solution of the present invention is as follows.

Means for Solving the Problem

[0009] The present invention provides a brushless DC motor including a series-expanded wound circular stator coil assembly, a rotor assembly, and an integrally formed motor casing. A circular hollow inner cavity for accommodating the series-expanded wound circular stator coil assembly is provided in the motor casing, and the series-expanded wound circular stator coil assembly is fixed in the circular hollow inner cavity. A front cover is further provided in the motor casing, and a coaxial and vertically penetrating central axis hole is provided in the front cover and the series-expanded wound circular stator coil assembly. The rotor assembly penetrates through the central axis hole, and the series-expanded wound circular stator coil assembly, the rotor assembly, and the motor casing form an integral structure.

[0010] Furthermore, the series-expanded spiral stator coil assembly includes a series-expanded stator core, a stator coil, and a stator sealing bracket. The series-expanded stator core includes a plurality of stator teeth, and stator slots are formed between adjacent stator teeth. The stator coil is installed in the stator slots and is composed of a certain number of coil turns along the stator teeth. The stator sealing bracket is encapsulated by the series-expanded stator core to form an integral structure that unfolds the winding and merges the spiral coils.

[0011] Furthermore, the series-expanded stator core includes a stator yoke. The stator yoke is integrally formed with the stator teeth, and V-shaped meshing openings are installed at the edges of both ends of the stator yoke. The other adjacent stator yokes are connected, and V-shaped openings are installed at the connection parts. Thereby, the stator coil can wind the wire on the series-expanded stator core and form a series-expanded spiral stator coil assembly after winding and spiraling.

[0012] Furthermore, the stator sealing bracket is injection-molded with a plastic material onto the series-expanded stator core to form a sealing structure of an integral structure, and a plastic insulation layer is formed around the stator teeth. In addition, a plastic front part and a plastic rear part are respectively formed at the upper and lower ends of the series-expanded stator core.

[0013] Furthermore, a plurality of dispersedly arranged plastic bosses are formed by injection-molding a plastic material on the plastic front part, and wire pins are fixed to each plastic boss. The number of the plastic bosses and the wire pins is the same as that of the stator slots and the stator teeth.

[0014] Furthermore, the motor casing is a circular casing with both ends open and a hollow interior, and a bearing fixing support frame integrally formed is provided at the tail of the motor casing. The motor casing has heat dissipation windows on both sides of the bearing fixing support frame.

[0015] Furthermore, the bearing fixing support frame includes a ring-shaped end cover that is perpendicular and concentric to the axial direction. On both sides of the ring-shaped end cover, support connection ribs are provided between the motor casing along the vertical direction, and the ring-shaped end cover forms an integral molding structure with the motor casing through the support connection ribs. At the central part of the ring-shaped end cover, a first bearing mounting groove for fixing the rotor assembly is provided.

[0016] Furthermore, a plurality of guide fins are provided between the circular hollow inner cavity and the inner wall of the motor casing, and they are evenly arranged on the inner wall of the motor casing. Thereby, a guide groove for air circulation is formed between the motor casing and the circular hollow inner cavity.

[0017] Furthermore, the rotor assembly includes a rotor shaft, permanent magnets, and limit rings. The lower end of the rotor shaft penetrates through the central axis hole of the in-line developed spiral stator coil assembly. The permanent magnets and the limit rings are mounted on the rotor shaft. Two limit rings are provided, and the permanent magnets are arranged between the two limit rings.

[0018] Furthermore, an upper bearing is mounted on the upper end of the rotor shaft, and a lower bearing is mounted on the lower end. Bearing silicon covers are respectively mounted on the upper bearing and the lower bearing. The tail of the rotor shaft is fixed in the first bearing mounting groove of the bearing fixing support frame in combination with the lower bearing and the bearing silicon cover. The front cover is mounted on the plastic rear part of the in-line developed stator core, and the upper end of the rotor shaft penetrates through the central axis hole of the front cover. A second bearing mounting groove corresponding to the bearing silicon cover is provided in the front cover, and the second bearing mounting groove is located directly below the central axis hole of the front cover. After the upper bearing and the bearing silicon cover are combined, they are installed in the second bearing mounting groove.

Advantages of the Invention

[0019] The advantages of the present invention are as follows compared with the prior art.

