SHAFT AND ROTOR FOR AN ELECTRIC MACHINE, ELECTRIC MACHINE, VEHICLE AND MANUFACTURING METHOD FOR A ROTOR

Description

[0001] The present invention relates to a shaft for an electric machine, comprising a stack seat for a stack of laminated metal sheets and two shaft ends extending axially outwards from the stack seat in opposite directions.

[0002] In addition, the invention relates to a rotor lamination for an electric machine, a rotor for an electric machine, a method for manufacturing a rotor, an electric machine and a vehicle.

[0003] DE 10 2017 001 987 A1 discloses a rotor for an electric machine with a rotor shaft and a laminated core arranged on the rotor shaft, which is connected to the rotor shaft in a rotationally fixed manner by means of a press fit formed at least in respective length regions of the rotor shaft and the laminated core.

[0004] For this purpose, an external toothing is provided in the length of the rotor shaft, into which a corresponding internal toothing engages in the length of the lamination stack.

[0005] Such a corresponding gearing is difficult to manufacture and weakens the mechanical stability of the laminated core, which reduces the transmission of torques to the shaft.

[0006] CN 205 566 057 U discloses a hexagonal shaft with the features of the characterizing part of claim 1.

[0007] The invention is therefore based on the objective of providing an improved method for connecting a shaft to a laminated core.

[0008] To solve this problem, a shaft according to claim 1 is provided according to the invention.

[0009] The invention is based on the idea of ​​equipping the laminated core seat with a polygon profile, which is advantageously easy to manufacture and does not require any mechanical weakening of the laminated core to be applied, such as through toothing or the like. This significantly increases torque transmission between the laminated core and the shaft and improves the mechanical stability of the connection between the shaft and the laminated core.

[0010] For the purposes of this invention, a polygon profile is not limited to a polygonal profile with straight sides in the sense of a triangle or a square. Rather, the term also includes the profile of a polygon connection as defined in DIN 32711 and DIN 32712. The polygon profile can therefore, in particular, be a P3G profile or a P4C profile.

[0011] In detail, the shaft according to the invention is provided in that a regular internal N-gon with N ≥ 3 is inscribed in the polygon profile, and the polygon profile is inscribed in a circumcircle to which each vertex of the internal N-gon touches. The internal N-gon can, for example, be an internal triangle, an internal quadrilateral, an internal pentagon, or an internal hexagon. Typically, N ≤ 12, in particular N ≤ 10, and in particular N ≤ 6.

[0012] For an eccentric polygon profile, it is provided that an incircle concentric to the circumcircle is inscribed in the polygon profile and a chord of the incircle runs on each side of the inner N-gon.

[0013] The use of a polygon profile proves particularly advantageous for a shaft in a staggered rotor. For this purpose, the core seat can be designed with two core seat sections that are offset from each other circumferentially. The offset is, in particular, less than 360°·N⁻¹. A step can be formed between the core seat sections. Typically, the core seat sections are directly adjacent to each other.

[0014] With regard to the production of a staggered rotor, the offset stack seat sections enable simple manufacturing. Individual laminations are slid onto one stack seat section from both sides of the shaft, abutting the other stack seat section due to the step, and thus automatically assuming the correct alignment relative to each other, as the polygonal profile prevents the individual laminations from twisting against each other. This is particularly advantageous compared to conventional techniques, where lamination stacks must first be packed from individually aligned laminations and then fitted onto the shaft at the correct angle to each other. Consequently, the susceptibility to errors during rotor assembly can be reduced.

[0015] Typically, a straight line extending axially along one of the corners of a given stack seat section lies parallel to the shaft's central axis. Furthermore, a helical curve touching a corner at a central axial position of a given stack seat section can form an angle with this straight line. This angle can then define the step angle.

[0016] The problem underlying the invention is further solved by a rotor for an electric machine comprising a shaft according to the invention and a rotor lamination stack formed from layered rotor laminations according to the invention, wherein the central through-openings are located on the stack seat.

[0017] The problem underlying the invention is also solved by a method for manufacturing a rotor according to the invention, wherein the through-openings of a respective rotor lamination are guided over the stack seat.

