Electric motor and oral cavity cleaning apparatus

Abstract

Disclosed in the embodiments of the present description are an electric motor and an oral cavity cleaning apparatus. The electric motor comprises a stator assembly and a rotor assembly, wherein the stator assembly comprises at least one pair of stator cores, and the rotor assembly comprises a power shaft and a magnet assembly. In an energized state, the stator cores can drive the rotor assembly to vibrate back and forth; when the stator assembly is not energized and the rotor assembly is not subjected to any external force, the rotor assembly is in an equilibrium position. The rotor assembly is in a non-equilibrium position when subjected to an external force, and the rotatable angle of the rotor assembly when subjected to the external force is greater than 360°; once the external force is removed, the rotor assembly returns to the equilibrium position under the action of cogging torque. Since the rotor assembly can be rotated to any angle under the action of an external force, and can return to the equilibrium position once the external force is removed, a user can manually rotate a brush head, which is connected to the rotor assembly, to any desired equilibrium position or to a position near said equilibrium position as needed, thereby improving the convenience for users when using the oral cavity cleaning apparatus.

Description

An electric motor and oral cleaning device

[0001] Cross-referencing

[0002] This application claims priority to Chinese Patent Application No. 202411670207X, filed on November 20, 2024, entitled "An Electric Motor and Oral Cleaning Device". The entire contents of that Chinese patent application are incorporated herein by reference. Technical Field

[0003] This application relates to the field of oral cleaning equipment technology, specifically to a motor used in oral cleaning equipment, and an oral cleaning equipment. Background Technology

[0004] Oral hygiene devices typically use a motor's output shaft connected to the brush head to drive the brush head and perform the cleaning operation when the device is running. Because the brush head is connected to the motor's output shaft, it can only rotate within a small, fixed range when subjected to external force, resulting in poor user convenience.

[0005] Therefore, how to provide an oral cleaning device that can improve user convenience has become an urgent technical problem to be solved. Summary of the Invention

[0006] This specification proposes a motor for use in oral hygiene equipment, and an oral hygiene equipment to solve the technical problem of poor user convenience in existing motors and oral hygiene equipment.

[0007] An electric motor for use in oral hygiene equipment, the electric motor comprising: a stator assembly and a rotor assembly;

[0008] A stator assembly is arranged to generate a magnetic field, wherein the stator assembly includes at least one pair of stator cores uniformly distributed in a circumferential direction;

[0009] A rotor assembly, at least partially arranged within the magnetic field of the stator assembly, the rotor assembly including a drive shaft and a magnet assembly disposed on the drive shaft and cooperating with the stator core;

[0010] The stator core is configured to drive the rotor assembly to reciprocate at a predetermined angle when energized; when de-energized, the rotor assembly is configured to rotate at an angle greater than 360° when subjected to external force.

[0011] The rotor assembly has a balanced position that mates with the stator core, and an unbalanced position that deviates from the stator core; in the unbalanced position, the rotor assembly is configured to return to the balanced position under the action of cogging torque after the external force is removed.

[0012] Optionally, the number of the balance positions is configured to correspond to the number of the stator cores; the balance positions include at least a first balance position and a second balance position corresponding to a pair of stator cores respectively;

[0013] In an unbalanced position, the magnet assembly is configured to reset toward the first or second balance position with the smallest angle, depending on the angle between the current position and the first or second balance position.

[0014] Optionally, the stator assembly includes two stator cores that are mirror-symmetrical; the rotor assembly includes two sets of magnet assemblies that are mirror-symmetrical.

[0015] Optionally, the angle between the first equilibrium position and the second equilibrium position is configured as a first angle, and the range of the first angle is 180°-3° to 180°+3°.

[0016] Optionally, the magnet assembly includes a first magnet and a second magnet, the first magnet and the second magnet being spaced apart on the power shaft.

[0017] Optionally, both the first magnet and the second magnet are arc-shaped, including an outer arc and an inner arc distributed radially, and two side edges that connect the corresponding ends of the outer arc and the inner arc, respectively.

[0018] Optionally, the first magnet and the second magnet are arranged circumferentially around the power shaft, and the central angle corresponding to the interval between the first magnet and the second magnet is the second included angle; the range of the second included angle is 23.5° to 38°.

[0019] Optionally, in a plane perpendicular to the rotation axis of the rotor assembly, the third angle between the centerline of the first magnet and the centerline of the second magnet ranges from 73° to 87°; the centerline of the first magnet is the centerline pointing from the center of the first magnet to the rotation axis of the rotor assembly, and the centerline of the second magnet is the centerline pointing from the center of the second magnet to the rotation axis.

