Shaft, rotor lamination and rotor for an electric machine, electric machine, vehicle, and method for producing a rotor

Abstract

Shaft for an electric machine, includes a core seat for a laminated core and two shaft ends extending axially outwardly from the core seat in opposite directions, wherein the core seat has at least one core seat portion extending in the axial direction with a polygonal profile for forming a polygonal connection to the laminated core.

Claims

1. A shaft for an electric machine, comprising a core seat for a laminated core and two shaft ends extending axially outwardly from the core seat in opposite directions, wherein the core seat has two core seat portions separated from each other and offset in a circumferential direction, and extending in an axial direction with a polygonal profile for forming a polygonal connection to the laminated core, and the polygonal profile includes a regular inner N-sided shape, with N≥3, inscribed in the core seat and located in an outer circle with each corner touching the regular inner N-sided shape and an inner circle concentric with the outer circle, and chords of the inner circle running along a side of the inner N-sided shape.

2. The shaft according to claim 1, wherein a straight line lying on one of the corners in an axial extent of the core seat portions is parallel to a central axis of the shaft.

3. The shaft according to claim 2, wherein a screw curve at the core seat portions touches the corner at a central axial position of the core seat portions form an angle with the straight line.

4. A rotor lamination for an electric machine, having a central through-opening with a polygonal profile, wherein the polygonal profile is an inverted shape with respect to the two core seat portions of the shaft of claim 1.

5. A rotor for an electric machine, comprising the shaft according claim 1 and a rotor laminated core formed from stacked rotor laminations, each rotor lamination having a central through-opening with a polygonal profile, wherein the polygonal profile is an inverted shape with respect to the two core seat portions of the shaft, and the central through-openings sit on the core seat.

6. A method for producing the rotor according to claim 5, wherein the through-openings of each rotor lamination are guided over the core seat.

7. An electric machine comprising the rotor according to claim 5 wherein the through-openings (13) of each rotor lamination are guided over the core seat, wherein the rotor is rotatably supported within a stator of the electric machine.

8. The electric machine according to claim 7, wherein the stator has Z stator teeth and an angle is between 360°.Math.(r−1)r.sup.−1.Math.Z.sup.−1 and 360°.Math.(r+1)r.sup.−1.Math.Z.sup.−1, wherein r≥10, and is a real number.

9. A vehicle comprising the electric machine according to claim 7, which is designed to drive the vehicle.

10. The shaft according to claim 1, wherein the polygonal profile is a P3G profile, or a P4C profile.

11. The shaft according to claim 1, wherein the two core seat portions have a same polygonal profile with a plurality of projections arranged parallel to a center shaft and angularly offset from each other on a periphery of the core seat.

12. The shaft according to claim 1, wherein each of the two core seat portions has three eccentric protuberances extending parallel to a center shaft and curved codes connecting the three eccentric protuberances, and the two core seat portions are connected axially, and angularly displaced along the center shaft such that each of the three eccentric protuberances of one of the two core seat portions is located in a center between two of the three eccentric protuberances of another of the two core seat portions.

Description

(1) Further advantages and details of the present invention will become clear from the exemplary embodiments described in the following and from the drawings. These are schematic representations and show:

(2) FIGS. 1 and 2 in each case a perspective representation of a first exemplary embodiment of the shaft according to the invention;

(3) FIG. 3 a basic sketch of an exemplary embodiment of the rotor lamination according to the invention;

(4) FIG. 4 a basic sketch of a first exemplary embodiment of the electric machine according to the invention with a first exemplary embodiment of the rotor according to the invention;

(5) FIGS. 5 and 6 in each case a perspective representation of a second exemplary embodiment of the shaft according to the invention;

(6) FIG. 7 a basic sketch of a second exemplary embodiment of the electric machine according to the invention with a second exemplary embodiment of the rotor according to the invention; and

(7) FIG. 8 a basic sketch of an exemplary embodiment of the vehicle according to the invention.

