Plastic gear stepping motor capable of improving rotor assembly concentricity

Abstract

The utility model discloses a plastic gear stepping motor capable of improving rotor assembly concentricity, which comprises a motor shaft, a rotor assembly and a stator assembly coated outside the rotor assembly, the motor shaft penetrates through the rotor assembly, and a transmission gear is fixed at one end of the rotor assembly. The stator assembly is provided with an opening allowing the transmission gear to be in transmission fit with an external component, one end, away from the transmission gear, of the stator assembly is fixed to one end of the motor shaft, one end, right facing the transmission gear, of the stator assembly is provided with a limiting hole allowing the other end of the motor shaft to be inserted, and the limiting hole does not penetrate through the end face of the stator assembly. According to the utility model, the phenomenon of iron rubbing caused by inclination of the motor shaft can be avoided, and the motor shaft cannot swing, so that the vibration noise of the motor is greatly improved compared with that of the original structure, the risk that the motor shaft falls off due to long-time swing does not exist, and the operation reliability of the motor is greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of stepping motors, in particular to a plastic gear stepping motor for improving the concentricity of rotor assembly. Background Art

[0002] The plastic gear stepping motor is a widely used motor, mainly composed of a stepping motor and a transmission gear, and is widely used in the fields of smart home, intelligent vehicle drive, intelligent medical drive, communication equipment drive, electronic product drive, etc.

[0003] The plastic gear stepping motor is different from the conventional motor. The gear of the conventional motor is a metal part, and the primary gear is fixed on the motor shaft. The motor shaft and the magnetic ring form a rotatable rotor assembly. While the gear in the plastic gear stepping motor is a plastic part, which is driven by the rotor assembly to rotate. The motor shaft in the plastic gear stepping motor is fixed to the stator assembly and cannot rotate with the rotor assembly.

[0004] For the traditional PM stepping motor with a plastic gear, generally, the process of integrally injection molding the magnetic ring and the plastic gear is adopted. The stator part is composed of a coil assembly, a housing, and a motor shaft. After the stator part of the motor is made, the rotor is directly placed from the top of the stator, and the inner hole of the rotor is sleeved inside the motor shaft. Since one end of the motor is an open structure, only one end of the motor shaft is fixed to the coil assembly through the injection molding process. Due to the certain deformation of the injection molded parts, the motor shaft will be inclined, which is likely to cause poor concentricity between the motor shaft and the inner diameter of the stator. For motors with a small air gap, such as the PM25 type motor, there is a risk of the rotor rubbing against the iron after the motor shaft is inclined. After the motor runs, since only one end of the motor shaft is fixed, the rotation of the rotor will cause the motor shaft to swing, which will cause the outer diameter of the rotor to rub against the inner diameter of the stator. Over time, there is a risk of the motor shaft loosening and falling off.

[0005] The present invention improves the iron rubbing phenomenon caused by poor concentricity of rotor assembly, the vibration and noise problems caused by the swing of the motor shaft, and the problem of loosening and falling off of the motor shaft. Content of the Utility Model

[0006] In order to solve the iron rubbing phenomenon caused by poor concentricity of rotor assembly, the vibration and noise problems caused by the swing of the motor shaft, and the problem of loosening and falling off of the motor shaft in the plastic gear stepping motor in the prior art, the utility model provides a plastic gear stepping motor for improving the concentricity of rotor assembly to solve the above problems.

[0007] The technical solution adopted by the utility model to solve its technical problems is: a plastic gear stepping motor for improving the concentricity of rotor assembly, including a motor shaft, a rotor assembly, and a stator assembly covering the outside of the rotor assembly. The motor shaft passes through the rotor assembly, and a transmission gear is fixed at one end of the rotor assembly.

[0008] The stator assembly has an opening for the transmission gear to be in transmission cooperation with an external component. One end of the stator assembly away from the transmission gear is fixed to one end of the motor shaft. One end of the stator assembly facing the transmission gear has a limiting hole for the other end of the motor shaft to be inserted, and the limiting hole does not penetrate the end face of the stator assembly.

[0009] Furthermore, the stator assembly includes an upper skeleton and a lower skeleton processed separately. The motor shaft is injection-molded on the lower skeleton, and the lower skeleton and the lower skeleton with the motor shaft are injection-molded into one body. The upper part of the upper skeleton has an upper cover covering the transmission gear. The motor shaft is connected to the bottom surface of the lower skeleton. The opening and the limiting hole are both located on the upper cover.

