Brushless direct current motor

Abstract

The invention discloses a brushless direct current motor, and relates to the technical field of motors, the brushless direct current motor comprises a driving circuit and a motor body, and the driving circuit adopts a single H-bridge motor driving circuit; the motor body comprises a shell, a stator, a rotor and a shaft core; the shaft core penetrates through the front side and the rear side of the shell and is rotationally connected with the shell through a bearing, the rotor sleeves the shaft core and is located in the shell, and the stator is fixed to the inner wall of the shell and surrounds the rotor by a circle. A plurality of first grooves are formed in the inner side of the stator, a plurality of second grooves are formed in the outer side of the rotor, the first grooves and the second grooves are arranged in a staggered manner, a winding coil bypassing the first grooves is arranged on the stator, and the winding coil is provided with a winding lead and a Hall lead which are connected with a driving circuit. The single winding is adopted, so that the structure and the production process are simpler, efficient mechanical production is more convenient, and the manufacturing cost is reduced. According to the invention, single H-bridge driving is adopted, so that the motor operates stably and reliably, the application range of the motor is wider, and the motor is especially suitable for outdoor use.

Description

Technical Field

[0001] The invention relates to the technical field of motors, and in particular to a brushless DC motor. Background Art

[0002] With the development and progress of society, the requirements for energy conservation and environmental protection will become higher and higher. Therefore, the demand for motors that are cost-effective and widely used will also increase. At present, the service life of brushed permanent magnet DC motors is limited, and the manufacturing cost of three-phase permanent magnet DC brushless motors is relatively high. The single-phase AC capacitor-start induction motors for home or factory use are complicated and have low working efficiency. They can only be used in places with mains power, especially the upper speed limit is limited by the power supply frequency.

[0003] Therefore, a permanent magnet single-winding single H-bridge driven brushless DC motor has become an urgent problem to be solved. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a brushless DC motor, which uses the closed loop characteristics of magnetic lines of force according to the path with the minimum magnetic resistance, and adopts an asymmetric structure on the stator and rotor poles. Under the action of the magnetic lines of force, the stator and rotor poles naturally produce a certain angle misalignment, thereby providing a correct detection signal to the Hall element. The signal detected by the Hall element is used to control the operation of the H-bridge circuit, so that the direction of the winding current changes accordingly, so that the motor can operate reliably.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is: a brushless DC motor, comprising a drive circuit and a motor body, wherein the drive circuit adopts a single H-bridge motor drive circuit;

[0006] The motor body comprises a housing, a stator, a rotor and a shaft core; the shaft core passes through the front and rear sides of the housing and is rotatably connected to the housing through a bearing, the rotor is sleeved on the shaft core and is located inside the housing, and the stator is fixed to the inner wall of the housing and is arranged around the rotor;

[0007] A plurality of first grooves are provided on the inner side of the stator, a plurality of second grooves are provided on the outer side of the rotor, the first grooves and the second grooves are staggered, a winding coil bypassing the first grooves is provided on the stator, and the winding coil is provided with winding leads and Hall leads connected to the drive circuit.

[0008] Furthermore, the stator includes a stator outer frame and a coil winding frame, the coil winding frame is evenly arranged along the stator outer frame, one end of the coil winding frame is integrally formed with the stator outer frame, and the other end extends to both sides to form a left limit frame and a right limit frame respectively, and the first groove is arranged on the outside of the left limit frame.

[0009] Furthermore, the rotor includes a rotor inner core and a rotor outer frame, the rotor inner core is provided with an axial hole at the center, the rotor outer frame and the rotor inner core are integrally formed and are evenly arranged around the rotor inner core, a magnet socket is provided inside the rotor outer frame, a magnet is inserted and fixed in the magnet socket, and the second groove is arranged on the outside of the rotor outer frame and is offset from the first groove.

[0010] Furthermore, the single H-bridge motor drive circuit includes a Hall element, an interlocking module and a single H-bridge motor drive module, the Hall element connects the power supply and the Hall lead and receives the signal transmitted by the Hall lead, and the interlocking module connects the Hall element and the single H-bridge motor drive module.