[0018] Typically, the rotor laminations are shrunk onto the package seat after being guided over it.

[0019] All descriptions of the shaft according to the invention can be applied analogously to the method according to the invention, so that the advantages described above can also be achieved with this method.

[0020] The problem underlying the invention is further solved by an electric machine comprising a rotor according to the invention or a rotor obtained by the method according to the invention, wherein the rotor is rotatably mounted within a stator of the electric machine.

[0021] In particular, it can be provided that the stator Z has stator teeth and the angle lies between 360°·(r-1) r -1< ·Z -1< and 360°·(r+1) r -1< ·Z -1<, where r ≥ 2, in particular r ≥ 10, is a real number.

[0022] The electric machine is typically permanent magnet or separately excited and / or a synchronous machine.

[0023] The problem underlying the invention is also solved by a vehicle comprising an electric machine according to the invention, which is designed to drive the vehicle.

[0024] Further advantages and details of the present invention will become apparent from the exemplary embodiments described below and from the drawings. These are schematic representations and show: Figs. 1 and 2 each show a perspective view of a first embodiment of the shaft according to the invention; Fig. 3 shows a schematic diagram of an embodiment of the rotor lamination according to the invention; Fig. 4 shows a schematic diagram of a first embodiment of the electric machine according to the invention with a first embodiment of the rotor according to the invention; Figs. 5 and 6 each show a perspective view of a second embodiment of a shaft not according to the invention; Fig. 7 shows a schematic diagram of a second embodiment of the electric machine not according to the invention with a second embodiment of a rotor not according to the invention; and Fig. 8 shows a schematic diagram of an embodiment of the vehicle according to the invention.

[0025] Fig. 1 and Fig. 2 Each of these is a perspective representation of a first embodiment of a wave 1.

[0026] The shaft 1 has a mounting seat 2 and two shaft ends 3, 4 extending axially outwards from the mounting seat 2 in opposite directions. The shaft end 4 is located on an output side of the shaft 1.

[0027] The package seat 2 comprises a first package seat section 5 and a second package seat section 6, each extending axially and having a polygonal profile. The package seat sections 5 and 6 are offset from each other circumferentially. The polygonal profiles are each P3G profiles according to DIN 32711 and accordingly have three eccentric protrusions 7. The polygonal profile extends axially straight along the respective package seat section 5 or 6, such that each protrusion 7 extends along a straight line 8 or 9 that runs parallel to a central axis A of the shaft 1. At the central axial positions of the package seat sections 5 and 6, the straight lines 8 and 9 each lie on a helical curve 10 with a constant pitch. The helical curve 10 intersects the straight lines 8 and 9 at an angle 11.

[0028] Fig. 3 is a schematic diagram of an exemplary embodiment of a rotor lamination 12.

[0029] The rotor lamination 12 has a central through-opening 13 with a polygonal profile. In addition, the rotor lamination 12 includes a plurality of further through-openings 14, each located at the same radial position and equidistant from one another circumferentially by a fixed angle. Each through-opening 14 serves to form a magnetic pocket for a permanent magnet when several rotor laminations 12 are stacked to form a rotor lamination stack.

[0030] In addition, it shows Fig. 3 some geometric properties of the polygon profile, which are therefore also applicable to the polygon profile of the first embodiment of shaft 1 (see Figs. 1 and 2The following conditions apply. A regular inner triangle 15 is inscribed in the polygon profile, and the polygon profile itself is inscribed in a circumcircle 16 that touches each vertex 17 of the inner triangle 15. The respective position of the vertices 17 corresponds to the position of the protrusions 7. The eccentricity of the polygon profile results from the fact that an incircle 18 concentric with the circumcircle 16 is inscribed in it, and a chord of the incircle 18 runs along each side 19 of the inner triangle 15.

[0031] Fig. 4 is a schematic diagram of a first embodiment of an electrical machine 20.

[0032] The electric machine 20 is in this case a permanent magnet synchronous machine and comprises a stator 21 with a number Z stator teeth 22.

