Rotor for an external rotor motor
The rotor design uses train anchors and a final ring to securely connect the sheet metal stack to the carrier, addressing torque transfer and axial movement issues in outer rotor motors, ensuring reliable and cost-effective operation.
Patent Information
- Application Number
- DE102023119401
- Authority / Receiving Office
- DE · DE
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-07-21
- Publication Date
- 2025-01-23
AI Technical Summary
The challenge in connecting a ferromagnetic short circuit ring made of sheet metal stack to a carrier in an outer rotor motor is to effectively transfer torque while preventing axial movement without additional costs.
The solution involves using train anchors, such as pins, to pull the sheet metal stack against the carrier, with removable end pieces or brackets, and incorporating a final ring to secure permanent magnets, utilizing openings with slits to prevent axial movement.
This design ensures reliable torque transfer and prevents axial movement of the sheet metal stack and permanent magnets, achieving a cost-effective and robust connection.
Smart Images
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Abstract
Description
[0001] The invention relates to a rotor for an electric motor having the features specified in the preamble of claim 1.
[0002] In a rotor for an external rotor motor, the short-circuit ring made of ferromagnetic material, formed by a stack of laminations, must be connected to a support with a hub for a shaft. This connection must be able to transfer significant torque from the stack of laminations to the support during operation and also prevent axial movement of the stack of laminations relative to the support.
[0003] The object of the invention is to show a way in which this can be done reliably and cost-effectively.
[0004] This object is achieved by a rotor having the features specified in claim 1. Advantageous developments of the invention are the subject of subclaims.
[0005] A rotor according to the invention has tie rods that protrude in the axial direction through the carrier and the lamination stack and pull the lamination stack against the carrier. Suitable openings for the tie rods can be created when punching out the individual laminations at no additional cost. The tie rods can be designed as pins that protrude through these openings in the laminations and matching openings in the carrier and have an end piece at at least one end that has a greater width than the channel formed by the openings. The end pieces can be attached to the pins, for example, by riveting, for example by forming the end piece or by means of a separate rivet, or can be designed as removable end pieces. One possibility for this is for the end pieces to be screwed onto matching threads on the pins, for example as nuts. Another possibility is for the removable end pieces to be designed as clamps or clips.
[0006] The tie rods can be designed as pins with removable end pieces at both ends. However, it is also possible for the pins to have a removable end piece at only one end and a head at the other end that is wider than the channel formed by the openings in the sheets and the beam.
[0007] An advantageous development of the invention provides that the lamination stack has a closure ring at its end facing away from the support, which forms an axial stop for the permanent magnets, and the tie rods also extend through the closure ring. In this way, the permanent magnets arranged on the inside of the lamination stack can be easily secured against axial movement.
[0008] A further advantageous development of the invention provides that the openings in the sheets through which the tie rods protrude each have a round main surface and a slot extending from the main surface. The tie rod essentially completely fills this main surface, which is shaped to fit it. The round main surface can, for example, be a circular surface or have a slightly different shape. A slot extending from this main surface can advantageously prevent the tie rod from rotating during the screwing on of an end piece, for example, by a lug on the tie rod head engaging in the slot.
[0009] For example, the slot can have a length that is between half and the entire width of the main surface of the opening, i.e., for a circular main surface, between the radius and the diameter. The width of the slot can, for example, be between 20% and 40% of the width of the main surface of the opening, i.e., for a circular main surface, between 10% and 40% of the diameter of the main surface.
[0010] Further details and advantages of the invention are explained using an exemplary embodiment of the invention with reference to the accompanying drawings. They show: Fig. 1 a rotor for an external rotor motor; Fig. 2 a sectioned detailed view of the rotor; and Fig. 3 a detailed view of rotor components.
[0011] In Fig. 1 shows a rotor for an electric motor, more specifically an external rotor motor. The rotor has an annular stack 1 of ferromagnetic steel sheets, permanent magnets 2 attached to an inner side of the stack 1, and a support 3 attached to the stack 1, which has a hub 4 for a shaft (not shown). The support 3 can be made, for example, of aluminum or an aluminum-based alloy. The steel sheets of the stack 1 are made of electro-beam, i.e., soft magnetic steel, for example, silicon steel, and are stacked one on top of the other in the axial direction. The sheet plane of the individual sheets thus extends perpendicular to the axial direction.
