motor

Abstract

Provided is an electric motor, comprising: a shaft; a rotor assembly including a rotor disk and a bushing; and a commutator adapted to supply power to a coil, the total number N of a plurality of commutator segments of the commutator satisfying the formula: U / [(N - p) / 2]*p < 30, where (N + 1) / p is an integer or (N - 1) / p is an integer; U is the rated voltage of the electric motor, and p is the number of pole pairs of the electric motor. The plurality of commutator segments are evenly spaced along a circumference centered on the axis of the electric motor, and a plurality of brushes of the electric motor are arranged in pairs, and two brushes in each pair of brushes are arranged symmetrically with respect to the axis and are configured such that the circumferential width of each brush satisfies the formula: Wb < Ws / 2 + Wi*3 / 2, where Wb is the circumferential width of each brush, Ws is the circumferential width of each commutator segment, and Wi is the circumferential width of the gap between every two adjacent commutator segments. The present invention provides an electric motor capable of reducing commutator electric sparks for use in high-voltage applications.

Description

Technical Field

[0001] The present invention relates to electric motors, and in particular to an improved ironless disc motor. Background Art

[0002] In the field of electric motors, a DC disc motor is a drive motor that utilizes an axial magnetic field and an ironless rotor structure. This coreless disc DC motor offers advantages such as zero cogging torque, low noise, low moment of inertia, responsive operation, small axial dimensions, high efficiency, and a simple structure. It is widely used in industries such as household appliances, automobiles, and electric bicycles.

[0003] The armature of an ironless disc motor has two structures: printed circuit board (PCB) and coil disc. PCB armatures are printed on copper-clad substrates using methods such as etching and electrochemical deposition. They offer a simple structure, small size, and light weight, but they are expensive to manufacture. Coil disc armatures are typically manufactured by molding a formed coil with a thermosetting material (such as epoxy resin). Compared to PCB armatures, coil disc armatures are more cost-effective and are therefore more widely used.

[0004] However, disc-type coreless DC motors are generally powered by batteries with a relatively low rated voltage, typically 12V to 48V, which prevents the motor from being directly applied to higher voltage (eg, 120V or 220V) applications.

[0005] Patent CN 201805335 U discloses a coreless disc motor. The motor comprises a flat, disc-shaped rotor end cap, a rotor, a coil winding, and an electromagnetic disk, all coaxially arranged and mounted on the same motor shaft. The rotor end cap, rotor, and electromagnetic disk are nested with the motor shaft via a centrally embedded bearing. The center hole of the stator coil winding is directly fastened and nested outside the motor shaft. The rotor end cap and rotor are fixed as a whole, with a gap between the rotor, coil winding, and electromagnetic disk. Multiple evenly distributed magnets are fixed to the side of the rotor facing the coil winding. This motor's open structure reduces its weight and size. This motor is a brushless motor without a commutator and requires a corresponding drive for use.

[0006] Patent CN 203617869 U discloses a fully enclosed aluminum alloy disc motor. This motor consists of an aluminum alloy base and a housing cover forming a hollow housing. The rotating shaft is supported on bearings within the housing, with one end of the shaft extending outside the housing. A rotor, formed by an ironless, plastic-encapsulated disc rotor, is fixed to the shaft within the housing. A stator, formed by magnets, is fixed to the housing cover opposite the rotor disc. A brush assembly is also fixed to the housing cover. The brush assembly works with the commutator on the rotor disc to transmit power to the rotor coils. A skeleton oil seal is installed between the base and the rotating shaft. The yoke iron is mounted on the aluminum alloy base by inlay or die-casting. This motor adopts a fully enclosed structure, effectively meeting requirements for water, oil, and dust resistance, is maintenance-free, and has a long service life.

[0007] Patent CN 204465265 U discloses a thermostatic disc-type DC motor. A shaft, one end of which extends outside the base, is supported by a bearing on the axis of a base, housing, and cover, which are fixedly connected in sequence. A rotor disk with a rotor winding, fixed to the shaft and electrically connected to the commutator, is located within the rotor cavity formed between the base and the housing. Heat dissipation fins are evenly distributed on the outer cylindrical surface of the rotor disk within the rotor cavity. A circle of radially conductive heat dissipation holes is evenly distributed on the outer side of the heat dissipation fins relative to the housing. The commutator is fixed to the shaft, and brushes fixed to the cover are in contact with the commutator for electrical conduction. A circle of magnets with an even number of poles is evenly adhered to the inner wall surfaces of the base and housing. The rotor cavity formed by the base and housing forms a closed magnetic circuit space. The base and housing are either stamped, one-piece iron parts or die-cast aluminum alloy parts with iron sheets as yoke inserts. When the motor is running, the heat sink blades rotate along with the rotor disk, dissipating the heat generated by the rotor disk through air convection. The faster the motor speed, the faster the heat sink blades rotate, dissipating more heat, and vice versa. This maintains thermal balance in the motor, keeping the temperature rise within a reasonable range and enabling long-term stable operation.

