ROTOR FOR AN ELECTRIC MACHINE

Description

[0001] The invention relates to a rotor for an electrical machine, comprising a rotor lamination stack with a plurality of base lamination stacks, each of which has a plurality of rotor laminations stacked in the stacking direction and each having at least one through-opening extending in the stacking direction, wherein the through-openings of the base lamination stacks overlap in the circumferential direction and together form at least one coolant channel.

[0002] Electrical machines, particularly electrical machines with high power ratings / power densities, such as the electrical machine of an electric vehicle, generate relatively high levels of heat loss during operation. This loss of heat should be dissipated using cooling technology to improve efficiency and extend the service life of the electrical machine. Typically, the loss of heat generated in the rotor of an electrical machine is conducted to the stator via an air gap between the rotor and the stator of the electrical machine, and from there, by cooling the stator, is transferred to a housing of the electrical machine or to a cooling medium flowing around the stator. A further portion of the loss of heat at the rotor can be dissipated via the rotor shaft.To dissipate heat from the rotor shaft, it typically has a coolant channel that is fluidly connected to a cooling circuit and through which a coolant flows. The disadvantage of heat dissipation using a coolant channel formed exclusively in the rotor shaft is that the heat transfer surface between the coolant and the rotor shaft is relatively small, resulting in a relatively low cooling effect.

[0003] Another possibility for dissipating the heat loss from the rotor is to provide a plurality of coolant channels in a rotor lamination stack extending in the stacking direction of the rotor lamination stack, i.e., in the axial direction of the electric machine and the rotor. This increases the heat transfer surface in contrast to a coolant channel running exclusively through the rotor shaft, and the rotor lamination stack is cooled directly, so that the cooling effect can be increased and the heat loss can be dissipated directly at the point of its generation. DE 10 2016 210 930 A1, for example, discloses a rotor lamination stack with a plurality of stacked rotor laminations and a plurality of coolant channels extending in the stacking direction.The coolant channels are formed by a plurality of through-openings in the rotor laminations, wherein the rotor laminations are identical at least in the region of the coolant channel and are arranged offset from one another in the circumferential direction such that a plurality of spiral-shaped coolant channels are formed. Alternatively, the rotor laminations can be divided into a plurality of partial lamination stacks adjoining one another in the stacking direction, wherein the partial lamination stacks are arranged offset from one another in the circumferential direction and the coolant channels therefore have a substantially spiral course. In all of the aforementioned embodiments, the coolant flows into the coolant channel at one of the two axial ends of the rotor lamination stack and flows out of the coolant channel at the other axial end of the rotor lamination stack. The coolant inlet and the coolant outlet of the coolant channel are thus formed at two mutually opposite axial ends of the rotor lamination stack.

[0004] US 2004 / 222714 A1 discloses a rotor for an electrical machine, comprising a rotor lamination stack with a plurality of lower lamination stacks, each of which has a plurality of rotor laminations stacked in the stacking direction and each has at least one through-opening extending in the stacking direction, wherein the through-openings of the lower lamination stacks overlap in the circumferential direction and together form at least one coolant channel, wherein a first partial lamination stack has a first through-opening forming a coolant inlet.

[0005] The disadvantage of all designs is that the heat transfer surface is relatively small and therefore either additional cooling is required to dissipate the heat loss generated in the rotor core during operation or the electrical machine is limited in its power class.

[0006] The task therefore arises to provide a rotor by means of which the cooling of the rotor can be increased in a simple and cost-effective manner.

[0007] This object is achieved by a rotor for an electrical machine having the features of main claim 1.

[0008] By virtue of the fact that a first partial laminated core has a first through-opening forming a coolant inlet and a second through-opening forming a coolant outlet, wherein both through-openings of the first partial laminated core overlap with a single, third through-opening of a second partial laminated core, wherein the third through-opening of the second partial laminated core is closed on the side facing away from the first partial laminated core, the heat transfer surface between the coolant and the rotor laminated core, and thus the cooling effect, is increased in a simple and cost-effective manner. The coolant channel has a U-shaped profile, wherein the coolant flows into the coolant channel at a first axial end of the rotor laminated core and flows through the first through-opening of the first partial laminated core.The third through-hole of the second partial laminated core adjoins the opposite end of the first through-hole, with the coolant being deflected by 180° through the third through-hole. The second through-hole of the first partial laminated core adjoins the third through-hole and extends to the first axial end of the rotor laminated core. Thus, the first through-hole forms a coolant inlet, the second through-hole forms a coolant outlet, and the third through-hole forms a 180° deflection of the coolant flow.