[0020] First, the brushless DC motor of the present invention has an in-line developed wound round stator coil assembly and can perform winding by unfolding. As a result, the winding method of the coil changes from the conventional inner winding method to the outer winding method, and the space for the winding needle becomes larger. At the same iron core size, the space area in the winding slot effectively increases, and the slot filling rate of the stator coil improves. At the same time, since the winding space becomes larger, the number of turns of the enameled wire to be wound relatively increases, and the adjustment space also expands. This makes it easier to adjust the output of the motor, and the wire diameter can be adjusted according to the output grade of the motor to match a reasonable current density. Thereby, the temperature rise of the stator coil can be effectively reduced, the failure rate of the product can be decreased, and the life of the product can be effectively improved.

[0021] Next, a bearing fixing support frame integrally formed is provided at the tail of the brushless DC motor and is used to fix the rotor and the bearing. As a result, the rotor structure becomes more robust. Compared with the conventional motor casing and the separate bearing fixing support frame, the position of this bearing fixing support frame does not shift, the structure is more robust, and the stability is improved.

[0022] Furthermore, in the present invention, the bearing silicon cover and the upper bearing are installed in the second bearing mounting groove of the front cover. The rotor shaft penetrates the front cover and adheres the front cover to the motor casing to firmly fix the rotor assembly within the motor casing. At the same time, by means of the upper and lower end type bearing mounting method formed by the bearing fixing support frame at the tail of the motor casing and the second bearing mounting groove in the front cover, the assembly position can be pre-adjusted to be vertically aligned, limiting the bearings at both the upper and lower ends and realizing an assembly process with good concentricity. Thereby, the stability during the high-speed operation of the rotor is effectively guaranteed. Also, the bearings at both the upper and lower ends of the rotor assembly are respectively installed in the tail of the motor casing and the upper front cover. Since the bearing spacing at both ends is wide, even if one end bearing of the rotor sways, the influence on the other end bearing is small, and the structure is more stable.

[0023] Finally, bearing silicon covers are installed on the bearings at both the upper and lower ends of the rotor shaft, effectively reducing the vibration and noise generated when the rotor operates at high speed with the bearings. It also has an insulation effect, preventing the current of the coil from being transmitted from the rotor bearing to the motor casing and avoiding electric leakage.

Brief Description of the Drawings

[0024]

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Embodiments for Carrying Out the Invention

[0025] To make the purpose, technical solution, and advantages of the present invention clearer, the present invention will be described in more detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described here are for the purpose of explaining the present invention and are not intended to limit the present invention.

[0026] Referring to FIGS. 1 to 11, in order to achieve the above object, the technical solution of the present embodiment is as follows.

[0027] This embodiment provides a brushless DC motor including a series-expanded spiral stator coil assembly 1, a rotor assembly 2, and an integrally formed motor casing 3. Inside the motor casing 3, a circular hollow inner cavity 31 for accommodating the series-expanded spiral stator coil assembly 1 is provided, and the series-expanded spiral stator coil assembly 1 is fixed within the circular hollow inner cavity 31. A front cover 4 is further provided inside the motor casing 3, and a coaxial and vertically penetrating central axis hole 5 is provided in the front cover 4 and the series-expanded spiral stator coil assembly 1. The rotor assembly 2 penetrates through the central axis hole 5, integrating the series-expanded spiral stator coil assembly 1, the rotor assembly 2, and the motor casing 3 into an integral structure.

[0028] Furthermore, the series-expanded spiral stator coil assembly 1 includes a series-expanded stator core 11, a stator coil (not shown), and a stator sealing bracket 13. The series-expanded stator core 11 has a plurality of stator teeth 111, and stator slots 112 are formed between adjacent stator teeth 111. The stator coil is installed within the stator slots 112 and wound around the stator teeth 111 with a certain number of turns. The stator sealing bracket 13 is sealed to the series-expanded stator core 11 to form a structure that unfolds for winding and integrates after being wound into a spiral.

[0029] Furthermore, the series-expanded stator core 11 also includes a stator yoke 115. The stator yoke 115 is integrally formed with the stator teeth 111, and V-shaped meshing ports 113 are provided at both edge ends of one stator yoke 115. Adjacent other stator yokes are connected, and a V-shaped opening 114 is provided at the connection part. Thereby, the stator coil can be wound on the series-expanded stator core 11. After the winding is completed, a winding circle is performed to form a series-expanded wound stator coil assembly 1. When the series-expanded wound stator coil assembly 1 is expanded, the winding method of the coil changes from the conventional inner winding method to the outer winding method, and the space for the winding needle becomes larger. At the same size of the iron core, the space area in the winding slot is effectively increased, and the slot filling rate of the stator coil is improved. At the same time, since the winding space becomes larger, the number of turns of the enameled wire to be wound is relatively increased, and the adjustment space is also widened. Thereby, it becomes easier to adjust the output of the motor, the wire diameter can be adjusted according to the output grade of the motor, and a reasonable current density can be matched. Thereby, the temperature rise of the stator coil can be effectively reduced, the failure rate of the product can be decreased, and the service life of the product can be effectively improved.

