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CN-122029727-A - Improved axial flux electric motor

CN122029727ACN 122029727 ACN122029727 ACN 122029727ACN-122029727-A

Abstract

The invention relates to an axial flux electric motor (1) extending around a central axis (X) and comprising a stator (20) with electrical windings (24) and a rotor (10) arranged axially adjacent to the stator (20) and rotationally movable around the central axis (X), the rotor (10) comprising at least one rotor disc (12), the rotor disc (12) comprising magnets (14) and ferromagnetic pieces (13) distributed circumferentially around the central axis (X), each ferromagnetic piece (13) being arranged between two adjacent magnets (14), the rotor disc (12) comprising at least one concave axial face (121, 122) such that the thickness of the rotor disc (12) at the inner diameter (Di) of the rotor disc is smaller than the thickness of the rotor disc (12) at the outer diameter (De).

Inventors

  • G. Bote
  • S. S. Ayat

Assignees

  • 赛峰电气与电源公司

Dates

Publication Date
20260512
Application Date
20240812
Priority Date
20230818

Claims (11)

  1. 1. An axial flux electric motor (1), the axial flux electric motor (1) extending around a central axis (X) and comprising a stator (20) with electrical windings (24) and a rotor (10) arranged axially adjacent to the stator (20) and rotationally movable around the central axis (X), the rotor (10) comprising at least one rotor disc (12), the rotor disc (12) comprising magnets (14) and ferromagnetic pieces (13) distributed circumferentially around the central axis (X), each ferromagnetic piece (13) being arranged between two adjacent magnets (14), the rotor disc (12) comprising at least one concave axial face (121, 122) such that the thickness of the rotor disc (12) at an inner diameter (Di) of the rotor disc is smaller than the thickness of the rotor disc (12) at an outer diameter (De), the distance between two adjacent magnets (14) being zero or kept constant from the inner diameter (Di) to the outer diameter (De).
  2. 2. The electric motor (1) according to claim 1, characterized in that the concave axial face (121, 122) of the rotor disc (12) has the shape of a cone portion.
  3. 3. The electric motor (1) according to claim 1 or 2, characterized in that each magnet (14) has a flared shape, the cross section of which increases linearly from the inner diameter (Di) to the outer diameter (De).
  4. 4. An electric motor (1) according to any one of claims 1 to 3, characterized in that each of the magnets has a circular, oblong or polygonal radial cross section.
  5. 5. The electric motor (1) according to any one of claims 1 to 4, characterized in that the stator (20) comprises at least one stator disc (22 a, 22 b), one axial face (221, 222) of the stator disc (20) facing the concave axial face (121, 122) of the rotor disc (12) and being convex and having a shape complementary to the concave axial face (121, 122) of the rotor disc (12) such that an air gap (F) between the concave axial face (121, 122) of the rotor disc (12) and the convex axial face (221, 222) of the stator disc (20) has a constant thickness.
  6. 6. The electric motor (1) according to claim 5, characterized in that the concave axial face of the rotor disc (12) is a first axial face (121), the stator disc is a first stator disc (22 a), the rotor disc (12) comprises a second concave axial face (122) opposite to the first axial face (121), and the stator (20) comprises a second stator disc (22 b), the axial face (222) of the second stator disc (22 b) faces the second concave axial face (122) of the rotor disc (12) and is convex and has a shape complementary to the second concave axial face (122) of the rotor disc (12) such that the air gap between the second concave axial face (122) of the rotor disc (12) and the convex axial face (222) of the second stator disc (22 b) has a constant thickness.
  7. 7. The electric motor (1) according to claim 1, characterized in that the stator (20) comprises a single stator disc (22), the single stator disc (22) having two planar axial faces (221, 222), the rotor disc being a first rotor disc (12 a), the rotor (10) comprising a second rotor disc (12 b), the second rotor disc (12 b) having a concave axial face (122), the first rotor disc (12 a) and the second rotor disc (12 b) also each having a planar axial face (120) opposite to the concave axial face and facing one of the planar axial faces (221, 222) of the stator disc (22).
  8. 8. The electric motor (1) according to any one of claims 1 to 7, characterized in that the rotor disc (12) comprises a holding base (15), the holding base (15) being capable of holding the magnet (14) and the ferromagnetic piece (13) in place.
  9. 9. The electric motor (1) according to any one of claims 1 to 8, characterized in that the rotor disc (12) is formed to satisfy the relation e2=e1 (De/Di), wherein E1 and E2 are the thickness of the rotor disc (12) at the inner diameter (Di) and at the outer diameter (De), respectively.
  10. 10. The electric motor (1) according to any one of claims 1 to 9, characterized in that the magnets (14) are arranged around the central axis (X) such that the polarities of at least two adjacent magnets (14) are oriented differently from each other, so that the orientation of the magnetic flux is alternately induced between the adjacent magnets (14).
  11. 11. Intelligent motor (300) comprising at least one power module comprising an electric motor (1) according to any of the preceding claims, and two electronic control units (320) arranged on both sides of the electric motor (1).