[0020] Optionally, in a plane perpendicular to the rotation axis of the rotor assembly, the ratio of the first central angle corresponding to the outer arc of the first magnet facing the stator core to the second central angle corresponding to the inner arc of the stator core facing the magnet assembly ranges from 60% to 85%.

[0021] Optionally, in a plane perpendicular to the rotation axis of the rotor assembly, the ratio of the third central angle corresponding to the outer arc of the second magnet facing the stator core to the second central angle corresponding to the inner arc of the stator core facing the magnet assembly ranges from 60% to 85%.

[0022] Optionally, the motor further includes an output shaft, one end of which is connected to the brush head of the electric toothbrush.

[0023] This specification also provides an oral cleaning device having the aforementioned motor.

[0024] At least one embodiment of this specification can achieve the following beneficial effects: by allowing the rotor assembly to rotate at any angle under the action of external force and to return to the equilibrium position after the external force is removed, the user can manually rotate the brush head connected to the rotor assembly to any desired equilibrium position or near the equilibrium position as needed, thereby improving the convenience of the user in using the oral cleaning device. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 is a schematic diagram of the internal structure of a motor provided in an embodiment of this specification;

[0027] Figure 2 is a schematic diagram of an overall structure of a motor provided in an embodiment of this specification;

[0028] Figure 3 is a structural schematic diagram of the power shaft provided in the embodiment of this specification;

[0029] Figure 4 is a schematic diagram of a magnet structure provided in an embodiment of this specification;

[0030] Figure 5 is a schematic diagram of the first central angle and the third central angle structure provided in the embodiment of this specification;

[0031] Figure 6 is a schematic diagram of the second included angle structure provided in the embodiment of this specification;

[0032] Figure 7 is a schematic diagram of the third included angle structure provided in the embodiment of this specification;

[0033] Figure 8 is a schematic diagram of the fifth included angle structure provided in the embodiment of this specification;

[0034] Figure 9 is a schematic diagram of the second central angle structure provided in the embodiment of this specification;

[0035] Figure 10 is a schematic diagram of the fourth central angle structure provided in the embodiment of this specification;

[0036] Figure 11 is a schematic diagram of the distribution of simulation data of motor cogging torque provided in the embodiments of this specification;

[0037] Figure 12 is a schematic diagram of the distribution of simulation data of motor torque provided in the embodiments of this specification.

[0038] Reference numerals: 1. Stator assembly; 11. Stator core; 2. Rotor assembly; 21. Power shaft; 211. Rotor core; 2111. Mounting slot; 212. Output shaft; 22. Magnet assembly; 221. First magnet; 2211. Outer arc; 2212. Inner arc; 2213. Side; 222. Second magnet; 223. First central angle; 224. Second included angle; 225. Third included angle; 226. Fourth included angle; 227. Second central angle; 228. Third central angle; 229. Fifth included angle; 230. Fourth central angle; 231. Fifth central angle; 3. Motor housing; 4. Electromagnetic coil; 5. Air gap. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of one or more embodiments of this specification clearer, the technical solutions of one or more embodiments of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments in this specification without creative effort are within the protection scope of one or more embodiments of this specification.

[0040] An electric motor is provided, which can be used in oral hygiene devices or care devices such as electric toothbrushes, and can also be used in other electronic devices that require reciprocating oscillation, which will not be listed here. The motor in the embodiments of this specification may include a motor body, and a stator assembly and a rotor assembly disposed on the motor body.

[0041] The stator assembly is mounted on the motor body and arranged to generate a magnetic field. The stator assembly includes at least one pair of stator cores, which are fixed to the motor body to provide the magnetic field for the motor. One, two, or more pairs of stator cores can be used; the stator cores are typically evenly arranged circumferentially on the rotor assembly to facilitate reciprocating motion. The rotor assembly may include a drive shaft and magnet assemblies mounted on the drive shaft and cooperating with the stator cores. In the energized state, the rotor assembly can reciprocate at a predetermined angle; in the de-energized state, the rotor assembly can rotate more than 360° when subjected to an external force. The rotor assembly has a balanced position cooperating with the stator cores and an unbalanced position deviating from the stator cores; under the action of an external force, the rotor assembly can be in the unbalanced position, and after the external force is removed, the rotor assembly can return to the balanced position under the action of cogging torque.

[0042] In existing technologies, with industry development, oral hygiene devices can have an electronic display area on the handle. This display area can show information about the user's oral hygiene, such as reminders of missed brushing, excessive pressure, and brushing time. Currently, the brush head of oral hygiene devices can only sweep or rotate within a fixed range, thus fixing the orientation of the bristles on the brush head relative to the electronic display area. For example, the bristles and the electronic display area may be on the same side. In this case, the user needs to stop brushing to view the information on the electronic display, resulting in poor user convenience. To address the shortcomings of existing technologies, this solution provides the following embodiment.

