ELECTRIC MACHINE

The invention relates to an electric machine (10) comprising a stator (16) that has a stator core (17). Said core has a substantially cylindrical opening (60) having a central axis (63), an internal diameter (D17i) and an external diameter (D17a) and the opening (60) accommodates a rotor (20). The stator core (17) has an axial length (L17a) and said core (17) holds a stator winding (18) together with the rotor (20) which has a rotational axis (66). The rotor (20) has an axial end face (69), on which a fan (30) with fan blades (72) is located and is non-rotatably connected to the rotor (20). The rotor (20) has an electromagnetically excitable path (75) having a pole shank (78), a respective pole plate (22, 23) adjoining each axially rotational end (80, 82) of said shank. Claw poles (24) having a north polarity extend from one pole plate (22) and claw poles (25) having a south polarity extend from the other pole plate (23), said claw poles (24, 25) alternating between north and south polarities around the periphery of the rotor (20). The electromagnetic path (75) between two opposite-facing sides (69, 90) of the pole plates (22, 23) has an axially rotational length (L75), the ratio of the axial length (L17a) of the stator core (17) to the axially rotational length (L75) of the electromagnetic path (75) of the rotor (20) being between 0.68 and 1.0. The pole shank (78) has a diameter (D78) and an axially rotational length (L78), and a ratio of the axially rotational length (L78) of the pole shank (78) to the diameter (D78) of the pole shank (78) is between 0.21 and 0.36. The ratio of the internal diameter (D17i) of the stator core (17) to the external diameter (D17a) of the stator core (17) is greater than 0.788 and less than 0.854.