Electric mower and outer rotor motor thereof

Abstract

The utility model relates to a kind of electric mower and its outer rotor motor, and the outer rotor motor includes outer rotor and inner stator. Outer rotor includes shell, the rotor seat of magnetic assembly and shell one end connection, the rotor shaft of rotation center fixedly connected to rotor seat. Inner stator includes stator core and stator winding, and stator core includes including several stator teeth and stator center through-hole. Wire slot is formed between adjacent stator teeth;Stator winding is wound to stator tooth and is housed in wire slot;Rotor shaft is rotatably threaded to stator center through-hole;Magnetic assembly is arranged between shell and stator tooth and fixedly connected to rotor seat;Magnetic assembly has several blocks evenly spaced permanent magnet, and each block permanent magnet forms the magnetic pole of outer rotor;The utility model outer rotor motor can be miniaturized while, running smoothly and reducing the jitter of running.

Description

Technical Field

[0001] This utility model relates to the field of motor technology, and in particular to an electric lawnmower and its external rotor motor. Background Technology

[0002] The operating mechanical characteristics of an electric motor are its external characteristics, that is, the mechanical characteristics that the motor can output. Specifically, given the rated voltage and rated load, the motor can output the corresponding torque, speed, and required current. The operating quality characteristics of an electric motor are its internal characteristics, controlled by certain important factors. These include the motor's cogging torque, torque ripple, harmonics, induced electromotive force and waveform, maximum output power, noise, and vibration.

[0003] At present, improving the mechanical and quality characteristics of external rotor motors, such as their cogging torque, torque ripple, harmonics, induced electromotive force and waveform, maximum output power, noise and vibration, has become an important topic in motor design. Utility Model Content

[0004] The purpose of this invention is to provide an electric lawnmower that optimizes and improves the operating characteristics of the motor and provides a motor that operates smoothly and reduces vibration.

[0005] The first aspect of this utility model provides an external rotor motor, including an external rotor and an inner stator. The external rotor includes a housing, a rotor seat connected to one end of the housing, and a rotor shaft fixedly connected to the rotation center of the rotor seat. The housing and the rotor seat are connected to form a receiving cavity, and the inner stator is received in the receiving cavity. The inner stator includes a stator core and a stator winding. The stator core includes a main body and a plurality of stator teeth extending radially outward from the main body. A winding slot is formed between adjacent stator teeth. The stator winding is wound onto the stator teeth and housed in the winding slot. The main body forms a stator center through hole. The rotor shaft rotatably passes through the stator center through hole. The outer rotor also includes a magnetic component, which is disposed between the housing and the stator teeth and fixedly connected to the rotor base; the magnetic component has a plurality of evenly spaced permanent magnets, each of which forms a magnetic pole of the outer rotor.

[0006] Preferably, the stator teeth have a total of 12 evenly spaced winding slots, and the magnetic component has a total of 14 magnetic poles.

[0007] Furthermore, the external rotor motor also includes a magnetic shielding ring and / or a magnetic shielding part; the magnetic shielding part is disposed on the rotor seat, the magnetic shielding part includes a first ring body and a plurality of first spacer teeth extending axially from the first ring body, the plurality of first spacer teeth being evenly spaced along the circumference of the first ring body; the magnetic shielding ring is disposed on the side of the magnetic assembly away from the rotor seat, the magnetic shielding ring includes a second ring body and a plurality of second spacer teeth extending axially from the second ring body, the plurality of second spacer teeth being evenly spaced along the circumference of the second ring body; the second spacer teeth and the first spacer teeth are disposed opposite to each other on both sides of the permanent magnet; two adjacent permanent magnets are separated by corresponding first spacer teeth and second spacer teeth; the permanent magnets, the first spacer teeth and the second spacer teeth are all located on the inner side of the housing.

[0008] Furthermore, the inner stator also includes a stator seat, which is located at both ends of the stator core, along with the rotor seat. The stator seat includes a stator core and a hollow fixed shaft extending axially from the stator core. The hollow fixed shaft extends into the central through hole of the stator and provides fixed support for the stator core. The rotor shaft rotatably passes through the hollow hole of the hollow fixed shaft. The hollow fixed shaft does not completely penetrate the central through hole of the stator, and a first bearing assembly is provided at one end of the central through hole near the rotor seat to support the rotor shaft.