[0030] Furthermore, the stator sealing bracket 13 is injection-molded with a plastic material on the series-expanded stator core 11 to form an integral sealing structure, and a plastic insulation layer (not shown) is formed around the stator teeth 111. Also, a plastic front part 131 and a plastic rear part 132 are respectively formed at the upper and lower ends of the series-expanded stator core 11.

[0031] Furthermore, a plurality of dispersedly arranged plastic bosses 133 are formed by injection-molding a plastic material on the plastic front part 131, and a wire pin 12 is fixed to each plastic boss 133. The number of the plastic bosses 133 and the wire pins 12 is the same as that of the stator slots 112 and the stator teeth 111.

[0032] Furthermore, the motor casing 3 is a circular casing with both ends open and a hollow interior. A bearing fixing support frame 32 integrally formed is provided at the tail of the motor casing 3. The motor casing 3 has heat dissipation windows 35 on both sides of the bearing fixing support frame 32. In the present application, the bearing fixing support frame 32 is used to fix the rotor and the bearing, making the rotor structure more robust and the use safer. The heat dissipation windows 35 can be used not only for ventilation and heat dissipation but also for wiring of electric wires, making the wiring easier.

[0033] Furthermore, the bearing fixing support frame 32 includes a ring-shaped end cover 321 perpendicular and concentric to the axial direction. Support connection ribs 322 are provided on both sides of the ring-shaped end cover 321 along the vertical direction between it and the motor casing 3. The ring-shaped end cover 321 forms an integrally molded structure with the motor casing 3 via the support connection ribs 322. A first bearing mounting groove 323 for fixing the rotor assembly is provided at the central portion of the ring-shaped end cover 321. Compared with the conventional motor casing and the separable bearing fixing support frame 32, the present bearing fixing support frame 32 is integrally molded with the casing, does not shift in position, has a more robust structure and improved stability.

[0034] Furthermore, a plurality of guide fins 33 are provided between the circular hollow inner cavity 31 and the inner wall of the motor casing 3, and are evenly arranged on the inner wall of the motor casing 3. Thereby, a guide groove 34 for air circulation is formed between the motor casing 3 and the circular hollow inner cavity 31. The guide groove 34 communicates with the heat dissipation window 35.

[0035] Furthermore, the rotor assembly 2 includes a rotor shaft 21, a permanent magnet 22, and a limit ring 23. The lower end of the rotor shaft 21 passes through the central axis hole 5 of the series-expanded spiral stator coil assembly 1. The permanent magnet 22 and the limit ring 23 are mounted on the rotor shaft 21. Two limit rings 23 are provided, and the permanent magnet 22 is disposed between the two limit rings 23.

[0036] Furthermore, an upper bearing 24 is mounted on the upper end of the rotor shaft 21, and a lower bearing 25 is mounted on the lower end. Bearing silicon covers 26 are respectively mounted on the upper bearing 24 and the lower bearing 25. The tail part of the rotor shaft 21 is fixed in the first bearing mounting groove 323 of the bearing fixing support frame 32 in combination with the lower bearing 25 and the bearing silicon cover 26. The front cover 4 is attached to the plastic rear part 132 of the in-line stator core 11, and the upper end of the rotor shaft 21 passes through the central axis hole 5 of the front cover 4. A second bearing mounting groove 41 corresponding to the bearing silicon cover 26 is provided in the front cover 4, and the second bearing mounting groove 41 is located directly below the central axis hole 5 of the front cover 4. After the upper bearing 24 and the bearing silicon cover 26 are combined, they are installed in the second bearing mounting groove 41. In the present application, the bearing silicon cover 26 and the upper bearing 24 are installed in the second bearing mounting groove 41 of the front cover 4, and the rotor shaft 21 passes through the front cover 4 and adheres the front cover 4 to the motor casing 3, firmly fixing the rotor assembly 2 in the motor casing 3. At the same time, by means of the upper and lower end type bearing mounting method formed by the bearing fixing support frame 32 at the tail part of the motor casing 3 and the second bearing mounting groove 41 in the front cover 4, the assembly position can be adjusted in advance to make it coincide up and down, limit the bearings at both the upper and lower ends, and realize an assembly process with good concentricity. Thereby, the stability of the rotor during high-speed operation is effectively guaranteed. Also, the bearings at both the upper and lower ends of the rotor assembly 2 are respectively installed in the tail part of the motor casing 3 and inside the upper front cover 4. Since the distance between the bearings at both ends is wide, even if one end bearing of the rotor sways, the influence on the other end bearing is small, and the structure is more stable. The bearing silicon cover 26 incorporated into the structure effectively reduces the vibration and noise generated when the rotor operates at high speed with the bearings.Moreover, it also has an insulating effect, preventing the current of the coil from being transmitted from the rotor bearing to the motor casing 3, effectively blocking the circuit of the axial current, and avoiding electric leakage.