[0010] Furthermore, the upper skeleton includes an upper cover, an upper pole plate, and an upper middle pole plate arranged in sequence from top to bottom. The lower skeleton includes a lower middle pole plate, a lower pole plate, and a bottom plate. The end faces of the upper middle pole plate and the lower middle pole plate are in contact. The upper middle pole plate and the lower middle pole plate have a convex hull and a mating hole that cooperate with each other. The motor shaft is injection-molded on the bottom plate.

[0011] Furthermore, the upper cover includes a cap, a first annular plate at the bottom of the cap, and a second annular plate connected to the outer edge of the first annular plate. The second annular plate is in contact with the end face of the upper pole plate. The cap is located outside the transmission gear. The opening and the limiting hole are located on the cap.

[0012] Furthermore, the thickness of the second annular plate is less than that of the first annular plate, and the top of the first annular plate has a reinforcing rib protruding upward.

[0013] Furthermore, the stepping motor further includes a motor housing. The surface of the motor housing facing the upper cover has a groove that cooperates with the reinforcing rib.

[0014] Furthermore, the upper middle pole plate and the lower middle pole plate have the same structure and are both formed by stamping silicon steel sheets. The convex hull is formed on part of the mating holes during injection molding.

[0015] Furthermore, the limiting hole is a tapered hole with a gradually decreasing diameter from bottom to top.

[0016] Furthermore, the rotor assembly includes a magnetic ring, an injection-molded body, and a bushing. The magnetic ring and the injection-molded body are integrally injection-molded. The center of the injection-molded body has a middle hole for installing the motor shaft. The bottom of the injection-molded body has an installation groove. The bushing is press-fitted and assembled in the installation groove, and the bushing abuts against the bottom plate.

[0017] Furthermore, the motor shaft is a smooth shaft made of metal.

[0018] The beneficial effects of the present utility model are:

[0019] (1) The stator assembly of the traditional plastic gear stepper motor of the present utility model is improved from a semi-closed structure to a both-end closed structure, effectively avoiding the risk of the motor shaft falling off. At the same time, the end of the motor shaft is supported by the limit hole, avoiding the occurrence of the iron rubbing phenomenon caused by the inclination of the motor shaft, and the motor shaft cannot swing, greatly improving the vibration noise of the motor compared with the original structure, and there is no risk of the motor shaft falling off due to long-term swinging, greatly improving the operation reliability of the motor.

[0020] (2) The present utility model is provided with raised reinforcing ribs on the upper cover. The reinforcing ribs will make the connection strength between the upper cover and the upper pole plate higher, effectively reducing the deformation of the upper cover, and can cooperate with the convex grooves on the motor housing for limiting, preventing the skeleton from shaking after assembly and affecting the performance of the motor.

[0021] (3) After the upper skeleton and the lower skeleton of the present utility model are respectively manufactured, they are positioned by fitting the upper middle pole plate and the lower middle pole plate with better positional accuracy, so as to ensure the concentricity of the upper skeleton and the lower skeleton. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present utility model will be further described below in conjunction with the drawings and embodiments.

[0023] Figure 1 is a perspective view of the specific embodiment of the plastic gear stepper motor for improving the concentricity of rotor assembly of the present utility model;

[0024] Figure 2 is an axial sectional view of the specific embodiment of the plastic gear stepper motor for improving the concentricity of rotor assembly of the present utility model;

[0025] Figure 3 is an axial sectional view of the rotor assembly in the present utility model;

[0026] Figure 4 is a schematic diagram of the upper skeleton when the upper cover is not assembled in the present utility model;

[0027] Figure 5 is a schematic diagram after the lower skeleton is assembled with the motor shaft;

[0028] Figure 6 is a schematic diagram of the lower pole plate in the present utility model;

[0029] Figure 7 is a schematic diagram of the lower middle pole plate in the present utility model.

[0030] In the figure, 1 is the motor shaft, 2 is the rotor assembly, 201 is the transmission gear, 202 is the magnetic ring, 203 is the injection molded body, 204 is the bushing, 3 is the stator assembly, 4 is the upper skeleton, 401 is the upper cover, 4011 is the cap, 4012 is the first annular plate, 4013 is the second annular plate, 5 is the lower skeleton, 501 is the lower middle plate, 502 is the lower plate, 503 is the bottom plate, 6 is the opening, 7 is the limit hole, 8 is the convex hull, 9 is the mating hole, 10 is the middle hole, 11 is the installation groove, 12 is the installation boss, and 13 is the reinforcing rib. Detailed implementation mode

[0031] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0032] Embodiment 1

[0033] As Figure 1 and Figure 2 shown, a plastic gear stepper motor for improving the concentricity of rotor assembly includes a motor shaft 1, a rotor assembly 2, and a stator assembly 3 wrapped around the outside of the rotor assembly 2. The motor shaft 1 passes through the rotor assembly 2, and a transmission gear 201 is fixed at one end of the rotor assembly 2.

