External Rotor Motor With A Cooling Wheel For Cooling The Stator

Abstract

An external rotor motor (1) has a stator (10), a rotor (20) and a cooling wheel (30) that rotates with the rotor (20) and the stator (10) to cool the stator (10). The stator (10) has an inner portion (11), enabling fluid flow, and a surrounding outer portion (12) enabling fluid flow. The flow is fluidically separate from the inner portion (11) in the radial direction (X ). The cooling wheel (30) has a plurality of blades (33) to generate an overpressure and a negative pressure. The cooling wheel (30) generates a directed air flow (L) flowing from the outer diameter (32) of the cooling wheel (30) through the outer portion (12) and the inner portion (11) to the inner diameter (31) of the cooling wheel (30).

Claims

1-10. (canceled)

11. An external rotor motor comprising: a stator, a rotor and a cooling wheel that rotates about an axis of rotation with the rotor and the stator for cooling the stator; the stator has an inner portion, where fluid can flow parallel to the axis of rotation, and an outer portion, where fluid can flow parallel to the axis of rotation, the outer portion annularly surrounds the inner portion and is fluidically separated from the inner portion in the radial direction, the cooling wheel, including a plurality of blades arranged and positioned adjacent to the stator, generates an overpressure, at an outer diameter of the cooling wheel adjacent to the outer portion, and a negative pressure, at an inner diameter of the cooling wheel adjacent to the inner portion, the cooling wheel generating a directed air flow flowing from the outer diameter of the cooling wheel through the outer portion and the inner portion to the inner diameter of the cooling wheel.

12. The external rotor motor of claim 11, wherein the cooling wheel is fixed on one side of a bearing shield facing the stator, via which the rotor is rotatably mounted on the stator.

13. The external rotor motor of claim 12, further comprising a housing surrounding the stator, the housing rotating with the rotor and is closed on one side by the bearing shield, a case formed by the housing and the bearing shield is fluidically tight.

14. The external rotor motor of claim 11, further comprising a clearance fluidically connecting the outer portion to the inner portion at one side of the stator facing away from the cooling wheel along the axis of rotation.

15. The external rotor motor of claim 11, wherein the stator has a plurality of stator teeth, each has a winding portion for receiving stator windings in the outer portion of the stator and a connecting portion for connecting the stator to an axis of the electric motor in the inner portion of the stator.

16. The external rotor motor of claim 15, wherein the stator includes a plurality of individual teeth that are mechanically connected to one another at a connecting portion in the circumferential direction.

17. The external rotor motor of claim 11, wherein the stator has a ring element fluidically separating the inner portion from the outer portion.

18. The external rotor motor of claim 17, wherein the ring member extends parallel to the axis of rotation along the entire stator.

19. The external rotor motor according to claim 11, wherein the cooling wheel has a closed ring where the blades extend in the radial direction and the blades protrude parallel to the axis of rotation in the direction of the stator.

Description

DRAWINGS

[0025] Other developments of the disclosure are included in the dependent claims or are listed below together with the description of the preferred embodiment of the disclosure based on the figures. In particular:

[0026] FIG. 1 is a cross-section view through an external rotor;

[0027] FIG. 2 is a perspective view of the cooling wheel of an external rotor.

DETAILED DESCRIPTION

[0028] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0029] The figures are schematic by way of example. The same reference numbers in the figures indicate the same functional and/or structural features.

[0030] FIG. 1 shows a sectional view of an external rotor motor 1, shown in perspective, with a cooling wheel 30 used in the external rotor motor 1, according to FIG. 1 being shown in FIG. 2. In this case, the rotor 20 can rotate about the stator 10 or about the axis of rotation R. The rotor 20 is firmly connected to the housing 22 and via the housing to the bearing shield 21. The rotor 20 is fixed on the axis 40, with which the stator 10 is rotatably connected, via the housing 22 and bearing shield 21 via bearings provided for this purpose, such as to rotate about the axis of rotation R.

[0031] In the present case, the bearing shield 21 is connected to the housing 22 and sealed against it. Thus, the case formed by the housing 22 and the bearing shield 21 is substantially airtight and air flow is prevented in and out of the case.

[0032] The stator 10 has a radially inner portion 11, through which air can flow, and a radially outer portion 12, through which air can flow. Thus, the latter is further away in the radial direction X from the axis of rotation R than the inner portion 11.

[0033] The inner portion 11 is fluidically separated from the outer portion 12 by a ring element 15, so that no air can flow between the inner portion 11 and the outer portion 12 at least on or in the stator 10.

[0034] A cooling wheel 30 is rotatably fixed to the bearing shield 21 with the rotor 20. The cooling wheel 30 generates a negative pressure on its inner diameter 31 and an overpressure on its outer diameter 32. This is due to its rotation about the axis 40 or about the axis of rotation R and due to its blades 33.

[0035] An upper edge of the blades 33 of the cooling wheel 30 extend, at least in portions, parallel and adjacent to the ring element 15. An air gap is formed between the ring element 15 and the blades 33 or the upper edges of all blades 33. This enables free rotation of the cooling wheel 30 relative to the stator while hindering or preventing a direct back flow of air between the stator 10 and the cooling wheel 30 from the region with positive pressure to the region with negative pressure.

[0036] To equalize the pressure in the case, the overpressure and the negative pressure generate a directed air flow L from the outer diameter 32 of the cooling wheel 30 through the outer portion 12 in a clearance 13, that is opposite to the bearing shield 21 with respect to the stator 10, and from the clearance 13 through the inner portion 11 to the inner diameter 31 of the cooling wheel 30. The clearance 13 fluidically connects the outer portion 12 with the inner portion 11 of the stator 10 and is delimited along the axis of rotation R by the stator 10 and the housing 22.

[0037] The directed air flow L or the air transported by the air flow L absorbs heat as it flows through the outer portion 12 of the stator 10 from stator windings 14, wound on individual stator teeth of the stator 10, and transfers the heat to cooler regions of the external rotor motor 1. For example, it transfers the heat to the housing 22, the inner portion 11 or the axle 40 in order to cool the outer portion 12 or the stator windings 14 in a defined way by the directed air flow L.

[0038] The implementation of the disclosure is not limited to the preferred exemplary embodiments specified above. Rather, a number of variants are conceivable that make use of the solution shown even in the case of fundamentally different embodiments.

[0039] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.