[0037] The above are only the preferred embodiments of the present invention and do not limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principle scope of the present invention shall be included in the protection scope of the present invention.

Claims

1. In a brushless DC motor, a series-wound circular stator coil assembly, a rotor assembly, and an integrally formed motor casing, wherein a circular hollow inner cavity for accommodating the series-wound circular stator coil assembly is provided within the motor casing, the series-wound circular stator coil assembly is fixed within the circular hollow inner cavity, a front cover is further provided within the motor casing, coaxial and vertically penetrating central axis holes are provided in the front cover and within the series-wound circular stator coil assembly, the rotor assembly penetrates through the central axis hole, and the series-wound circular stator coil assembly, rotor assembly, and motor casing are of an integral structure, furthermore, the series-wound circular stator coil assembly includes a series-wound stator core, a stator coil, and a stator sealing bracket, the series-wound stator core has a plurality of stator teeth, stator slots are formed between adjacent stator teeth, the stator coil is installed within the stator slots and wound along the stator teeth with a certain number of turns.

2. In the brushless DC motor according to Claim 1, the series-wound stator core further includes a stator yoke, the stator yoke is integrally formed with the stator teeth, V-shaped meshing openings are provided at both end edges of the stator yoke, adjacent other stator yokes are connected, and a V-shaped opening is provided at the connection part, thereby enabling the stator coil to be wound on the series-wound stator core, forming a circular coil after winding is completed, and forming the series-wound circular stator coil assembly.

3. In the brushless DC motor according to Claim 2, the stator sealing bracket is injection-molded from a plastic material onto the series-wound stator core to form an integral sealing structure, forming a plastic insulation layer around the stator teeth, and plastic front and rear parts are respectively formed at both upper and lower ends of the series-wound stator core.

4. In the brushless DC motor according to Claim 3, On the plastic front part, a plurality of plastic bosses are formed by injection molding of a plastic material and are dispersedly arranged, and a wire pin is fixed to each of the plastic bosses. The number of the plastic bosses and wire pins is the same as that of the status slots and stator teeth.

5. In the brushless DC motor according to claim 4, The motor casing is a circular casing with both ends open and the interior hollow. At the tail of the motor casing, an integrally formed bearing fixing support frame is provided. The motor casing is characterized by having heat dissipation windows on both sides of the bearing fixing support frame.

6. In the brushless DC motor according to claim 5, The bearing fixing support frame includes a ring-shaped end cover perpendicular and concentric in the axial direction. On both sides of the ring-shaped end cover, support connection ribs are provided between the ring-shaped end cover and the motor casing along the vertical direction. The ring-shaped end cover forms an integrally molded structure with the motor casing via the support connection ribs. A first bearing mounting groove for fixing the rotor assembly is provided at the central part of the ring-shaped end cover.

7. In the brushless DC motor according to claim 1, Between the circular hollow inner cavity and the inner wall of the motor casing, a plurality of guide fins are provided and are evenly arranged on the inner wall of the motor casing. Thereby, a guide groove for air circulation is formed between the motor casing and the circular hollow inner cavity.

8. In the brushless DC motor according to claim 6, The rotor assembly includes a rotor shaft, a permanent magnet, and a limit ring. The lower end of the rotor shaft penetrates through the central axis hole of the series-expanded coiled stator coil assembly. The permanent magnet and the limit ring are mounted on the rotor shaft. Two limit rings are provided. The permanent magnet is arranged between the two limit rings.

9. In the brushless DC motor according to claim 8, An upper bearing is mounted on the upper end of the rotor shaft, and a lower bearing is mounted on the lower end of the rotor shaft. Bearing silicon covers are respectively mounted on the upper bearing and the lower bearing. The tail of the rotor shaft is fixed in the first bearing mounting groove of the bearing fixing support frame in combination with the lower bearing and the bearing silicon cover. The front cover is mounted on the plastic rear part of the series-expanded stator core. The upper end of the rotor shaft penetrates the central axis hole of the front cover. A second bearing mounting groove corresponding to the bearing silicon cover is provided in the front cover, which is characterized by this.

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