[0033] In addition, the electric machine 20 comprises an embodiment of a rotor 23. The rotor 23 comprises the first embodiment of the shaft 1 and a rotor lamination 12 made of layered laminations according to the embodiment in Fig. 3 The rotor lamination stack 24 is formed. The central through-openings 13 of each rotor lamination 12 are located on a respective stack seat section 5, 6. The rotor laminations 12 are stacked congruently with each other, so that magnet pockets for permanent magnets 25 of the rotor 23 are formed.

[0034] Rotor 23 is therefore a staggered rotor, whose stagger angle corresponds to the angle 11 between the straight line 8 or 9 and the helix curve 10.

[0035] According to a first embodiment of a method for manufacturing the rotor 23 according to Fig. 4The through-openings 13 of each rotor lamination 12 are guided over the stack seat 2. The rotor laminations 12 for the first stack seat section 5 are guided over the stack seat 2 from the shaft end 3, and the rotor laminations 12 for the second stack seat section 6 are guided over the stack seat 2 from the shaft end 4. The rotor lamination 12 that is guided over the stack seat 2 first abuts a shoulder 26 formed by the offset between the stack seat sections 5 and 6. Because of the opposing polygon profiles of the stack seat sections 5 and 6 on the one hand and the rotor laminations 12 on the other, undesired twisting of the rotor laminations 12 is thus prevented.

[0036] The rotor laminations 12 and the shaft 1 are joined by shrink-fitting. Before the rotor laminations 12 are guided over the stack seat 2, the rotor laminations 12 are heated and / or the shaft 1 is cooled so that the polygon profile of the rotor laminations 12 is slightly wider than that of the shaft 1. The temperatures of the shaft 1 and the rotor laminations 12 are then equalized, and the rotor laminations 12 are joined to the shaft 1.

[0037] Fig. 5 and Fig. 6 Each of the following is a perspective representation of a second embodiment of a shaft 1, for which all descriptions of the first embodiment apply according to Fig. 1 and Fig. 2 The same applies unless otherwise described below. Identical or equivalent components are designated with identical reference symbols.

[0038] The package seat 2 of shaft 1 is formed by a package seat section 5 whose polygonal profile is axially inclined. This means that the positions in the circumferential direction of a protrusion 7 at the end of the package seat 2 facing the shaft end 3 and a protrusion 7 at the end of the package seat 2 facing the shaft end 4 are offset from each other. Accordingly, the axial extent of each corner 17 (see Fig. 3 ) 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.

[0039] The geometric details of the polygon profile of the rotor plate 12 in Fig. 3 These principles can be applied analogously to the polygon profile of the second embodiment of shaft 1.

[0040] Fig. 7 is a schematic diagram of a second embodiment of an electrical machine 20, which is similar to the first embodiment according to Fig. 4This applies unless otherwise described below. Identical or equivalent components are designated with identical reference numerals.

[0041] The electric machine 20 comprises a second embodiment of a rotor 23, which is designed as a skewed rotor. The laminated core 24 of the rotor 23 is divided by rotor laminations 12 according to the embodiment shown in Fig. 3 The magnets are formed, each exhibiting a constant circumferential offset relative to its predecessor. This creates correspondingly inclined magnet pockets in which the permanent magnets 25 are arranged. The angle 11 corresponds to a helix angle of the rotor 23, which is enclosed by the lines 27, 28.

[0042] According to a second embodiment of a method for manufacturing a rotor according to Fig. 7The through-openings 13 of each rotor lamination 12 are guided over the stack seat 2, which can be done from any end of the stack seat 2, i.e., from the end facing the shaft end 3 or the end facing the shaft end 4. This is achieved by applying an axial force to the rotor laminations 12, whereby rotation of each rotor lamination 12 is realized by sliding along an inner contour of the through-opening 13 against an outer contour of the stack seat 2.

[0043] This has the advantage that the rotor laminations 12 align themselves automatically in the inclined angle due to the oppositely formed polygon profiles, thus avoiding the need for a complex pre-threading of the rotor laminations 12 before the actual threading of the rotor lamination package thus formed.