[0043] The technical solutions provided in the various embodiments of this specification are described in detail below with reference to the accompanying drawings.

[0044] This specification provides an embodiment of a motor used in an oral hygiene device, enabling the device to operate based on the motor, clean teeth and gums, and protect oral health.

[0045] Figure 1 is a schematic diagram of the internal structure of a motor according to an embodiment of this specification; Figure 2 is a schematic diagram of the overall structure of a motor according to an embodiment of this specification. As shown in Figures 1 and 2, the motor may include a stator assembly 1, a rotor assembly 2, a motor housing 3, and an electromagnetic coil 4. An air gap 5 is also provided between the rotor assembly 2 and the stator assembly 1.

[0046] The stator assembly 1 can be integrally injection molded and embedded in both sides of the motor housing 3, and the rotor assembly 2 can be installed inside the motor housing 3. The stator assembly 1 and the rotor assembly 2 can be coaxially fitted. The stator assembly 1 does not require secondary manual assembly, which can result in a smaller concentricity tolerance between the stator assembly 1 and the rotor assembly 2, effectively reducing the cumulative tolerance of the assembled motor, reducing the vibration generated by the rotor assembly 2 during rotation, and reducing the noise during motor operation. The electromagnetic coil 4 is arranged around the stator core 11 and responds to the control signal applied to the electromagnetic coil 4.

[0047] In the embodiments of this specification, the stator assembly 1 may include one or more pairs of stator cores 11 evenly distributed in the circumferential direction, and an electromagnetic coil 4 arranged around the stator core 11. When the electromagnetic coil 4 is energized, the stator assembly 1 can generate a magnetic field. Specifically, the stator assembly can generate an alternating magnetic field during the energizing process, and by changing the magnetic field, the rotor assembly corresponding to the stator core can be controlled to reciprocate according to the changing frequency of the magnetic field.

[0048] In practical applications, the stator core 11 can be made of silicon steel sheets with high magnetic permeability. Silicon steel sheets are an alloy material mainly composed of silicon, carbon, and iron, and have excellent magnetic permeability and corrosion resistance. In addition to silicon steel sheets, the stator core 11 can also be made of materials such as aluminum alloys and copper-nickel alloys.

[0049] The rotor assembly 2 may include a power shaft 21 and a magnet assembly 22 arranged circumferentially around the power shaft 21, the magnet assembly 22 being configured to cooperate with the stator core 11.

[0050] Figure 3 is a schematic diagram of the power shaft provided in the embodiment of this specification. As shown in Figure 3, the power shaft 21 may include a rotor core 211 and an output shaft 212 disposed at the center of the rotor core 211. The output shaft 212 can be used to connect with the working parts of an oral cleaning device, such as a toothbrush head or a water flosser head, and drive the working parts of the oral cleaning device to clean the teeth and gums.

[0051] The rotor assembly 2 is at least partially located within the magnetic field generated by the stator assembly 1, so that the rotor assembly 2 can reciprocate at a predetermined angle under the action of the magnetic field generated by the energized stator assembly 1, thereby driving the brush head to perform oral cleaning operations.

[0052] When the stator assembly 1 is not energized, the rotor assembly 2 can have a balanced position that mates with the stator core 11. The rotor assembly 2 can be in this balanced position when no external force is applied; the balanced position can be the position where the rotor assembly 2 is stationary relative to the stator assembly 1; the rotor assembly being in the balanced position ensures normal motor starting. In practical applications, the number of balanced positions corresponds to the number of stator cores 11. For example, when the stator assembly 1 includes only one pair of stator cores 11, the rotor assembly 2 can include two balanced positions, which can be a first balanced position and a second balanced position. Here, the two stator cores in the pair of stator cores 11 can be mirror-symmetrical, and the first included angle between the first and second balanced positions can range from 180°-3° to 180°+3°.

[0053] Furthermore, when rotor assembly 2 is subjected to an external force, it can remain in an unbalanced position under the influence of that force. The motor in this embodiment does not have a limiting structure, allowing rotor assembly 2 to rotate at an angle greater than 360° under external force; that is, the rotation angle of rotor assembly 2 under external force can be any value. When the external force is removed, rotor assembly 2 can reset to its equilibrium position under the influence of cogging torque. Specifically, the equilibrium position of rotor assembly 2 can be determined based on the angle between the current unbalanced position and the first and second equilibrium positions. For example, when the external force is removed, rotor assembly 2 can reset towards the first or second equilibrium position with the smallest angle.

