Axial positioning structure of motor shaft and electric toothbrush

Abstract

The utility model provides an axial positioning structure of a motor shaft, which comprises a motor assembly, the motor assembly comprises a shaft core, a feedback assembly and an induction piece, and the feedback assembly is fixedly sleeved on the shaft core; the feedback assembly comprises a fixing sleeve, a bearing and a feedback piece, the bearing is fixedly arranged at one end of the fixing sleeve, and the feedback piece is fixedly arranged at the other end of the fixing sleeve, so that the feedback assembly is fixed into an integrated structure; the sensing piece is arranged at one end, far away from the fixed sleeve, of the feedback piece, and the sensing piece and the feedback piece are arranged at an interval; the bearing and the feedback piece are firstly installed at the two ends of the fixing sleeve to form the feedback assembly of the integrated structure, then the feedback assembly is pressed on the shaft core at a time, the installation space occupied by the bearing and the fixing sleeve for the shaft core is optimized, the installation precision and the installation efficiency of the feedback assembly are further improved, and the installation cost is reduced. Therefore, the installation loss of the motor assembly of the electric toothbrush is greatly reduced, and the production efficiency is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of electric toothbrushes, and particularly relates to an axial positioning structure of a motor shaft and an electric toothbrush. Background Art

[0002] In daily life, with the improvement of people's living quality, electric toothbrushes have become an indispensable daily necessity for most people. An electric toothbrush includes a brush head and a handle. A motor is provided inside the handle. Under the rapid rotation of the motor movement, the brush head rotates or swings rapidly to achieve the purpose of tooth cleaning.

[0003] In the prior art, an inductor is usually arranged on the motor movement, a sensor for detecting the position of the inductor is arranged inside the handle housing, and the rotation speed of the motor is controlled by detecting the position change of the inductor through the sensor, so as to achieve the purpose of controlling the rotation or swinging rate of the brush head. Since the inductor needs to rotate at a high speed along with the motor movement, the installation structure of the inductor seriously affects the detection accuracy of the sensor.

[0004] For example, in the Chinese utility model patent CN219814387U, a motor assembly of an electric toothbrush is disclosed, which includes an output shaft, a bearing, a mounting seat, a position feedback member and a position sensor. The mounting seat is fixedly sleeved on the output shaft and a position feedback member is installed at its bottom. A position sensor is installed at an interval below the position feedback member. At the same time, the bearing is fixedly sleeved on the output shaft and abuts against the top of the mounting seat to improve the rotation stability of the position feedback member. However, both the bearing and the mounting seat are fixedly connected to the output shaft. During the installation process, it is necessary to first press-fit the output shaft through the bearing and then through the mounting seat. Once it is found that the installation position error of the mounting seat is relatively large, it is necessary to readjust the installation positions of the bearing and the mounting seat. And since the connection method between the bearing and the mounting seat is interference fit or bonding, it increases the difficulty of position adjustment for the position feedback member and is not conducive to the quick positioning and installation of the position feedback member. Summary of the Utility Model

[0005] (1) Technical Problems to be Solved

[0006] The utility model provides an axial positioning structure of a motor shaft and an electric toothbrush, aiming to solve the problems of unreasonable installation structures of the inductor and the sensor in the prior art, resulting in great assembly difficulty and inaccurate sensor detection.

[0007] (2) Technical Solutions

[0008] The utility model provides an axial positioning structure for a motor shaft, which comprises a motor assembly. The motor assembly includes a shaft core, a feedback assembly and an induction component. The feedback assembly is fixedly sleeved on the shaft core. Wherein, the feedback assembly includes a fixed sleeve, a bearing and a feedback component. The bearing is fixedly arranged at one end of the fixed sleeve, and the feedback component is fixedly arranged at the other end of the fixed sleeve, so that the feedback assembly is fixed into an integral structure. The induction component is arranged at one end of the feedback component away from the fixed sleeve, and the two are arranged at an interval.

