electric machine

Abstract

The invention relates to a rotor (7) for an electric machine, which rotor cooperates with a radially outer stator (5) and is spaced apart from the stator via an air gap (8). According to the invention, the rotor (7) has a coolant run-off profile (51) at its outer periphery, which exerts an axial force component on coolant which is unintentionally located in the air gap (8) when the rotor is rotating (D), whereby the coolant can be transported from the air gap (8) in the direction of the rotor end side.

Description

Technical Field

[0001] The present invention relates to an electric motor having a rotor that interacts with and is spaced apart from a radially outer stator via an air gap, wherein a winding head space is connected at each end of the rotor in the axial direction, the winding head space being capable of being loaded with coolant, and wherein the air gap is opened into the winding head space, thereby allowing the coolant to potentially, particularly unintentionally, reach the air gap; and a rotor for such an electric motor, the rotor interacting with and being spaced apart from a radially outer stator via an air gap. Background Technology

[0002] This type of motor has a rotor that interacts with and is spaced apart from a radially external stator via an air gap. Within the internal space of the motor housing, winding head spaces are connected axially at each of the rotor end sides. These winding head spaces can be loaded with coolant. Here, the stator is sprayed with coolant either through the rotor or via a separate supply system to dissipate heat generated by power losses.

[0003] One problem with this direct cooling method is that coolant can seep into the gap between the rotor and stator. This increases the drag torque in the air gap as the rotor rotates, significantly reducing the motor's efficiency. The narrower the air gap between the rotor and stator, the greater this effect.

[0004] A cooling unit for use with an electric motor is known from US 2017 / 0012500 A1. The cooling unit may have arcuate grooves constructed along the outside of the rotor and configured such that it throws cooling oil to the opposite ends of the rotor.

[0005] An electric motor is known from EP 4 178 080 A1, in which a serpentine cooling path is formed in the fluid cooling channel, the cooling path extending axially through the laminated plate. An electric motor is known from US 2020 / 0244123 A1, in which cooling fluid flows through the air gap between the rotor and stator. An electric motor is known from JP 2021-78305 A, in which three coolant channels are provided on the outer circumferential surface of the rotor core. Summary of the Invention

[0006] The objective of this invention is to provide an electric motor in which efficiency is improved in a simple manner compared to the prior art.

[0007] This task is accomplished by the motor and rotor according to the invention. Preferred improvements to the invention are disclosed in the remaining embodiments.

[0008] This invention relates to an electric motor having a rotor that interacts with and is radially separated from a stator via an air gap. A winding head space, which can be loaded with coolant, is connected at each of the rotor end sides in the axial direction. An air gap extends into the winding head space, allowing coolant to potentially enter unintentionally. According to the invention, measures are taken to keep the air gap largely coolant-free: the rotor has a coolant-deflecting profile at its outer periphery that applies an axial force component to the coolant located in the air gap during rotor rotation, thereby enabling coolant to be transported from the air gap toward the winding head space.

[0009] In one implementation, the coolant guide profile may have at least one coolant channel that is groove-shaped in cross-section and opens radially outward toward the air gap. This coolant channel may extend continuously along the entire axial length of the rotor. Furthermore, the coolant channel may axially extend into the winding head space on both sides of the channel outlet. In this case, the coolant channel may have a channel apex between the two channel outlets in the rotor axial direction. The channel apex of this coolant channel may lead relative to the two channel outlets in the preferred rotor rotation direction. This results in a channel orientation in which the obliquely extending cooling channel flanks, originating from the two axially arranged channel outlets on both sides, converge in a V-shape at the channel apex.

[0010] In common practice, the rotor may have lamination assemblies, which can be divided into axially adjacent lamination sub-assemblies. Each of these lamination sub-assemblies is constructed from a large number of laminations. Furthermore, each lamination may have at least a permanent magnet recess, which is part of a magnet housing in the joined lamination sub-assemblies, in which at least one permanent magnet is located. The permanent magnet may have the same axial length as the magnet housing in the axial direction. Additionally, each lamination may have at least a coolant channel recess, which is part of a sub-assembly channel section in the lamination sub-assembly. This sub-assembly channel section, in turn, is part of the coolant channel in the assembled lamination assembly.

