Rotor for electric machine

Abstract

A rotor (1) for an electric machine, the rotor comprising: a rotor shaft (2); a laminated core (3) fixedly arranged on the rotor shaft (2), the laminated core (3) having at least two laminated segments (4a, 4b, 4c, 4d) which are arranged next to one another in the axial direction with respect to the axis of rotation (5) of the rotor (1); and at least one first coolant channel (6) extending axially with respect to a rotational axis (5) of the rotor (1), the first coolant channel (6) being formed in the lamination stack (3) or between the lamination stack (3) and the rotor shaft (2), a sealing lamination (7) being arranged in the axial direction between at least two adjacent lamination segments (4a, 4b, 4c, 4d), wherein the sealing lamination (7) substantially has a contour corresponding to the lamination segments (4a, 4b, 4c, 4d) and at least one bead (8) which is designed in such a way that, by pressing adjacent lamination segments (4a, 4b, 4c, 4d) axially against each other, in addition to the sealing action between two adjacent lamination segments (4a, 4b, 4c, 4d), the bead (8) extends between the two adjacent lamination segments (4a, 4b, 4c, 4d) at least in the radial direction. 4d) also acts as a spring.

Description

Technical Field

[0001] The present invention relates to a rotor for an electric machine, comprising: a rotor shaft; a laminated core fixedly arranged on the rotor shaft, wherein the laminated core has at least two laminated core sections, which are arranged side by side in an axial direction with respect to the rotational axis of the rotor; and at least one first coolant channel extending axially with respect to the rotational axis of the rotor, wherein the first coolant channel is formed in the laminated core, wherein sealing laminates are arranged at least between the laminated core sections in the axial direction. Background Art

[0002] Electric machines of the aforementioned type serve to convert electrical energy into mechanical energy and vice versa and are used numerous times in the field of automotive technology as electric motors and / or generators.

[0003] An electric motor comprises a stationary stator and a movable rotor, wherein, in the most common design of an electric motor, the rotor is rotatably mounted in an annular stator.

[0004] Electric motors generate heat due to dielectric losses during operation, which, on the one hand, reduces the efficiency of the motor and, on the other hand, negatively impacts the reliable operation of the motor over its service life. Therefore, drives with electric motors are typically equipped with cooling devices that cool the components of the motor that are to be cooled.

[0005] Conventional cooling systems for electric motors use a circulating gaseous or liquid coolant. For example, the coolant circulates in the motor housing or in a hollow rotor shaft, on which the rotor of the motor is mounted. Due to its heat capacity, the coolant absorbs heat and transports it away.

[0006] The rotor's lamination stack typically has multiple lamination segments, each of which in turn consists of a number of individual electrical steel sheets. According to the "stacking method," the electrical steel sheets of the lamination segments are pressed or glued together. The individual lamination segments are simply stacked together. Due to tolerances, resistance during the pressing process, the springback effect of the lamination segments, and also the fanning during rotor operation, air gaps form between the lamination segments of the lamination stack. These air gaps cause radial leaks, allowing coolant to escape radially during rotor operation. Summary of the Invention

[0007] The object of the present invention is to provide an improved rotor for an electric machine.

[0008] Said need is met by the subject matter of the invention according to the first independent claim. Advantageous embodiments of the invention are described in the dependent claims.

[0009] A rotor for an electric motor according to the present invention comprises: a rotor shaft; a laminated core fixedly arranged on the rotor shaft, wherein the laminated core has at least two laminated sections arranged side by side in an axial direction with respect to the rotational axis of the rotor; and at least one first coolant channel extending axially with respect to the rotational axis of the rotor, wherein the first coolant channel is formed in the laminated core or between the laminated core and the rotor shaft.

[0010] According to the invention, a sealing laminate is arranged between at least two adjacent laminate segments in the axial direction.

[0011] The sealing laminate is made of metal, such as steel, aluminum, copper, zinc, titanium, etc.