[0009] Further, an upward convex ring is arranged at one end of the fixed sleeve, and a downward convex ring is arranged at the other end. The bearing is fixedly sleeved on the upward convex ring, and the feedback component is fixedly sleeved on the downward convex ring.

[0010] Further, the bearing is in interference connection with the upward convex ring, and the feedback component is adhesively connected and / or in interference connection with the fixed sleeve.

[0011] Further, a first step is arranged between the upward convex ring and the downward convex ring of the fixed sleeve. The bearing includes an inner ring and an outer ring. During installation, the bottom of the inner ring of the bearing abuts against the top surface of the first step, and the top of the feedback component abuts against the bottom surface of the first step.

[0012] Further, the motor assembly further includes a housing. The shaft core is rotatably arranged in the housing. A support member and the circuit board are arranged at the bottom of the housing. The support member is located between the housing and the circuit board. A cavity is arranged in the middle of the support member. The feedback assembly is arranged in the cavity. The induction component is fixedly connected to the top surface of the circuit board and corresponds to the feedback component in position.

[0013] Further, inside the housing, a support sleeve abuts against the top of the support member. The support sleeve includes a downward concave installation cavity and a ring-shaped support platform. A through hole is arranged at the bottom of the installation cavity. The installation cavity is arranged in the cavity. The bearing is arranged in the installation cavity. At least a part of the outer side wall of the installation cavity abuts against the inner side wall of the support member.

[0014] Further, the fixed sleeve includes a fixed hole. The fixed hole includes a fastening part and a guiding part that has a guiding effect on the shaft core. The diameter D1 of the guiding part is larger than the diameter D2 of the fastening part. During installation, there is a gap between the outer wall of the shaft core and the inner wall of the guiding part, and the shaft core is in interference connection with the fastening part.

[0015] Further, the feedback component is a ring-shaped magnet. There are two induction components on the circuit board, and the induction components are Hall sensors corresponding to the feedback component.

[0016] Further, the material of the fixed sleeve is copper or aluminum.

[0017] The present utility model also provides an electric toothbrush, including the axial positioning structure of the motor shaft as described above.

[0018] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0019] The innovation of the present utility model lies in that by first respectively installing the bearing and the feedback member at both ends of the fixed sleeve to form an integrated feedback assembly, and then press-fitting the feedback assembly onto the shaft core at one time, not only the installation space of the bearing and the fixed sleeve occupying the shaft core is optimized, but also while ensuring good stability of the feedback assembly on the shaft core, the installation accuracy and installation efficiency of the feedback assembly are further improved, thereby greatly reducing the installation loss of the electric toothbrush motor assembly, and further improving the production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a structural schematic diagram of the present utility model.

[0021] Figure 2 is an exploded view of the present utility model.

[0022] Figure 3 is an overall cross-sectional view of the present utility model.

[0023] Figure 4 is an exploded view of the feedback assembly of the present utility model.

[0024] Figure 5 is a cross-section of the feedback assembly of the present utility model Figure 1 .

[0025] Figure 6 is a partial exploded view of the present utility model.

[0026] Figure 7 is a partial cross-sectional view of the present utility model.

[0027] Figure 8 is a structural schematic diagram of the outer shell and the support sleeve of the present utility model.

[0028] Figure 9 is a cross-section of the feedback assembly of the present utility model Figure 2 .