[0054] In this embodiment, because the rotor assembly 2 can rotate at any angle under external force, the user can manually rotate the brush head to any desired balance position, or to a position near any desired balance position. For example, when the bristle area on the brush head of the oral hygiene device is on the same side as the electronic display area, it is understood that the rotor assembly 2 is in one of the balance positions. When the rotor assembly is in this balance position, if the user wants to view the information in the electronic display area during brushing, they must first stop brushing and remove the oral hygiene device from their mouth. If the user finds this inconvenient, they can manually rotate the brush head 180°, so that the bristle area and the electronic display area face different sides. The user can then view the prompts displayed in the electronic display area through a mirror, avoiding the need to stop brushing and ensuring the brushing process is not affected. This satisfies the user's needs and improves the convenience of using the oral hygiene device. It is understood that after the user manually rotates the brush head 180°, the rotor assembly 2 is in another balance position.

[0055] In this embodiment, the rotor assembly 2 may include two sets of magnet assemblies 22, which may be mirror-symmetrical. Each set of magnet assemblies 22 may include a first magnet 221 and a second magnet 222, and the first magnet 221 and the second magnet 222 may be spaced apart on the power shaft 21. Specifically, the first magnet 221 and the second magnet 222 may be spaced apart on the rotor core 211 of the power shaft 21, making the magnetic field distribution on the rotor assembly 2 more uniform. This reduces cogging torque, and with the motor output torque remaining constant, increases the swing angle to extend the drive time of a single cycle, thereby reducing the frequency at which the rotor assembly 2 drives the brush head to swing and improving the user experience of using a motor-driven oral cleaning device.

[0056] In this embodiment of the specification, the rotor core 211 is further provided with a mounting groove 2111 for mounting the magnet assembly 22. Specifically, the magnets in the magnet assembly 22 can be embedded into the mounting groove using an adhesive, such as glue. Alternatively, the magnets in the magnet assembly 22 can be placed into the mounting groove by welding. The first magnet 221 and the second magnet 222 in the magnet assembly 22 can be embedded into different mounting grooves respectively, thereby fixing the magnets in the magnet assembly 22 into the mounting grooves and preventing the magnet assembly 22 from falling off the mounting grooves and affecting the normal operation of the motor.

[0057] In the embodiments described in this specification, the number of mounting slots can be set according to the number of magnet assemblies 22. Preferably, the number of magnet assemblies 22 can be 2 sets, and correspondingly, the number of mounting slots can be 4.

[0058] Figure 4 is a schematic diagram of a magnet structure provided in an embodiment of this specification. As shown in Figure 4, in this embodiment, the cross-sections of the first magnet 221 and the second magnet 222 can be arc-shaped. Specifically, both the first magnet 221 and the second magnet 222 can include an outer arc 2211 and an inner arc 2212 distributed radially, and two side edges 2213 connecting the two endpoints of the outer arc 2211 and the inner arc 2212 on the same side, respectively. The central angle corresponding to the outer arc 2211 is the same as the central angle corresponding to the inner arc 2212. The central angle corresponding to the outer arc 2211 can be the angle between two first connecting line segments formed by connecting the two endpoints of the outer arc 2211 to the center of the power shaft 21. The central angle corresponding to the inner arc 2212 can be the angle between two second line segments formed by connecting the two endpoints of the inner arc 2212 to the center of the power shaft 21. Understandably, the two first connecting segments and the two side edges 2213 can overlap, and the two second connecting segments and the two side edges 2213 can also overlap. The arc-shaped magnet can better match the shape of the air gap 5 between the rotor assembly 2 and the stator assembly 1, which helps to generate a more uniform magnetic field distribution, thereby reducing vibration and noise caused by uneven magnetic field.

[0059] In the actual construction of the motor, the width of the air gap 5 between the outer arc 2211 of the first magnet 221 and the inner arc of the stator core 11 facing the magnet assembly 22 can be set to 0.15 mm to 0.25 mm, thereby improving the fit between the rotor assembly 2 and the stator assembly 1 without affecting the normal operation of the rotor assembly 2.

[0060] In this embodiment, the thickness of both the first magnet 221 and the second magnet 222 can be set within a preset thickness range, which can be 1 mm to 2 mm. The thickness of the first magnet 221 and the second magnet 222 can be the radial distance between the outer arc 2211 and the inner arc 2212. It is understood that the radial distance between the outer arc 2211 and the inner arc 2212 can represent the shortest distance between the outer arc 2211 and the inner arc 2212. Preferably, the thickness of both the first magnet 221 and the second magnet 222 can be constructed to be 1.5 mm. The depth of the mounting groove can be set to 0.7 mm; the distance between the bottom of the mounting groove and the rotation axis can be set to 2.5 mm; the distance between the outer arc 2211 of the magnet in the magnet assembly 22 and the rotation axis is 4 mm. It is understood that a portion of the magnet in the magnet assembly 22 is exposed outside the mounting groove to enhance the fit between the rotor assembly 2 and the stator assembly 1.

