Method for balancing a rotor of an external rotor motor

Abstract

A method for balancing a rotor of an external rotor motor is described, wherein the rotor has a short-circuit ring (1), permanent magnets (2) attached to the inside of the short-circuit ring (1), and a carrier (3) which is attached to the short-circuit ring (1) and forms a hub (4) for a shaft, and wherein, in order to eliminate an imbalance, material is removed from the carrier (3) at several points which are arranged at an axial distance from each other.

Description

[0001] The invention relates to a method for balancing a rotor of an external rotor motor, wherein the rotor has a short-circuit ring, permanent magnets attached to the inside of the short-circuit ring, and a carrier having annularly arranged projections and a hub for a shaft.

[0002] To correct an imbalance, material is usually removed from the rotor of an electric motor. The support of an external rotor motor may have annular projections for this purpose, from which material can be removed as needed.

[0003] The object of the present invention is to show a cost-effective way how rotors of external rotor motors can be better balanced.

[0004] This object is achieved by a method having the features specified in claim 1. Advantageous developments of the invention are the subject of subclaims.

[0005] According to the invention, to eliminate an imbalance, material is removed from the carrier at several points. These points are arranged at an axial distance from one another. This makes it easier and more effective to eliminate an imbalance. The axial distance of the points refers to the respective position on the surface of the carrier before material removal begins.

[0006] The material can be removed from points on the support that are not highlighted by a special shape, especially if the walls of the support are made thicker than would be necessary for mechanical reasons. Another possibility is for the support to have one or more groups of annularly arranged projections from which material is removed to eliminate an imbalance. The points at which material is removed from the support can therefore be defined by projections. For balancing, material is then removed from one or more projections (first point) of a group of projections. In addition, for balancing, material can be removed from one or more points on the support that are at an axial distance from this group of projections, i.e. a second point. This second point can be defined by projections or another surface of the support.The second location may be one or some projections of a second group of projections that are axially spaced from this group of projections, but it does not have to be.

[0007] An advantageous development of the invention provides for the use of a carrier having two groups of annularly arranged projections, from which material can be removed to eliminate an imbalance. A first group of annularly arranged projections can be formed as humps on an end face of the carrier, which protrude in the axial direction. A second group of annularly arranged projections can be arranged radially outside of the first group. In this way, more material is advantageously available, and at different locations, which can be removed for balancing.

[0008] Further details and advantages of the invention are explained using exemplary embodiments with reference to the accompanying drawings. Identical and corresponding components are provided with identical reference numerals. They show: Fig. 1 a schematic representation of a rotor of an external rotor motor; Fig. 2 a detailed view of the rotor; and Fig. 3 another detailed view of the rotor.

[0009] In Fig. 1 shows a rotor of an electric motor, more specifically an external rotor motor. The rotor has a short-circuit ring 1, which can be formed, for example, from a stack of sheet steel, and permanent magnets 2, for example rare earth magnets based on Nd2Fe, attached to the inside of the short-circuit ring 1. 14B, and a carrier 3, which has a hub 4 for a shaft and is attached to the short-circuit ring 1. The carrier 3 can be made, for example, of an aluminum-based alloy.

[0010] The short-circuit ring 1 can, for example, be fastened to the carrier 3 by means of holders 5 which extend along an outer side of the short-circuit ring 1 and which bear with angled end sections against an end surface of the short-circuit ring 1 and an axially opposite surface of the carrier 3.

[0011] How Fig. As shown in Figure 2, the carrier 3 has a first group of annularly arranged projections 10, which are formed as axially projecting protrusions on one end face of the carrier 3. To balance the rotor, material can be removed from the projections 10 defined by these protrusions.

[0012] The carrier 3 additionally has a second group of annularly arranged projections 11, which are arranged radially outside of the first group. Material can also be removed from these projections 11 to eliminate an imbalance. The projections 11 of the second group thus define second locations on the carrier 3 from which material can be removed to eliminate an imbalance. The projections 11 of the second group can, in particular, be arranged radially outside of the first group of projections 10 so that the projections 11 of the second group are each arranged at least partially radially further outward than the short-circuit ring 1.

[0013] The second group of annularly arranged projections 11 can be formed, like the group of axially protruding protrusions on an end face of the carrier 3. In the illustrated embodiment, the second group of projections 11 is arranged on a stepped step of the carrier 3. The second group of projections 11 is therefore arranged at a distance in the axial direction from the first group of projections 10, which facilitates balancing.

[0014] A further second group of projections 12 is arranged on an outer side of the short-circuit ring 1. Material can also be removed from these projections 12 for balancing purposes. The projections 12 can be provided in pairs, with one pair of projections 12 forming a slot into which a radial projection 6 of the short-circuit ring 1 engages, forming a shaft-hub connection between the short-circuit ring 1 and the carrier 3.

[0015] The projections 12 of the further second group extend on the outside of the short-circuit ring 1 in the axial direction and can have a thickening 12a at their distal end, in particular a thickening 12a rising in the radial direction, so that more material can be removed to eliminate an imbalance without impairing the shaft-hub connection between the short-circuit ring 1 and the carrier 3. List of reference symbols 1 short-circuit ring 2 permanent magnets 3 carriers 4 Hub 5 brackets 6 lead 10 projections 11 projections 12 projections 12a Thickening

Claims

[1] Method for balancing a rotor of an external rotor motor, wherein the rotor a short-circuit ring (1), permanent magnets (2) attached to the inside of the short-circuit ring (1), and a carrier (3) which is fastened to the short-circuit ring (1) and forms a hub (4) for a shaft, and wherein, in order to eliminate an imbalance, material is removed from the carrier (3) at a plurality of locations which are arranged at an axial distance from one another. [2] Method according to claim 1, characterized by that a first location is at least one projection of a first group of annularly arranged projections (10) on an end face of the carrier (3). [3] Method according to one of the preceding claims, characterized by that a second location is at least one projection of a second group of annularly arranged projections (11, 12). [4] Method according to claim 3, characterized bythat the projections (11, 12) of the second group are arranged radially outside of the first group. [5] Method according to one of claims 2 to 4, characterized by that the projections (10) of the first group and the projections (11, 12) of the second group are arranged as humps projecting in the axial direction on an end face of the carrier (3). [6] Method according to one of claims 3 to 5, characterized by that the projections (11, 12) of the second group are each arranged at least partly radially further outwards than the short-circuit ring (1). [7] Method according to one of claims 3 to 5, characterized by that the second group of projections (11, 12) of the carrier (3) is arranged on an outer side of the short-circuit ring (1). [8] Method according to claim 7, characterized bythat the projections (12) of the second group are arranged in pairs and define a slot between them into which a radial projection (6) of the short-circuit ring (1) engages. [9] Method according to claim 7 or 8, characterized by that the projections (12) of the second group extend along the outside of the short-circuit ring (1) and have a thickening (12a) at their distal end. [10] Method according to claim 9, characterized by that the thickening (12a) rises in the radial direction. [11] Method according to one of claims 3 to 10, characterized by that the second group of projections (11, 12) is arranged at a distance in the axial direction from the first group of projections (10). [12] Method according to one of the preceding claims, characterized by that the carrier (3) is made of an aluminum-based alloy.

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