Rotor shaft, rotor, electrical machine and manufacturing method for a rotor shaft

1 . A rotor shaft comprising:

a base shaft including a lateral surface having a conical shape,

a rotor shaft seat configured to support a plate stack, the rotor shaft seat located on an outer lateral surface of the rotor shaft in the area of the base shaft,

a conical sleeve including a lateral surface having a conical shape, the lateral surface of the conical sleeve facing the lateral surface of the base shaft, the conical shapes of the base shaft and the conical sleeve running opposite each other, the conical shape of the base shaft and the conical shape of the conical sleeve each having an angle of less than 1°,

a first bearing area provided at a longitudinal end of the base shaft and connected to the base shaft in a force-fit, positive mechanical-fit, or material-fit connection; and

a second bearing area provided at a longitudinal end of the conical sleeve; wherein an inner diameter of the first and second bearing areas is smaller than an inner diameter of the base shaft in the rotor shaft seat.

2 . The rotor shaft of claim 1 , wherein the conical sleeve and the base shaft are made from different materials and have different coefficients of thermal conductivity and/or coefficients of thermal expansion.

3 . The rotor shaft of claim 1 , wherein

an opposing tapered interface between the base shaft and the conical sleeve includes a radially outer material forming one of the conical sleeve and the base shaft, and a radially inner material forming the other of the conical sleeve and the base shaft, the radially inner material having a higher coefficient of thermal expansion than the radially outer material such that thermal expansion of the radially inner material increases frictional engagement between the rotor shaft seat and a plate stack supported thereon.

4 . The rotor shaft of claim 1 , wherein the conical sleeve is slotted in an axial direction.

5 . The rotor shaft of claim 1 , wherein the rotor shaft is a hollow shaft comprising a cavity.

6 . The rotor shaft of claim 1 , wherein the conical sleeve surrounds the base shaft, and the rotor shaft seat is configured on an outer lateral surface of the conical sleeve.

7 . The rotor shaft of claim 1 , wherein the base shaft includes a plurality of parts connected to each other with a material bond, positive mechanical fitting, frictional fitting, or a combination thereof.

8 . The rotor shaft of claim 1 , wherein a wall thickness (D W ) of the base shaft proximate the rotor shaft seat is less than 8 mm.

9 . The rotor shaft of claim 1 , wherein the rotor shaft is a rotor shaft of a rotor of an electric machine.

10 . The rotor shaft of claim 9 , wherein the electric machine is a vehicle.

11 . A method of manufacturing the rotor shaft of claim 1 , the method comprising:

providing the base shaft and the conical sleeve for the rotor shaft, and

tensioning the conical sleeve relative to the base shaft to achieve a frictional fit between the rotor shaft and the plate stack arranged thereon.

12 . A rotor shaft comprising:

a base shaft including a lateral surface having a conical shape;

a rotor shaft seat configured to support a plate stack, the rotor shaft seat located on an outer lateral surface of the rotor shaft in the area of the base shaft, and

a conical sleeve including a lateral surface having a conical shape, the lateral surface of the conical sleeve facing the lateral surface of the base shaft, the conical shapes of the base shaft and the conical sleeve running opposite each other, wherein the conical sleeve is in contact with an inner lateral surface of the base shaft, and the rotor shaft seat is configured on an outer lateral surface of the base shaft.

13 . The rotor shaft of claim 12 , wherein the conical sleeve is tensioned relative to the base shaft with at least one fastening element to exert a radially acting force on the plate stack.

14 . The rotor shaft of claim 12 , wherein the base shaft includes a cavity, and a cooling device is arranged in the cavity, the cooling device configured to increase a surface area of an inner lateral surface of the base shaft and direct a cooling fluid in the base shaft, the cooling device and the base shaft being made from different materials having different coefficient of thermal conductivity and/or coefficient of thermal expansion.

15 . The rotor shaft of claim 12 , wherein the conical sleeve is configured as a cooling device.

16 . A rotor shaft comprising:

a base shaft including a lateral surface having a conical shape;

a rotor shaft seat configured to support a plate stack, the rotor shaft seat located on an outer lateral surface of the rotor shaft in the area of the base shaft; and

a conical sleeve including a lateral surface having a conical shape, the lateral surface of the conical sleeve facing the lateral surface of the base shaft, the conical shapes of the base shaft and the conical sleeve running opposite each other, wherein the conical sleeve comprises at least two concentric sleeve parts arranged radially successively with the base shaft to form a multi-layer radial layup including the base shaft and at least two concentric sleeve parts.

17 . The rotor shaft of claim 16 , wherein the at least two concentric sleeve parts are each conically shaped and are located opposite each other.

18 . The rotor shaft of claim 16 , wherein an outer lateral surface of a first sleeve part has a generally cylindrical shape, and an inner lateral surface of the first sleeve part has a conical shape that corresponds to an outer lateral surface of a second sleeve part.