[0061] In practical applications, the first magnet 221 and the second magnet 222 can both be constructed with thicknesses of 1.2 mm and 1.8 mm, respectively. The thickness of the first magnet 221 and the second magnet 222 can be determined based on the spatial distance between the power shaft 21 and the stator assembly 1. An appropriate magnet thickness can be selected to ensure that the magnets, after being arranged on the power shaft, have a certain gap with the stator assembly, while also ensuring that the magnetic field generated by the magnets meets the preset requirements. This allows for a reduction in cogging torque, an increase in the swing angle, and a reduction in frequency without affecting the rotation of the rotor assembly 2.

[0062] Figure 5 is a schematic diagram of the first and third central angle structures provided in the embodiments of this specification. As shown in Figure 5, in the embodiments of this specification, the central angle corresponding to the outer arc 2211 of the first magnet 221 and the central angle corresponding to the inner arc 2212 can be the first central angle 223, and the angle range of the first central angle 223 can be 42° to 57°; the central angle corresponding to the outer arc 2211 of the second magnet 222 and the central angle corresponding to the inner arc 2212 can be the third central angle 228, and the angle range of the third central angle 228 can be 42° to 57°. Specifically, the first magnet 221 and the second magnet 222 can both be magnets with a central angle of 49.5° corresponding to the outer arc 2211 and a central angle of 45° corresponding to the inner arc 2212; or both can be magnets with a central angle of 54° corresponding to the outer arc 2211 and a central angle of 45° corresponding to the inner arc 2212.

[0063] Figure 6 is a schematic diagram of the second included angle structure provided in the embodiment of this specification. As shown in Figure 6, in the embodiment of this specification, the central angle corresponding to the circumferential interval between the first magnet 221 and the second magnet 222 on the power shaft 21 can be a second included angle 224. The second included angle 224 can be the angle between the first connecting line segment and the second connecting line segment that are close in distance. The range of the second included angle 224 can be from 23.5° to 38°. Specifically, the central angle corresponding to the interval between the first magnet 221 and the second magnet 222 in a set of magnet assemblies 22 can be 25°, 27°, 30.5°, 34.4°, etc. It can be understood that when constructing the rotor assembly 2, the interval between the first magnet 221 and the second magnet 222 can be reasonably set to make the magnetic field generated by the magnet assembly 22 more uniform, thereby reducing the cogging torque, increasing the swing angle, and reducing the frequency of the rotor.

[0064] Furthermore, the fourth included angle 226 between the two sets of magnet assemblies 22 can be greater than the second included angle 224 between the first magnet 221 and the second magnet 222 within the magnet assembly 22. This allows a stator core 11 and a magnet assembly 22 to cooperate with each other, avoiding abnormal influence on adjacent magnet assemblies 22 that could prevent the motor from operating normally.

[0065] Figure 7 is a schematic diagram of the third included angle structure provided in the embodiment of this specification. As shown in Figure 7, in the embodiment of this specification, in a plane perpendicular to the rotation axis of the rotor assembly 2, the included angle between the center line of the first magnet 221 and the center line of the second magnet 222 can be a third included angle 225. The center line of the first magnet 221 can be a line pointing from the center of the first magnet 221 to the rotation axis; the center line of the second magnet 222 can be a line pointing from the center of the second magnet 222 to the rotation axis. The rotation axis can be the center line of the power shaft 21, and understandably, it is also the center line of the output shaft 212. The center line of the first magnet 221 can be perpendicular to the rotation axis; the center line of the second magnet 222 can also be perpendicular to the rotation axis. The range of the third included angle 225 can be from 73° to 87°, specifically, the third included angle 225 can be set to 75°, 79°, 83°, 85°, etc. In practical applications, the size of the third included angle 225 can also be set based on actual needs, and no specific limitation is made here.