[0009] Such a design of the coolant channel can increase the cooling effect of the rotor, while increasing the heat transfer area compared to linear coolant channels. The U-shaped configuration of the coolant channel can be implemented simply and cost-effectively by simply combining a first partial laminated core with the first through-opening and the second through-opening, and a second partial laminated core with the third through-opening. The two partial laminated cores can be adjusted using a simple and cost-effective stamping process.

[0010] Preferably, a third partial laminated core is provided, which is arranged on the side of the second partial laminated core facing away from the first partial laminated core, wherein the third partial laminated core has a closed surface in the region of the third through-opening of the second partial laminated core. As a result, the third through-opening can be easily closed on its side facing away from the first partial laminated core, wherein no additional component is required to close the third through-opening. Preferably, the rotor laminated cores are adhesively bonded to one another, thereby ensuring a fluid-tight connection between the rotor laminations. Alternatively, the rotor laminations can be stamped together.To avoid a leakage path of the coolant between the individual rotor laminations, an embossing can be provided on the rotor laminations radially inside and / or outside relative to the coolant channel, thereby creating a seal for the gap between two adjacent rotor laminations.

[0011] In a preferred embodiment, at least one further partial laminated core is arranged between the first partial laminated core and the second partial laminated core, wherein the at least one further partial laminated core has a first through-opening and a second through-opening, which overlap with the through-openings of the first laminated core and the through-opening of the second partial laminated core such that the through-openings of all partial laminated cores delimit the common coolant channel. This makes it possible to increase the heat transfer area between the coolant and the rotor laminated core. Preferably, the through-openings of the further partial laminated core are arranged offset in the circumferential direction relative to the two through-openings of the first partial laminated core, whereby the leg sections of the U-shaped coolant channel additionally have a winding around the axis of rotation of the rotor.This allows the heat transfer surface between the coolant and the rotor core to be further increased.

[0012] Preferably, all partial laminated cores are identically designed, with each partial laminated core having at least one first through-opening, at least one second through-opening, and at least one third through-opening. The partial laminated cores are arranged offset from one another in the circumferential direction such that the through-openings of the partial laminated cores jointly define at least one coolant channel. This allows all rotor laminations and all rotor laminated cores to be manufactured using a single punching tool, thereby reducing the manufacturing effort for the rotor laminated core.

[0013] Preferably, a first balancing disk is arranged on the side of the second partial laminated core facing away from the first partial laminated core, wherein the first balancing disk has at least one radially extending coolant supply channel and one coolant discharge channel that can be fluidically connected to a cooling circuit, wherein the coolant supply channel and the coolant discharge channel are fluidically connected to the coolant channel. As a result, the coolant channel can be connected to a cooling circuit in a cost-effective and space-saving manner, with no additional components being required. The first balancing disk thus takes over both the balancing of the rotor and the fluidic connection between the cooling circuit and the coolant channel. Preferably, the coolant discharge channel is designed as an axial through-opening, wherein the coolant flows axially through the first balancing disk and is thrown away by the rotation of the rotor.

[0014] In a preferred embodiment, the balancing disc has at least one radially extending groove on a side facing the first partial laminated core, wherein the groove and a surface of the partial laminated core facing the balancing disc define the at least one radially extending coolant supply channel. This allows for a simple implementation of the coolant supply channel, eliminating the need for complex bores in the first balancing disc.

[0015] In a preferred embodiment, the partial laminated cores have a plurality of first through-openings, a plurality of second through-openings and a plurality of third through-openings, wherein the partial laminated cores are arranged offset from one another in the circumferential direction in such a way that at least one first coolant channel and at least one second coolant channel are formed, wherein the first coolant channel is formed by the first through-opening, the second through-opening of at least one partial laminated core and the third through-opening of another partial laminated core and the second coolant channel is formed exclusively by the third through-openings of at least two partial laminated cores or by the first or second through-opening of at least one partial laminated core and a third through-opening of at least one other partial laminated core,The first coolant channel has a coolant inlet and a coolant outlet at a single axial end, and the second coolant channel has a coolant inlet at one of the two axial ends and a coolant outlet at the other axial end. This allows the cooling level of the rotor core to be increased.

[0016] In a preferred embodiment, a second balancing disc is arranged on a side of the first partial laminated core facing away from the second partial laminated core. The second balancing disc has a coolant discharge channel, the coolant discharge channel and a coolant supply channel provided on the first balancing disc being fluidly connected to the second coolant channel. This allows the coolant to be supplied to and discharged from the coolant channel simply and cost-effectively, with no additional components required. The coolant discharge channel is designed as a through-opening, so that the coolant is thrown away by the rotation of the rotor.