[0029] Reference numerals: 1 - motor assembly, 2 - shaft core, 21 - drive assembly, 22 - housing, 221 - limiting groove, 3 - feedback assembly, 31 - fixing sleeve, 311 - upper convex ring, 312 - lower convex ring, 313 - first step, 314 - fixing hole, 3141 - guiding portion, 3142 - fastening portion, 32 - bearing, 321 - inner ring, 322 - outer ring, 33 - feedback member, 4 - support member, 41 - cavity, 42 - second step, 43 - positioning post, 5 - circuit board, 51 - sensing member, 6 - support sleeve, 61 - installation cavity, 611 - through hole, 62 - support platform, 63 - positioning hole, 64 - limiting projection, 65 - third step, 7 - screw, 8 - gap. Detailed implementation manner

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0031] As Figures 1-3 shown, the present invention provides an axial positioning structure for a motor shaft, including a motor assembly 1, the motor assembly 1 includes a shaft core 2, a drive assembly 21, a feedback assembly 3 and a sensing member 51, the drive assembly 21 is fixedly sleeved on the shaft core 2 for driving the shaft core 2 to rotate; the feedback assembly 3 is fixedly sleeved on the shaft core 2 and is located on one side of the drive assembly 21, the feedback assembly 3 includes a fixing sleeve 31, a bearing 32 and a feedback member 33, the bearing 32 is fixedly arranged at one end of the fixing sleeve 31, and the feedback member 33 is fixedly arranged at the other end of the fixing sleeve 31, so that the feedback assembly 3 is fixed into an integral structure; the sensing member 51 is spaced from the end of the feedback member 33 away from the fixing sleeve 31, that is, there is a gap between the sensing member 51 and the feedback member 33; at the same time, the motor assembly 1 further includes a circuit board 5, and the circuit board 5 is electrically connected to the drive assembly 21 and the sensing member 51 respectively;

[0032] During use, under the control of the circuit board 5, the drive assembly 21 drives the shaft core 2 to rotate at a high speed, thereby driving the feedback assembly 3 to rotate. At this time, the feedback member 33 rotates at a high speed and generates a distance change with the sensing member 51, so that the sensing member 51 is sensed and generates an electrical signal (not shown), the electrical signal is transmitted into the circuit board 5, and the circuit board 5 identifies and judges the electrical signal, so as to adjust the output power of the drive assembly 21;

[0033] It should be noted that the setting of the bearing 32 can effectively reduce the rotational resistance of the shaft core 2, so that the shaft core 2 can obtain a higher rotational speed. At the same time, it can also improve the rotational stability of the shaft core 2 and prevent the rotational axis of the shaft core 2 from shifting due to excessive rotational speed. Therefore, the bearing 32 is an important component of the motor assembly 1. In the prior art, the bearing 32 and the fixing sleeve 31 are usually sleeved on the shaft core 2 respectively. However, this method usually causes the following two problems. One is that it increases the installation space of the bearing 32 and the fixing sleeve 31 on the shaft core 2, resulting in the need to increase the axial length of the motor assembly 1 or compress the volume of the internal components of the motor assembly 1, greatly reducing the convenience of use and the installation convenience for consumers. The other is that during the installation process, when the position of the fixing sleeve 31 is installed incorrectly, it is necessary to repeatedly adjust the axial positions of the bearing 32 and the fixing sleeve 31, thereby reducing the production efficiency and the installation accuracy.

[0034] In order to effectively solve the above problems, as Figures 4-5 shown, the upper end of the fixing sleeve 31 is provided with an upwardly protruding upper convex ring 311, and the bearing 32 is sleeved on the upper convex ring 311. Among them, the bearing 32 includes an inner ring 321 and an outer ring 322. When installed, the inner ring 321 of the bearing 32 and the outer peripheral wall of the upper convex ring 311 can be in interference fit or glued, or interference fit can be used on the basis of gluing, so that the bearing 32 and the fixing sleeve 31 are fixed into an integral structure, thereby preventing the bearing 32 and the fixing sleeve 31 from separating under the high-speed rotation of the shaft core 2, and further improving the connection firmness of the feedback assembly 3.

[0035] Furthermore, the feedback member 33 is fixedly connected to the lower end surface of the fixing sleeve 31 by bonding. The method of gluing is convenient for the quick assembly of the feedback member 33 and the fixing sleeve 31, and improves the production efficiency.

