Abstract
A rotor for an electric machine comprises at least one structure-borne sound absorbing element made of a cellular metallic material being arranged in the rotor. The electric machine comprises a rotor shaft, two roller bearings and a bearing seat for each one of the two roller bearings, the rotor shaft being rotatably mounted in the two roller bearings, and a structure-borne sound absorbing element made of a cellular metallic material being arranged in the region of at least one of the two bearing seats.
Claims
1. A rotor for an electric machine comprising: at least one structure-borne sound absorbing element made of a cellular metallic material being arranged in the rotor.
2. The rotor as claimed in claim 1, further comprising a rotor shaft with a bore, the structure-borne sound absorbing element being arranged within the bore of the rotor shaft.
3. The rotor as claimed in claim 1, further comprising a laminated rotor core with at least one slot, the structure-borne sound absorbing element being arranged in the slot of the laminated rotor core.
4. The rotor as claimed in claim 1, further comprising: a first shaft journal; a second shaft journal spaced apart from the first shaft journal; and a carrier for a laminated rotor core, the carrier for the laminated rotor core being arranged between the first shaft journal and the second shaft journal, the carrier, the first shaft journal and the second shaft journal delimiting a cavity between them, and the structure-borne sound absorbing element being arranged within the cavity.
5. The rotor as claimed in claim 1, wherein the cellular metallic material is a metal foam.
6. The rotor as claimed in claim 5, wherein the cellular metallic material is an aluminum foam.
7. The rotor as claimed in claim 5, wherein the metal foam comprising hollow spherical structures.
8. The rotor as claimed in claim 7, wherein the hollow spherical structures which are filled with particles
9. The rotor as claimed in claim 8, wherein the hollow spherical structures which are filled with ceramic particles.
10. An electric machine comprising: a rotor shaft; two roller bearings; a bearing seat for each one of the two roller bearings, the rotor shaft being rotatably mounted in the two roller bearings; and a structure-borne sound absorbing element made of a cellular metallic material being arranged in the region of at least one of the two bearing seats.
11. The electric machine as claimed in claim 10, wherein the cellular metallic material being a metal foam.
12. The electric machine as claimed in claim 11, wherein the metal foam is an aluminum foam.
13. The electric machine as claimed in claim 11, wherein the metal foam comprises hollow spherical structures.
14. The electric machine as claimed in claim 13, wherein the hollow spherical structures are filled with particles.
15. The electric machine as claimed in claim 14, wherein the hollow spherical structures are filled with ceramic particles.
Description
BRIEF DESCRIPTION OF THE FIGURES
[0025] Exemplary embodiments of the invention will be discussed in more detail below on the basis of the partially schematic drawing. In the drawing:
[0026] FIG. 1 shows a partially sectioned representation of a known electric axle drive;
[0027] FIG. 2 shows a longitudinal sectional representation of a known rotor with a rotor shaft and with a laminated rotor core;
[0028] FIG. 3 and FIG. 4 an show a longitudinal sectional representation of exemplary embodiment of a rotor according to the invention with a structure-borne sound absorbing metal foam integrated in a rotor shaft;
[0029] FIG. 5 shows a longitudinal sectional representation of a known rotor with a multi-part rotor shaft;
[0030] FIG. 6 and FIG. 7 show a longitudinal sectional representation of an exemplary embodiment of a rotor according to the invention with a structure-borne sound absorbing metal foam integrated in a cavity of a multi-part rotor shaft;
[0031] FIG. 8 and FIG. 9 show a longitudinal sectional representation of an exemplary embodiment of a rotor according to the invention with a structure-borne sound absorbing metal foam integrated in slots of a laminated rotor core;
[0032] FIG. 10 shows a longitudinal sectional representation of a part of an electric machine with a rotor shaft, a roller bearing and a housing that forms a bearing seat for the roller bearing;
[0033] FIG. 11 and FIG. 12 show a longitudinal sectional representation of a part of an exemplary embodiment of an electric machine according to the invention with a structure-borne sound absorbing metal foam in the region of a bearing seat;
[0034] FIG. 13 shows a longitudinal sectional representation of an exemplary embodiment of an electric machine according to the invention with structure-borne sound absorbing metal foam in the region of the bearing seats and in the interior of a multi-part rotor shaft; and
[0035] FIG. 14 shows a longitudinal sectional representation of an exemplary embodiment of an electric machine according to the invention with structure-borne sound absorbing metal foam in the interior of a multi-part rotor shaft and in slots of a laminated rotor core.
DETAILED DESCRIPTION
[0036] FIG. 1 shows an electric axle drive 1 of a motor vehicle 2. The electric axle drive 1 comprises an electric machine 3 with a laminated rotor core 4, with a stator 5 and with a rotor shaft 6. The stator 5 of the electric machine 3 is coupled to a chassis 8 of the motor vehicle 2 by means of an assembly bearing 7 with springs and dampers. The rotor shaft 6 is coupled to a transmission 9, which is coupled to the vehicle 2 via a transmission bearing 10 with a spring element.
[0037] One of the main causes of noises in the electric axle drive 1 is typically the non-uniformity of the torque in the electric machine 3. The non-uniformity of the torque in the electric machine 3 is dependent on the type of construction, and can be influenced by the design of the electric machine 3.
[0038] However, the non-uniformity of the torque may also be a result of the activation of the electric machine 3, if for example a switching frequency that is too low and a low leakage inductance in the electric machine 3 produce significant harmonic currents, which can cause torque fluctuations 11, which are often also referred to as torque ripple.