[0011] In terms of manufacturing technology, it is preferable that all the laminations in the lamination assembly are constructed identically (especially during the stamping process). Exemplarily, the channel segments of each lamination sub-assembly can extend continuously in the axial direction with axial alignment. Furthermore, in the assembled lamination assembly, the individual lamination sub-assemblies can be slightly twisted relative to each other with a sub-assembly rotational angular misalignment, thus forming a V-shaped coolant channel orientation. The channel segments of adjacent lamination sub-assemblies can here transition into each other in a stepped manner.

[0012] In one specific embodiment, within each lamination, the circumferentially distributed permanent magnet notches can be arranged regularly, i.e., with the same permanent magnet indexing spacing. The circumferentially distributed coolant channel notches can be arranged irregularly, i.e., with slightly different coolant channel indexing spacing. Furthermore, each lamination subgroup can be divided into a first lamination stack and a second lamination stack. In the respective lamination stacks, the permanent magnet notches and coolant channel notches can be axially aligned in the axial direction. Furthermore, the two lamination stacks can be twisted relative to each other by at least one permanent magnet indexing spacing, such that their coolant channel notches—due to the slightly different coolant channel indexing spacing—are slightly misaligned in a stepped manner in the circumferential direction, while the permanent magnet notches—in both the first and second lamination stacks—remain axially aligned with each other due to the same permanent magnet indexing spacing. This stepped misalignment between the two lamination stacks of the lamination subgroup supports a V-shaped coolant channel orientation. Attached Figure Description

[0013] Embodiments of the present invention will now be described with reference to the accompanying figures.

[0014] in: Figures 1 to 9 Different views are shown, based on which the structure of the motor according to the present invention is explained. Detailed Implementation

[0015] exist Figure 1 The upper half of the motor 1 is roughly schematically shown within the scope necessary for understanding the invention. Accordingly, the motor 1 has a hollow cylindrical stator housing 3, on the inner side of which a stator 5 is fixed. The stator 5 interacts with a radially inward rotor 7 and is spaced apart from the rotor via an air gap 8. The air gap is constructed by a rotor shaft 9 and a lamination assembly 11 fixed thereon. In the figure, the motor 1 is exemplary a permanent magnet excitation synchronous motor, in which the lamination assembly 11 has magnet receiving portions 13 in which permanent magnets 15 are placed. These permanent magnets are secured in the magnet receiving portions 13 by means of a plastic casting material 40.

[0016] The rotor shaft 11 is rotatably supported in a bearing bore at the housing wall 17, which is axially opposite to the stator housing 3. Axially, winding head spaces 19 exist on both sides of the rotor / stator arrangement within the stator housing 3, into which the winding heads 21 of the stator windings 23 of the stator 5 extend. The winding heads 21 here protrude axially beyond the lamination end sides 33, 39 of the rotor 7.

[0017] To cool the motor 1, the rotor 7 is connected to a coolant supply device 25. By means of this coolant supply device 25, coolant is fed from the rotor shaft interior space 27 through the rotor shaft transverse bore 29 into the first (in) coolant supply device 25 via a flow path. Figure 1 In the annular gap 31 within the inner corner region between the lamination assembly end 33 (left side) and the rotor shaft 9. The annular gap 31 is limited by a coolant guide ring 35. Further along, the flow path extends from the annular gap 31 through radially inward, circumferentially distributed coolant channels 37 to the opposing second lamination assembly end 39. In the second (in Figure 1 A ring-shaped distributor housing 41 is arranged around the rotor shaft 9 at position 39 on the right side of the lamination group.

[0018] By means of the annular distributor housing 41, the coolant outlet 43 of the radially inner coolant channel 37 is alternately opened in the circumferential direction either for the swirl cooling of the winding head 21 as described later, or led to the flow connection 42 with the radially outer coolant channel 45, which is also constructed in the lamination assembly 11. Figure 1 The radially outer coolant channels 45 serve as return channels through which coolant flows back to the first lamination end 33 in the opposite flow direction. The coolant outlet 43 of the radially outer coolant channels 45 at the first lamination end 33 is also axially open for swirling cooling of the winding head 21.