[0036] In addition to the above-mentioned gluing method, in another embodiment, the lower end of the fixing sleeve 31, that is, the end far from the bearing 32, is provided with a downwardly protruding lower convex ring 312, and the feedback member 33 is sleeved on the lower convex ring 312. The inner wall of the feedback member 33 and the peripheral wall of the lower convex ring 312 can be connected by interference fit, or by gluing the outer surface of the fixing sleeve 31, or by a combination of interference fit and gluing, so that the feedback member 33 is fixedly connected to the end of the fixing sleeve 31 far from the bearing 32. Through the design of the lower convex ring 312 and interference fit and bonding, the installation of the feedback member 33 is more convenient and can more effectively improve the rotational stability of the feedback member 33.

[0037] By first fixedly sleeving the bearing 32 and the feedback member 33 on the upper end and the lower end of the fixed sleeve 31 respectively, the feedback assembly 3 is fixed into an integral structure. Then, the shaft core 2 is press-fitted through the feedback assembly 3, so that the feedback member 33 can be more accurately installed on the shaft core 2 and a one-step press-fitting is realized. This effectively solves the problem in the prior art that when the position error of the feedback member 33 is found, it is necessary to re-press-fit and adjust each component one by one, resulting in difficult adjustment. Therefore, the integral structure of the feedback assembly 3 can effectively improve the installation accuracy and installation convenience of the motor assembly 1. At the same time, since both the bearing 32 and the feedback member 33 are sleeved on the fixed sleeve 31, the axial space of the shaft core 2 in the motor assembly 1 is effectively saved, thereby reducing the production cost.

[0038] Furthermore, in order to improve the installation convenience and stability of the bearing 32 and the feedback member 33 on the fixed sleeve 31, a first step 313 is further provided on the fixed sleeve 31 between the upper convex ring 311 and the lower convex ring 312. The diameter of the first step 313 is greater than the outer wall diameter of the upper convex ring 311 or the outer wall diameter of the lower convex ring 312. During installation, the bearing 32 is press-fitted on the upper convex ring 311, the bottom of the inner ring 321 of the bearing 32 abuts against the top surface of the first step 313, the feedback member 33 is installed on the lower convex ring 312, and the top of the feedback member 33 abuts against the bottom surface of the first step 313. The setting of the first step 313 not only facilitates the accurate positioning and installation of the bearing 32 and the feedback member 33, but also has a limiting effect on the bearing 32 and the feedback member 33 in the axial direction of the shaft core 2 during high-speed rotation, thereby improving the rotation stability of the bearing 32 and the feedback member 33, and further improving the detection accuracy of the sensing member 51.

[0039] Preferably, the top diameter of the first step 313 is smaller than the outer diameter of the outer ring 322 of the bearing 32. Therefore, during installation, only the bottom of the inner ring 321 of the bearing 32 abuts against the top of the first step 313, which does not affect the rotation of the bearing 32.

[0040] Specifically, as Figures 6-8As shown, the motor assembly 1 further includes a housing 22. The shaft core 2 is rotatably arranged within the housing 22, and both ends of the shaft core 2 extend to the outside of the housing 22. A support member 4 and the circuit board 5 are provided at the bottom of the housing 22. The support member 4 is located between the housing 22 and the circuit board 5. The top of the support member 4 abuts against the bottom of the housing 22, and the bottom of the support member 4 abuts against the top of the circuit board 5. The support member 4 is of an annular structure and has a cavity 41 in the middle. During installation, the feedback assembly 3 is arranged within the cavity 41, and the sensing member 51 is fixedly connected to the top surface of the circuit board 5 and corresponds to the position of the feedback member 33.