[0012] According to the present invention, the sealing laminate essentially has a contour corresponding to the laminate segment and at least one rib, which is designed so that by pressing adjacent laminate segments axially against each other, in addition to the sealing effect between two adjacent laminate segments, the rib also exerts and constitutes a spring effect between two adjacent laminate segments at least in the radial direction.

[0013] In this context, the term "contour of a laminated section" should be understood to include all shaped elements, such as recesses for accommodating magnets or electrical conductors, central openings for passing the rotor shaft, screw openings, coolant channels, anti-twist devices, positioning elements, etc. The contour of a rotor's laminated section is formed by the contours of the individual laminates that form the laminated section—the individual laminates are essentially identical in this case. The sealing laminate differs from the individual laminates in particular by the design of the at least one rib.

[0014] The rib preferably has a trapezoidal cross section.

[0015] Preferably, each lamination segment has at least one axial cavity, wherein the respective axial cavity is designed to accommodate at least one permanent magnet and / or to conduct a cooling fluid. Thus, the axial cavity can form a magnet pocket for accommodating at least one permanent magnet and, as a whole, a first coolant channel—in this way, the cooling fluid flows directly around the permanent magnet. However, the magnet pocket and the first coolant channel can also be formed separately by the axial cavity.

[0016] In an advantageous embodiment variant of the invention, the laminated sections are arranged in such a way that the axial cavities and thus in particular the permanent magnets are offset relative to one another with respect to the circumferential direction of the rotor.

[0017] The sealing laminate preferably has at least one recess corresponding to the contour of the laminate segment, via which the axial cavities of at least two adjacent laminate segments and / or the first coolant channels of two adjacent laminate segments are at least fluidically connected, wherein a rib is formed at least partially circumferentially around the recess or the recess bundle in the sealing laminate.

[0018] In this context, a “bundle of recesses” is to be understood as meaning two or more recesses.

[0019] If the laminated sections are arranged so that the permanent magnets are offset from one another with respect to the circumferential direction of the rotor, ribs are formed in the sealing laminate around the recesses or recess bundles so that at least the outlet of the axial cavity of the laminated section and the inlet of at least one axial cavity of an adjacent laminated section are partially or completely radially surrounded by the ribs.

[0020] Furthermore, at least one rib can be formed circumferentially in the sealing core, following the outer contour and / or the inner contour of the sealing core.

[0021] In a preferred embodiment variant of the invention, the rotor shaft is at least partially hollow, so that a second coolant channel for conducting the coolant is formed, wherein the second coolant channel is fluidically connected to the first coolant channel.

[0022] An end cap may be provided at at least one end of the laminated core following the laminated core in the axial direction, wherein the end cap is designed such that it guides coolant from second coolant channels in the rotor shaft of the rotor into first coolant channels in the laminated core of the rotor.

[0023] In the axial direction, a sealing lamination is preferably provided between the lamination stack and the end cover.

[0024] The rotor shaft can have at least one radial opening, wherein the second coolant channel is fluidically connected to the first coolant channel via the radial opening.

[0025] The present invention offers the following advantages: the introduction of sealing laminations between the lamination segments does not negatively affect the stacking factor and, therefore, the magnetic properties of the rotor's laminated core, because the sealing laminations do not geometrically engage the spaces between the individual laminations of the lamination segments, but rather utilize the existing gaps between the segments. Since the individual laminations of the segments press against one another after the segments are fixedly mounted on the rotor shaft, the design and arrangement of the sealing laminations according to the present invention achieves a spring action between the segments in addition to the sealing action. Furthermore, the sealing laminations do not need to be rotationally fixed, since they are part of the rotor's laminated core. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be described below by way of example with reference to the accompanying drawings.

[0027] Figure 1 A schematic sectional view of a first exemplary embodiment of a rotor is shown, which has a first coolant channel in the lamination stack of the rotor.

[0028] Figure 2 A first schematic top view of a sealing laminate is shown.

