ROTOR WITH INTEGRATED FAN, ELECTRIC MOTOR, PUMP DEVICE, HOUSEHOLD APPLIANCE AND PRODUCTION METHOD

Abstract

A rotor for an electric motor includes a ring portion and a hub portion. The ring portion contains a permanent magnet material and is configured to at least partially rotate about at least a portion of a stator of the electric motor. The hub portion is configured as a fan including two or more blade elements each being connected to the ring portion. The blade elements encompass two or more axial air passages. An electric motor including the rotor, a pump device and a household appliance each including the electric motor, as well as a method of producing the rotor, are also provided.

Claims

1. A rotor for an electric motor, the rotor comprising: a ring portion and a hub portion; said ring portion containing a permanent magnet material and said ring portion being configured to at least partially rotate about at least a portion of a stator of the electric motor; and said hub portion being configured as a fan including two or more blade elements each being connected to said ring portion, said blade elements encompassing two or more axial air passages.

2. The rotor according to claim 1, wherein at least one of said blade elements has at least one section with a thinning margin, said at least one blade element thinning in said thinning margin towards an edge delimiting said at least one blade in circumferential direction.

3. The rotor according to claim 1, wherein said ring portion includes a first sub-portion and a second sub-portion, said ring portion having a weaker magnetic field in said second sub-portion than in said first sub-portion.

4. The rotor according to claim 3, wherein said second sub-portion separates said first sub-portion from said hub portion in axial direction.

5. The rotor according to claim 1, wherein said ring portion has a radially outer surface narrowing towards said hub portion.

6. The rotor according to claim 1, wherein at least one of said ring portion or said hub portion of said rotor is made of a plastic material.

7. An electric motor, comprising a rotor according to claim 1 and a stator.

8. A pump device, comprising an impeller and an electric motor according to claim 7.

9. A household appliance, comprising an electric motor according to claim 7.

10. A household appliance, comprising a pump device according to claim 8.

11. A method of producing a rotor according to claim 1, the method comprising manufacturing at least one of said ring portion or said hub portion by at least one of injection molding or additive manufacturing.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0032] FIG. 1 is a diagrammatic, perspective view of a rotor according to an exemplary embodiment of the present invention;

[0033] FIGS. 2A-2D are different cross-sectional views of an exemplary rotor according to the present invention;

[0034] FIG. 3 is a cross-sectional view of an electric motor according to an embodiment of the present invention along with an air flow;

[0035] FIG. 4 is an exploded, perspective view of components of an electric motor according to an embodiment of the present invention; and

[0036] FIG. 5 is a cross-sectional view of a pump assembly according to the present invention with a cooling air flow.

DETAILED DESCRIPTION OF THE INVENTION

[0037] Referring now to the figures of the drawings in detail and first, particularly, to FIG. 1 thereof, there is seen an exemplary embodiment of a rotor 10 according to the present invention.

[0038] The rotor 10 includes a ring portion 11, a hub portion 12 and a shaft 13. The ring portion 11 is configured to at least partially rotate, (i.e., to rotate with at least a portion thereof), about at least a portion of a stator of an electric motor, such as about a stator 20 as depicted in FIG. 3. In particular, the rotor 10 may be included in an electric motor included in a (dry or wet) pump device.

[0039] In the embodiment depicted, the ring portion 11 and the hub portion 12 are integrated in a common monolithic part. Thereby, the rotor 10 can be made particularly solid.

[0040] As is seen in FIG. 1, the hub portion 12 is configured as a fan: In the exemplary case depicted, it includes (exactly) four blade elements 12a, 12b, 12c, 12d which each extend in radial direction (with respect to the designated rotation axis X of the rotor 10) and which at their respective radially outer end are connected to the ring portion 11. An axial air passage P is provided between each two blade elements which are adjacent each other in circumferential direction.

[0041] Accordingly, in operation of an electric motor including the rotor 10, an air flow is effected through an inner region surrounded by the ring portion 11 and—thereafter—through the air passages P. The air flow serves to cool down elements of the electric motor. Additionally, the air passages provide for a reduced mass of the rotor.

[0042] Preferably, at least the ring portion 11 and/or the hub portion 12 of the rotor 10 are made of plastic material, in particular of a plastomagnet material. The manufacturing may be realized by injection molding and/or additive manufacturing.

[0043] In the embodiment depicted, the ring portion 11 includes a first sub-portion 11f and a second sub-portion 11s. In axial direction (i.e., parallel to the designated rotation axis X), the second sub-portion 11s is disposed between the hub portion 12 and the first sub-portion 11f, thus separating them in axial direction. Therefore, the second sub-portion 11s connects the first sub-portion 11f (of the ring portion) with the hub portion 12. In the embodiment depicted, the first and the second sub-portions both have an annular shape.

[0044] At least the first sub-portion 11f, which is configured to at least partially rotate about the stator (not shown in FIG. 1), contains a permanent magnet material (not visible in FIG. 1). Therefore, the magnetic field is weaker in the second sub-portion 11s than in the first sub-portion 11f. Thereby, magnet material can be saved.

[0045] For example, the second sub-portion 11s may be non-magnetic (magnet-free), so that only the first sub-portion 11f of the ring portion has a magnetic field. In particular, the first sub-portion 11f may be anisotropic and the second sub-portion 11s may be isotropic.

[0046] Thereby, in operation of the electric motor including the rotor 10, an axial force between the rotor 10 and the stator stack can be reduced or even prevented, which minimizes friction losses.

[0047] As illustrated in FIG. 2A (showing the rotor 10 in cross section taken along the designated rotation axis X) the second sub-portion 11s has diameter d (measured in radial direction with respect to the designated rotation axis X) which is smaller than a diameter D (likewise measured in radial direction with respect to the axis X) of the first sub-portion 11f. In particular, the radially outer surface of the ring portion 11 narrows towards the hub portion 12.

