Method for balancing rotor of external rotor electric machine

Abstract

A method is described for balancing a rotor of an external rotor electric machine, in which the rotor comprises a back iron ring (1), permanent magnets (2) attached to the inside of the back iron ring (1), and a carrier part (3) attached to the back iron ring (1) and forming a hub (4) for a shaft, in which material is removed from a plurality of points on the carrier part (3) arranged at an axial distance from each other in order to eliminate imbalance.

Description

Technical Field

[0001] The invention relates to a method for balancing a rotor of an outer rotor electric machine, wherein the rotor comprises a back iron ring, permanent magnets attached to the inside of the back iron ring and a carrier having annularly arranged protrusions and a hub for a shaft. Background Art

[0002] In order to eliminate the imbalance, it is usually necessary to remove material from the rotor of the electric motor. For this purpose, the carrier part of the outer rotor motor disclosed in FR2865584 has an annular protrusion from which material can be removed as needed. Summary of the invention

[0003] The object of the present invention is to provide a cost-effective method for improving the rotor balance of an outer rotor motor.

[0004] According to the invention, material is removed from several points of the load-bearing component to eliminate the imbalance. These points are arranged at an axial distance from each other. This helps to eliminate the imbalance. The axial spacing of these points refers to their respective positions on the surface of the load-bearing component before the material removal begins.

[0005] Material can be removed from areas of the load-bearing component that are not designated as having a special shape, in particular if the wall of the load-bearing component is designed to be thicker than is necessary for mechanical reasons. Another possibility is that the load-bearing component has one or more groups of annular protrusions, from which material is removed to eliminate the imbalance. The points at which material is removed from the load-bearing component can therefore be defined by the protrusions. For the sake of balancing, material is then removed from one or more protrusions of the group of protrusions (the first points). Furthermore, for the sake of balancing, material can also be removed from one or more points of the load-bearing component that are axially distanced from the group of protrusions (i.e. the second points). The second point can be defined by the protrusions, or it can be another surface of the load-bearing component. Thus, the second point can be one or more protrusions of the second group of protrusions that are axially spaced from the group of protrusions, but this is not necessary.

[0006] An advantageous development of the invention is to use a load-bearing part with two groups of annularly arranged protrusions from which material can be removed to eliminate the imbalance. The first group of annularly arranged protrusions can be designed as ridges on the end face of the load-bearing part, which protrude in the axial direction. The second group of annular protrusions can be arranged radially outside the first group. In this way, more material is available to be removed at different locations to achieve balance. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Further details and advantages of the present invention will be described with reference to the accompanying drawings. Identical and corresponding components will be provided with corresponding reference numerals.

[0008] Figure 1A schematic diagram of a rotor of an external rotor motor is shown;

[0009] Figure 2 shows a detailed view of the rotor; and

[0010] Figure 3 Another detailed view of the rotor is shown. DETAILED DESCRIPTION

[0011] Figure 1 The rotor of an electric motor, more precisely an outer rotor motor, is shown. The rotor comprises: a back iron ring 1, which can be formed, for example, from a stack of steel sheets; a permanent magnet 2, for example a rare earth magnet, for example based on Nd; 2 Fe 14 and a bearing member 3 having a hub 4 for the shaft and attached to the back iron ring 1. For example, the bearing member 3 may be made of an aluminum-based alloy.

[0012] For example, the back iron ring 1 may be attached to the carrier member 3 by means of brackets 5 which extend along the outside of the back iron ring 1 and whose angled ends abut against the end faces of the back iron ring 1 and the axially opposite faces of the carrier member 3 .

[0013] like Figure 2 As shown, the carrier part 3 has a first group of annularly arranged protrusions 10, which are designed as bumps protruding in the axial direction on one end face of the carrier part 3. Material can be removed from these defined protrusions 10 in order to balance the rotor.

[0014] The load bearing part 3 also has a second set of annular protrusions 11, which are arranged radially outside the first set. Material can also be removed from these protrusions 11 to eliminate imbalance. Therefore, the second set of protrusions 11 defines a second point of the load bearing part 3 from which material can be removed to eliminate imbalance. In particular, the second set of protrusions 11 can be arranged radially outside the first set of protrusions 10, so that each of the second set of protrusions 11 is at least partially arranged radially further outside than the back iron ring 1.

[0015] The second group of annularly arranged protrusions 11 may also be designed as convex blocks protruding in the axial direction on the end face of the bearing member 3. In the illustrated embodiment, the second group of protrusions 11 are arranged on an offset ledge of the bearing member 3. Therefore, the second group of protrusions 11 are arranged at a certain distance from the first group of protrusions 10 in the axial direction, which is beneficial to balance.

[0016] A further second set of protrusions 12 is also provided on the outside of the back iron ring 1. For balancing purposes, material can also be removed from these protrusions 12. The protrusions 12 can be provided in pairs, with a pair of protrusions 12 forming a groove, wherein the radial protrusions 6 of the back iron ring 1 engage with the groove and form a shaft-hub connection between the back iron ring 1 and the carrier part 3.

[0017] Another second set of protrusions 12 extend in the axial direction on the outside of the back iron ring 1 and may have thickened portions 12a at their distal ends, particularly thickened portions 12a that bulge in the radial direction, so that more material can be removed to eliminate imbalance without affecting the shaft-hub connection between the back iron ring 1 and the bearing component 3.

[0018] Reference numerals list

[0019] 1 back iron ring;

[0020] 2 permanent magnets;

[0021] 3 bearing components;

[0022] 4 hubs;

[0023] 5 brackets;

[0024] 6 protrusions;

[0025] 10 protrusions;

[0026] 11 protrusions;

[0027] 12 protrusions;

[0028] 12a Thickened portion.

Claims

1. A method for balancing a rotor of an external rotor motor, The rotor comprises: Back iron ring (1); A permanent magnet (2) attached to the inside of the back iron ring (1); as well as a bearing member (3) attached to the back iron ring (1) and forming a hub (4) for the shaft; as well as In this case, material is removed from a plurality of points on the carrier component (3) which are arranged at an axial distance from one another in order to eliminate the imbalance.

2. The method according to claim 1, wherein: The first point is at least one protrusion of a first group of annularly arranged protrusions (10) on the end surface of the bearing component (3).

3. The method according to claim 1, wherein: The second point is at least one protrusion of the second group of annularly arranged protrusions (11, 12).

4. The method according to claim 3, wherein: The second group of protrusions (11, 12) are arranged radially outside the first group of protrusions.

5. The method according to claim 3, wherein: The first group of protrusions (10) and the second group of protrusions (11, 12) are arranged as convex blocks protruding in the axial direction on the end surface of the bearing component (3).

6. The method according to claim 3, wherein each of the second set of protrusions (11, 12) is at least partially arranged radially outwardly further than the back iron ring (1).

7. The method according to claim 3, wherein: The second group of protrusions (11, 12) of the bearing component (3) is arranged on the outside of the back iron ring (1).

8. The method according to claim 7, wherein: The second set of protrusions (12) are each arranged in pairs and define a groove therebetween, wherein the radial protrusions (6) of the back iron ring (1) engage in the groove.

9. The method according to claim 7, wherein: The second group of protrusions (12) extend along the outer side of the back iron ring (1) and have thickened portions (12a) at their distal ends.

10. The method according to claim 9, wherein: The thickened portion (12a) bulges in the radial direction.

11. The method according to claim 3, wherein: The second group of protrusions (11, 12) are arranged at a certain distance from the first group of protrusions (10) in the axial direction.

12. The method according to claim 1, wherein: The bearing component (3) is made of an aluminum-based alloy.

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