[0008] In existing motor commutator designs, the number of commutator segments must ensure that the voltage between the segments is not too high, generally not exceeding 30V. Excessive voltage can easily cause large commutation sparks. In common disc-type motors, due to limited internal space, the number of commutator segments and coils is typically small. However, due to the low rated voltage, large sparks are generally not caused. However, when the rated voltage is higher, the number of commutator segments needs to be increased to prevent large commutator sparks.

[0009] Regarding prior art motor commutator designs, the inventors of this application note that disc motor windings typically employ a single-wave winding method, with the number of branches in this winding method being constant at two, regardless of the number of brushes or poles. The inventors of this application also note that, compared to a two-brush design, a greater number of brushes results in an increase in the number of short-circuited coils in the armature winding, reducing the number of actually useful coils. This increases the voltage between the commutator segments and increases commutator sparking. Furthermore, the brush width should not be too wide, as this increases the number of commutator segments in contact with the brushes, resulting in an increase in the number of short-circuited coils and, consequently, an increase in the voltage between the commutator segments.

[0010] Secondly, the rotor of an ironless disc motor is traditionally manufactured using a thermoset molded material, which is then interference-fitted onto the motor shaft. When the motor is operating under load, torque is directly transmitted to the shaft through the rotor coil disk. Because polymer materials are unstable at high temperatures, the connection between the rotor coil disk and the shaft is weak and unable to withstand high torque. This connection is particularly prone to failure under frequent starting and stopping conditions and high temperatures.

[0011] Furthermore, the disc motor's casing needs to have a certain level of magnetic permeability to form a magnetic circuit. Using aluminum alloy and inlaid yoke iron can save material costs, but the process is complex and reliability is low. A simpler approach is to use an iron casing directly. This iron casing can be manufactured by stamping or machining. However, due to the limitations of the stamping process, the casing cannot be too thick if stamping is used, otherwise it cannot be manufactured. However, the thinner the casing, the greater the magnetic resistance and the lower the motor efficiency. Therefore, to improve motor efficiency, a certain casing thickness is required.

[0012] In summary, the armature structure of the coreless disc motor in the prior art has the following defects: the printed circuit board type armature is expensive; the coil disc voltage is low and cannot be directly used for high voltage, which easily generates electric sparks; the rotor attachment is unstable; the components on the magnetic flux path have high magnetic resistance and high cost, etc.

[0013] It should be pointed out here that the technical content provided in this section is intended to help those skilled in the art understand the present invention, and does not necessarily constitute prior art. Summary of the Invention

[0014] An object of the present invention is to reduce commutator sparking by improving the brush and commutator structure so as to be applicable to high voltage motors.

[0015] An object of the present invention is to provide a motor with low cost, high component attachment strength, high performance and compact structure.

[0016] The present invention provides a motor, comprising: a shaft; a rotor assembly, the rotor assembly comprising a rotor disk and a bushing, the bushing being arranged between the shaft and the rotor disk, the rotor assembly being fixed to the shaft via the bushing, the rotor disk being provided with a coil; and a commutator, the commutator being suitable for transmitting power to the coil, the commutator comprising a plurality of commutator segments, the total number N of the commutator segments satisfying the following formula: U / [(Np) / 2]*p<30, and (N+1) / p is an integer or (N-1) / p is an integer; wherein U is the rated voltage of the motor, and p is the number of pole pairs of the motor.

[0017] Moreover, the plurality of commutator segments are evenly spaced along a circumference centered on the axis of the motor. The motor further includes a plurality of brushes adapted to contact the commutator segments to conduct electricity. The plurality of brushes are arranged in pairs, and the two brushes in each pair are symmetrically arranged with respect to the axis. The two brushes in each pair are configured such that the circumferential width of each brush satisfies the following formula: Wb < Ws / 2 + Wi*3 / 2, where Wb is the circumferential width of each brush, Ws is the circumferential width of each commutator segment, and Wi is the circumferential width of the gap between every two adjacent commutator segments.