[0048] FIGS. 2B and 2C each show a respective cross section taken orthogonally to the rotation axis X, as indicated in FIG. 2A by respective section lines A-A and B-B, wherein the viewing direction in both figures is towards the hub portion 12 of the rotor 10. In FIG. 2D, a cross section parallel to the rotation axis X is shown, as indicated (in FIG. 2C), by a section line C-C.

[0049] As is seen in FIGS. 2B-2D, each two blade elements 12a, 12b, 12c, 12d, which are adjacent in circumferential direction, are separated by a respective air passage P. The blade elements 12a, 12b, 12c, 12d each thin at their edges, towards the air passages P.

[0050] In order to improve clarity of the drawings, only thinning margins 12a-i, 12-a-ii of the blade element 12a and thinning margins 12b-i and 12b-ii of the blade element 12b are indicated, although it is to be understood that the blade elements 12c and 12d are shaped alike.

[0051] Therefore, as can be seen in FIGS. 2B-2D, the blade elements 12a, 12b each thin towards opposite directions at their edges which are opposite to each other in circumferential direction. That is, the thinning margins 12a-i, 12a-ii at the opposite edges of the blade element 12a face in opposite directions (parallel to the rotation axis X), in such a way that the thinning margins are identifiable from different sides. The same holds for the thinning margins at the opposite edges of the other blade elements.

[0052] Indeed, in FIG. 2B having a viewing direction from a space surrounded by the ring portion 11 towards the hub portion 12, only the thinning margins 12a-i, 12b-i are visible. By contrast, in FIG. 2C having a reverse viewing direction, the thinning margins 12a-ii, 12b-ii can be discerned.

[0053] As is in particular seen in FIG. 2D, the blade element 12b has a cross section which has a rotational symmetry of order two.

[0054] As further shown in FIG. 2D, the thinning margins 12b-i, 12b-ii of the blade 12b of the exemplary embodiment depicted (and likewise of the other blade elements) are rounded. According to alternative embodiments, the edges of the blade elements may include a chamfered section; in particular, the thinning margins may be flat.

[0055] According to preferred embodiments, the ring portion, in particular the first sub-section 11f thereof, has a direction of magnetization which is skewed with respect to the designated rotation axis X. In FIG. 2D, a corresponding skew angle α between the direction of magnetization and a line parallel to the rotation axis X is indicated. Preferably, such an angle α is larger than 5°, than 10° or than 15°, and/or smaller than 40°, than 35° or than 30°. Thereby, a reduced motor cogging torque can be achieved.

[0056] In FIG. 3, the rotor 10 is shown as being included in an electric motor 100 according to an exemplary embodiment of the present invention. The electric motor 100 is depicted in cross section along the dedicated rotation axis X of the rotor 10.

[0057] In addition to the rotor 10, the electric motor 100 includes a stator 20 including stator windings. In the cross section of FIG. 3, stator windings 21a, 21b are visible. The stator is held by a first housing component 30, which is connected to a second housing component 40 encompassing the ring portion 11 and the hub portion 12 of the rotor 10 as well as the stator windings. A shaft 13 is rotatably mounted in the combined first and second housing components 30, 40 by using bearing elements 51, 52.

[0058] Air inlets I are provided in the first housing component 30, and air outlets O are provided in the second housing component 40. Due to the hub portion 12 of the rotor 10 according to the present invention being configured as a fan, a cooling air flow is thereby facilitated, as indicated in FIG. 3 by arrows: Air entering the electric motor 100 through the air inlets I can thus cool inner components of the electric motor (such as the stator windings and/or the bearing elements 51, 52). Therefore, the air can be heated by those components and exit the electric motor through the air outlets O.

[0059] In FIG. 4, an exploded view illustrates how the rotor 10 is mounted in the second housing component 40 of the electric motor 100 shown in FIG. 3. A perspective view, particularly of the second housing component 40 is thereby provided, in particular.

[0060] FIG. 5 depicts a pump 1000 according to an embodiment of the present invention. In particular, such a pump may be included in a household appliance such as a washing machine, a tumble dryer or a dishwasher.

[0061] The pump 1000 includes an electric motor 100 according to the present invention. The shaft 13 of the rotor 10 of the electric motor 100 is connected to an impeller 200 of the pump 1000 and thereby configured to drive the impeller 200 within a pump housing 300.

[0062] Arrows in FIG. 5 illustrate the cooling air flow through the electric motor 100, as facilitated by the present invention.

[0063] A rotor 10 for an electric motor 100 is therefore disclosed. The rotor includes a ring portion 11 and a hub portion 12, wherein the ring portion 11 contains a permanent magnet material and is configured to at least partially rotate about at least a portion of a stator 20 of the electric motor 100. The hub portion 12 is configured as a fan including two or more blade elements 12a, 12b, 12c, 12d each being connected to the ring portion 11, the blade elements encompassing two or more axial air passages P.

[0064] Further disclosed are an electric motor 100 including such a rotor 10, a pump device 1000 and a household appliance each including such an electric motor 100, and a method of producing the rotor 10.

[0065] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention:

10 rotor
11 ring portion
11f first sub-portion
11s second sub-portion
12 hub portion
12a, 12b, 12c, 12d blade element
12a-i, 12a-ii, 12b-i, 12b-ii thinning margin
13 shaft
20 stator
21a, 21b stator winding
30 first housing component
40 second housing component
51, 52 bearing elements
100 electric motor
200 impeller
300 pump housing
1000 pump
α skewing angle
d diameter of second sub-portion 11s
D diameter of first sub-portion 11f
I air inlet
O air outlet
P air passage
X designated rotation axis