[0066] Figure 8 is a schematic diagram of the fifth included angle structure provided in the embodiment of this specification. As shown in Figure 8, in the embodiment of this specification, the included angle formed by the two outer boundaries of the magnet assembly 22 extending to the rotation axis of the rotor assembly 2 can be a fifth included angle 229, and the range of the fifth included angle 229 can be from 122° to 141°. Specifically, the fifth included angle 229 can be 127°, 127.5°, or 136°. The above-mentioned included angle range can make the proportion occupied by a set of magnet assemblies 22 on the power shaft 21 more reasonable, avoiding the proportion of a set of magnet assemblies 22 on the power shaft 21 being too large, thereby causing the rotor assembly 2 to be unable to reciprocate; at the same time, it avoids the proportion of a set of magnet assemblies 22 on the power shaft 21 being too small, thereby reducing the fit between the rotor assembly 2 and the stator assembly 1, and thus causing the rotor assembly 2 to fail to operate normally.

[0067] Figure 9 is a schematic diagram of the second central angle structure provided in the embodiment of this specification. As shown in Figure 9, in the embodiment of this specification, in a plane perpendicular to the rotation axis of the rotor assembly 2, the ratio of the first central angle 223 corresponding to the outer arc 2211 of the first magnet 221 facing the stator core 11 to the second central angle 227 corresponding to the inner arc of the stator core 11 facing the magnet assembly 22 can range from 60% to 85%; the ratio of the third central angle 228 corresponding to the outer arc 2211 of the second magnet 222 facing the stator core 11 to the second central angle 227 corresponding to the inner arc of the stator core 11 facing the magnet assembly 22 can also range from 60% to 85%. In addition, when the shape, size, and structure of the second magnet 222 and the first magnet 221 are the same, the size of the third central angle 228 corresponding to the outer arc 2211 of the second magnet 222 facing the stator core 11 is the same as the size of the first central angle 223. By setting a reasonable ratio range between the central angle corresponding to the outer arc 2211 of a single magnet and the second central angle 227 corresponding to the inner arc of the stator core, the cogging torque can be reduced, the swing angle increased, and the vibration frequency of the motor reduced.

[0068] In practical applications, the cogging torque can be reduced and the swing angle increased by setting a reasonable ratio range between the arc length of the outer arc 2211 of a single magnet and the arc length of the inner arc of the stator core 11. Specifically, in a plane perpendicular to the rotation axis of the rotor assembly 2, the ratio range between the arc length of the outer arc 2211 of the first magnet 221 facing the stator core 11 and the arc length of the inner arc of the stator core 11 facing the magnet assembly 22 can be set to 60% to 70%; the ratio range between the arc length of the outer arc 2211 of the second magnet 222 facing the stator core 11 and the arc length of the inner arc of the stator core 11 facing the magnet assembly 22 can also be set to 60% to 70%. The arc length of the inner arc of the stator core 11 facing the magnet assembly 22 may include the chamfered portion of the stator core 11; it may also exclude the chamfered portion of the stator core 11, depending on the actual structural requirements of the motor.

[0069] Figure 10 is a schematic diagram of the fourth central angle structure provided in the embodiment of this specification. As shown in Figure 10, in this embodiment, when the rotor assembly 2 is in the equilibrium position, the first magnet 221 and the second magnet 222 are located on both sides of the stator core 11. The radial center projections of the first magnet 221 and the stator core 11 partially overlap, and the radial center projections of the second magnet 222 and the stator core 11 also partially overlap. The ratio of the fourth central angle 230 corresponding to the overlapping portion of the projections of the first magnet 221 and the stator core 11 to half of the second central angle 227 corresponding to the inner arc of the stator core 11 facing the magnet assembly 22 can be between 40% and 70%; and / or, the ratio of the fifth central angle 231 corresponding to the overlapping portion of the projections of the second magnet 222 and the stator core 11 to half of the second central angle 227 corresponding to the inner arc of the stator core 11 facing the magnet assembly 22 can also be between 40% and 70%. And / or, the fourth central angle 230 is the same as the fifth central angle 231. The central projection can be the projection of the first magnet 221, the second magnet 222 and the stator core 11 with a point on the rotation axis as the projection center when the rotor assembly 2 is in the equilibrium position.

[0070] In the actual construction of the motor, the width of the air gap 5 between the outer arc 2211 of the first magnet 221 and the inner arc of the stator core 11 facing the magnet assembly 22 can be set to 0.15 mm to 0.25 mm, thereby improving the fit between the rotor assembly 2 and the stator assembly 1 without affecting the normal operation of the rotor assembly 2.