[0039] The non-uniformity of the torque of the electric machine 3 can contribute to noise generation in various ways. For example, the torque ripple 11 can reach the transmission 9 via the rotor shaft 6 and generate transmission noises there. Furthermore, the torque ripple 11 can reach the chassis 8 of the vehicle 2 via the assembly bearing 7 (if the damping is insufficient) and provide vibration excitation and associated noise. In addition, a housing 12 of the stator 5 (if the dimensions are insufficient) can be excited by the rotating power sources to structure-borne sound 12, which can then take the form of airborne sound.
[0040] FIG. 2 shows a known rotor with a rotor shaft 6 and with a laminated rotor core 4, which is mounted on the rotor shaft 6 for conjoint rotation.
[0041] FIGS. 3 and 4 each show a rotor with a rotor shaft 6, which comprises a central bore 14, which extends in a longitudinal direction L of the rotor shaft 6. Arranged within the bore 14 is a structure-borne sound absorbing element 15, which may for example be produced from a metal foam, for example from an aluminum foam.
[0042] FIG. 5 shows a known rotor, which comprises a first shaft journal 16, a second shaft journal 17, a laminated rotor core 4 (magnetically relevant region) and a carrier 18 for the laminated rotor core 4. The carrier 18 is arranged between the first shaft journal 16 and the second shaft journal 17 in a longitudinal direction L of the rotor. Furthermore, the carrier 18, the first shaft journal 16 and the second shaft journal 17 delimit a cavity 19 between them. Furthermore, the laminated rotor core 4 is mounted on the carrier 18 for conjoint rotation.
[0043] FIGS. 6 and 7 each show a rotor, which has the same basic structure as the rotor shown in FIG. 5. However, a structure-borne sound absorbing element 15 is arranged within the cavity 19 of the rotor as shown in FIGS. 6 and 7, it being possible for the element 15 to be produced for example from a metal foam, for example from an aluminum foam. The structure-borne sound absorbing element 15 may in this case completely fill the cavity 19.
[0044] FIGS. 8 and 9 each show a rotor with a rotor shaft 6 and with a laminated rotor core 4, which is mounted on the rotor shaft 6 for conjoint rotation. The laminated rotor core 4 comprises a number of slots 20 distributed in the circumferential direction, which run in the axial direction L through the individual laminations of the laminated rotor core 4. A structure-borne sound absorbing element 15 is arranged in each one of the slots 20. The elements 15 may for example be produced from a metal foam, for example from an aluminum foam. In the exemplary embodiments shown by FIGS. 8 and 9, the slots 20 extend parallel to a longitudinal axis L of the rotor shaft 6.
[0045] FIG. 10 shows a part of a known electric machine 21 with a rotor shaft 6 and with two roller bearings 22, one of which is shown in FIG. 10. The electric machine 21 may further comprise a housing 23 which forms two bearing seats 24, one of which is shown in FIG. 10. The rotor shaft 6 is rotatably mounted in the two roller bearings 22, and the two bearing seats 24 each receive a roller bearing 22.
[0046] FIGS. 11 and 12 each show a part of an electric machine 21, which has the same basic structure as the electric machine as shown in FIG. 10. However, a structure-borne sound absorbing element 15 made of a cellular metallic material is arranged in the region of the two bearing seats 24 (for example, the element 15 may be molded around the two bearing seats 24), it being possible for the element 15 to be produced for example from a metal foam, for example from an aluminum foam.
[0047] FIG. 13 shows a further electric machine 21. Similarly, as shown in FIGS. 11 and 12, a structure-borne sound absorbing element 15 made of a cellular metallic material is arranged in the region of each of two bearing seats 24. Similarly, as shown in FIGS. 6 and 7, a structure-borne sound absorbing element 15 made of a cellular metallic material is arranged within a cavity 19 of a multi-part rotor, which may comprise a first shaft journal 16, a second shaft journal 17, a laminated rotor core 4 and a carrier 18 for the laminated rotor core 4. The elements 15 may for example be produced from a metal foam, for example from an aluminum foam. According to the exemplary embodiment as shown in FIG. 13, the electric machine 21 may further comprise a stator 25 and a transmission 26 integrated in the electric machine, within which a structure-borne sound absorbing element 15 made of a cellular metallic material may also be arranged.
[0048] FIG. 14 shows a further electric machine 21. Similarly, as shown in FIGS. 3 and 4, a rotor of the electric machine has a rotor shaft 6 with a central bore 14, which extends in a longitudinal direction L of the rotor shaft 6. A structure-borne sound absorbing element 15 is arranged within the bore 14. Similar to as shown in FIGS. 8 and 9, a laminated rotor core 4 of the rotor comprises a number of slots 20 distributed in the circumferential direction, a structure-borne sound absorbing element 15 being arranged in each one of the slots 20. The elements 15 may for example be produced from a metal foam, for example from an aluminum foam. According to the exemplary embodiment as shown in FIG. 14, the electric machine 21 further comprises a liquid-cooled housing 23, a closure 27 of the laminated rotor core 4, a bearing plate 28 and an inverter 29.
[0049] The metal foam shown in the figures described above may comprise hollow spherical structures, for example hollow spherical structures which are filled with, for example with ceramic particles.
[0050] The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the scope of the following claims.