[0017] Preferably, a rotor shaft is provided, wherein the rotor laminated core is fastened to an outer circumferential surface of the rotor shaft, wherein the rotor shaft has a coolant supply channel which is fluidly connected to the coolant channel via the coolant supply channel. The coolant is thus supplied to the coolant channel via the rotor shaft and the first balancing disk, whereby no additional components are required for this. This allows the rotor to be designed simply and in a space-saving manner. In a preferred embodiment, the coolant supply channel has an axial section extending from an end face and a radial section, wherein the radial section extends from the axial section to the outer circumferential surface of the rotor shaft.

[0018] Preferably, a plurality of magnet through-openings offset from one another in the circumferential direction are provided for receiving permanent magnets, wherein the magnet through-openings are produced in a common manufacturing step, ie in a common punching process, with the through-openings which form the coolant channel.

[0019] An embodiment of a rotor according to the invention is shown in the figures and is described below. Figure 1 shows a rotor core of a rotor in perspective view, Figure 2 shows an example of the course of two coolant channels, Figure 3 shows the rotor, Figure 4 shows a first balancing disc of the rotor from Figure 3 , and Figure 5 shows a second balancing disc of the rotor from Figure 3 .

[0020] The Figure 1shows a rotor lamination stack 10 of a rotor 2. The rotor lamination stack 10 has a plurality of partial lamination stacks 12, 14, 16, 18, each of which has a plurality of rotor laminations 20 stacked in the axial direction of the rotor 2, which forms the stacking direction. A first partial lamination stack 12 forms a first axial end of the rotor lamination stack 10. A second partial lamination stack 14 adjoins the first partial lamination stack 12 in the stacking direction, with a further partial lamination stack 18 being arranged between the first partial lamination stack 12 and the second partial lamination stack 14. A third partial lamination stack 16 adjoins the second partial lamination stack 14 in the stacking direction of the rotor laminations 20.

[0021] All partial laminated cores 12, 14, 16, 18 have a plurality of magnet through-openings 40 in the radially outer region, which extend in the stacking direction of the rotor laminations 20, i.e. in the axial direction of the rotor 2, between the respective end faces of the partial laminated cores 12, 14, 16, 18. The magnet through-openings 40 are designed in pairs and are distributed over the entire circumference of the rotor laminated core 10, with two magnet through-openings 40 each forming a V-shaped pair.

[0022] The partial laminated cores 13, 14, 16, 18 also each have a plurality of through-openings 21, 23, 25, which extend in the stacking direction of the rotor laminations 20 between the respective end faces of the partial laminated cores 12, 14, 16, 18 and are arranged distributed over the circumference. In each case, a first through-opening 21 and a second through-opening 23 form a matching pair. In addition, a plurality of third through-openings 25 are provided, which are larger in cross-section than the first through-opening 21 and the second through-opening 23. The through-openings 21, 23, 25 are arranged over the circumference in such a way that two third through-openings 25 are arranged between two pairs of a first through-opening 21 and a second through-opening 23.

[0023] The partial laminated cores 12, 14, 16, 18 are arranged offset from one another in the circumferential direction such that the first through-openings 21, the second through-openings 23, and the third through-openings of the individual partial laminated cores 12, 14, 16, 18 overlap in the circumferential direction. The further partial laminated core 18 arranged between the first partial laminated core 12 and the second partial laminated core 14 is offset by an angle a1 relative to the first partial laminated core 12. The second partial laminated core 14 is offset by an angle a2, and the third partial laminated core 16 is offset by an angle a3 relative to the first partial laminated core 12. The angles a1, a2 and a3 are selected such that some through openings 21, 23, 25 of the partial laminated cores 12, 14, 16, 18 overlap in the circumferential direction such that a coolant channel 22, 24, 26, 28, 30, 32, 34, 36 with a coolant inlet 27, 31 and a coolant outlet 29, 33 is formed.In this case, several first, U-shaped coolant channels 24, 28, 32, 36 and several second, straight coolant channels 22, 26, 30, 34 are provided. Alternatively or additionally, the partial laminated cores 14, 18 can be arranged rotated by 180° around a vertical axis.