[0011] Furthermore, the shell includes a shell, a front cover and a rear cover, the front cover is arranged at the front end of the shell, and the rear cover is arranged at the rear end of the shell. The front cover, stator and rear cover are all provided with mounting holes, and the three are connected and fixed by screws passing through the mounting holes on the front cover, stator and rear cover in turn.

[0012] Furthermore, two bearings are provided, which are respectively located on the inner side of the front cover and the inner side of the rear cover.

[0013] The advantages of the present invention compared with the prior art are:

[0014] 1. The present invention adopts an asymmetric structure on the stator and rotor poles to increase the magnetic resistance of the magnetic circuit, making it difficult for the magnetic lines of force to pass through. The magnetic lines of force will form a closed loop characteristic with the minimum magnetic resistance path, so that the relative angles of the stator and the rotor are offset and stable, thereby providing the Hall element with a correct commutation signal.

[0015] 2. The present invention adopts a single winding to make the structure and production process simpler, and more convenient for efficient mechanized production, thereby reducing manufacturing costs.

[0016] 3. The present invention adopts a single H-bridge drive, which not only makes the motor run stably and reliably, but also makes the motor have a wider application range, and is particularly suitable for outdoor use. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a cross-sectional view of a brushless DC motor of the present invention.

[0018] Figure 2 It is a schematic diagram of the layout of the stator and rotor.

[0019] Figure 3 is a side view of the stator.

[0020] Figure 4 is a side view of the rotor.

[0021] Figure 5 It is the circuit schematic diagram of a single H-bridge motor drive circuit.

[0022] As shown in the figure: 1. Shell, 2. Stator, 3. Rotor, 4. Shaft core, 5. Bearing, 6. First groove, 7. Second groove, 8. Winding coil, 9. Winding lead, 10. Hall lead, 11. Stator frame, 12. Coil winding frame, 13. Left limit frame, 14. Right limit frame, 15. Rotor inner core, 16. Rotor frame, 17. Shaft hole, 18. Magnet, 19. Hall element, 20. Interlocking module, 21. Single H-bridge motor drive module, 22. Shell, 23. Front cover, 24. Rear cover, 25. Mounting hole, 26. Screw. DETAILED DESCRIPTION

[0023] In the description of the present invention, it is necessary to understand that the orientations or positional relationships indicated by terms such as “upper”, “lower”, “front”, “back”, “left”, “right”, “inside”, “outside”, “vertical” and “circumferential” are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0024] In the description of the present invention, "first feature" and "second feature" may include one or more of the features. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0025] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] A brushless DC motor of the present invention is further described in detail below with reference to the accompanying drawings.

[0027] Combined with Figure 1-5 The specific implementation process of a brushless DC motor of the present invention is as follows:

[0028] A brushless DC motor adopts a single H-bridge motor driving circuit, which simplifies the circuit structure, reduces the cost, and ensures stable control of the motor.

[0029] The motor body includes a housing 1, a stator 2, a rotor 3 and a shaft core 4. The shaft core 4 is rotatably connected to the housing 1 through a bearing 5, the rotor 3 is sleeved on the shaft core 4, and the stator 2 is fixed to the inner wall of the housing 1 and arranged around the rotor 3.

[0030] The stator 2 includes a stator outer frame 11 and a coil winding frame 12. The coil winding frame 12 is evenly arranged along the stator outer frame 11, one end of which is integrally formed with the stator outer frame 11, and the other end forms a left limit frame 13 and a right limit frame 14, which are used to fix the winding coil 8, and the winding coil 8 is provided with a winding lead 9 and a Hall lead 10 connected to the drive circuit. A first groove 6 is provided on the outer side of the left limit frame 13, which is staggered with the second groove 7 on the rotor 3 to achieve optimal magnetic field distribution.

[0031] The left limiting frame 13 and the right limiting frame 14 play an axial limiting role. When the motor is running, the motor shaft core 4 will be displaced or axially moved by the axial force, thereby affecting the motor performance. A circlip, a tight ring or a stepped shaft can be used to replace the axial limiting sleeve.