[0009] Preferably, the stator core is provided with a second bearing assembly; the wall of the central through hole of the stator directly or indirectly serves as the bearing seat of the first bearing assembly; the rotor shaft is rotatable relative to the stator core under the support of the first bearing assembly and the second bearing assembly.

[0010] Preferably, the first bearing group includes two or more bearings arranged along the motor axial direction, and the second bearing group includes two or more bearings arranged along the motor axial direction.

[0011] Preferably, an elastic washer is provided between the first bearing assembly and the rotor seat, and the rotor shaft passes through the elastic washer, the first bearing assembly, and the second bearing assembly in sequence.

[0012] Preferably, the rotor base includes a rotor core and a first end cover plate extending radially outward from the rotor core; the inner stator further includes a stator base, the stator base including a stator core and a second end cover plate extending radially outward from the stator core; the first end cover plate and the second end cover plate are respectively located at both ends of the housing, the housing is fixedly connected to at least one of the first end cover plate and the second end cover plate, and the inner wall of the housing is supported by at least one of the first end cover plate and the second end cover plate.

[0013] Preferably, a first retaining ring is fitted at the outer end of the rotor shaft where it meets the rotor seat to prevent the rotor seat from detaching from the rotor shaft; and / or The rotor shaft is fitted with a second retaining ring at the outer end of the stator base to prevent the stator base from detaching from the rotor shaft.

[0014] The second aspect of this utility model provides an electric lawnmower, including a blade disc and a motor for driving the blade disc, wherein the motor is the external rotor motor provided in the first aspect above.

[0015] The external rotor motor structure of this utility model achieves motor miniaturization while optimizing and improving the motor's operating quality characteristics; it can ensure smooth operation of the motor and electric lawnmower and reduce vibration during operation. Attached Figure Description

[0016] Figure 1 This is a three-dimensional schematic diagram of one type of external rotor motor provided in Embodiment 1 of this utility model; Figure 2 yes Figure 1 The diagram shows an exploded view of the outer rotor and inner stator of an external rotor motor. Figure 3 yes Figure 1 A longitudinal section schematic diagram of the external rotor motor shown; Figure 4 This is a schematic diagram showing the connection of the magnet assembly, the magnetic shielding ring, and the magnetic shielding part of the rotor seat after the outer rotor motor of this utility model has been removed. Figure 5 This is an exploded structural diagram of the magnet assembly, rotor base, and magnetic shielding ring of the external rotor motor of this utility model. Figure 6 This is a three-dimensional schematic diagram of an external rotor motor with a stator base provided by this utility model; Figure 7 yes Figure 6 A three-dimensional schematic diagram of an external rotor motor with a stator mount, shown from another angle; Figure 8 yes Figure 6 A longitudinal section schematic diagram of the external rotor sub-motor shown; Figure 9 yes Figure 6 The diagram shows a three-dimensional representation of the stator mount of the external rotor sub-motor. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Example 1 Please see Figure 1 , Figure 2 and Figure 3Embodiment 1 of this utility model provides an external rotor motor 100, which includes an external rotor 20 and an inner stator 30.

[0019] The outer rotor 20 includes a housing 10, a rotor seat 21 connected to one end of the housing 10, and a rotor shaft 22 fixedly connected to the rotation center of the rotor seat 21. The housing 10 and the rotor seat 21 are connected to form a receiving cavity 11, into which the inner stator 30 is received. The housing 10 of this invention is both the outer shell of the outer rotor motor 100 and the outer rotor 20; this makes the product more compact.

[0020] The inner stator 30 includes a stator core and a stator winding. The stator core includes a main body and a plurality of stator teeth 31 extending radially outward from the main body. A winding slot 33 is formed between adjacent stator teeth 31; the stator winding is wound onto the stator teeth 31 and housed in the winding slot 33. In this embodiment, the stator core also includes a stator insulating sleeve. The stator insulating sleeve wraps around the stator teeth 31 forming the winding slot 33, thus insulating the stator teeth 31 from the stator winding. Specifically, the main body of the stator core forms a stator central through hole 35; the rotor shaft 22 is rotatably inserted into the stator central through hole 35. The rotor shaft 22 is fixedly connected to the rotor seat 21. When the rotor seat 21 rotates, it drives the rotor shaft 22 to rotate, thus rotating the rotor shaft 22 within the stator central through hole 35.