[0034] The stator assembly 3 generally includes a skeleton and a coil wound around the skeleton. The coil structure is not shown in the drawings of the present invention, that is, the stator assembly 3 in the drawings is actually the skeleton. The difference between this skeleton and the traditional skeleton is that its top is changed from an open type to a closed type, thus forming a wrapped shape to surround the outer circumference, top surface, and bottom surface of the rotor assembly 2.

[0035] In order to enable the transmission gear 201 at the top of the rotor assembly 2 to be in transmission cooperation with the outside, an opening 6 for the transmission gear 201 to be in transmission cooperation with external components is provided on the stator assembly 3.

[0036] After the stator assembly 3 is changed to a closed top, the two ends of the motor shaft 1 can be limited. For the lower end of the motor shaft 1, it is the same as the traditional connection method, that is, it is fixed to the end of the stator assembly 3 away from the transmission gear 201. The fixing method can be integral injection molding, or welding, interference fit, or glue fixing, etc. For the upper end of the motor shaft 1, a limit hole 7 for the other end of the motor shaft 1 to be inserted is provided at the end of the stator assembly 3 facing the transmission gear 201, and the limit hole 7 does not penetrate the end face of the stator assembly 3.

[0037] The utility model effectively avoids the inclination of the motor shaft 1 by supporting both ends of the motor shaft 1, thereby avoiding the phenomenon of the rotor assembly 2 rubbing against the iron. Moreover, when the motor is running, the motor shaft 1 will not shake, nor will it cause vibration noise due to rotation with the rotor assembly 2 after the fixation fails. In addition, since the motor shaft 1 of the plastic gear stepper motor is usually a smooth shaft made of metal, if its fixation with the stator assembly 3 fails, it is very easy to fall off from the open other end. The closed structure at both ends of the stator assembly 3 in the utility model can also play the role of dust prevention and preventing the motor shaft 1 from falling off, thereby improving the reliability of the motor.

[0038] The skeleton of the stator assembly 3 is integrally injection-molded by multiple pole plates and a middle pole plate, and can be directly injection-molded outside the rotor assembly 2. However, in order to improve the structural strength of the skeleton and reduce the injection time during the assembly process of the rotor assembly 2 and the stator assembly 3, and to avoid the influence of high-temperature injection on the performance of the rotor assembly 2, the utility model preferably divides the skeleton of the stator assembly 3 into an upper skeleton 4 and a lower skeleton 5. The upper skeleton 4 and the lower skeleton 5 are injection-molded separately. The motor shaft 1 is injection-molded on the lower skeleton 5. After the rotor assembly 2 is installed into the upper skeleton 4 and the lower skeleton 5, as long as the lower skeleton 5 is injection-molded into one body with the lower skeleton 5 with the motor shaft 1, the injection time is shortened.

[0039] As Figures 4 - 6 shown, the traditional upper skeleton 4 includes an upper pole plate 402 and an upper middle pole plate 403, and the lower skeleton 5 includes a lower middle pole plate 501, a lower pole plate 502 and a bottom plate 503. The utility model adds an upper cover 401 covering the transmission gear 201 outside the upper part of the upper skeleton 4. The upper cover 401 is connected to the upper pole plate 402. The motor shaft 1 is connected to the bottom surface of the lower skeleton 5, that is, connected to the bottom plate 503. The opening 6 and the limiting hole 7 are both located on the upper cover 401. As Figure 1 shown, the opening 6 is located on the side surface of the upper cover 401, and it is an arc cutout for exposing part of the teeth of the transmission gear 201. The limiting hole 7 is located on the top of the upper cover 401 and is in plug-in fit with the motor shaft 1.

[0040] When the motor is assembled as a whole, first, the rotor assembly 2 is sleeved into the lower skeleton 5 equipped with the motor shaft 1. Since the rotor assembly 2 has magnetism, it will cause the motor shaft 1 to tilt in a certain direction. Then it is assembled with the upper skeleton 4, and the top end of the motor shaft 1 is inserted into the limiting hole 7 of the upper skeleton 4. Since the limiting hole 7 can play a guiding role, even if the motor shaft 1 has an inclination phenomenon, the assembly accuracy can still be guaranteed, effectively preventing the problem of the rotor assembly 2 rubbing against the iron caused by the inclination of the motor shaft 1.