[0029] Figure 3 A second schematic top view of the sealing laminate is shown.

[0030] Figure 4 A third schematic top view of the sealing laminate is shown.

[0031] Figure 5 A fourth schematic top view of a sealing laminate is shown.

[0032] Figure 6 A schematic detailed cross-sectional view of a sealing laminate between two laminate segments is shown.

[0033] Figure 7a A detailed cross-sectional view of the sealing laminate is shown in the uncompressed state.

[0034] Figure 7b A detailed cross-sectional view shows the sealing laminate in the compressed state. DETAILED DESCRIPTION

[0035] exist Figure 1 Schematically shows an exemplary rotor 1 for an electric machine. The rotor 1 comprises a rotor shaft 2 and a substantially hollow cylindrical lamination stack 3 fixedly arranged on the rotor shaft 2. The rotor shaft 2 is guided through a central opening ( Figure 1 ).

[0036] In this embodiment, the laminated core 3 comprises four hollow cylindrical laminated sections 4a, 4b, 4c, 4d, which are arranged side by side in the axial direction with respect to the rotation axis 5 of the rotor 1 ( Figure 1 However, the laminated core 3 can also have any other desired number of laminated core segments 4a, 4b, 4c, 4d.

[0037] The directional specification “axial” therefore corresponds to a direction along or parallel to the rotation axis 5 of the rotor 1 .

[0038] The rotor 1 also has a plurality of first coolant channels 6 extending axially with respect to the axis of rotation 5 of the rotor 1 , which are formed in the lamination stack 3 . Furthermore, the rotor has a plurality of permanent magnets evenly distributed in the circumferential direction. These permanent magnets are arranged in axial cavities 12 of the lamination stack 3 .

[0039] exist Figure 1 In the embodiment shown in FIG, the rotor shaft 2 is partially hollow, thereby forming a second coolant channel 11 ( Figure 1 ).

[0040] The direction of the coolant flow through the first coolant channel 6 and the second coolant channel 11 is Figure 1 Indicated by arrow X.

[0041] The rotor shaft 2 has a first end (about Figure 1 is the left end) and the second end (about Figure 1 is the right end).

[0042] In the region of the first end, a rotor nozzle 14 for conveying coolant is at least partially guided into the second coolant channel 11. Via the rotor nozzle 14, the coolant is guided into the second coolant channel 11 ( Figure 1 ).

[0043] Following the lamination stack 3 in the axial direction, in the region of the second end of the rotor shaft 2, an end cap 10 is fixedly arranged on the rotor shaft 2 ( Figure 1 In addition, a sealing lamination 7 is provided between the lamination stack 3 and the end cover 10 in the axial direction ( Figure 1 、 Figure 3 ).

[0044] The end cap 10 is designed so that it guides the coolant from the second coolant channel 11 in the rotor shaft 2 of the rotor 1 to the first coolant channel 6 in the lamination stack 3 of the rotor 1 ( Figure 1 ).

[0045] exist Figure 1 FIG. 4 also shows the arrangement of the sealing laminations 7 between two lamination segments 4 a , 4 b , 4 c , 4 d that follow one another in the axial direction.

[0046] All sealing laminations 7 are designed identically and have a contour corresponding to the lamination segments 4a, 4b, 4c, 4d—the sealing laminations 7 in particular have a plurality of recesses 9 corresponding to the axial cavities 12 in the individual lamination segments 4a, 4b, 4c, 4d. Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 ).

[0047] exist Figures 2 to 5 1 and 2 show the sealing laminate 7 in different embodiments—thus, in particular, different possible embodiments of the ribs 8 on the sealing laminate 7. The individual variants of the ribs 8 can also be combined differently on the sealing laminate 7 in terms of embodiment and number.

[0048] exist Figure 2 , a sealing core 7 is shown with ribs 8 which are formed along the inner contour of the sealing core, ie radially between the central recess 9 and all other recesses 9 .