[0012] The individual sheets of the sheet stack 1 can be ring-shaped sheets or each form only one ring segment.
[0013] At its end facing away from the carrier 3, the sheet stack 1 can carry a closure ring 5, which forms an axial stop for the permanent magnets 2 and secures the permanent magnets 2 against axial movement. The permanent magnets 2 can, for example, be made of a material based on Nd2Fe. 14 B and be attached to the sheet stack 1 by means of adhesive, in particular in grooves on the inside of the sheet stack 1. Another possibility is that the permanent magnets 2 are clamped to the sheet stack 1.
[0014] The sheet stack 1, the support 3 and the end ring 5 are connected by tie rods 6, which in the sectional view of Fig. 2 and extend axially through the support 3, the sheet stack 1, and the end ring 5. The tie rods 6 pull the sheet stack 1 against the support 3 and fix the sheet stack 1, support 3, and the end ring 5 to one another.
[0015] The tie rods 6 are designed as pins, each arranged in a channel leading through the sheet stack 1 and the support 3, and having a removable end piece 9 at at least one end that is wider than the channel. The end piece 9 can, for example, be screwed onto a thread of the tie rods 6. Corresponding end pieces 9 can be attached to both ends of the tie rods 6. In the embodiment shown, however, the tie rod 6 has a removable end piece 9 at only one end. At its other end, it has a widened head 6a that is wider than the channel.
[0016] The channel is formed by aligned openings 11, 12, 13 in the carrier 3, in the sheet stack 1 and in the end ring 5, which are particularly Fig. 3 can be seen.
[0017] In Fig.3 shows components of the rotor, namely a detail of one of the annular laminations 8 forming the lamination stack 1, a detail of the support 3, a detail of the end ring 5, and a tie rod 6 with a removable end piece 9.
[0018] The openings 12 in the sheet stack 1 and the openings 13 in the end ring 5 have a substantially circular main surface from which a radially inwardly directed slot extends. This slot can, for example, have a width between a quarter and half the diameter of the main surface, in particular 15% to 30%, and a length between a third and half the diameter of the main surface. A lug of the head 6a can engage in this slot during assembly, thus preventing the tension rod 6 from rotating when an end piece 9 is screwed on. List of reference symbols 1 stack of sheets 2 permanent magnets 3 carriers 4 Hub 5 end ring 6a Head 6 tie rods 8 sheet metal 9 End piece 11 Opening 12 openings 13 openings
Claims
[1] Rotor for an external rotor motor, with an annular lamination stack (1) made of steel, Permanent magnets (2) which are attached to an inner side of the sheet stack (1), and a carrier (3) having a hub (4) for a shaft and being attached to the sheet stack (1), characterized by Tie rods (6) which protrude in the axial direction through the support (3) and the sheet stack (1) and pull the sheet stack (1) against the support (3). [2] Rotor according to claim 1, characterized by that the tie rods (6) are designed as pins, each of which is arranged in a channel leading through the sheet stack (1) and the support (3) and which carries at least one end an end piece (9) which has a greater width than the channel. [3] Rotor according to claim 2, characterized by that the end piece (9) is removable. [4] Rotor according to claim 2 or 3, characterized by that the pins have an end piece (9) at both ends. [5] Rotor according to claim 2, characterized by that the pins have a widened head (6a) at one end which has a greater width than the channel. [6] Rotor according to one of the preceding claims, characterized by that the pins are threaded pins and the end pieces (9) are screwed onto the pins. [7] Rotor according to one of the preceding claims, characterized by that the sheet stack (1) carries at its end facing away from the carrier (6) an end ring (5) which forms an axial stop for the permanent magnets (2), and the tie rods (6) also protrude through the end ring (5). [8] Rotor according to one of the preceding claims, characterized by that the sheet stack (1) is formed from sheets (8) which have a plurality of openings (12) for the tie rods (6), wherein the openings (12) each have a round main surface and a slot which extends from the main surface. [9] Rotor according to claim 8, characterized by that the slot is directed radially inwards.
Citation Information
Patent Citations
Electric machine
CN109149799A
Permanent Magnet Alternator with Segmented Construction
US20090218900A1
CN000109149799A