[0041] Furthermore, a support sleeve 6 is further provided at the top of the support member 4. The middle of the support sleeve 6 is provided with a downwardly recessed installation cavity 61, so that the top of the support sleeve 6 forms an annular support platform 62. A through hole 611 is provided at the bottom of the installation cavity 61. The diameter of the through hole 611 is smaller than the outer diameter 322 of the bearing 32 and larger than the diameter of the first step 313 of the fixing sleeve 31. During installation, the shaft core 2 and the fixing sleeve 31 pass through the support sleeve 6 through the through hole 611, and the bearing 32 is arranged within the installation cavity 61. At this time, the bottom wall of the installation cavity 61 abuts against the bottom wall of the outer ring 322 of the bearing 32. At the same time, the outer ring 322 of the bearing 32 and the inner wall of the installation cavity 61 can be fixed by gluing or interference fit. Since there is a gap between the inner wall of the installation cavity 61 and the inner ring 321 of the bearing 32 and they do not contact, the setting of the support sleeve 6 does not affect the rotation of the shaft core 2.

[0042] Even further, a ring-shaped second step 42 is provided at the top of the support member 4. The inner diameter of the inner side wall of the second step 42 corresponds to the outer diameter of the installation cavity 61. During installation, the inner side wall of the second step 42 abuts against the outer wall of the installation cavity 61, so as to realize the horizontal fixation of the support sleeve 6, thereby improving the rotation stability of the bearing 32 and the feedback member 33, and further improving the detection accuracy of the sensing member 51.

[0043] Preferably, a positioning post 43 is provided at the top of the second step 42, and the support platform 62 is provided with a positioning hole 63 corresponding to the positioning post 43. During installation, the positioning post 43 passes through the positioning hole 63, so as to realize the relative fixation between the support sleeve 6 and the support member 4. It should be noted that the positioning post 43 and the positioning hole 63 can be interchanged between the support platform 62 and the second step 42.

[0044] More preferably, a third step 65 is provided on the inner wall of the bottom of the outer shell 22. During installation, the top of the support platform 62 abuts against the bottom of the third step 65, the peripheral wall of the support platform 62 abuts against the side wall of the outer shell 22 below the third step 65, and the bottom of the support platform 62 abuts against the support member 4, thereby realizing multi-directional locking of the support sleeve 6 and further improving the rotational stability of the bearing 32, the shaft core 2, and the feedback member 33;

[0045] Furthermore, a limiting protrusion 64 is provided on the peripheral wall of the support platform 62, and the outer shell 22 is provided with a limiting groove 221 corresponding to the limiting protrusion 64. The limiting groove 221 has a guiding effect on the installation of the support sleeve 6 and a limiting effect on the rotation in the horizontal direction;

[0046] During installation, the limiting protrusion 64 of the support platform 62 is correspondingly arranged in the limiting groove 221 and moves along the direction of the shaft core 2 along the limiting groove 221 until its top abuts against the third step 65, thereby completing the installation of the support sleeve 6 and the outer shell 22. Then, the support member 4 is correspondingly installed through the corresponding arrangement of the positioning post 43 and the positioning hole 63. Finally, after installing the circuit board 5 at the bottom of the support member 4, the three are fixedly connected by using a screw 7 passing through the circuit board 5, the support member 4, and the support sleeve 6.

[0047] Specifically, as Figure 9 shown, the fixing sleeve 31 includes a fixing hole 314. The fixing sleeve 31 is sleeved on the shaft core 2 through the fixing hole 314. The fixing hole 314 includes a guiding portion 3141 and a fastening portion 3142. The guiding portion 3141 is arranged at the upper end or the lower end of the fastening portion 3142. When the shaft core 2 is press-fitted with the fixing sleeve 31, the end of the shaft core 2 first passes through the guiding portion 3141 and then through the fastening portion 3142 and is finally fixedly connected with the fastening portion 3142;