[0071] In another implementation, the ratio of the fourth central angle 230 corresponding to the overlapping portion of the projections of the first magnet 221 and the stator core 11 to the first central angle 223 corresponding to the outer arc 2211 of the first magnet 221 facing the stator core 11 can be a first ratio, and the range of the first ratio can be 30% to 45%. The ratio of the fifth central angle 231 corresponding to the overlapping portion of the projections of the second magnet 222 and the stator core 11 to the third central angle 228 corresponding to the outer arc 2211 of the second magnet 222 facing the stator core 11 can be a second ratio, and the range of the second ratio can also be 30% to 45%. In addition, when the second magnet 222 and the first magnet 221 have the same shape, size and structure, and the first magnet 221 and the second magnet 222 are symmetrically arranged along the horizontal axis, the size of the fifth central angle 231 is the same as the size of the fourth central angle 230, and the first ratio and the second ratio are also the same. The first ratio and the second ratio can be values ​​such as 35%, 37%, 40% to improve the fit between the stator core 11 and the magnet assembly 22.

[0072] In this embodiment, the electromagnetic coil 4 can respond to a control signal applied to it. At this time, the stator core 11 can cause the rotor assembly 2 to rotate relative to the stator core 11 around its rotation axis. The unidirectional rotation angle of the rotor assembly 2 relative to the stator core 11 around its rotation axis can range from 0° to 20°; correspondingly, the bidirectional rotation angle of the rotor assembly 2 relative to the stator core 11 around its rotation axis can range from 0° to 40°. This larger swing angle helps meet the teeth-cleaning needs of different consumers. Furthermore, the motor's operating frequency range is 100 Hz to 180 Hz; it can further stabilize and operate normally between 140 Hz and 150 Hz. Reducing the motor's vibration frequency can avoid the prominent toothache and tooth sensitivity caused by high-frequency vibration, and can also avoid increased motor noise caused by high-frequency vibration, thus improving the user experience of oral cleaning equipment with this type of motor.

[0073] Figure 11 is a schematic diagram showing the distribution of simulation data of motor cogging torque in the embodiments of this specification; Figure 12 is a schematic diagram showing the distribution of simulation data of motor torque in the embodiments of this specification; the specific parameters of the test samples in Figures 11 and 12 are as follows:

[0074] Scheme A is represented by the dotted and dashed lines in Figure 11 and Figure 12; the central angles of the first magnet 221 and the second magnet 222 in the magnet assembly are both 49.5°, that is, the central angles of the outer arc 2211 and the inner arc 2212 of the first magnet 221 and the second magnet 222 are both 49.5°; the second included angle 224 between the first magnet and the second magnet is 28.5°; the magnet thickness is constructed to be 1.5 mm; the mounting groove depth is constructed to be 0.7 mm; the angle of the fourth included angle 226 between the two magnet assemblies 22 is constructed to be 52.5°.

[0075] Scheme B, represented by the solid lines in Figure 11 and Figure 12, features a first magnet 221 and a second magnet 222 with central angles of 45°. Specifically, the central angles of the outer arc 2211 and the inner arc 2212 of the first magnet 221 and the second magnet 222 are both 45°. The second included angle 224 between the first magnet 221 and the second magnet 222 is 37°. The magnet thickness is 1.5 mm. The mounting groove depth is 0.7 mm. The fourth included angle 226 between the two magnet assemblies 22 is 53°.

[0076] Scheme C, represented by the dashed lines in Figure 11 and Figure 12, features a first magnet 221 and a second magnet 222 with central angles of 54°. Specifically, the central angles of the outer arc 2211 and the inner arc 2212 of the first magnet 221 and the second magnet 222 are both 54°. The second included angle 224 between the first magnet 221 and the second magnet 222 is 28°. The magnet thickness is 1.5 mm. The mounting groove depth is 0.7 mm. The angle of the fourth included angle 226 between the two magnet assemblies 22 is 44°.

[0077] It is understandable that as the rotation angle of the rotor assembly 2 in the motor changes, the cogging torque of the motor will also change. Figure 11 is used to illustrate the relationship between the cogging torque of the motor and the rotor assembly 2 in the motor. The horizontal axis in Figure 11 can represent the rotation angle of the rotor assembly 2 in the motor; the vertical axis can represent the cogging torque corresponding to the rotation angle of the rotor assembly 2.

[0078] For motors used in oral hygiene devices such as electric toothbrushes, the electromagnetic torque and cogging torque resist each other during the motor's oscillation. By reducing the cogging torque, it is beneficial to increase the oscillation angle under the same electromagnetic torque, while simultaneously shifting the resonant frequency downwards. Through simulation testing of the motor in the embodiment of this specification, Figure 12 shows the experimental data obtained under a 0.5A forward current load. The horizontal axis represents the rotation angle of the rotor assembly; the vertical axis represents the motor torque. As can be seen from the distribution diagrams of motor torque simulation data shown in Figure 12 and cogging torque simulation data shown in Figure 11, the zero-position torque of scheme A is 9.03 mN.m and the NR position is 8.04°; the zero-position torque of scheme B is 8.23 ​​mN.m and the NR position is 9.71°; and the zero-position torque of scheme C is 9.6 mN.m and the NR position is 9.16°. Based on this, the zero-position torque of the motor in the embodiments of this specification is low. This is because the modified electromagnetic structure significantly reduces the cogging torque and also has a certain impact on the starting torque at the equilibrium position. The NR position angle is increased, that is, the position angle at which the electromagnetic torque and the cogging torque cancel each other out to 0. This is beneficial for a larger swing angle and a lower resonant frequency.