[0018] Advantageously, the outer radial side of the bushing is provided with teeth embedded in the rotor disk.

[0019] Advantageously, the bushing is a copper bushing in interference fit with the shaft, and / or the bushing and the rotor disk are integrally molded using a thermosetting material.

[0020] Advantageously, the rotor disk has a radially outer region and a radially central region. The motor further includes a first end cover and a second end cover. The first end cover is arranged on the first side of the rotor disk and faces the radially outer region. The second end cover is arranged on the second side of the rotor disk opposite to the first side and faces the radially outer region, such that the rotor disk is located within the space defined by the first end cover and the second end cover.

[0021] Advantageously, the first end cover and the second end cover are made of a magnetically conductive material.

[0022] Advantageously, the motor further includes a permanent magnet. The permanent magnet is arranged on the inner surface of the first end cover facing the radially outer region, and: the permanent magnet is a circular permanent magnet and the coil is a rhombic coil, or the permanent magnet is a sector-shaped permanent magnet and the coil is a sector-shaped coil

[0023] Advantageously, the commutator in the form of a disk is arranged on the second side of the rotor disk and attached to the radially central region, and the commutator projects through the hole of the second end cover.

[0024] Advantageously, the motor further includes: a cylindrical housing, a first bearing cover, and a second bearing cover. The first bearing cover, the first end cover, the cylindrical housing, the second end cover, and the second bearing cover are sequentially connected along the axis of the motor. The first bearing cover and the second bearing cover face the radially central region. The cylindrical housing, the first bearing cover, and the second bearing cover are made of a non-magnetically conductive material.

[0025] Advantageously, the brush holder of the brush assembly of the motor is fixed to the second bearing cover, and the brushes of the brush assembly of the motor are attached to the brush holder in a telescopic movement manner and can remain in contact with the commutator.

[0026] Advantageously, the motor is a motor with a rated voltage greater than or equal to 120V and the coils are implemented in a single-wave winding.

[0027] The present invention also provides a motor, including: a rotor assembly, the rotor assembly includes a rotor disk, and coils are arranged in the rotor disk; a commutator, the commutator is adapted to supply power to the coils, the commutator includes a plurality of commutator segments, and the plurality of commutator segments are evenly spaced along a circumference centered on the axis of the motor; and two brushes, the two brushes are adapted to contact the commutator segments to supply power, the two brushes are symmetrically arranged with respect to the axis, and the two brushes are configured such that the circumferential width of each brush satisfies the following formula to reduce the voltage between the commutator segments: Wb < Ws / 2 + Wi*3 / 2, where, Wb is the circumferential width of each brush, Ws is the circumferential width of each commutator segment, and Wi is the circumferential width of the gap between every two adjacent commutator segments.

[0028] Compared with the existing motor designs, the beneficial effects of the present invention are as follows: 1. It is applicable to higher voltages. The number of commutator segments is related to the rated voltage of the motor. The higher the voltage, the more the number of commutator segments, thereby reducing the voltage between the commutator segments and reducing the spark; 2. The width of the brushes is restricted to reduce the commutation spark; 3. The rotor assembly is embedded with a toothed copper sleeve to transmit a greater torque; 4. The parts of the magnetic flux path adopt magnetic conductive materials to improve the performance, and the parts of the non-magnetic flux path adopt non-magnetic conductive materials to reduce the material and processing costs; 5. The motor structure is compact and the axial dimension is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Through the following detailed description of specific embodiments provided by referring to the drawings, the features and advantages of the present invention can be more easily understood. In the drawings, the same features or components are denoted by the same reference numerals and the drawings are not necessarily drawn to scale, and in the drawings:

[0030] Figure 1 is a schematic cross-sectional view of a motor with an improved armature structure according to the present invention.

[0031] Figure 2A and Figure 2B are respectively Figure 1 schematic longitudinal and axial cross-sectional views of the rotor assembly of the motor, and the rotor assembly includes a commutator, a rotor disk and a bushing.

[0032] Figure 3A is Figure 1A schematic axial cross-sectional view of the brush assembly and commutator segments in contact with each other.

[0033] Figure 3B It is along Figure 3A Schematic diagram of the cross section of the circle dotted line. DETAILED DESCRIPTION

[0034] The following describes an exemplary embodiment of the present invention in detail with reference to the accompanying drawings. The description of the exemplary embodiment is only for illustrative purposes and is in no way intended to limit the present invention, its application, or usage.