[0048] Furthermore, the diameter D1 of the guiding portion 3141 is slightly larger than the diameter D2 of the fastening portion 3142 and the diameter of the shaft core 2, so that there is a gap 8 between the outer wall of the shaft core 2 and the inner wall of the guiding portion 3141; at the same time, the diameter D2 of the fastening portion 3142 is slightly smaller than the diameter of the shaft core 2, thereby realizing an interference fit between the fastening portion 3142 and the shaft core 2; due to the existence of the gap 8 between the shaft core 2 and the guiding portion 3141, when the shaft core 2 is press-fitted with the fixing sleeve 31, the guiding portion 3141 has a guiding effect on the press-fitting of the shaft core 2, greatly reducing the press-fitting force when the shaft core 2 is pressed into the fixing sleeve 31, and effectively preventing the shaft core 2 from being bent during press-fitting, thereby improving the press-fitting success rate and installation convenience of the shaft core 2;

[0049] Further, in order to balance the guiding space between the shaft core 2 and the guiding portion 3141 and the fastening force of the fastening portion 3142 on the shaft core 2, in the length direction of the shaft core 2, the length L1 of the guiding portion 3141 accounts for 10%-50% of the total length L2 of the fixing sleeve 32;

[0050] Preferably, the length L1 of the guiding portion 3141 accounts for 40% of the total length L2 of the fixing sleeve 32.

[0051] Specifically, the feedback member 33 is a magnet having at least two magnetic poles and is in a ring structure, and there are two induction members 51 provided on the circuit board 5, and the induction members 51 are Hall sensors corresponding to the magnet; during operation, the shaft core 2 drives the feedback member 33 to rotate, and different rotation speeds cause the Hall sensors to generate different electrical signals, so as to achieve the purpose of detecting the rotation speed of the shaft core 2, and further, the rotation speed of the shaft core 2 can be adjusted through the regulation of the circuit board 5;

[0052] Preferably, the feedback member 33 and the induction member 51 can also detect the rotation speed of the shaft core 2 by means of infrared induction;

[0053] Specifically, the fixing sleeve 31 is made of plastic material or non-magnetic (i.e., cannot be adsorbed by a magnet) metal material, the plastic material or metal material has good toughness, the fixing sleeve 31 can be in interference fit with the shaft core 2 through slight deformation to complete the fixation with the shaft core 2, and at the same time, the elastic force generated by the deformation can further strengthen the fastening force of the fixing sleeve 31 on the shaft core 2;

[0054] More preferably, the fixing sleeve 31 is made of copper or aluminum material.

[0055] The present utility model also provides an electric toothbrush, and the electric toothbrush includes the axial positioning structure of the motor shaft.

[0056] The following is a detailed description of the working principle of the present utility model;

[0057] During installation, first install the bearing 32 and the feedback member 33 at both ends of the fixing sleeve 31 to form an integral structure, and then use a press-fitting machine (not shown) to press-fit the shaft core 2 into the fixing hole 314 of the fixing sleeve 31, so as to complete the precise and rapid press-fitting of the feedback assembly 3, and then install the driving assembly 21 and the shaft core 2 together into the housing 22, and then install the support sleeve 6, the support member 4 and the circuit board 5 in sequence from the bottom of the housing 22, and finally fix the three together with screws 7 to complete the overall installation of the motor assembly 1. The installation process is simple and convenient, effectively improving the installation accuracy and installation efficiency of the motor assembly 1.

[0058] The innovation of the present utility model lies in that by first separately installing a bearing and a feedback member at both ends of a fixed sleeve to form an integrated feedback assembly, and then press-fitting the feedback assembly onto the shaft core at one time, not only the installation space of the shaft core occupied by the bearing and the fixed sleeve is optimized, but also while ensuring good stability of the feedback assembly on the shaft core, the installation accuracy and installation efficiency of the feedback assembly are further improved, thereby greatly reducing the installation loss of the electric toothbrush motor assembly and further improving the production efficiency.

[0059] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

[0060] For those skilled in the art, it is obvious that the present utility model is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present utility model. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present utility model is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes falling within the meaning and scope of the equivalent elements of the claims in the present utility model. Any reference signs in the claims should not be regarded as limiting the claimed rights.