[0032] The rotor 3 includes a rotor inner core 15 and a rotor outer frame 16. An axial hole 17 is provided at the center of the rotor inner core 15. The rotor outer frame 16 is integrally formed with the rotor inner core 15 and has a magnet 18 insertion hole inside, into which the magnet 18 is inserted and fixed. A second groove 7 is provided on the outer side of the rotor outer frame 16, which is offset from the first groove 6 of the stator 2, to further optimize the magnetic field path.

[0033] When the magnetic poles of stator 2 and rotor 3 are facing each other, the effective length of the magnetic arc line should be reduced by the length of the first groove 6 and the length of the second groove 7 respectively, which is not the minimum magnetic resistance magnetic circuit. When the stator 2 and rotor 3 are offset by a certain angle, the length of the magnetic arc line only needs to be reduced by the length of one groove. At this time, the magnetic resistance of the magnetic circuit is the smallest, which is most consistent with the characteristics of the magnetic lines of force. Therefore, after the stator 2 and rotor 3 are assembled into a motor, under the action of the magnet 18 of the rotor 3, there must be a corresponding position relationship of the angle offset. When the Hall element 19 is installed in the middle slot between the two magnetic poles connected to the stator 2, it just detects that the magnetic pole of the rotor 3 is either the N pole or the S pole, providing the correct commutation signal for the single H-bridge drive circuit, so as to operate.

[0034] The single H-bridge motor driving circuit includes a Hall element 19 , an interlocking module 20 and a single H-bridge motor driving module 21 . The Hall element 19 receives a position signal from the Hall lead 10 and controls the single H-bridge motor driving module 21 through the interlocking module 20 .

[0035] Due to the asymmetric structure of the stator 2 and the rotor 3, and the relative number of poles of the magnet installed in the rotor 3, the closed loop characteristics are formed according to the magnetic lines of force along the path of minimum magnetic resistance, which naturally causes the angular relationship between the stator and the rotor to be misaligned, providing either N or S signals to the Hall element 19, so that the Hall element S41 generates a relative output signal; combined with the attached Figure 5When the Hall element S41 outputs a high level, Q1 is turned on and Q2 is turned off. The collector of Q2 outputs a high level, which turns on Q3, turns on the H-bridge P1 and N1, and the direction of the motor winding current is from right to left. On the contrary, when the Hall element S41 outputs a low level, Q1 is turned off, Q2 is turned on, Q3 is turned off, Q4 is turned on, P2N2 is turned on, P1N1 is turned off, and the direction of the motor winding current is from right to left, completing the commutation of the rotor 3 and ensuring that the motor rotor 3 runs in the set direction.

[0036] When the current exceeds the protection value detected by the 0.5 ohm resistor, the unidirectional thyristor is turned on, and through D1 and D2, the left and right paths of the H bridge are not working, thus playing an overcurrent protection role.

[0037] By changing the parameters of the H-bridge circuit components, it can be made suitable for different power supply voltages and different motor power requirements. In the case of high voltage and low power, a crystal triode can be used instead of a MOS tube, which can reduce costs. It can even be developed into a modular circuit to further reduce costs.

[0038] By changing the motor chip size and material, the number of magnetic poles, the chip stacking thickness and winding parameters, motors with various speed and torque requirements can be made.

[0039] The housing 1 is composed of a housing 22, a front cover 23 and a rear cover 24, and the front cover 23 and the rear cover 24 are respectively arranged at the front and rear ends of the housing 22. The front cover 23, the stator 2 and the rear cover 24 are all provided with mounting holes 25, which are fixed by screws 26 to ensure the stability of the motor structure.

[0040] A bearing 5 is disposed on the inner side of the front cover 23 and the inner side of the rear cover 24 to support the smooth rotation of the shaft core 4 and reduce friction loss.