[0021] The outer rotor 20 also includes a magnetic component, which is disposed between the housing 10 and the stator teeth 31 and fixedly connected to the rotor base 21. In this embodiment, the magnetic component has a plurality of uniformly spaced permanent magnets 25; each permanent magnet 25 forms a magnetic pole of the outer rotor 20.

[0022] This invention optimizes and improves the operational quality characteristics of the outer rotor motor 100 by cooperating the winding slots 33 of the inner stator 30 with the magnetic poles of the permanent magnets 25 of the outer rotor 20. Preferably, the stator teeth 31 have a total of 12 evenly spaced winding slots 33, and the magnetic components have a total of 14 magnetic poles. This slot-pole combination enables the outer rotor motor 100 to achieve a better sinusoidal effect in cogging torque and lower torque fluctuation.

[0023] Please see Figure 4 and Figure 5Furthermore, the external rotor motor 100 also includes a magnetic shielding ring 40 and a magnetic shielding section. This magnetic shielding section is disposed on the rotor base 21; or in other words, the rotor base 21 has an integrally formed magnetic shielding section. Specifically, the magnetic shielding section includes a first ring body and a plurality of first teeth 211 extending axially from the first ring body. The plurality of first teeth 211 are evenly spaced along the circumference of the first ring body. The magnetic shielding ring 40 is disposed on the side of the magnetic assembly away from the rotor base 21. The magnetic shielding ring 40 includes a second ring body and a plurality of second teeth 41 extending axially from the second ring body. The plurality of second teeth 41 are evenly spaced along the circumference of the second ring body. The second teeth 41 and the first teeth 211 are disposed opposite to each other on both sides of the permanent magnet 25; adjacent permanent magnets 25 are separated by corresponding first teeth 211 and second teeth 41. In this embodiment, the permanent magnet 25, the first teeth 211, and the second teeth 41 are all located inside the housing 10. The magnetic shielding ring 40 and the magnetic shielding part ensure the spacing structure of each permanent magnet in the magnet assembly, improving circumferential uniformity; thereby increasing the stability of the product signal output and reducing vibration during motor operation. Understandably, using either the magnetic shielding ring 40 or the magnetic shielding part alone can also achieve the function of a spacing structure; however, this invention preferably uses a dual magnetic shielding structure using both the magnetic shielding ring 40 and the magnetic shielding part simultaneously, ensuring a more reliable effect.

[0024] Please see Figure 6 , Figure 7 , Figure 8 and Figure 9 Furthermore, the inner stator 30 also includes a stator seat 37, which, along with the rotor seat 21, is located at both ends of the stator core. The stator seat 37 includes a stator core 373 and a hollow fixed shaft 371 extending axially from the stator core 373. The hollow fixed shaft 371 extends into the stator center through-hole 35 and provides fixed support to the stator core. The rotor shaft 22 rotatably passes through the hollow hole of the hollow fixed shaft 371. The hollow fixed shaft 371 does not completely penetrate the stator center through-hole 35. In conventional designs, the stator seat 37 and rotor seat 21 are located on opposite sides of the stator core along its axial direction, resulting in a longer axial dimension of the motor. This invention, by having the hollow fixed shaft 371 extend into but not completely penetrate the stator center through-hole 35, reduces the axial dimension of the outer rotor motor 100.

[0025] In this embodiment, a first bearing assembly 61 is provided at one end of the stator central through hole 35 near the rotor seat 21 to support the rotor shaft 22. A second bearing assembly 62 is provided in the stator core 373. The hole wall of the stator central through hole 35 directly or indirectly serves as the bearing seat of the first bearing assembly 61; the rotor shaft 22 is rotatable relative to the stator core under the support of the first bearing assembly 61 and the second bearing assembly 62. This structure, in which the bearings are located in the stator central through hole 35, allows for a more compact overall structure of the external rotor motor 100.