Claims

1. An axial positioning structure for a motor shaft, characterized in that: The motor assembly (1) comprises a shaft core (2), a feedback assembly (3) and an induction element (51), wherein the feedback assembly (3) is fixedly sleeved on the shaft core (2); The feedback component (3) comprises a fixed sleeve (31), a bearing (32) and a feedback member (33); the bearing (32) is fixedly arranged at one end of the fixed sleeve (31), and the feedback member (33) is fixedly arranged at the other end of the fixed sleeve (31), so that the feedback component (3) is fixed into an integrated structure; the sensing member (51) is arranged at one end of the feedback member (33) away from the fixed sleeve (31), and the two are arranged at an interval.

2. The axial positioning structure of a motor shaft according to claim 1, characterized in that: One end of the fixed sleeve (31) is provided with an upper convex ring (311) protruding upward, and the other end is provided with a lower convex ring (312) protruding downward. The bearing (32) is fixedly sleeved on the upper convex ring (311), and the feedback member (33) is fixedly sleeved on the lower convex ring (312).

3. The axial positioning structure of a motor shaft according to claim 2, characterized in that: The bearing (32) is interference-connected with the upper convex ring (311), and the feedback member (33) is bonded and / or interference-connected with the fixing sleeve (31).

4. The axial positioning structure of a motor shaft according to claim 3, characterized in that: A first step (313) is provided between the upper convex ring (311) and the lower convex ring (312) of the fixing sleeve (31), and the bearing (32) comprises an inner ring (321) and an outer ring (322); during installation, the bottom of the inner ring (321) of the bearing (32) abuts against the top surface of the first step (313), and the top of the feedback member (33) abuts against the bottom surface of the first step (313).

5. The axial positioning structure of a motor shaft according to claim 1, characterized in that: The motor assembly (1) also includes a housing (22), and the shaft core (2) is rotatably arranged in the housing (22); a support member (4) and a circuit board (5) are provided at the bottom of the housing (22), the support member (4) is located between the housing (22) and the circuit board (5), a cavity (41) is provided in the middle of the support member (4), the feedback assembly (3) is arranged in the cavity (41), and the induction member (51) is fixedly connected to the top surface of the circuit board (5) and corresponds to the position of the feedback member (33).

6. The axial positioning structure of a motor shaft according to claim 5, characterized in that: In the housing (22), the top of the support member (4) is in contact with a support sleeve (6), the support sleeve (6) comprises a downwardly recessed installation cavity (61) and a support platform (62) of an annular structure, a through hole (611) is provided at the bottom of the installation cavity (61), the installation cavity (61) is arranged in the cavity body (41), the bearing (32) is arranged in the installation cavity (61), and at least a portion of the outer wall of the installation cavity (61) is in contact with the inner wall of the support member (4).

7. The axial positioning structure of a motor shaft according to claim 1, characterized in that: The fixing sleeve (31) comprises a fixing hole (314), and the fixing hole (314) comprises a fastening portion (3142) and a guiding portion (3141) having a guiding function for the shaft core (2), and a diameter D1 of the guiding portion (3141) is larger than a diameter D2 of the fastening portion (3142); during installation, a gap (8) exists between the outer wall of the shaft core (2) and the inner wall of the guiding portion (3141), and the shaft core (2) is interference-connected with the fastening portion (3142).

8. The axial positioning structure of a motor shaft according to claim 1, characterized in that: The feedback member (33) is a magnet with an annular structure, and two induction members (51) are provided. The induction members (51) are Hall sensors corresponding to the feedback member (33).

9. The axial positioning structure of a motor shaft according to any one of claims 1 to 8, characterized in that: The material of the fixing sleeve (31) is copper or aluminum.

10. An electric toothbrush, characterized in that: An axial positioning structure for a motor shaft comprising any one of claims 1 to 9.

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