Rotor for external rotor electric machine
By setting grooves and protruding structures on the bracket of the outer rotor motor, the imbalance problem caused by temperature fluctuations between the back iron ring and the bracket is solved, the stable concentric positioning of the rotor and material saving are achieved, and the efficiency of the motor is improved.
Patent Information
- Application Number
- CN202421687986.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Priority Date
- 2023-07-21
- Filing Date
- 2024-07-16
- Publication Date
- 2025-07-11
- Estimated Expiration
- 2034-07-16
AI Technical Summary
In the rotor manufacturing of an outer rotor motor, the imbalance problem caused by temperature fluctuations between the back iron ring and the bracket is difficult to effectively avoid.
A bracket made of non-ferromagnetic material is used, with grooves on the bracket to accommodate the back iron ring, and external and internal protrusions are provided on the outside and inside of the back iron ring, through which the concentric positioning of the back iron ring is maintained when the temperature changes to avoid imbalance.
It effectively avoids imbalance caused by temperature changes, saves materials and weight, and improves the efficiency of the motor.
Smart Images
Figure CN223093564U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a motor rotor, which comprises a back iron ring made of ferromagnetic steel, a permanent magnet fixed to the inner side of the back iron ring, and a bracket made of non-ferromagnetic material, the bracket having a hub for the shaft and being attached to the back iron ring. Background Art
[0002] In the rotor of an outer rotor motor, a back iron ring made of ferromagnetic material must be connected to a bracket having a hub for the shaft. A common problem in rotor manufacturing is to avoid imbalance as much as possible. This problem becomes more difficult because during the operation of the motor, the rotor usually undergoes considerable temperature fluctuations, which may cause relative movement of the back iron ring relative to the bracket, resulting in imbalance. Summary of the Utility Model
[0003] The object of the utility model is to show a method by which a rotor for an outer rotor motor can be produced cost-effectively, in which imbalance is largely avoided even in the case of temperature fluctuations. This object is achieved by the rotor described in the utility model, which comprises a back iron ring made of ferromagnetic steel, a permanent magnet fixed to the inner side of the back iron ring, and a bracket made of non-ferromagnetic material, the bracket having a hub for the shaft and being attached to the back iron ring, wherein the bracket has a groove into which the back iron ring is inserted. Advantageous improvements of the utility model are the subject matter of the dependent claims.
[0004] In the rotor according to the utility model, the bracket has a groove into which the back iron ring is inserted. In this way, the back iron ring is guided between the inner diameter and the outer diameter of the groove in the rotor. If the bracket expands more than the back iron ring due to temperature, the back iron ring abuts against the inner wall of the groove, and if the bracket contracts more than the back iron ring due to temperature, the back iron ring abuts against the outer wall of the groove. In both cases, the back iron ring is reliably held concentrically on the bracket, and imbalance can be largely avoided.
[0005] The groove can be an annular groove extending continuously over the entire circumference. However, the bracket can also have a series of slots, each slot extending only over a part of the circumference.
[0006] To avoid imbalance during temperature changes, a groove depth significantly less than the axial length of the back iron ring is usually sufficient. An advantageous improvement of the utility model is that the depth of the groove is less than the axial length of the back iron ring, and preferably less than one fifth of the axial length of the back iron ring, and particularly preferably not more than one tenth of the axial length of the back iron ring. In this way, the material and weight of the rotor can be saved, thus achieving a more efficient motor.
[0007] A further improvement of the present utility model provides a bracket with an external protrusion that extends axially along the outer side of the back iron ring. In this way, the guidance of the back iron ring can be improved with the least amount of material. Preferably, the external protrusion extends only over a part of the axial length of the back iron ring, for example, extending more than 20% to 50% of the axial length of the back iron ring.
[0008] A further improvement of the present utility model provides a bracket with an internal protrusion that extends axially on the inner side of the back iron ring between the permanent magnets. In this way, the guidance of the short - circuit plate can be improved with the least amount of material. For mechanical reasons, the external protrusion is more advantageous than the internal protrusion. In order to keep the rotor light in weight, the internal protrusion is therefore shorter than the external protrusion, that is, the external protrusion extends further axially than the internal protrusion.