[0044] The shrinking of the rotor laminations 12 onto the shaft 1 is carried out analogously to the first embodiment of the method.

[0045] In both embodiments of the electric machine 20, the angle 11, i.e., the step angle or the helix angle, lies between 360°·(r-1) r -1< ·Z -1< and 360°·(r+1) r -1< ·Z -1<, where r ≥ 2, and in particular r ≥ 10, is a real number. If, for example, the number of stator teeth is Z = 48, the angle 11 can therefore be 7.5° ± 3.25° or 7.5° ± 0.75°.

[0046] According to a further embodiment of the shaft, which otherwise corresponds to one of the previously described embodiments, and a further embodiment of the rotor lamination, which otherwise corresponds to the embodiment according to Fig. 3 If the polygon profile corresponds to this, it is a P4C profile according to DIN 32712. In this case, an inner quadrilateral is inscribed instead of an inner triangle.

[0047] According to another embodiment of the electric machine, which otherwise corresponds to one of the embodiments described above, the electric machine is a separately excited synchronous machine.

[0048] Fig. 8 Figure 1 is a schematic diagram of an embodiment of a vehicle 29, comprising an electric machine 20 according to one of the previously described embodiments. The electric machine 20 is configured to drive the vehicle 29. The vehicle can be a battery electric vehicle (BEV) or a hybrid vehicle.

Claims

1. Shaft (1) for an electric machine (20), comprising a stack seat (2) for a laminated stack (24) and two shaft ends (3, 4) extending axially outward from the stack seat (2) in opposite directions, wherein the laminated core seat (2) has at least one laminated core seat section (5, 6) extending in the axial direction with a polygonal profile for forming a polygonal connection with the laminated core (24) , wherein a regular inner N-corner (15) with N ≥ 3 is inscribed in the polygon profile and the polygon profile is inscribed in a circumference (16) that touches each corner (17) of the inner N-corner (15), wherein a circle inscribed in the polygon profile is concentric with the circumference (16), and a chord of the inscribed circle runs on a respective side of the inner N-corner (15) characterized in that the package seat (2) comprises a first package seat section (5) and a second package seat section (6), which each extend in the axial direction and have a polygon profile, and the package seat sections (5, 6) are offset from each other in the circumferential direction.

2. Shaft according to claim 1, wherein the polygonal profile is a P3G profile or a P4C profile.

3. Shaft according to claim 2, wherein a straight line (8, 9) lying on one of the corners (17) in the axial extension of a respective package seat section (5, 6) is parallel to the center axis (A) of the shaft (1).

4. Shaft according to claim 3, wherein a helical curve (10) which, at a respective packet seat section (5, 6), contacts the corner (17) at a central axial position of the packet seat section (5, 6) forms an angle (11) with the straight line (8, 9).

5. Rotor (23) for an electric machine (20), comprising a shaft (1) according to one of claims 1 to 4 and a rotor laminations package (24) formed from laminated rotor laminations (12) (24) formed from laminated rotor sheets (12), which has a central through-opening (13) with a polygonal profile that is opposite to that of a shaft according to one of the preceding claims, wherein the central through-openings (13) of a respective rotor sheet (12) rest on the respective stack seat section (5, 6).

6. Method for manufacturing a rotor (23) according to claim 5, wherein the through openings (13) of a respective rotor plate (12) are guided over the respective stack seat (2) .

7. An electric machine (20) comprising a rotor (23) according to claim 5 or a rotor (23) obtained by the method according to claim 6, wherein the rotor (23) is rotatably mounted within a stator (21) of the electric machine (20).

8. Electric machine according to claim 7, if dependent on claim 4 or 5, wherein the stator has Z stator teeth (22) and the angle (11) between 360°·(r-1) r-1 ·Z1 and 360°·(r+1) r-1 ·Z-1 lies between 360°·(r 1)r-1 ·Z-1 and 360°·(r+1) r-1·Z-1 , wherein r ≥ 2, in particular r ≥ 10, is a real number .

9. Vehicle (29) comprising an electric machine (20) according to claim 7 or 8, which is arranged to drive the vehicle (29).