[0041] Rotor 3 production process: insert the shaft core 4 into the shaft hole 17 of the rotor 3, put it on the automatic shaft insertion machine, after the shaft is inserted, move the rotor 3 to the magnet insertion machine fixture, and first arrange the magnet 18 into the material trough according to the NS polarity. Start the magnet insertion machine, press the magnet 18 into the rotor slot, and then enter the assembly process. The entire rotor 3 production only requires two processes, two machines, and one person to operate, and can produce 600 rotors 3 per hour, which is quite efficient.

[0042] Stator 2 production process: Put stator 2 into the slot paper machine jig, start the slot paper machine, and punch the insulating slot paper into the stator slots in turn. Install insulating end plates on both ends of the stator 2 with slot paper (there are installation positions for Hall element 19 on the end plates to ensure that the Hall element 19 will not loosen when the motor is running), and then put it on the hook-type winding machine jig (one winding machine puts six), start the winding machine, and wind the winding on the stator magnetic pole in turn according to the preset number of turns and winding direction. Then weld the winding lead 9, and insulate and fix the welding point. Then use a comprehensive tester to test the winding, and those that pass the test can enter assembly. The entire stator 2 production process only requires three machines and three to four people. The equipment investment and labor costs are not high, so the manufacturing cost is naturally not high.

[0043] The present invention and its embodiments are described above, and such description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. A brushless DC motor, characterized in that: It includes a drive circuit and a motor body, wherein the drive circuit adopts a single H-bridge motor drive circuit; The motor body comprises a housing (1), a stator (2), a rotor (3) and a shaft core (4); the shaft core (4) passes through the front and rear sides of the housing (1) and is rotatably connected to the housing (1) via a bearing (5); the rotor (3) is sleeved on the shaft core (4) and is located inside the housing (1); the stator (2) is fixed to the inner wall of the housing (1) and is located outside the rotor (3) and surrounds the rotor (3); A plurality of first grooves (6) are provided on the inner side of the stator (2), a plurality of second grooves (7) are provided on the outer side of the rotor (3), the first grooves (6) and the second grooves (7) are arranged in a staggered manner, a winding coil (8) bypassing the first grooves (6) is provided on the stator (2), and the winding coil (8) is provided with a winding lead (9) and a Hall lead (10) connected to a drive circuit.

2. A brushless DC motor according to claim 1, characterized in that: The stator (2) comprises a stator outer frame (11) and a coil winding frame (12); the coil winding frame (12) is evenly arranged along the stator outer frame (11); one end of the coil winding frame (12) is integrally formed with the stator outer frame (11); the other end extends to two sides to form a left limit frame (13) and a right limit frame (14); the first groove (6) is arranged on the outside of the left limit frame (13).

3. A brushless DC motor according to claim 2, characterized in that: The rotor (3) comprises a rotor inner core (15) and a rotor outer frame (16); an axial hole (17) is provided at the center of the rotor inner core (15); the rotor outer frame (16) and the rotor inner core (15) are integrally formed and evenly arranged around the rotor inner core (15); a magnet (18) insertion hole is provided inside the rotor outer frame (16); a magnet (18) is inserted and fixed in the magnet (18) insertion hole; and the second groove (7) is arranged outside the rotor outer frame (16) and is offset from the first groove (6).

4. A brushless DC motor according to claim 3, characterized in that: The single H-bridge motor drive circuit comprises a Hall element (19), an interlocking module (20) and a single H-bridge motor drive module (21); the Hall element (19) is connected to a power source and a Hall lead (10) and receives a signal transmitted by the Hall lead (10); and the interlocking module (20) is connected to the Hall element (19) and the single H-bridge motor drive module (21).

5. A brushless DC motor according to claim 1, characterized in that: The housing (1) comprises a shell (22), a front cover (23) and a rear cover (24); the front cover (23) is arranged at the front end of the shell (22); the rear cover (24) is arranged at the rear end of the shell (22); the front cover (23), the stator (2) and the rear cover (24) are all provided with mounting holes (25); screws (26) are passed through the mounting holes (25) on the front cover (23), the stator (2) and the rear cover (24) in sequence to connect and fix the three.

6. A brushless DC motor according to claim 5, characterized in that: The bearings (5) are provided with two, which are respectively located on the inner side of the front cover (23) and the inner side of the rear cover (24).

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