[0041] The limiting hole 7 is preferably a tapered hole with a gradually decreasing aperture from bottom to top. The tapered hole is more conducive to the insertion of the motor shaft 1 and has a better guiding effect. The setting of the limiting hole 7 can also reduce the concentricity requirement during the injection molding of the motor shaft 1 and the lower skeleton 5. Even if the concentricity between the motor shaft 1 and the inner wall of the lower skeleton 5 is poor after injection molding, it can be corrected by the cooperation between the upper end of the motor shaft 1 and the limiting hole 7 after assembling with the upper skeleton 4.

[0042] In addition to the transmission gear 201, the rotor assembly 2 generally further includes a magnetic ring 202, an injection molded body 203, and a bushing 204. The magnetic ring 202 and the injection molded body 203 are integrally injection molded. The injection molded body 203 has a central hole 10 for installing the motor shaft 1, and an installation groove 11 at the bottom. The bushing 204 is press-fitted into the installation groove 11 and abuts against the bottom plate 503. As Figure 2 and Figure 3 shown, the injection molded body 203 includes two upper and lower parts. The upper part is used to assemble the transmission gear 201, and the lower part is used to assemble the magnetic ring 202. The bushing 204, as the abutting component between the rotor assembly 2 and the lower skeleton 5, can prevent the magnetic ring 202 below from contacting the lower skeleton 5 and causing wear of the magnetic ring 202. The bottom plate 503 of the lower skeleton 5 has an installation boss 12 extending into the installation groove 11. The installation boss 12 can not only abut against the bushing 204 but also increase the contact area between the lower skeleton 5 and the injection molding of the motor shaft 1.

[0043] Regarding the shape design of the upper cover 401, as long as it can surround the upper part of the rotor assembly 2 and provide design space for the opening 6 and the limiting hole 7. In order to ensure the connection strength between the upper cover 401 and the upper pole plate 402, the upper cover 401 in this embodiment is preferably of a cap-shaped structure, and the specific structure is as follows: As Figure 1 and Figure 2 shown, the upper cover 401 includes a cap 4011, a first annular plate 4012 located at the bottom of the cap 4011, and a second annular plate 4013 connected to the outer edge of the first annular plate 4012. The second annular plate 4013 is attached to the end face of the upper pole plate 402. The cap 4011 is located outside the transmission gear 201, and the opening 6 and the limiting hole 7 are located on the cap 4011. The second annular plate 4013 can provide a connection end face with the upper pole plate 402, improve the connection strength by increasing the contact surface, and positioning structures, such as positioning holes and positioning protrusions, can be designed on the connection end face to correctly position the second annular plate 4013 and the upper pole plate 402 and control the orientation of the opening 6 on the cap 4011.

[0044] Since the outer diameter of the magnetic ring 202 of the rotor assembly 2 is larger than the outer diameter of the transmission gear 201, and the cap 4011 is located outside the transmission gear 201. In the traditional skeleton, each pole plate is located outside the magnetic ring 202. Therefore, there will be a radial distance between the cap 4011 and the second annular plate 4013, which needs to be connected by the first annular plate 4012.

[0045] Example Two

[0046] Based on the above embodiments, the following further improvements are made in this embodiment:

[0047] During assembly, the end faces of the upper middle plate 403 and the lower middle plate 501 are in contact. The upper middle plate 403 and the lower middle plate 501 have mating convex hulls 8 and mating holes 9. The upper middle plate 403 and the lower middle plate 501 have the same structure and are collectively referred to as the middle plate. The middle plate is usually formed by stamping silicon steel sheets. Therefore, the flatness of the middle plate and the position accuracy of the positioning holes are good. In this embodiment, the positioning surfaces of the upper frame 4 and the lower frame 5 are selected on the opposite end faces of the upper middle plate 403 and the lower middle plate 501. By using the good flatness of the middle plate and the position accuracy of the positioning holes, the concentricity of the upper frame 4 and the lower frame 5 is ensured. The cooperation of the convex hull 8 and the mating hole 9 can improve the connection strength between the upper middle plate 403 and the lower middle plate 501.

[0048] As Figure 7 shown is the structure of the lower middle plate 501 before injection molding. The upper middle plate 403 is the same as it. Before injection molding, four mating holes 9 are provided on both the upper middle plate 403 and the lower middle plate 501. During injection molding, two mating holes 9 on each middle plate are injection molded into convex hulls 8 (as Figure 4 and Figure 5 shown).