[0026] The first bearing group 61 includes two or more bearings arranged axially along the motor axis, and the second bearing group 62 includes two or more bearings arranged axially along the motor axis. In this embodiment, the first bearing group 61 has two bearings. In conventional designs, the bearing groups are axially located on the two outer sides of the stator core, resulting in a longer axial dimension of the motor. This invention, through the structure of the first bearing group 61, the hollow fixed shaft 371 of the stator seat 37, and the second bearing group 62, reduces the axial dimension of the motor, enabling the external rotor motor 100 to operate more smoothly and reducing vibration during motor operation.

[0027] In this embodiment, an elastic washer 50 is provided between the first bearing assembly 61 and the rotor seat 21. The rotor shaft 22 passes sequentially through the elastic washer 50, the first bearing assembly 61, and the second bearing assembly 62. Understandably, if the stator seat 37 and the rotor seat 21 are too close, they will compress the elastic washer 50. The elasticity of the elastic washer 50 allows for slight axial adjustment of the stator seat 37 and the rotor seat 21, thereby preventing the rotation of the rotor seat 21 from being restricted when the stator seat 37 and the rotor seat 21 are too close.

[0028] In this embodiment, the rotor base 21 further includes a rotor core 213 and a first end cover 215 extending radially outward from the rotor core 213. The inner stator 30 further includes a second end cover 375 extending radially outward from the stator core 373. The first end cover 215 and the second end cover 375 are respectively located at both ends of the housing 10. The housing 10 is fixedly connected to at least one of the first end cover 215 and the second end cover 375. When the housing 10 is fixedly connected to the first end cover 215, the inner wall of the housing 10 is supported by the first end cover 215, and when the rotor base 21 rotates, the housing 10 is also driven to rotate by the rotor base 21. When the housing 10 is fixedly connected to the second end cover 375, the inner wall of the housing 10 is supported by the second end cover 375; at this time, the housing 10 and the stator base 37 are fixedly connected and cannot rotate.

[0029] Please see Figure 4 , Figure 5 and Figure 7 Understandably, the first ring of the magnetic shielding part of the rotor seat 21 can be fixedly connected to the first end cover plate 215, or it can be integrally formed with the first end cover plate 215. Preferably, the rotor core 213, the first end cover plate 215, the first ring of the magnetic shielding part of the rotor seat 21, and the first tooth 211 are interconnected as a single piece; together forming a single piece of rotor seat 21.

[0030] Please see Figure 6 , Figure 7 and Figure 8Preferably, a first retaining ring 221 is fitted at the outer end of the rotor shaft 22 where it meets the rotor seat 21 to prevent the rotor seat 21 from detaching from the rotor shaft 22. A second retaining ring 222 is fitted at the outer end of the rotor shaft 22 where it meets the stator seat 37 to prevent the stator seat 37 from detaching from the rotor shaft 22. Thus, by fixing the first retaining ring 221 and the second retaining ring 222 at both ends of the rotor shaft 22, the risk of cross-movement and component separation can be eliminated when the external rotor motor 100 is running. It is understood that, depending on the actual situation, retaining rings may be selectively provided to fix one end of the rotor shaft 22 that has the risk of cross-movement or separation.

[0031] Example 2 This embodiment also provides an electric lawnmower, which includes a blade disc and a motor for driving the blade disc. The motor is the external rotor motor 100 of the first embodiment described above. The overall configuration of the external rotor motor 100 enables the miniaturization of the electric lawnmower while ensuring smooth and vibration-free operation of the blade disc, and reducing noise and vibration amplitude.

[0032] The above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, such as combining different features in various embodiments, and these all fall within the protection scope of the present invention.

Claims

1. An external rotor motor, comprising an external rotor (20) and an inner stator (30), characterized in that, The outer rotor (20) includes a housing (10), a rotor seat (21) connected to one end of the housing (10), and a rotor shaft (22) fixedly connected to the rotation center of the rotor seat (21); the housing (10) and the rotor seat (21) are connected to form a receiving cavity (11), and the inner stator (30) is received in the receiving cavity (11). The inner stator (30) includes a stator core and a stator winding. The stator core includes a main body and a plurality of stator teeth (31) extending radially outward from the main body. A winding slot (33) is formed between adjacent stator teeth (31). The stator winding is wound onto the stator teeth (31) and housed in the winding slot (33). The main body forms a stator center through hole (35). The rotor shaft (22) is rotatably inserted into the stator center through hole (35). The outer rotor also includes a magnetic component, which is disposed between the housing (10) and the stator teeth (31) and fixedly connected to the rotor seat (21); the magnetic component has a plurality of evenly spaced permanent magnets (25), each permanent magnet (25) forming a magnetic pole of the outer rotor (20).