Description

Improved axial flux electric motor Technical Field The present disclosure relates to the field of electric motors, in particular but not limited to electric motors, in particular electromagnetic motors, for use in aircraft turbines. More particularly, the present disclosure relates to an axial flux electric motor, and to a smart motor including such an electric motor. Background In a known manner, the electric motor comprises a fixed part (stator) and a movable part (rotor) rotating around a central axis. The rotor may include magnets and the stator includes wire windings that produce a magnetic field when powered by an electrical current. In synchronous electric motors, the interaction of the orthogonal magnetic fields of the rotor magnets with the stator currents allows electromagnetic torque to be generated, which can then rotate the rotor. Rotation of the rotor may then produce rotation of a machine component, such as a propeller. Unlike radial flux motors in which a cylindrical rotor rotates inside an annular stator (or vice versa) so as to generate radial magnetic flux perpendicular to a central axis of rotation, axial flux motors comprise at least one stator and one rotor axially opposite each other and thus generate axial magnetic flux parallel to the central axis of rotation. In general, an axial flux motor may include a stator disk sandwiched between two rotor disks, with a planar air gap formed between the different disks. However, other configurations are also possible, in particular a rotor disc sandwiched between two stator discs, a single rotor disc and a single stator disc facing each other, or a multi-rotor arrangement, for example comprising three rotor discs and two stator discs, each stator disc being interposed between two consecutive rotor discs. Axial flux electric motors offer several advantages over radial flux motors, particularly better performance in terms of power to weight ratio and torque to weight ratio. In particular, since the rotor disk is not radially constrained by the stator, it may have a larger diameter, which allows for increased torque, thereby improving the performance of the axial flux motor compared to a radial flux motor. However, axial flux electric motors also have drawbacks. In particular, the increase in torque involves an increase in rotor diameter, which requires a large amount of material to mechanically retain the effective electromagnetic components of the motor, consuming more resources and increasing costs. Larger rotor diameters also result in increased rotational inertia, uneven flux distribution, and greater difficulty or even inability to integrate into compact machines. Furthermore, the rotor of an axial flux electric motor includes magnets, but typically little or no iron, unlike the rotor of a modern radial flux electric motor, does not allow for optimization of torque to weight performance. Accordingly, there is a need for a system that at least partially overcomes the above-described drawbacks and improves the performance of axial-flux electric motors. Disclosure of Invention The present disclosure relates to an axial flux electric motor extending around a central axis and comprising a stator with electrical windings and a rotor arranged axially adjacent to the stator and rotationally movable around the central axis, the rotor comprising at least one rotor disc comprising magnets and ferromagnetic pieces distributed circumferentially around the central axis, each ferromagnetic piece being arranged between two adjacent magnets, the rotor disc comprising at least one concave axial face such that the thickness of the rotor disc at the inner diameter of the rotor disc is smaller than the thickness of the rotor disc at the outer diameter. In the present disclosure, the terms "axial direction", "radial direction" and derivatives thereof are defined with respect to a central axis of the electric motor, which is also the axis of rotation about which the rotor rotates. Typically, the rotor disk is fixed to the rotating shaft and extends between a radially inner end and a radially outer end fixed to the rotating shaft. Furthermore, it should be understood that the thickness of the rotor disc corresponds to its thickness in the axial direction, i.e. along said central axis. In a known manner, the stator comprises a ferromagnetic circuit with slots which house electrical windings, typically made of copper wire. The rotor disc comprises magnets, typically permanent magnets, each extending radially between a radially inner end and a radially outer end, i.e. between an inner diameter of the rotor disc and an outer diameter thereof. The magnets are preferably distributed at regular intervals around the central axis. The rotor disk also includes ferromagnetic pieces that are not permanent magnets, but include iron, and may also include nickel and cobalt. Thus, the magnetic flux generated by two adjacent magnets may be deflected to the ferromagnetic piece, whi