[0035] The inventive concept of this application is to design the total number of commutator segments by correlating the number of commutator segments with the rated voltage of the power supply and the number of pole pairs of the motor. This design increases the number of commutator segments as the voltage increases, thereby reducing the voltage between the commutator segments and minimizing spark generation. The inventive concept of this application is also to design the structure of the commutator segments and brushes, such as their width, based on the number of commutator segments in contact with the brushes during motor operation, thereby reducing the voltage between the commutator segments and minimizing spark generation.

[0036] Next, combine Figures 1 to 3B The motor of the present invention is described below. The motor of the present invention takes an ironless disc permanent magnet DC motor as an example, but the motor of the present invention can also be applied to other motors.

[0037] See also Figures 1 to 2B The motor of the present invention includes: a shaft 5; a rotor assembly 7, which is fixed to the shaft 5 and includes a rotor disk 71, in which a coil is disposed; and a commutator 73, which is suitable for transmitting power to the coil. The commutator includes a plurality of commutator segments 73A. The commutator 73 is constructed according to the rated voltage and the number of pole pairs of the motor, so that the total number N of commutator segments 73A satisfies the following formula to reduce the voltage between the commutator segments: U / [(Np) / 2]*p<30; and (N+1) / p is an integer, or (N-1) / p is an integer, where U is the rated voltage and p is the number of pole pairs. The motor of the present invention having the above characteristics is suitable for higher voltages. The number of commutator segments is related to the rated voltage of the motor. The higher the voltage, the more commutator segments are used, thereby reducing the voltage between the commutator segments and reducing sparks.

[0038] In one aspect of this embodiment, the rated voltage of the motor can be 150V, and the number of pole pairs P is 3. According to the above formula, the total number of commutator segments N is greater than 33. N can be an odd number, for example. The total number of commutator segments can be set to 35 as needed, or can be set to a different value based on needs (e.g., structural and cost factors). Furthermore, in other aspects of the embodiment, the number of pole pairs P can be different, such as 4 pairs (8 poles), 5 pairs (10 poles), or 6 pairs (12 poles).

[0039] and combined with Figure 3A and Figure 3B , a plurality of commutator segments 73A are uniformly spaced along a circumference centered on the axis of the motor, and each commutator segment has the same size. The motor further includes two brushes 10A adapted to contact the commutator segments 73A to conduct electric power. The two brushes are arranged symmetrically (180° apart) with respect to the axis of the motor. The two brushes are configured such that the circumferential width of each brush 10A satisfies the following formula: Wb < Ws / 2 + Wi*3 / 2, where Wb is the circumferential width of each brush, Ws is the circumferential width of each commutator segment, and Wi is the circumferential width of the gap between every two adjacent commutator segments.

[0040] Specifically, in one aspect according to this embodiment, the motor can be a motor with a rated voltage greater than or equal to 120V and implemented with a single-wave winding of coils. The brushes can be carbon brushes, and 35 (numbered 1 to 35) commutator segments are uniformly spaced along the circumference. Assuming that in the initial state, one brush 10A is located at the center of the commutator segment 73A numbered 1, due to the 180-degree symmetric arrangement of the two brushes, the other brush 10A is located at the center of the commutator segments 73A numbered 18 and 19. Since the more commutator segments in contact with the brushes, the more short-circuited coils and the higher the voltage between the commutator segments, and the easier it is to generate sparks. Designing the brushes and commutator segments according to the above formula Wb < Ws / 2 + Wi*3 / 2 ensures that the number of commutator segments in contact with the brushes during rotation never exceeds 3. That is, it is ensured that when the above-mentioned one brush 10A contacts the commutator segment 2, the other brush 10A has already disengaged from the commutator segment 18, that is, it is ensured that D1 is greater than D2, thereby reducing the voltage between the commutator segments and reducing or eliminating the generation of electric sparks, which is particularly applicable to the case where the rated voltage of the motor is high.

[0041] Although Figure 3B the circumferential width Wb of the brushes shown in is less than the circumferential width Ws of the commutator segments, those skilled in the art can know that the above formula also applies to the case where the circumferential width Wb of the brushes is greater than the circumferential width Ws of the commutator segments.