(8) FIG. 1 and FIG. 2 are each a perspective representation of a first exemplary embodiment of a shaft 1.

(9) The shaft 1 has a core seat 2 and two shaft ends 3, 4 extending axially outwardly from the core seat 2 in opposite directions. The shaft end 4 is situated on an output side of the shaft 1.

(10) The core seat 2 comprises a first core seat portion 5 and a second core seat portion 6, each extending in the axial direction and having a polygonal profile. The core seat portions 5, 6 are offset here in relation to each other in the circumferential direction. The polygonal profiles are each P3G profiles according to DIN 32711 and, accordingly, have three eccentric protuberances 7. The polygonal profile extends axially in a straight line along the particular core seat portion 5, 6, so that each protuberance 7 extends along a straight line 8, 9, which runs parallel to a central axis A of the shaft 1. At central axial positions of the core seat portions 5, 6, the straight lines 8, 9 each lie on a screw curve 10 with a constant pitch. The screw curve 10 intersects the straight lines 8, 9 at an angle 11.

(11) FIG. 3 is a basic sketch of an exemplary embodiment of a rotor lamination 12.

(12) The rotor lamination 12 has a central through-hole 13 with a polygonal profile. In addition, the rotor lamination 12 comprises multiple further through-openings 14, which are each located at the same radial position and are equidistantly offset from each other by a fixed angle in the circumferential direction. Each through-opening 14 serves to form a magnet pocket for a permanent magnet when a plurality of rotor laminations 12 are stacked to form a rotor laminated core.

(13) In addition, FIG. 3 shows some geometrical properties of the polygonal profile, which in this respect also apply to the polygonal profile of the first exemplary embodiment of the shaft 1 (see FIGS. 1 and 2). A regular inner triangle 15 is inscribed in the polygonal profile and the polygonal profile itself is inscribed in an outer circle 16 which each corner 17 of the inner triangle 15 touches. The eccentricity of the polygonal profile is due to the fact that an inscribed inner circle 18 is concentric with the outer circle 16 and a chord of the inner circle 18 runs along a side 19 of the inner triangle 15.

(14) FIG. 4 is a basic sketch of a first exemplary embodiment of an electric machine 20.

(15) The electric machine 20 is, in the present case, a permanently excited synchronous machine and comprises a stator 21 with a number Z of stator teeth 22.

(16) In addition, the electric machine 20 comprises an exemplary embodiment of a rotor 23. The rotor 23 comprises the first exemplary embodiment of the shaft 1 and a rotor laminated core 24 formed from stacked rotor laminations 12 according to the exemplary embodiment in FIG. 3. In this case, the central through-openings 13 of each rotor lamination 12 sit on a corresponding core seat portion 5, 6. The rotor laminations 12 are stacked congruently to each other so that magnet pockets for permanent magnets 25 of the rotor 23 are formed.

(17) The rotor 23 is therefore a staggered rotor of which the stagger angle corresponds to the angle 11 between the straight line 8 or 9 and the screw curve 10.

(18) According to a first exemplary embodiment of a method for producing the rotor 23 according to FIG. 4, the through-openings 13 of each rotor lamination 12 are guided over the core seat 2. The rotor laminations 12 for the first core seat portion 5 are guided from the shaft end 3 and the rotor laminations 12 for the second core seat portion 6 are guided from the shaft end 4 over the core seat 2, wherein a rotor lamination 12 guided first over the core seat 2 hits against a step 26 formed by the offset between the core seat portions 5, 6. Due to the mirror-inverted polygonal profiles of the core seat portions 5, 6 on the one hand and of the rotor laminations 12 on the other hand, an undesirable rotation of the rotor laminations 12 is thus avoided.

(19) The rotor laminations 12 and the shaft 1 are joined by shrinking. For this purpose, the rotor laminations 12 are heated and/or the shaft 1 is cooled before the rotor laminations 12 are guided over the core seat 2 so that the polygonal profile of the rotor laminations 12 is slightly wider than that of the shaft 1. Then, the temperatures of the shaft 1 and of the rotor laminations 12 are equalised and the rotor laminations 12 are joined to the shaft 1.