[0049] Example Three

[0050] Based on Embodiment One or Embodiment Two, since the lower part of the first annular plate 4012 is suspended and there is no connection structure up and down, in order to ensure the connection strength between the upper cover 401 and the upper plate 402, it is preferred that the thickness of the second annular plate 4013 is less than the thickness of the first annular plate 4012, and at the same time, upwardly protruding reinforcing ribs 13 are provided on the top of the first annular plate 4012.

[0051] In further design, the stepping motor usually further includes a motor housing. To prevent the stator assembly 3 from shaking, the motor housing and the stator assembly 3 need to be connected and positioned. The reinforcing ribs 13 in this embodiment can also be used as the structure for connecting and positioning with the motor housing, that is, grooves matching with the reinforcing ribs 13 are provided on the surface of the motor housing facing the upper cover 401. During assembly, part or all of the reinforcing ribs 13 are inserted into the corresponding grooves. When the motor is running, the stator assembly 3 will not shake due to the limitation of the motor housing.

[0052] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "top", "bottom", "inner", "outer", "axial direction", "radial direction", "circumferential direction", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present utility model.

[0053] In addition, terms such as "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0054] In this specification, the schematic expression of the above terms does not necessarily refer to the same embodiment. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments.

[0055] Taking the above-mentioned ideal embodiment of the present utility model as an inspiration, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this utility model. The technical scope of this utility model is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A plastic gear stepper motor for improving rotor assembly concentricity, characterized in that: It includes a motor shaft, a rotor assembly and a stator assembly covered on the outside of the rotor assembly, wherein the motor shaft passes through the rotor assembly, and a transmission gear is fixed at one end of the rotor assembly; The stator assembly has an opening for the transmission gear to cooperate with the external component. The end of the stator assembly away from the transmission gear is fixed to one end of the motor shaft. The end of the stator assembly facing the transmission gear has a limiting hole for inserting the other end of the motor shaft, and the limiting hole does not pass through the end face of the stator assembly.

2. The plastic gear stepper motor with improved rotor assembly concentricity according to claim 1, characterized in that: The stator assembly includes an upper frame and a lower frame that are processed separately, the motor shaft is injection molded on the lower frame, and the lower frame and the lower frame with the motor shaft are injection molded as a whole. The upper part of the upper frame has an upper cover covering the outside of the transmission gear, and the opening and the limit hole are both located in the upper cover.

3. The plastic gear stepper motor with improved rotor assembly concentricity according to claim 2, characterized in that: The upper frame includes an upper cover, an upper electrode plate and an upper middle electrode plate arranged in sequence from top to bottom, and the lower frame includes a lower middle electrode plate, a lower electrode plate and a bottom plate. The upper middle electrode plate is fitted with the end surface of the lower middle electrode plate, and the upper middle electrode plate and the lower middle electrode plate have mutually matching convex humps and matching holes, and the motor shaft is injection molded on the bottom plate.

4. The plastic gear stepper motor with improved rotor assembly concentricity according to claim 3, characterized in that: The upper cover includes a cap and a first annular plate located at the bottom of the cap and a second annular plate connected to the outer edge of the first annular plate, the second annular plate is fitted with the end surface of the upper electrode plate, the cap is located outside the transmission gear, and the opening and the limiting hole are located on the cap.

5. The plastic gear stepper motor with improved rotor assembly concentricity according to claim 4, characterized in that: The thickness of the second annular plate is smaller than that of the first annular plate, and the top of the first annular plate has a reinforcing rib protruding upward.

6. The plastic gear stepper motor with improved rotor assembly concentricity according to claim 5, characterized in that: The stepper motor further comprises a motor housing, and a surface of the motor housing facing the upper cover has a groove matched with the reinforcing rib.

7. The plastic gear stepper motor with improved rotor assembly concentricity according to claim 3, characterized in that: The upper middle electrode plate has the same structure as the lower middle electrode plate and is both formed by stamping of silicon steel sheets. The convex bump is formed on part of the matching hole during injection molding.

8. The plastic gear stepper motor with improved rotor assembly concentricity according to claim 1, characterized in that: The limiting hole is a tapered hole whose diameter gradually decreases from bottom to top.

9. The plastic gear stepper motor with improved rotor assembly concentricity according to claim 3, characterized in that: The rotor assembly includes a magnetic ring, an injection molded body and a bushing. The magnetic ring and the injection molded body are integrally injection molded. The center of the injection molded body has a center hole for mounting the motor shaft. The bottom of the injection molded body has a mounting groove. The bushing is assembled in the mounting groove by interference fit, and the bushing abuts against the base plate.

10. The plastic gear stepper motor with improved rotor assembly concentricity according to any one of claims 1 to 9, characterized in that: The motor shaft is an optical shaft made of metal material.

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