[0009] A further improvement of the present utility model provides a gap that extends circumferentially between one end face of the permanent magnet and the bracket, and a bump of the bracket that protrudes into this gap. Such a bump can simplify production by serving as a stop for the rotor permanent magnet. In principle, the permanent magnet can be attached to the back iron ring before inserting the back iron ring into the slot of the bracket. However, from a manufacturing perspective, it is usually more advantageous to first insert the back iron ring into the slot of the bracket and then attach the magnet to the inner side of the back iron ring (especially by gluing). Then, the bump on the bracket can be used as a stop, making it easier to position the magnet (especially in the case where the permanent magnet is magnetized only after attachment).
[0010] In an embodiment of the present utility model, the permanent magnet is attached to the back iron ring by an adhesive. Description of the Drawings
[0011] The further details and advantages of the present utility model are explained with reference to the accompanying drawings.
[0012] Figure 1 A rotor for an outer - rotor motor is shown; and
[0013] Figure 2 is shown Figure 1 a cross - sectional view of the details of the rotor. Detailed Description of the Invention
[0014] Figure 1 The rotor shown in includes a back iron ring 1 made of ferromagnetic steel, a permanent magnet 2 attached to the inner side of the back iron ring 1, and a bracket 3 made of non - ferromagnetic material, which is attached to the back iron ring 1 and has a hub for an axis (not shown). The bracket 3 can be made of, for example, aluminum or an aluminum - based alloy.
[0015] Figure 2A cross-sectional view of the rotor is shown. It can be seen that the bracket 3 has a groove 4, and the back iron ring 1 is located in the groove 4. Since the bracket 3 and the back iron ring 1 are made of different materials, different thermal expansions will occur when the temperature changes. Since the back iron ring 1 is arranged in the groove 4 of the bracket 3, when the bracket 3 expands more than the back iron ring 1, the back iron ring 1 abuts against the inner wall of the groove 4; when the back iron ring 1 expands more than the bracket 3, the back iron ring 1 abuts against the outer wall of the groove 4. In both cases, the back iron ring 1 is concentrically held on the hub by the bracket 3, thereby largely avoiding imbalance.
[0016] Specifically, as Figure 1 shown, the bracket 3 has external protrusions 5 that extend axially on the outer side of the back iron ring 1. When the back iron ring 1 presses against the outer wall of the groove 4 and also presses against the external protrusions 5 due to thermal expansion, these external protrusions 5 stabilize the position of the back iron ring 1 relative to the bracket 3. The external protrusions 5 can extend over the entire axial length of the back iron ring 1. However, it is generally advantageous if the external protrusions 5 extend only over a part of the axial length of the back iron ring 1 (e.g., 20% to 50% of the axial length of the back iron ring 1). In this way, reliable positioning of the back iron ring 1 relative to the bracket 3 can be achieved, while reducing the use of materials and thus advantageously reducing the rotor weight, thereby avoiding imbalance.
[0017] The bracket 3 also has internal protrusions 6 that extend axially on the inner side of the back iron ring 1 between the permanent magnets 2. When the back iron ring 1 presses against the inner wall of the groove 4 and thus also presses against the internal protrusions 6, the internal protrusions 6 stabilize the position of the back iron ring 1 relative to the bracket 3. The internal protrusions 6 can extend over the entire axial length of the back iron ring 1. However, it is generally advantageous if the internal protrusions 6 extend only over a part of the axial length of the back iron ring 1 (especially shorter than the external protrusions 5). In the illustrated embodiment, for example, the internal protrusions 6 extend no more than 10% of the axial length of the back iron ring 1. In this way, reliable positioning of the back iron ring 1 relative to the bracket 3 can be achieved, while reducing the use of materials and thus advantageously reducing the rotor weight, thereby avoiding imbalance.
