Electric motor

Patent metadata

Field	Value
Publication number	US-10069359-B2
Application number	US-201415026587-A
Country	US
Kind code	B2
Filing date	Oct 1, 2014
Priority date	Oct 2, 2013
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

An electric motor has an internal stator (21) and an external rotor (2). The external rotor (2) has a rotor housing (3) and a plurality of magnets (9) mounted therein and is adapted to rotate around a rotation axis (10); the magnets (9) are preferably bar magnets; the rotor housing (3) has an inner surface (7), a first end (5), and a second end (6) located opposite the first end (5) and the inner surface defines respective receiving surfaces (11) for reception of the magnets. each receiving surface features a channel depression (13) to receive a magnet (9). The magnets (9) are each fastened on a respective one of the receiving surfaces (11) with the aid of an adhesive mounting agent (36). A first bearing seat (14) for reception of a first bearing cage (15) is formed at the second end (6) of the rotor housing (3).

First claim

The invention claimed is:

1. An electric motor having an internal stator ( 21 ) and an external rotor ( 2 ), said external rotor ( 2 ) including a rotor housing ( 3 ) and a plurality of magnets ( 9 ) and being adapted to rotate, in operation, about a rotation axis ( 10 ) of said rotor, wherein
said magnets ( 9 ) are formed as bar magnets,
said rotor housing ( 3 ) has an inner surface ( 7 ), a first axial end ( 5 ), and a second axial end ( 6 ) located opposite the first end ( 5 ), said inner surface ( 7 ) being formed with respective receiving surfaces ( 11 ) adapted to receive said bar magnets ( 9 );
said receiving surfaces ( 11 ) each define, with respect to a remainder of said inner surface ( 7 ), a channel depression ( 13 ),
said receiving surfaces ( 11 ) have formed at least predominantly planar both in a direction parallel to the rotation axis ( 10 ) of the rotor housing ( 3 ) and in a circumferential direction along the inner surface ( 7 ),
wherein said bar magnets ( 9 ) are respectively fastened onto one of the respective receiving surfaces ( 11 ) using an adhesive mounting agent ( 36 ),
wherein a dimension (E 1 P), of the respective receiving surfaces ( 11 ) in a first direction (DIRP) that is parallel to the rotation axis ( 10 ), is larger than a dimension (E 2 P) of the associated magnets ( 9 ) in the first direction (DIRP), and
in which a dimension (E 1 T), of the respective receiving surfaces ( 11 ) in a second direction (DIRT) that is perpendicular to the first direction (DIRP), is larger than a dimension (E 2 T) of the associated magnet ( 9 ) in the second direction (DIRT),

and further comprising, at said second end ( 6 ) of the rotor housing ( 3 ), a first bearing seat ( 14 ) formed in said rotor housing and a first bearing cage ( 15 ) mounted in said first bearing seat ( 14 ).

2. The electric motor according to claim 1 , wherein
the respective receiving surfaces ( 11 ) and the associated magnets ( 9 ), at interfaces therebetween, define a series of respective connecting regions ( 38 ) in which said magnets ( 9 ) are arranged adjacently to one another, the receiving surfaces ( 11 ) each extending laterally beyond the respective connecting region ( 38 ) on all sides, thereby avoiding any need to provide a magnet abutment shoulder on the inner surface ( 7 ) of the rotor housing ( 3 ).

3. The electric motor according to claim 1 , wherein a cross-sectional contour of a transition portion ( 35 ) of the inner surface ( 7 ), between two adjacent receiving surfaces ( 11 ), has a generally concave shape.

4. The electric motor according to claim 1 , wherein the transition portion of the inner surface ( 7 ) has a polygonally shaped cross-sectional contour.

5. The electric motor according to claim 4 , wherein the inner surface ( 7 ) has a 14-sided polygonal cross-sectional contour.

6. The electric motor according to claim 1 , wherein the channel depressions ( 13 ) extend in a direction parallel to the rotation axis ( 10 ) of the rotor.

7. The electric motor according to claim 1 , wherein the channel depressions ( 13 ) have, in a direction parallel to the rotation axis ( 10 ), a first length (L 1 ) that is greater than a second length (L 2 ) of the magnets ( 9 ), which second length (L 2 ) extends in a direction parallel to the rotation axis ( 10 ).

8. The electric motor according to claim 1 , wherein
the rotor housing ( 3 ) has an inside diameter (D) that is constant or decreasing, proceeding from the first end ( 5 ) of the rotor housing ( 3 ) to the second end ( 6 ) of the rotor housing ( 3 ).

9. The electric motor according to claim 1 , wherein the rotor housing ( 3 ) has, at the second end ( 6 ), a first rotor housing portion ( 301 ) having an inside diameter, which inside diameter is smaller than an inside diameter (D) of the rotor housing ( 3 ) in a second rotor housing portion ( 302 ) in which the magnets ( 9 ) are mounted, thereby defining, at said second end ( 6 ), a bearing seat ( 14 ).

10. The electric motor according to claim 9 , wherein the rotor housing ( 3 ) tapers in a third rotor housing portion ( 303 ), arranged between the first rotor housing portion ( 301 ) and the second rotor housing portion ( 302 ), said taper forming a shoulder ( 305 ).

11. The electric motor according to claim 9 , wherein the bearing seat ( 14 ) and the rotor housing ( 3 ) are implemented as a single integral element.

12. The electric motor according to claim 1 , wherein the magnets ( 9 ) are implemented as cuboidal bar magnets.

13. The electric motor according to claim 1 , wherein a lateral distance between two adjacent magnets ( 9 ), within a predefined radial inner-surface distance range (ID) from the respectively associated inner surface ( 7 ) of the rotor housing ( 3 ), decreases, at least locally, as the inner-surface distance increases.

14. The electric motor according to claim 1 , wherein a predefined minimum lateral distance (D 3 ) is always provided between each two adjacent magnets ( 9 ).

15. The electric motor according to claim 1 , wherein the plurality of magnets ( 9 ) are each formed predominantly of a magnetically anisotropic material.

16. The electric motor according to claim 1 , wherein the plurality of magnets ( 9 ) are each formed of a permanently magnetic material.

17. The electric motor according to claim 1 , wherein the magnets ( 9 ) each comprise sintered material.

18. The electric motor according to claim 1 , wherein the rotor housing ( 3 ) is implemented as a deep drawn part by means of a deep-drawing process.

Assignees

• Ebm Papst St Georgen Gmbh & Co Kg

Inventors

• Ginter Andreas
• Flaig Markus

Classifications

• H02K5/173

  using bearings with rolling contact, e.g. ball bearings · CPC title

• H02K5/161

  radially supporting the rotary shaft at both ends of the rotor (H02K5/165, H02K5/167, H02K5/173 take precedence) · CPC title

• H02K5/1732

  radially supporting the rotary shaft at both ends of the rotor (H02K5/1737 takes precedence) · CPC title

• H02K7/14

  Structural association with mechanical loads, e.g. with hand-held machine tools or fans (with fan or impeller for cooling the machine H02K9/06) · CPC title

• H02K21/22

  with magnets rotating around the armatures, e.g. flywheel magnetos · CPC title