PM stepping motor

Abstract

A rotor assembly penetrates through a stator and then is connected with a bearing assembly, a nut is located in an inner hole of the rotor assembly and fixed to the rotor assembly, a screw assembly penetrates through the nut and is in threaded connection with the nut, a guide sleeve is fixed to one end of a shell, the stator comprises a winding framework and a winding, the winding is installed on the winding framework, and the winding is connected with the bearing assembly. The winding framework comprises a plurality of polar plates, each polar plate comprises a polar plate body, a plurality of polar claws and a plastic layer, the polar claws are arranged along the circumferential direction of the polar plate body, one end of each polar claw is fixed with the polar plate body, two polar plates form a group, the polar claws in the two polar plates are mutually crossed, and the polar plate body is wrapped by the plastic layer; the outer surface of each pole claw and a part of the pole claw in the thickness direction are wrapped by a plastic layer, the other end of the pole claw is provided with a supporting part fixed with the pole claw, and the supporting part is completely wrapped by the plastic layer. After the working temperature of the motor rises, bending deformation of the pole claws can be avoided.

Description

Technical Field

[0001] This utility model relates to motors, specifically to a PM stepper motor. Background Technology

[0002] The pole plates inside a PM (permanent magnet) stepper motor consist of a pole plate body and pole claws fixed to the pole plate body, serving as the stator magnetic poles and participating in electromagnetic energy conversion. The motor pole plates are manufactured using injection molding, where a portion of the pole plate body and pole claws are encased in high-temperature resistant engineering plastic to form an integral winding frame. The stator windings are mounted on the winding frame.

[0003] For micro motors with small diameters, the thin material of the pole plate (≤0.6mm) and the slender structure of the pole claws result in relatively low strength. As the motor's operating temperature rises, due to the different shrinkage ratios of metal and plastic, and the inherent weakness of the pole claws, part of the claws may be exposed outside the plastic. In extreme cases, this can lead to the pole claws separating from the injection-molded plastic, causing them to bend and deform towards the inner hole of the winding frame. This results in a reduction in the air gap between the stator and rotor, decreased motor thrust, and reduced step angle accuracy. In extreme cases, the bent and deformed pole claws can even collide with the rotor's magnets, leading to a quality accident. Utility Model Content

[0004] This invention provides a PM stepper motor that can prevent the pole claws from bending and deforming after the motor's operating temperature rises.

[0005] The technical solutions to the above technical problems are as follows:

[0006] A PM stepper motor includes a housing, a stator, a bearing assembly, a rotor assembly, a nut, a screw assembly, and a guide sleeve. The stator, bearing assembly, and rotor assembly are all mounted within the housing. The rotor assembly passes through the stator and connects to the bearing assembly. The nut is located in the inner hole of the rotor assembly and is fixed to it. The screw assembly passes through the nut and is threadedly connected to it. The guide sleeve is fixed to one end of the housing. The screw assembly includes a screw and a guide shaft. One end of the screw is fixed to the guide shaft. The guide shaft and guide sleeve are fixed circumferentially and slidingly fitted axially. The stator includes a winding frame and windings. The windings are mounted on the winding frame. The winding frame includes multiple pole plates. Each pole plate includes a pole plate body, pole claws, and a plastic layer. There are multiple pole claws arranged circumferentially along the pole plate body. One end of each pole claw is fixed to the pole plate body. Two pole plates form a group. The pole claws in the two pole plates intersect each other. The pole plate body is covered by the plastic layer. The outer surface of each pole claw and a portion of the pole claw in the thickness direction are covered by the plastic layer. The other end of each pole claw is provided with a support portion fixed to the pole claw. The support portion is completely wrapped by the plastic layer.

[0007] Furthermore, the thickness of the support portion is less than the thickness of the pole claw, forming a gap between the pole claw and the support portion.

[0008] Furthermore, the length of the notch is 0.4-0.6 mm, and the height of the notch is 0.15-0.25 mm.

[0009] Furthermore, the electrode plate body is provided with through holes, and the winding frame also includes a connecting column, which passes through the through holes and is integrally formed with the plastic layer.

[0010] In this invention, the support portion is completely encased in a plastic layer, which is injection-molded onto the various parts of the electrode plates. Even after the electrode claws in the two electrode plates intersect, gaps remain between them. During the injection molding process, the plastic fills these gaps. This structure provides support to the other end of the support portion through the plastic layer, thus providing support to both ends of the electrode claws. Compared to existing structures, this increases the strength of the electrode claws and prevents them from bending or deforming when the motor generates heat. This invention has the following advantages:

[0011] 1. No increase in the procurement cost of electrode plate components.