[0018] In the illustrated embodiment, the back iron ring 1 is a stack of electrical steel sheets, i.e., soft magnetic steel. The stacking direction is axial. Thus, the sheet planes of the individual sheets in the stack extend perpendicular to the axial direction of the rotor. The individual sheets of the stack are welded together and can also carry a retainer 8 that extends in the axial direction of the stack and clamps around its ends. In addition to being welded together, the individual sheets can also be mechanically connected to each other by stamping packaging or other means. The bracket 8 can also connect the stack to the bracket 3. The bracket 8 can be arranged outside the stack. Figure 1 The weld seam 9 shown in
[0019] The individual sheets of the stack can be annular sheets or each sheet forms only one ring segment.
[0020] The permanent magnet 2 is glued into the back iron ring 1. In principle, the permanent magnet can be attached to the back iron ring 1 before or after magnetization. In the rotor shown, the permanent magnet 2 is first attached to the back iron ring 1 and then magnetized. The back iron ring 1 has a groove on its inner side, and the permanent magnet 2 is glued into this groove. As Figure 1 shown, the carrier 3 has a projection 10, and the projection 10 forms a stop for the permanent magnet 2, thus facilitating assembly. During assembly, the permanent magnet 2 is pushed into the groove of the back iron ring 1 until the end face of the permanent magnet 2 contacts the projection 10. One or more projections 10 can be assigned to each permanent magnet 2. In the design example shown, exactly one projection 10 is assigned to each permanent magnet 2. Thus, between two adjacent inner projections 6, the carrier has exactly one projection 10 in each case. The permanent magnet can be, for example, a rare earth magnet based on Nd2Fe 14 B.
[0021] Reference numerals:
[0022] 1 Back iron ring;
[0023] 2 Permanent magnet;
[0024] 3 Carrier;
[0025] 4 Slot;
[0026] 5 Outer projection;
[0027] 6 Inner projection;
[0028] 8 Bracket;
[0029] 9 Weld seam;
[0030] 10 Projection.
Claims
1. A rotor for an outer rotor motor, comprising: A back iron ring (1), the back iron ring (1) being made of ferromagnetic steel; A permanent magnet (2), the permanent magnet (2) being fixed to the inner side of the back iron ring (1); And A bracket (3) made of a non-ferromagnetic material, the bracket (3) having a hub for a shaft and being attached to the back iron ring (1); Characterized in that: The bracket (3) has a groove (4), and the back iron ring (1) is inserted into the groove (4).
2. The rotor according to claim 1, characterized in that, The bracket (3) is made of an aluminum-based alloy.
3. The rotor according to claim 1, characterized in that, The back iron ring (1) is a stack of metal sheets.
4. The rotor according to claim 3, characterized in that, The sheets in the sheet stack are welded together.
5. The rotor according to claim 1, characterized in that, The bracket (3) has an external protrusion (5) extending axially on the outer side of the back iron ring (1).
6. The rotor according to claim 5, characterized in that, The external protrusion (5) extends only over a part of the axial length of the back iron ring (1).
7. The rotor according to claim 6, wherein The external protrusion (5) extends only more than 20% to 50% of the axial length of the back iron ring (1).
8. The rotor according to claim 5, wherein The bracket (3) has an internal protrusion (6), the internal protrusion (6) extending axially inside the back iron ring (1) between the permanent magnets (2).
9. The rotor according to claim 8, characterized in that, The external protrusion (5) extends further in the axial direction than the internal protrusion (6).
10. The rotor according to claim 1, characterized in that, A circumferentially extending gap is provided between one end face of the permanent magnet (2) and the bracket (3), and a bump (10) of the bracket (3) protrudes into the gap.
11. The rotor according to claim 10, characterized in that, Each permanent magnet (2) abuts exactly against one of the bumps (10).
12. The rotor according to claim 1, wherein, The depth of the groove (4) is less than the axial length of the back iron ring (1).
13. The rotor according to claim 1, characterized in that, The groove (4) is annular.
14. The rotor according to claim 1, characterized in that, The permanent magnet (2) is attached to the back iron ring (1) by an adhesive.