[0024] The courses of the first coolant channel 24 and the second coolant channel 22 are shown as examples in Figure 2shown. In the first coolant channel 24, a first through-opening 211, 212 and a second through-opening 231, 232 of the partial laminated cores 12, 18 and a third through-opening 253 of the second partial laminated core 14 overlap in the circumferential direction. The third partial laminated core 16 is arranged in the circumferential direction such that a closed, flat surface is arranged in the region of the third through-opening 253 of the second partial laminated core 14, whereby the third through-opening 253 is closed at the axial end facing the third partial laminated core 16. The coolant inlet 27 and the coolant outlet 29 of the U-shaped coolant channels 24, 28, 32, 36 are arranged at a common first axial end of the rotor core 10, wherein the coolant inlet 27 is formed by the first through-opening 21 and the coolant outlet 29 is formed by the second through-opening 23.The second coolant channel 22 extends from the first axial end of the rotor laminated core 10 to the opposite, second axial end of the rotor laminated core 10. The third through-openings 251, 252, 254 of the partial laminated cores 12, 18, 16 and a first through-opening 213 of the second partial laminated core 14 overlap. A coolant inlet 31 of the second coolant channel 22 is formed by the third through-opening 251 of the first partial laminated core 12 and a coolant outlet 33 is formed by the third through-opening 254 of the third partial laminated core 16.

[0025] The Figure 3 shows a rotor 2 with a rotor shaft 44, which is arranged in a central opening 42 of the rotor core 10. A balancing disk 46, 48 is arranged at each of the two axial ends of the rotor core 10. A first balancing disk 46 is arranged in Figure 4shown, wherein the first balancing disk 46 has grooves 62 and through-openings 61 distributed over the circumference and extending radially from the inner circumferential surface. The grooves 62 overlap with the first through-openings 21 and the third through-openings 25 of the first partial laminated core 12 and form a coolant supply channel 58 with the surface of the first partial laminated core 12 facing the first balancing disk 46. The through-openings 61 overlap in the circumferential direction with the second through-openings 23 of the first partial laminated core 12 and form a coolant discharge channel 60. A second balancing disk 48 is in Figure 5 and has several through openings 66 distributed over the circumference, which form a coolant discharge channel 67.

[0026] During operation of the electric machine, a relatively high level of heat loss occurs in the rotor 2, which is dissipated by the coolant flowing through the coolant channels 22, 24, 26, 28, 30, 32, 34, 36. The coolant flows into the coolant channels 22, 24, 26, 28, 30, 32, 34, 36 via a coolant supply channel 50 provided on the rotor shaft 44 and via the coolant supply channels 58 delimited by the first balancing disk 46. The balancing disk 46 has a circumferential groove 64 on an inner circumferential surface, and the coolant supply channel 50 has an axial section 52 and a radial section 54, with the coolant flowing from the coolant supply channel 50 into the groove 64 and from the groove 64 into the coolant supply channels 58.The coolant flows through the coolant channels 22, 24, 26, 28, 30, 32, 34, 36 and exits the coolant channels 22, 24, 26, 28, 30, 32, 34, 36 via the coolant discharge channels 60, 67, wherein the coolant is thrown away by the rotation of the rotor 2.

[0027] By such a design of the rotor 2, the heat transfer surface between the coolant and the rotor core 10 can be increased in a simple and cost-effective manner and thereby the cooling effect by the coolant can be increased.

[0028] It should be clear that various structural modifications of the rotor 2 are conceivable without departing from the scope of the main claim. For example, the rotor core 10, the balancing discs 46, 48, or the rotor shaft 44 may be designed differently.

Claims

1. Rotor for an electric machine, comprising a rotor laminate stack with a plurality of laminate sub-stacks (12, 14, 16, 18) which each comprise a multiplicity of rotor laminates (20) stacked in the stacking direction and each have at least one through opening (21, 23, 25) extending in the stacking direction, wherein the through openings (21, 23, 25) of the laminate sub-stacks (12, 14, 16, 18) overlap in the circumferential direction and together form at least one coolant channel (24, 28, 32, 36), wherein a first laminate sub-stack (12) comprises a first through opening (21) forming a coolant inlet (27) and a second through opening (23) forming a coolant outlet (29), wherein both through openings (21, 23) of the first laminate sub-stack (12) overlap with a single, third through opening (25) of a second laminate sub-stack (14), wherein the third through opening (25) of the second laminate sub-stack (14) is closed on the side facing away from the first laminate sub-stack (12).

2. Rotor according to claim 1, characterized in that the at least one coolant channel (24, 28, 32, 36) comprises a U-shaped configuration.