[0012] 2. No increase in the procurement cost of injection molded skeleton.

[0013] 3. By adopting a mechanical structure, the potential quality problem of the pole teeth bending and deforming into the inner hole due to high temperature is fundamentally solved, thereby improving the stability of product quality. Attached Figure Description

[0014] Figure 1 This is a cross-sectional view of the PM stepper motor.

[0015] Figure 2 This is a 3D view of the wire winding skeleton.

[0016] Figure 3 In order to be in Figure 2 The diagram conceals the plastic layer and the structure behind the connecting columns.

[0017] Figure 4 This is a three-dimensional view of a single electrode plate.

[0018] Labels in the attached diagram:

[0019] 1. Housing, 2. Stator, 2a. Pole plate body, 2b. Pole claw, 2b1. Outer surface, 2b2. Plastic layer, 2c. Support part, 2d. Notch, 2e. Through hole, 2f. Connecting column, 2g. Bearing assembly, 3. Rotor assembly, 4. Rotor body, 4a. Magnet, 4b. Positioning part, 4c. Nut, 5. Screw assembly, 6. Screw, 6a. Guide shaft, 6b. Guide sleeve, 7. Detailed Implementation

[0020] like Figures 1 to 4 As shown, the PM stepper motor of this utility model includes a housing 1, a stator 2, a bearing assembly 3, a rotor assembly 4, a nut 5, a screw assembly 6, and a guide sleeve 7. The stator 2, the bearing assembly 3, and the rotor assembly 4 are all installed inside the housing 1. There are two bearing assemblies 3, and the stator 2 is located between the two bearing assemblies 3.

[0021] The stator 2 includes a winding frame and windings (the windings are not shown in the figure). The windings are mounted on the winding frame. The winding frame includes multiple pole plates. Each pole plate includes a pole plate body 2a, pole claws 2b, and a plastic layer 2c. There are multiple pole claws 2b arranged around the circumference of the pole plate body 2a. One end of each pole claw 2b is fixed to the pole plate body 2a. The pole claws 2b and the pole plate body 2a are integrally formed. The pole claws 2b and the pole plate body 2a are made of metal, preferably carbon steel. The forming process of the pole plate is as follows: a circular plate is placed on a stamping machine, and the plate is stamped by the stamping machine to remove a portion of the plate. Pole claws 2b are initially formed on the plate at intervals. Each pole claw is bent so that the pole claw 2b and the pole plate body 2a form a 90-degree angle, thereby forming the pole plate.

[0022] Two electrodes form a group, and the electrode claws 2b in the two electrodes intersect each other. The electrode body 2a is covered by a plastic layer 2c. The outer surface 2b1 of each electrode claw 2b and a portion of the electrode claw 2b in the thickness direction are covered by the plastic layer 2c. The inner surface 2b2 of the electrode claw 2b and another portion of the electrode claw 2b in the thickness direction are exposed outside the plastic layer 2c. For example, the thickness of the electrode claw 2b is 5mm, of which 3mm of the electrode claw 2b is covered by the plastic layer 2c, and the remaining 2mm of the electrode claw 2b is not covered by the plastic layer 2c and the inner surface 2b2. That is, the remaining 2mm of the electrode claw 2b and the inner surface 2b2 are exposed outside the plastic layer 2c.

[0023] The other end of the pole claw 2b is provided with a support portion 2d fixed to the pole claw 2b, and the support portion 2d is completely wrapped by a plastic layer 2c. The plastic layer 2c is injection molded to the various parts of the electrode plate. After the pole claws 2b in the two electrode plates cross each other, there are still gaps between these pole claws 2b. During the injection molding process, the plastic fills these gaps, and the plastic completely wraps the support portion 2d. This structure allows the other end of the support portion 2d to be supported by the plastic layer 2c. Compared with the existing structure, the strength of the pole claw 2b is improved, and the pole claw 2b is prevented from bending and deforming when the motor is working and generating heat.

[0024] The thickness of the support portion 2d is less than the thickness of the pole claw 2b, and a notch 2e is formed between the pole claw 2b and the support portion 2d. The length of the notch 2e is 0.4-0.6 mm, and the height of the notch 2e is 0.15-0.25 mm. Preferably, the length of the notch 2e is 0.5 mm, and the height of the notch 2e is 0.2 mm.