(20) FIG. 5 and FIG. 6 are each a perspective representation of a second exemplary embodiment of a shaft 1, for which all variants of the first exemplary embodiment according to FIG. 1 and FIG. 2 apply analogously, unless otherwise described below. Like or functionally like components are provided with identical reference signs.

(21) The core seat 2 of the shaft 1 is formed by a core seat portion 5 of which the polygonal profile is axially inclined. This means that the positions in the circumferential direction of a protuberance 7 at the end of the core seat 2 pointing towards the shaft end 3 and a protuberance 7 at the end of the core seat 2 pointing towards the shaft end 4 are offset in relation to each other. Accordingly, the axial extent of each corner 17 (see FIG. 3) lies on a straight line 27 which forms an angle 11 with a straight line 28 parallel to the central axis A of the shaft 1.

(22) The geometric variants for the polygonal profile of the rotor lamination 12 in FIG. 3 may be transferred analogously to the polygonal profile of the second exemplary embodiment of the shaft 1.

(23) FIG. 7 is a basic sketch of a second exemplary embodiment of an electric machine 20 which corresponds to the first exemplary embodiment according to FIG. 4, unless otherwise described below. Here, like or functionally like components are provided with identical reference signs.

(24) The electric machine 20 comprises a second exemplary embodiment of a rotor 23, which is designed as a tilted rotor. The laminated core 24 of the rotor 23 is formed by rotor laminations 12 according to the exemplary embodiment in FIG. 3, which each have a constant offset in the circumferential direction in relation to their predecessor. This results in the formation of correspondingly inclined magnet pockets, in which the permanent magnets 25 are arranged. Here, the angle 11 corresponds to an angle of inclination of the rotor 23, which is enclosed by the straight lines 27, 28.

(25) According to a second exemplary embodiment of a method for producing a rotor according to FIG. 7, the through-openings 13 of each rotor lamination 12 are guided over the core seat 2, which may be performed from any end of the core seat 2, i.e. from the end facing the shaft end 3 or the end facing the shaft end 4. This is done by applying an axial force to the rotor laminations 12, with a rotation of each rotor lamination 12 being achieved by the sliding of an inner contour of the through-opening 13 along an outer contour of the core seat 2.

(26) This has the advantage that the rotor laminations 12 orient themselves automatically in the angle of inclination due to the mirror-inverted polygonal profiles, so that the complex pre-threading of the rotor laminations 12 before the actual threading of the rotor laminated core thus formed may be avoided.

(27) The rotor laminations 12 are shrunk onto the shaft 1 in the same way as in the first exemplary embodiment of the method.

(28) In both exemplary embodiments of the electric machine 20, the angle 11, i.e. the stagger angle or the angle of inclination, lies between 360°.Math.(r−1) r.sup.−1.Math.Z.sup.−1 and 360°.Math.(r+1) r.sup.−1.Math.Z.sup.−1, wherein r≥2, in particular r≥10, and is a real number. If, for example, the number of stator teeth is Z=48, the angle 11 may therefore be 7.5°±3.25° or 7.5°±0.75°.

(29) According to another exemplary embodiment of the shaft, which incidentally corresponds to one of the exemplary embodiments described above, and another exemplary embodiment of the rotor lamination, which incidentally corresponds to the exemplary embodiment according to FIG. 3, the polygonal profile is a P4C profile according to DIN 32712. In this case an inner quadrilateral is inscribed instead of an inner triangle.

(30) According to another exemplary embodiment of the electric machine, which incidentally corresponds to one of the exemplary embodiments described above, the electric machine is a separately excited synchronous machine.

(31) FIG. 8 is a basic sketch of an exemplary embodiment of a vehicle 29 comprising an electric machine 20 according to one of the exemplary embodiments described above. The electric machine 20 is designed to drive the vehicle 29. The vehicle may be an electric vehicle (BEV) or a hybrid vehicle.