[0019] The following problem exists during swirling cooling: coolant may flow into the air gap 8, thereby reducing motor efficiency due to fluid friction that occurs during rotor rotation. To avoid this reduction in motor efficiency, the following measures are taken according to the present invention: Thus, according to Figure 2 Coolant channels 51 are constructed on the outer periphery of the rotor 7. These coolant channels are groove-shaped and open radially outward toward the air gap 8. Figure 2 Each of the coolant passages 51 extends continuously along the entire axial length of the rotor in the axial direction and enters the winding head space 19 axially at both sides of the passage outlet 53.

[0020] also, Figure 2 As shown, the coolant passage 51 has a passage apex 55 in the rotor axial direction between the two passage outlets 53. This passage apex leads the two passage outlets 53 in the preferred rotor rotation direction D. Accordingly, the coolant passage 51 has obliquely extending passage wings 57 extending from the two axially arranged passage outlets 53 on both sides, which converge in a V-shape at the passage apex 55.

[0021] During motor operation, coolant may flow from the winding head space 19 into the air gap 8 and into the coolant passage 51. The coolant in the corresponding coolant passage 51 experiences an axial force component due to the obliquely arranged passage side 57, which forces the coolant back from the air gap 8 into the winding head space 19. In this way, the air gap 8 is kept largely coolant-free.

[0022] As from Figure 2 As further understood, the lamination group 11 is divided into axially adjacent lamination subgroups 58. Each of these lamination subgroups 58 consists of a large number of laminations 59. All of these laminations are manufactured identically during the stamping process. Figure 4 Each of the stacked wafers 58 has a magnet housing 13, in which permanent magnets 15 are positioned, the axial length of which is l. M Equal to the axial length l of the corresponding magnet housing 13 TP .

[0023] exist Figure 5 One of the laminations 59 is shown separately. Accordingly, the lamination 59 has circumferentially distributed permanent magnet recesses 61 and circumferentially distributed coolant channel recesses 63. The circumferentially distributed permanent magnet recesses 61 are regular in the circumferential direction, i.e., with the same permanent magnet indexing spacing α. P Arrangement. In the same manner, the circumferentially distributed coolant channel recesses 63 are regularly spaced in the circumferential direction, i.e., with the same coolant channel spacing α. K Arrangement. In Figure 4 In the stacked sheet subgroup 58 shown, a large number of such stacked sheets 59 are stacked on top of each other in the axial direction. Figure 4 The coolant passage recess 63 is part of the passage segment 65, which extends axially aligned in the axial direction. The laminated assemblies 58 are in... Figure 4 The channel segment 65 shown is also part of the coolant channel 51 when the laminate group 11 is assembled.

[0024] exist Figure 2 In this assembly, a total of seven such laminated sub-groups 58 are assembled into a laminated group 11. To achieve the V-shaped coolant channel orientation according to the invention, each laminated sub-group 58 is slightly twisted relative to each other by a sub-group rotation angle offset v. In this way, the channel sections 65 of adjacent laminated sub-groups 58 transition into each other in a stepped manner.

[0025] exist Figure 6 and Figure 7 A second embodiment of rotor 7 is shown, whose basic structure is the same as that of the previous embodiment. Therefore, refer to the foregoing description. Figure 6 and Figure 7In this process, all the stacked sheets 58 are identical to each other and are manufactured during the stamping process. However, compared with... Figure 5 The difference is that, in Figure 6 and Figure 7 The laminate 59 used has a modified laminate geometry, which is first based on Figure 7 Description: Accordingly, the circumferentially distributed permanent magnet notches 61 are also like... Figure 5 In the same way - regularly with the same permanent magnet indexing spacing α P Arrangement. However, with Figure 6 On the contrary, Figure 6 In the middle, the circumferentially distributed coolant channel recesses 63 no longer have a uniform coolant channel spacing α. K Instead of a different arrangement, the coolant channels are spaced at slightly different intervals α. K1 ,α K2 Arrangement.