[0025] In this embodiment, the electrode body 2a is provided with a through hole 2f, and the winding skeleton also includes a connecting column 2g, which passes through the through hole 2f and is integrally formed with the plastic layer 2c. In this embodiment, during injection molding, the molten plastic passes through the through hole 2f and forms the connecting column 2g in the mold. The connecting column 2g fixes two adjacent electrode bodies 2a on the one hand, and increases the strength of the winding skeleton on the other hand.

[0026] After passing through the stator 2, the rotor assembly 4 is connected to the bearing assembly 3. The rotor assembly 4 can rotate relative to the stator. The rotor assembly 4 includes a rotor body 4a and a magnet 4b. The magnet 4b is sleeved on the rotor body 4a and fixed to the rotor body 4a. The rotor body 4a is cylindrical. One end of the bearing assembly 3 is provided with a cylindrical body 3a, which is inserted into the rotor body and fixed to the rotor body 4a.

[0027] Nut 5 is located in the inner hole of rotor assembly 4 and fixed to rotor assembly 4. Radial through hole is provided on the circumferential surface of rotor body 4a. Rotor assembly 4 also includes positioning component 4c. Positioning component 4c passes through radial through hole and is fixed to nut 5, thereby fastening nut 5 and rotor body 4a into one piece.

[0028] The screw assembly 6 passes through the nut 5 and is threadedly connected to the nut 5. The screw assembly 6 includes a screw 6a and a guide shaft 6b. One end of the screw 6a is fixed to the guide shaft 6b, and the guide sleeve 7 is fixed to one end of the housing 1. In this utility model, the guide shaft 6b is preferably a spline shaft, and the guide sleeve 7 is preferably a spline sleeve. After the guide shaft 6b passes through the guide sleeve 7, the guide shaft 6b and the guide sleeve 7 form a fixed circumferential fit and a sliding fit axially.

Claims

1. A PM stepper motor, comprising a housing (1), a stator (2), a bearing assembly (3), a rotor assembly (4), a nut (5), a screw assembly (6), a guide sleeve (7), the stator (2), the bearing assembly (3), and the rotor assembly (4) are all installed in the housing (1), the rotor assembly (4) is connected with the bearing assembly (3) after passing through the stator (2), the nut (5) is located in the inner hole of the rotor assembly (4) and is fixed with the rotor assembly (4), the screw assembly (6) passes through the nut (5) and is threadedly connected with the nut (5), the guide sleeve (7) is fixed with one end of the housing (1), the screw assembly (6) comprises a screw rod (6a) and a guide shaft (6b), one end of the screw rod (6a) is fixed with the guide shaft (6b), the guide shaft (6b) is fixed with the guide sleeve (7) in the circumferential direction and is in sliding fit with the guide sleeve (7) in the axial direction, the stator (2) comprises a winding framework and a winding, the winding is installed on the winding framework, the winding framework comprises a plurality of pole plates, each pole plate comprises a pole plate body (2a), a pole claw (2b), and a plastic layer (2c), the pole claws (2b) are arranged along the circumferential direction of the pole plate body (2a), one end of each pole claw (2b) is fixed with the pole plate body (2a), two pole plates form a group, the pole claws (2b) of the two pole plates intersect with each other, the pole plate body (2a) is covered by the plastic layer (2c), and the outer surface (2b1) of each pole claw (2b) and a part in the thickness direction of the pole claw (2b) are covered by the plastic layer (2c), characterized in that, The other end of the pole claw (2b) is provided with a support part (2d) fixed with the pole claw (2b), and the support part (2d) is completely wrapped by the plastic layer (2c).

2. The PM stepper motor of claim 1, wherein, The thickness of the support part (2d) is less than the thickness of the pole claw (2b), and a gap (2e) is formed between the pole claw (2b) and the support part (2d).

3. The PM stepper motor of claim 2, wherein, The length of the gap (2e) is 0.4-0.6mm, and the height of the gap (2e) is 0.15-0.25mm.

4. The PM stepper motor of claim 1, wherein, The pole plate body (2a) is provided with a through hole (2f), and the winding framework further comprises a connecting column (2g), the connecting column (2g) passes through the through hole (2f), and the connecting column (2g) is integrally formed with the plastic layer (2c).

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