Motor and window lift
A window lift has a motor and a gearbox. The motor is a permanent magnet motor, comprising a stator and a rotor rotatably mounted to the stator. The stator or the rotor comprises a housing and magnets fixed to inner surface of the housing. The radial cross section of the housing comprises n side portions and n connecting portions, where n is an integer greater than 2. Adjacent side portions are connected together by one corresponding connecting portion and the magnets are fixed at portions corresponding to the connecting portions. The radial cross section of each side portion is like a convex curve line, which is curved outwardly relative to a straight line passing through the two ends of the convex curve line.
1. A permanent magnet motor, comprising a stator and a rotor rotatably mounted to the stator, one of the stator and the rotor comprising a housing and at least one magnet providing magnetic poles fixed to an inner surface of the housing, a radial cross section of the housing comprising n side portions and n connecting portions, where n is an integer greater than 2, adjacent side portions being connected together by one corresponding connecting portion, and the magnetic poles being located at locations corresponding to the connecting portions, wherein each of two circumferential ends of the radial cross section of each side portion has a curvature different from that of the radial cross section of each connection portion, and the radial cross section of each side portion is like a convex curve line, which is curved outwardly with respect to a straight line passing through the two circumferential ends of the convex curve line.
2. The motor of claim 1 , wherein the housing and the at least one magnet are parts of the stator, and the rotor comprises a rotor core confronting the magnetic poles.
3. The motor of claim 1 , wherein the convex curve line is arced as a portion of a circle.
4. The motor of claim 1 , wherein the radial cross section of each said side portion is like an arc, the circle center of which is offset from the axis of rotation of the rotor.
5. The motor of claim 1 , wherein the radial cross section of each side portion comprises two curve line segments connected together by a straight line segment.
6. The motor of claim 1 , wherein the radial cross section of each side portion comprises a curve line segment and two straight line segments which are connected together by the curve line segment.
7. The motor of claim 1 , wherein the radial cross section of each connecting portion is like an arc, the circumferential length of each connecting portion being smaller than the circumferential length of each side portion.
8. The motor of claim 1 , wherein the radial cross section of each connecting portion is like a straight line segment.
9. The motor of claim 1 , wherein n is equal to 3, 4, 6 or 8.
10. The motor of claim 1 , wherein the at least one magnet is a single piece ring magnet, the radial thickness of the ring magnet at portions corresponding to the connecting portions of the housing being greater than the radial thickness of the ring magnet at portions corresponding to the side portions of the housing.
11. A window lift, comprising the permanent magnet motor of claim 1 and a gearbox driven by the motor.
12. A permanent magnet motor, comprising a stator and a rotor rotatably mounted to the stator, one of the stator and the rotor comprising a housing and at least one magnet providing magnetic poles fixed to an inner surface of the housing, a radial cross section of the housing comprising n side portions and n connecting portions, where n is an integer greater than 2, adjacent side portions being connected together by one corresponding connecting portion, and the magnetic poles being located at locations corresponding to the connecting portions, wherein each of the connecting portions has a constant curvature, and each of two circumferential ends of the side portion has a curvature different from that of the connecting portion, each side portion is like a convex curve line, which is curved outwardly with respect to a straight line passing through the two ends of the convex curve line.
13. The motor of claim 12 , wherein each side portion comprises at least one curve line segment, which is arced as a portion of a circle.
14. The motor of claim 13 , wherein each side portion is formed as a curve line segment.
15. The motor of claim 14 , wherein the circle center of each side portion is offset from the axis of rotation of the rotor.
16. The motor of claim 13 , wherein each side portion comprises two curve line segments connected together by a straight line segment.
17. The motor of claim 13 , wherein each side portion comprises a curve line segment and two straight line segments which are connected together by the curve line segment.
18. The motor of claim 12 , wherein each connecting portion is like an arc, the circumferential length of each connecting portion being smaller than the circumferential length of each side portion.
19. The motor of claim 12 , wherein each connecting portion is like a straight line segment.