Permanent magnet rotor with sickle-shaped envelope for polar permanent magnet running arcuately along the rotor boundary

1. A rotor for an external rotor machine, said rotor comprising:

a permanent magnet including a north pole and a south pole as magnetic poles and sized to extend from a first end to a second end in parallel relation to an axis of rotation, with the first end having an end face with a contour shaped as a recess or a web protruding with respect to the end face, said permanent magnet having a cross-section in which a magnetization runs from the south pole to the north pole and which has an envelope in the form of a sickle with a concave section arranged along a boundary of the rotor, and a convex section, with the permanent magnet running in an arcuate manner along the convex section, and with the magnetic poles running in an arcuate manner along the concave section, said contour of the end face at the first end having within the envelope a surface and a boundary shaped to extend in an arcuate manner from a first point of the convex section to a second point of the convex section; and

a connection device for connecting with the permanent magnet via the surface of the end face at the first end by form fit.

2. The rotor of claim 1 , wherein the concave section of the envelope is a circular arc defined by a radius, and the convex section of the envelope is a circular arc defined by a radius, said radius of the circular arc of the concave section being greater than the radius of the circular arc of the convex section.

3. The rotor of claim 1 , wherein the permanent magnet has an axial contour running in a first direction in perpendicular relation to the cross-section shaped as a recess or a protruding web, said axial contour having a surface for connecting the connection device with the permanent magnet by form fit.

4. The rotor of claim 1 , wherein the permanent magnet has a recess at the concave section between the north pole and the south pole.

5. The rotor of claim 1 , wherein the permanent magnet runs along the concave section between the north pole and the south pole.

6. The rotor of claim 1 , wherein the permanent magnet is a sintered permanent magnet.

7. The rotor of claim 1 , wherein the connection device includes lightweight material having a mass density of less than 4.6 kg/dm 3 said permanent magnet and the lightweight material filling more than 90% of a mass volume between the boundary of the rotor and an envelope of the rotor.

8. The rotor of claim 1 , wherein the connection device includes a plastics material.

9. The rotor of claim 1 , further comprising a part made in one piece from a material and including a force-transmitting device, said part comprising more than 90% of a mass volume of the connection device.

10. The rotor of claim 1 , wherein the connection device in a cross-section of the rotor extends annularly adjacent to the permanent magnet and concentrically to the boundary of the rotor.

11. The rotor of claim 1 , wherein the permanent magnet directly faces an air gap between the rotor and a stator.

12. An external rotor machine, comprising:

a rotor comprising a permanent magnet including a north pole and a south pole as magnetic poles and sized to extend from a first end to a second end in parallel relation to an axis of rotation, with the first end having an end face with a contour shaped as a recess or a web protruding with respect to the end face, said permanent magnet having a cross-section in which a magnetization runs from the south pole to the north pole and which has an envelope in the form of a sickle with a concave section arranged along a boundary of the rotor, and a convex section, with the permanent magnet running in an arcuate manner along the convex section, and with the magnetic poles running in an arcuate manner along the concave section, said contour of the end face at the first end having within the envelope a surface and a boundary shaped to extend in an arcuate manner from a first point of the convex section to a second point of the convex section, and a connection device for connecting with the permanent magnet via the surface of the end face at the first end by form fit; and

a stator magnetically interacting with the rotor across an air gap during operation of the external rotor machine,

wherein the rotor is rotatably mounted about the axis of rotation.

13. A vehicle wheel, comprising a rim, said rim including a rotor comprising a permanent magnet including a north pole and a south pole as magnetic poles and sized to extend from a first end to a second end in parallel relation to an axis of rotation, with the first end having an end face with a contour shaped as a recess or a web protruding with respect to the end face, said permanent magnet having a cross-section in which a magnetization runs from the south pole to the north pole and which has an envelope in the form of a sickle with a concave section arranged along a boundary of the rotor, and a convex section, with the permanent magnet running in an arcuate manner along the convex section, and with the magnetic poles running in an arcuate manner along the concave section, said contour of the end face at the first end having within the envelope a surface and a boundary shaped to extend in an arcuate manner from a first point of the convex section to a second point of the convex section, and a connection device for connecting with the permanent magnet via the surface of the end face at the first end by form fit.

14. A wind turbine, comprising:

a rotor comprising a permanent magnet including a north pole and a south pole as magnetic poles and sized to extend from a first end to a second end in parallel relation to an axis of rotation, with the first end having an end face with a contour shaped as a recess or a web protruding with respect to the end face, said permanent magnet having a cross-section in which a magnetization runs from the south pole to the north pole and which has an envelope in the form of a sickle with a concave section arranged along a boundary of the rotor, and a convex section, with the permanent magnet running in an arcuate manner along the convex section, and with the magnetic poles running in an arcuate manner along the concave section, said contour of the end face at the first end having within the envelope a surface and a boundary shaped to extend in an arcuate manner from a first point of the convex section to a second point of the convex section, and a connection device for connecting with the permanent magnet via the surface of the end face at the first end by form fit; and

blades connected with the rotor.