[0079] In this embodiment of the specification, when the motor is in a no-load state (I = 0A), the rotor is stationary at the zero position with no output torque. When a positive current is applied, the rotor assembly 2 generates a negative zero-position torque and rotates in this direction until it reaches the position where the natural return NR output torque equals 0 Nm, and then shifts to the positive direction. Afterwards, if a positive holding current is applied, the rotor assembly will rotate backward around the NR position and stop at the preset NR position. If a negative current is applied, the direction of rotation of the rotor assembly 2 can be opposite to the direction of rotation when a positive current is applied, thereby applying alternating current to make the rotor assembly 2 in the motor reciprocate.

[0080] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0081] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0082] It should be noted that the terms "first," "second," etc., in the specification, claims, and drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0083] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. An electric motor used in oral hygiene equipment, characterized in that, The motor includes: a stator assembly and a rotor assembly; A stator assembly is arranged to generate a magnetic field, wherein the stator assembly includes at least one pair of stator cores uniformly distributed in a circumferential direction; A rotor assembly, at least partially arranged within the magnetic field of the stator assembly, the rotor assembly including a drive shaft and a magnet assembly disposed on the drive shaft and cooperating with the stator core; The stator core is configured to drive the rotor assembly to reciprocate at a predetermined angle when energized; when de-energized, the rotor assembly is configured to rotate at an angle greater than 360° when subjected to external force. The rotor assembly has a balanced position that mates with the stator core, and an unbalanced position that deviates from the stator core; in the unbalanced position, the rotor assembly is configured to return to the balanced position under the action of cogging torque after the external force is removed.

2. The motor according to claim 1, characterized in that, The number of balance positions is configured to correspond to the number of stator cores; the balance positions include at least a first balance position and a second balance position corresponding to a pair of stator cores respectively; In an unbalanced position, the magnet assembly is configured to reset toward the first or second balance position with the smallest angle, depending on the angle between the current position and the first or second balance position.

3. The motor according to claim 1, characterized in that, The stator assembly includes two stator cores that are mirror-symmetrical; the rotor assembly includes two sets of magnet assemblies that are mirror-symmetrical.

4. The motor according to claim 1, characterized in that, The angle between the first equilibrium position and the second equilibrium position is constructed as the first angle, and the range of the first angle is 180°-3° to 180°+3°.

5. The motor according to claim 1, characterized in that, The magnet assembly includes a first magnet and a second magnet, which are spaced apart on the power shaft.

6. The motor according to claim 5, characterized in that, Both the first magnet and the second magnet are arc-shaped, including an outer arc and an inner arc distributed radially, and two side edges that connect the corresponding ends of the outer arc and the inner arc, respectively.

7. The motor according to claim 6, characterized in that, The first magnet and the second magnet are arranged circumferentially around the power shaft, and the central angle corresponding to the interval between the first magnet and the second magnet is the second included angle; the range of the second included angle is 23.5° to 38°.

8. The motor according to claim 6, characterized in that, In a plane perpendicular to the rotation axis of the rotor assembly, the third angle between the centerline of the first magnet and the centerline of the second magnet ranges from 73° to 87°; the centerline of the first magnet is the centerline pointing from the center of the first magnet to the rotation axis of the rotor assembly, and the centerline of the second magnet is the centerline pointing from the center of the second magnet to the rotation axis.

9. The motor according to claim 6, characterized in that, In a plane perpendicular to the rotation axis of the rotor assembly, the ratio of the first central angle corresponding to the outer arc of the first magnet facing the stator core to the second central angle corresponding to the inner arc of the stator core facing the magnet assembly ranges from 60% to 85%.

10. The motor according to claim 6, characterized in that, In a plane perpendicular to the rotation axis of the rotor assembly, the ratio of the third central angle corresponding to the outer arc of the second magnet facing the stator core to the second central angle corresponding to the inner arc of the stator core facing the magnet assembly ranges from 60% to 85%.

11. The motor according to claim 2, characterized in that, The motor also includes an output shaft, one end of which is connected to the brush head of the electric toothbrush.

12. An oral hygiene device, characterized in that, The oral cleaning device has a motor as described in any one of claims 1-11.

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