2. The external rotor motor according to claim 1, characterized in that, The stator teeth (31) have a total of 12 evenly spaced winding slots (33), and the magnetic components have a total of 14 magnetic poles.

3. The external rotor motor according to claim 1, characterized in that, It also includes a magnetic shielding ring (40) and / or a magnetic shielding part; the magnetic shielding part is disposed on the rotor seat (21), the magnetic shielding part includes a first ring body and a plurality of first teeth (211) extending axially from the first ring body, the plurality of first teeth (211) being evenly spaced along the circumference of the first ring body; the magnetic shielding ring (40) is disposed on the side of the magnetic assembly away from the rotor seat (21), the magnetic shielding ring (40) includes a second ring body and a plurality of second teeth (41) extending axially from the second ring body, the plurality of second teeth (41) being evenly spaced along the circumference of the second ring body; the second teeth (41) and the first teeth (211) are disposed opposite to each other on both sides of the permanent magnet (25); two adjacent permanent magnets (25) are separated by corresponding first teeth (211) and second teeth (41); the permanent magnet (25), the first teeth (211) and the second teeth (41) are all located inside the housing (10).

4. The external rotor motor according to claim 1, characterized in that, The inner stator (30) also includes a stator seat (37), which and the rotor seat (21) are located at the two ends of the stator core, respectively. The stator seat (37) includes a stator core and a hollow fixed shaft (371) extending axially from the stator core. The hollow fixed shaft (371) extends into the stator center through hole (35) and fixes the stator core. The rotor shaft (22) rotatably passes through the hollow hole of the hollow fixed shaft (371). The hollow fixed shaft (371) does not completely penetrate the stator center through hole (35). A first bearing assembly (61) is provided at one end of the stator center through hole (35) near the rotor seat (21) to support the rotor shaft (22).

5. The external rotor motor according to claim 4, characterized in that, The stator core is provided with a second bearing assembly (62); the wall of the stator center through hole (35) directly or indirectly serves as the bearing seat of the first bearing assembly (61); the rotor shaft (22) is rotatable relative to the stator core under the support of the first bearing assembly (61) and the second bearing assembly (62).

6. The external rotor motor according to claim 5, characterized in that, The first bearing group (61) includes two or more bearings arranged along the motor axis, and the second bearing group (62) includes two or more bearings arranged along the motor axis.

7. The external rotor motor according to claim 5, characterized in that, An elastic washer (50) is provided between the first bearing assembly (61) and the rotor seat (21), and the rotor shaft (22) passes through the elastic washer (50), the first bearing assembly (61), and the second bearing assembly (62) in sequence.

8. The external rotor motor according to claim 1, characterized in that, The rotor base (21) includes a rotor core (213) and a first end cover plate (215) extending radially outward from the rotor core (213); the inner stator (30) also includes a stator base (37), the stator base (37) includes a stator core (373) and a second end cover plate (375) extending radially outward from the stator core (373); the first end cover plate (215) and the second end cover plate (375) are respectively located at both ends of the housing (10), the housing (10) is fixedly connected to at least one of the first end cover plate (215) and the second end cover plate (375), and the inner wall of the housing (10) is supported by at least one of the first end cover plate (215) and the second end cover plate (375).

9. The external rotor motor according to claim 8, characterized in that, The rotor shaft (22) is fitted with a first retaining ring (221) at its outer end where it meets the rotor seat (21) to prevent the rotor seat (21) from detaching from the rotor shaft (22); and / or The rotor shaft (22) is fitted with a second retaining ring (222) at the outer end of the stator seat (37) to prevent the stator seat (37) from detaching from the rotor shaft (22).

10. An electric lawnmower, comprising a blade disc and a motor for driving the blade disc, characterized in that, The motor is an external rotor motor as described in any one of claims 1-9.

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