[0049] exist Figure 3 , a sealing laminate 7 is shown with exemplary ribs 8 that are designed completely around the respective recesses 9. The recesses correspond to the axial cavities 12 formed in the laminate segments 4a, 4b, 4c, 4d, which simultaneously form the first coolant channels 6. For a better understanding, the recesses 9 are also designated by the reference numeral "6" for the first coolant channels and by the reference numeral "12" for the axial cavities.

[0050] exist Figure 4 , a sealing laminate 7 is shown with an exemplary rib 8 that is designed to completely circumscribe two recesses 9, i.e., a recess bundle. In this case, the recesses 9 also correspond to the axial cavities 12 formed in the laminate segments 4a, 4b, 4c, 4d, which simultaneously form the first coolant channels 6. For a better understanding, the recesses 9 are also designated by the reference numeral "6" for the first coolant channels and by the reference numeral "12" for the axial cavities.

[0051] exist Figure 5 , a sealing laminate 7 is shown with an exemplary rib 8 that is completely circumferentially formed around a recess 9 in the laminate sections 4a, 4b that is formed as a first coolant channel 6. For a better understanding, the recess 9 is also designated by the reference numeral "6" for the first coolant channel.

[0052] Figure 6 The cross-sectional view of the rib 8 between two laminated sections 4a, 4b, 4c, 4d is schematically shown. The rib 8 has a substantially trapezoidal cross-section.

[0053] exist Figure 7a and Figure 7b The diagram schematically illustrates the behavior of the rib 8 when the sealing laminate 7 is pressed together between two laminate segments 4a, 4b, 4c, 4d or between a laminate segment 4d and an end cap 10. Starting from a first axial extent a1, the rib 8 is compressed to a second axial extent a2. The reference numerals F1 and F2 describe the forces acting axially on the rib from both sides.

[0054] In the installed state of the sealing laminate 7 , the ribs 8 form a seal in the radial direction between the laminate segments 4 a , 4 b , 4 c , 4 d , so that coolant cannot escape radially from the first coolant channel 6 during operation of the rotor 1 .

[0055] The directional indication “radial” corresponds to the direction normal to the rotation axis 5 of the rotor 1 .

[0056] The respective sealing laminate 7 forms a metal rib seal between two laminate segments 4a, 4b, 4c, 4d, and also between a laminate segment 4d and the end cap 10. If the respective sealing laminate 7 is pressed together between two surfaces, a sealing surface can be produced. However, in addition to the sealing effect, the sealing laminate 7 also realizes a spring effect, by which the laminate segments 4a, 4b, 4c, 4d are each pressed together.

[0057] By rotor 1 corresponds to Figures 1 to 7b The design of the embodiment variant shown in FIG. 1 makes it possible to produce a sealed laminated core 3 in which, for example, the permanent magnets are cooled directly in the axial cavity 12 . When the rotor 1 is installed, coolant cannot escape into the air gap between the rotor 1 and the stator of the electric machine—thereby preventing increased drag losses due to fluid friction in the air gap. Furthermore, no additional installation space is required for radial sealing. Furthermore, the sealing core 7 can be manufactured in a simple manner—the individual cores of the core segments 4 a, 4 b, 4 c, 4 d can be adapted accordingly by forming the ribs 8 .

[0058] Reference Signs List

[0059] 1 rotor

[0060] 2 Rotor shaft

[0061] 3 lamination packs

[0062] 4a, 4b, 4c, 4d laminated sections

[0063] 5 Rotation axis

[0064] 6 First coolant channel

[0065] 7 Sealing laminations

[0066] 8 ribs

[0067] 9 blank space

[0068] 10 End cap

[0069] 11 Second coolant channel

[0070] 12 Axial cavity

[0071] 14 rotor nozzle

[0072] a1, a2 Axial extension of the rib

[0073] F1, F2 axial force

[0074] X Direction arrow (describing coolant flow)