3. Rotor according to claim 1 or 2, characterized in that a third laminate sub-stack (16) is provided, which is arranged on that side of the second laminate sub-stack (14) that faces away from the first laminate sub-stack (12), wherein the third laminate sub-stack (16) comprises a closed surface in the region of the third through opening (25) of the second laminate sub-stack (14).

4. Rotor according to one of the preceding claims, characterized in that at least one further laminate sub-stack (18) is arrange between the first laminate sub-stack (12) and the second laminate sub-stack (14), wherein the at least one further laminate sub-stack (18) comprises a first through opening (21) and a second through opening (23), which overlap with the through openings (21, 23) of the first laminate sub-stack (12) and the through opening (25) of the second laminate sub-stack (14) in such a way that the through openings (21, 23, 25) of all the laminate sub-stacks define the common coolant channel (24, 28, 32, 36).

5. Rotor according to one of the preceding claims, characterized in that all the laminate sub-stacks (12, 14, 16, 18) are configured identically, wherein each laminate sub-stack (12, 14, 16, 18) comprises at least one first through opening (21), at least one second through opening (23) and at least one third through opening (25), the laminate sub-stacks (12, 14, 16, 18) being arranged on the circumference offset from one another in such a way that the through openings (21, 23, 25) of the laminate sub-stacks (12, 14, 16, 18) together define at least one coolant channel (24, 28, 32, 36).

6. Rotor according to one of the preceding claims, characterized in that a first balancing disc (46) is arranged on a first axial end, forming by means of the first laminate sub-stack (12), of the rotor laminate stack (10), wherein the first balancing disc (46) comprises at least one coolant supply channel (58), which extends radially and can be connected in fluidic terms to a coolant circuit, and a coolant discharge channel (60), wherein the coolant supply channel (58) and the coolant discharge channel (60) are fluidically connected to the coolant channel (24, 28, 32, 36).

7. Rotor according to claim 6, characterized in that the first balancing disc (46) comprises at least one radially extending groove (62) on a side facing the first laminate sub-stack (12), wherein the groove (62) and a surface of the first laminate sub-stack (12) facing the first balancing disc (46) define the coolant supply channel (58).

8. Rotor according to one of the preceding claims, characterized in that all laminate sub-stacks (12, 14, 16, 18) comprise a plurality of first through openings (21), a plurality of second through openings (23) and a plurality of third through openings (25), wherein the laminate sub-stacks (12, 14, 16, 18) are arranged on the periphery offset relative to one another in such a way that at least one first coolant channel (24, 28, 32, 36) and at least one second coolant channel (22, 26, 30, 34) are formed, wherein the first coolant channel (24, 28, 32, 36) extends through the first through opening (21), the second through opening (23) of at least one laminate sub-stack (12, 14, 16) and the third through opening (25) of another laminate sub-stack (12, 14, 16), and the second coolant channel (24, 28, 32, 36) is formed exclusively by the third through openings (25) of at least two laminate sub- sub-stacks (12, 14, 16) or by the first or second through opening (21, 23) of at least one laminate sub-stack (12, 14, 16, 18) and a third through opening (25) of at least the other laminate sub-stack (12, 14, 16, 18), wherein the first coolant channel (24, 28, 32, 36) comprises the coolant inlet (27) and a coolant outlet (29) at a single axial end and the second coolant channel (22, 26, 30, 34) comprises a coolant inlet (31) at one of the two axial ends and a coolant.

9. Rotor according to claim 8, characterized in that a second balancing disc (48) is arranged on that side of the second laminate sub-stack (14) which faces away from the first laminate sub-stack (12), wherein the second balancing disc (48) comprises a coolant discharge channel (66), wherein the coolant discharge passage (66) and a coolant supply passage (58) provided on the first balance plate (46) are fluidically connected to the second coolant passage (22, 26, 30, 34).

10. Rotor according to one of claims 6 to 9, characterized in that a rotor shaft (44) is provided, wherein the rotor laminate stack (10) is attached to an outer circumferential surface of the rotor shaft (44), wherein the rotor shaft (44) comprises a coolant supply channel (50) which is fluidically connected to the coolant channel (22, 24, 26, 28, 30, 32, 34) via the coolant supply channel (58).

11. Rotor according to claim 10, characterized in that the coolant supply passage (58) comprises an axial portion (52) extending from an end face and a radial portion (54), wherein the radial portion (54) extends from the axial portion (52) to the outer circumferential surface of the rotor shaft (44).

12. Rotor according to one of the preceding claims, characterized in that a plurality of magnet through openings (40) are provided, which are offset from one another in the circumferential direction and are intended for accommodating permanent magnets.