[0042] In addition, the number of brushes shown in the figure is a pair of symmetrically arranged brushes, while those skilled in the art can know that the brushes can be arranged in multiple pairs of brushes. The two brushes in each pair of brushes are symmetrically arranged and ensure that the number of commutator segments in contact with the two brushes at the same time never exceeds 3. For example, when multiple brushes are arranged in two pairs of brushes, the number of commutator segments in contact with the two brushes in each pair of brushes never exceeds 3, and the total number of commutator segments in contact with the brushes never exceeds 6.

[0043] The rotor assembly 70 may further include a bushing 72, which is arranged between the shaft 5 and the rotor disk 71, and a protruding tooth 72A embedded in the rotor disk 71 is provided on the radial outer side of the bushing to improve the mechanical strength between the rotor disk and the bushing, thereby transmitting greater torque. Figure 2A and Figure 2B As shown, the bushing 72 is a copper sleeve that is interference fit with the shaft 5, and / or the bushing 72 and the rotor disk 71 are molded into one piece using a thermosetting material, which can be an epoxy resin or a phenolic resin, thereby achieving a reliable fixed connection between the rotor assembly and the shaft.

[0044] In another advantageous aspect of an embodiment according to the present invention, the rotor disk 71 has a radially outer region and a radially central region. The motor further includes a first end cap 2 and a second end cap 11. The first end cap 2 is arranged on a first side of the rotor disk 71 and faces the radially outer region, and the second end cap 11 is arranged on a second side of the rotor disk 71 opposite the first side and faces the radially outer region, such that the rotor disk 71 is located within the space defined by the first end cap 2 and the second end cap 11. The motor further includes permanent magnets 3, which are arranged on the inner surface of the first end cap 2 facing the radially outer region. In one example, six cylindrical permanent magnets 3 are bonded to the inner surface of the first end cap 2 and evenly distributed along the circumference, while being arranged with north and south poles interlaced.

[0045] With this arrangement, when the motor is powered on and running, a closed magnetic flux path is formed, extending from the permanent magnets 3, through the first end cap 2, the second end cap 11, the rotor disk 71, and back to the permanent magnets 3. The rotor disk 71 is disposed in the gap between the second end cap 11 and the permanent magnets 3. The first and second end caps 2 and 11, located in the closed magnetic flux path, are made of a magnetically conductive material, such as No. 10 steel, to reduce magnetic resistance and improve motor performance.

[0046] Advantageously, the permanent magnet 3 is a circular permanent magnet and the coil is a diamond coil, or the permanent magnet 3 is a sector-shaped permanent magnet and the coil is a sector-shaped coil, so as to increase the effective length within the magnetic field cutting range and improve the coil utilization.

[0047] Turn again Figure 1, the electric machine further includes: a cylindrical housing 1, and a first bearing cover 4 and a second bearing cover 9. Among them, the first bearing cover 4, the first end cover 2, the cylindrical housing 1, the second end cover 11, and the second bearing cover 9 are connected in sequence along the axis of the electric machine. Among them, the shaft 5 is supported by a first bearing 6 and a second bearing 8 respectively arranged in the first bearing cover 4 and the second bearing cover 9. And, the first bearing cover 4 and the second bearing cover 9 face the radially central region. The cylindrical housing 1, the first bearing cover 4 and the second bearing cover 9 are made of a non-magnetic material, and this non-magnetic material can be aluminum alloy to reduce costs. Advantageously, a disk-shaped commutator 73 is arranged on the second side of the rotor disk 71 and attached to the radially central region, and the commutator 73 protrudes through the hole of the second end cover 11 to contact the brush 10A of the brush assembly 10. With the above arrangement, the structure of the electric machine can also be made compact and the axial dimension can be small.

[0048] In an advantageous aspect of the embodiment, the brush holder of the brush assembly 10 of the electric machine is fixed to the second bearing cover 9. The brush 10A of the brush assembly 10 of the electric machine is attached to the brush holder in a telescopic movement manner and can keep in contact with the commutator to achieve reliable power transmission.

[0049] In another embodiment according to the present invention, the electric machine includes: a rotor assembly 7, the rotor assembly includes a rotor disk 71 in which a coil is provided; a commutator 73, the commutator is adapted to supply power to the coil, the commutator includes a plurality of commutator segments 73A, and the plurality of commutator segments 73A are evenly spaced along a circumference centered on the axis of the electric machine; and two brushes 10A, the two brushes 10A are adapted to contact the commutator segments 73A to supply power, the two brushes are symmetrically arranged with respect to the axis, and the two brushes are configured such that the circumferential width of each brush satisfies the following formula to reduce the voltage between the commutator segments: Wb < Ws / 2 + Wi*3 / 2, where Wb is the circumferential width of each brush, Ws is the circumferential width of each commutator segment, and Wi is the circumferential width of the gap between every two adjacent commutator segments, thereby reducing the voltage between the commutator segments and reducing or eliminating the generation of electric sparks.