Claims

1. A rotor (1) for an electric motor, comprising: - rotor shaft (2), a laminated core (3) fixedly arranged on the rotor shaft (2), wherein the laminated core (3) comprises at least two laminated core sections (4a, 4b, 4c, 4d) which are arranged adjacent to one another in the axial direction with respect to the axis of rotation (5) of the rotor (1), and at least one first coolant channel (6) extending axially with respect to the axis of rotation (5) of the rotor (1), wherein the first coolant channel (6) is formed in the laminated core (3) or between the laminated core (3) and the rotor shaft (2), A sealing laminate (7) is provided between at least two adjacent laminate sections (4a, 4b, 4c, 4d) in the axial direction, wherein the sealing laminate (7) substantially has a profile corresponding to the laminate sections (4a, 4b, 4c, 4d) and at least one rib (8), the rib being configured so that, by axially pressing the adjacent laminate sections (4a, 4b, 4c, 4d) against each other, in addition to a sealing effect between the two adjacent laminate sections (4a, 4b, 4c, 4d), the rib also exerts a spring effect between the two adjacent laminate sections (4a, 4b, 4c, 4d) at least in the radial direction.

2. The rotor (1) according to claim 1, It is characterized by: The rib (8) has a trapezoidal cross section.

3. The rotor (1) according to claim 1 or 2, It is characterized by: The laminated sections (4a, 4b, 4c, 4d) each have at least one axial cavity (12), wherein the respective axial cavity (12) is designed for accommodating at least one permanent magnet and / or for conducting a cooling fluid, i.e., is designed in such a way that the first coolant channel (6) is integrally formed.

4. The rotor (1) according to claim 3, It is characterized by: The laminated sections (4a, 4b, 4c, 4d) are arranged such that the axial cavities (12) and thus at least the permanent magnets are offset from one another with respect to the circumferential direction of the rotor (1).

5. The rotor (1) according to claim 3 or 4, It is characterized by: The sealing laminate (7) has at least one recess (9) corresponding to the contour of the laminate segments (4a, 4b, 4c, 4d), via which at least the axial cavities (12) of the two adjacent laminate segments (4a, 4b, 4c, 4d) and / or the first coolant channels (6) of the two adjacent laminate segments (4a, 4b, 4c, 4d) are at least fluidically connected, wherein a rib (8) is formed in the sealing laminate (7) at least partially around the recess (9) or the recess bundle.

6. Rotor (1) according to claims 4 and 5, It is characterized by: The rib (8) is formed around the recess (9) or the recess bundle in the sealing laminate (7) so that the outlet of the axial cavity (12) of the laminate segment (4a, 4b, 4c, 4d) and the inlet of the axial cavity (12) of the adjacent laminate segment (4a, 4b, 4c, 4d) are radially surrounded by the rib (8).

7. A rotor (1) according to any one of the preceding claims, It is characterized by: In the sealing laminate (7), at least one rib (8) is formed circumferentially following the outer contour and / or inner contour of the sealing laminate (7).

8. A rotor (1) according to any one of the preceding claims, It is characterized by: The rotor shaft (2) is at least partially hollow, thereby forming a second coolant channel (11) for axially guiding a coolant, wherein the second coolant channel (11) is fluidically connected to the first coolant channel (6).

9. The rotor (1) according to claim 8, It is characterized by: An end cap (10) is provided at at least one end of the lamination stack (3) of the rotor (1) following the lamination stack (3) in the axial direction, wherein the end cap (10) is designed such that it guides coolant from the second coolant channel (11) in the rotor shaft (2) into the first coolant channel (6) in the lamination stack (3).

10. The rotor (1) according to claim 9, It is characterized by: In the axial direction, a sealing lamination (7) is provided between the lamination stack (3) and the end cover (10).

11. The rotor (1) according to claim 8, It is characterized by: The rotor shaft (2) has at least one radial opening, wherein the second coolant channel (11) is fluidically connected to the first coolant channel (6) via the radial opening.

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