[0026] According to the present invention, this situation is utilized as follows: thus, in Figure 6 In this configuration, each lamination subgroup 58 mounted in the rotor 7 is divided into a first lamination stack 67 and a second lamination stack 69. In both the first and second lamination stacks 67 and 69, the permanent magnet recesses 63 of each lamination 59 are axially aligned in the axial direction. According to the invention, these two lamination stacks 67 and 69 are spaced at least one permanent magnet indexing distance α. P They twist to each other. In this way, the following is achieved: coolant channel notch 63 - due to slightly different coolant channel indexing spacing α K1 ,α K2 ( Figure 7 - They are misaligned in a stepped manner in the circumferential direction. In contrast, the permanent magnet notch 61 is in both the first stack 67 and the second stack 69 - due to the still identical permanent magnet indexing spacing α. P - Oriented axially aligned with each other. In this way, in Figure 6 The cooling section 65 in the stacked laminations 58 shown has a stepped transition section 66 in the middle. This stepped misalignment, or transition section 66, between the two stacked laminations 67 and 69 supports the V-shaped coolant channel orientation, as shown... Figure 7 As shown in the image.

[0027] exist Figure 8 and Figure 9 Another embodiment is shown. According to... Figure 8 The channel segment 65 (which forms the coolant channel 51) is no longer oriented axially aligned in the axial direction in the corresponding lamination group 58, but is oriented obliquely relative to the axial direction, so that a smooth transition without steps is created between the channel segments 65 of adjacent lamination groups 58.

[0028] exist Figure 9 The diagram shows a laminated sub-assembly 58 having a channel segment 65, which is part of the coolant channel 51 in the assembled laminated assembly 11. According to... Figure 9 The groove depth (and therefore the flow cross-section of the coolant passage 51) is no longer constant in the axial direction. Instead, the groove depth of the passage section 65 changes, that is, the groove depth increases in the assembled lamination group 11 toward the coolant outlet 53, thereby reducing the flow resistance in the coolant passage 51 axially outward.

[0029] List of reference numerals in the attached diagram: 1. Motor 3. Stator housing 5 stators 7 rotors 8. Air gap 9. Rotor shaft 11 stacked pieces 13 Magnet Receiving Section 15 permanent magnets 17. Shell wall 19. Winding head space 21 Winding head 23 Stator windings 25 Coolant supply device 27. Internal space of the rotor shaft 29. Transverse bore of rotor shaft 31 Annular gap 33. End side of the stacked assembly 35 Coolant guide ring 37. Radial internal coolant passages 39 Second stack end side 40 Plastic materials 41 Distributor housing 42 Flow connection part 43 Coolant outlet 45 Radial external coolant passages 51 Coolant passage 53 Channel Exit 55 Channel Vertex 57 Channel Flanking 58 stacked pieces 59 stacked pieces 61 Permanent magnet notch 63 Coolant passage notch 65 Channel Section 66 Stepped transition section 67,69 Stacked Pieces v Subgroup rotation angle misalignment α P Same permanent magnet indexing spacing α K Same coolant channel indexing spacing α K1 ,α K2 Slightly offset coolant channel indexing spacing D Preferred rotation direction l TP Subgroup length l M Magnet length.

Claims

1. An electric motor having a rotor (7) that interacts with a radially external stator (5) and is spaced apart from the stator via an air gap (8), wherein, A winding head space (19) is connected at each rotor end in the axial direction, the winding head space being capable of being loaded with coolant, and wherein the air gap (8) is introduced into the winding head space (19), thereby allowing the coolant to potentially reach the air gap (8) particularly unintentionally. The rotor (7) is characterized by having a coolant guide profile (51) at its outer periphery, the coolant guide profile applying an axial force component to the coolant located in the air gap (8) when the rotor rotates (D), thereby allowing the coolant to be transported from the air gap (8) toward the winding head space (19).