[0050] Although the preferred embodiments of the present invention have been described in detail herein, it should be understood that the present invention is not limited to the specific structures described and illustrated herein in detail. Other variations and modifications can be implemented by those skilled in the art without departing from the essence and scope of the present invention. All such variations and modifications fall within the scope of the claims of the present invention.

Claims

1. A motor comprising: axis (5); a rotor assembly (7), the rotor assembly comprising a rotor disk (71) and a bushing (72), the bushing (72) being arranged between the shaft (5) and the rotor disk (71), the rotor assembly (7) being fixed to the shaft via the bushing (72), and a coil being arranged in the rotor disk; and a commutator (73), the commutator being adapted to deliver power to the coil, the commutator comprising a plurality of commutator segments (73A), The total number N of the commutator segments (73A) satisfies the following formula: U / [(Np) / 2]*p<30, and (N+1) / p is an integer or (N-1) / p is an integer, Wherein, U is the rated voltage of the motor, and p is the number of pole pairs of the motor; Furthermore, the plurality of commutator segments (73A) are evenly spaced along a circumference centered on the axis of the motor. The motor further comprises a plurality of brushes (10A) adapted to contact the commutator segments (73A) to transmit power, the plurality of brushes being arranged in pairs, the two brushes in each pair being arranged symmetrically about the axis. The two brushes in each pair of brushes are configured so that the circumferential width of each brush (10A) satisfies the following formula: Wb <Ws / 2+Wi*3 / 2, Wherein, Wb is the circumferential width of each brush, Ws is the circumferential width of each commutator segment, and Wi is the circumferential width of the gap between each two adjacent commutator segments.

2. The motor according to claim 1, wherein The radial outer side of the bushing is provided with protruding teeth (72A) embedded in the rotor disk (71).

3. The motor according to claim 2, wherein The bushing (72) is a copper sleeve that is interference-fitted with the shaft (5), and / or the bushing (72) and the rotor disk (71) are molded into one piece using a thermosetting material.

4. The electric machine according to any one of claims 1 to 3, wherein: The rotor disk (71) has a radially outer region and a radially central region, The motor further comprises a first end cover (2) and a second end cover (11), wherein the first end cover (2) is arranged on a first side of the rotor disk (71) and faces the radially outer region, and the second end cover (11) is arranged on a second side of the rotor disk (71) opposite to the first side and faces the radially outer region, so that the rotor disk (71) is located in a space defined by the first end cover (2) and the second end cover (11).

5. The motor according to claim 4, wherein The first end cover (2) and the second end cover (11) are made of magnetic conductive material.

6. The motor according to claim 4, wherein The motor further comprises a permanent magnet (3) which is arranged on the inner surface of the first end cover (2) facing the radially outer region, and wherein: the permanent magnet (3) is a circular permanent magnet and the coil is a diamond coil, or the permanent magnet (3) is a sector-shaped permanent magnet and the coil is a sector-shaped coil.

7. The motor according to claim 4, wherein The commutator (73) having a disk shape is arranged on the second side of the rotor disk (71) and attached to the radially central region, and the commutator (73) protrudes through a hole of the second end cover (11).

8. The motor according to claim 4, wherein The motor further comprises: a cylindrical housing (1), and a first bearing cap (4) and a second bearing cap (9), The first bearing cover (4), the first end cover (2), the cylindrical housing (1), the second end cover (11), and the second bearing cover (9) are sequentially connected along the axis of the motor, and the first bearing cover (4) and the second bearing cover (9) face the radial central area, and the cylindrical housing (1), the first bearing cover (4), and the second bearing cover (9) are made of non-magnetic material.

9. The motor according to claim 8, wherein The brush holder of the brush assembly (10) of the motor is fixed to the second bearing cover (9), and the brush (10A) of the brush assembly (10) of the motor is attached to the brush holder in a telescopic manner and can maintain contact with the commutator.

10. The electric machine according to any one of claims 1 to 3, wherein: The motor has a rated voltage greater than or equal to 120V and is implemented with the coil in single-wave winding.

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