2. The motor according to claim 1, characterized in that, The coolant guide profile is at least one coolant channel (51) that is groove-shaped in cross-section and opens radially outward toward the air gap (8), and / or the coolant channel (51) extends continuously in the axial direction through the entire axial length of the rotor, and / or the coolant channel (51) opens axially into the winding head space (19) on both sides of the channel outlet (53).

3. The motor according to claim 2, characterized in that, The coolant passage (51) has a passage apex (55) in the rotor axial direction between two passage outlets (53), the passage apex being ahead of the two passage outlets (53) in the preferred rotor rotation direction (D), such that the coolant passage (51) has obliquely extending cooling passage wings (57) extending from the two axially arranged passage outlets (53) on both sides, the cooling passage wings converging in a V-shape at the passage apex (55).

4. The motor according to claim 1, 2 or 3, characterized in that, The rotor (7) has a lamination group (11) that can be divided into axially adjacent lamination subgroups (58), each of which is constructed of a large number of laminations (59), and in particular each of the laminations (59) is constructed with at least a permanent magnet recess (61), which is part of a magnet receiving portion (13) in the lamination subgroup (58), at least one permanent magnet (15) is located in the magnet receiving portion, and in particular the permanent magnet (15) has the same axial length in the axial direction as the magnet receiving portion (13), and / or each of the laminations (59) is constructed with at least a coolant channel recess (63), which is part of a subgroup channel segment (65) in the lamination subgroup (58), which is part of the coolant channel (51) in the assembled lamination group (11).

5. The motor according to claim 4, characterized in that, All the laminations (59) of the lamination group (11) are constructed in the same way, especially during the stamping process.

6. The motor according to claim 4 or 5, characterized in that, The channel segments (65) of each lamination subgroup (58) extend continuously in the axial direction in an axial alignment, and / or in the assembled lamination group (11), the individual lamination subgroups (58) are slightly twisted to each other with a subgroup rotation angle misalignment (v), that is, in the case of forming a V-shaped coolant channel orientation, and / or the channel segments (65) of adjacent lamination subgroups (58) transition into each other in a stepped manner.

7. The motor according to any one of claims 4 or 6, characterized in that, In each stack (59), the circumferentially distributed permanent magnet notches (61) are regular, i.e., with the same permanent magnet indexing spacing (α). P The coolant channel recesses (63) arranged and / or circumferentially distributed are irregular, i.e., with slightly different coolant channel spacing (α). K1 ,α K2 Arrangement.

8. The motor according to claim 7, characterized in that, Each stack subgroup (58) is divided into a first stack (67) and a second stack (68). In the respective stacks (67, 68), the permanent magnet notch (61) and the coolant channel notch (63) are axially aligned in the axial direction. The two stacks (67, 68) are aligned with at least one permanent magnet indexing spacing (α). P This twisting of the two ends causes the coolant passage notch (63) to be slightly different due to the varying coolant passage spacing (α). K1 ,α K2 They are slightly misaligned in a step-like manner in the circumferential direction (in the case of forming transition step 66), and the permanent magnet notches (61) are in both the first stack (67) and the second stack (68) - due to the same permanent magnet indexing spacing (α). P The )- remain axially aligned with each other, and especially the stepped misalignment (66) between the two stacks (67, 68) of the stacked subgroup (58) supports the V-shaped coolant channel orientation.

9. The motor according to any one of claims 1 to 4, characterized in that, The channel segments (65) in the corresponding laminations (58) are not oriented axially aligned in the axial direction, but are oriented obliquely relative to the axial direction, so that a smooth transition without steps is formed between the channel segments (65) of adjacent laminations (58), and / or the flow cross-section of the coolant channel (51) increases toward the coolant outlet (53), thereby reducing the flow resistance in the coolant channel (53) axially outward.

10. A rotor (7), particularly for use in an electric motor according to any one of the preceding claims, said rotor (7) interacting with a radially outer stator (5) and spaced apart from said stator via an air gap (8), characterized in that, The rotor (7) has a coolant deflection profile (51) at its outer periphery, which applies an axial force component to the coolant unintentionally located in the air gap (8) when the rotor rotates (D), thereby enabling the coolant to be transported from the air gap (8) toward the rotor end side.

Images