Rotor and electric machine

Abstract

Rotor of an electric machine for an electric vehicle, comprising a rotor body (34), several permanent magnets (381, 382, ​​383, 384), wherein one permanent magnet (381, 382, ​​383, 384) is arranged in a magnet receiving recess (341, 342, 343, 344) of the rotor body (34), wherein at least one permanent magnet (381, 382, ​​383, 384) is arranged in a cylindrical magnet carrier sleeve (361, 362, 363, 364), which together with the permanent magnet (381, 382, ​​383, 384) is rotatably arranged in a cylindrical magnet receiving recess (341, 342, 343, 344) of the rotor body (34), wherein the magnet carrier sleeve (361, 362, 363, 364) and / or the associated permanent magnet (381, 382, ​​383, 384) are connected to an adjusting device (39) such that the magnet carrier sleeve (361, 362, 363, 364) and the associated permanent magnet (381, 382, ​​383, 384) are adjusted by the adjusting device (39) within the magnet receiving recess (341, 342, 343,344) are rotatable between different angular positions.

Description

[0001] The invention relates to a rotor of an electric machine for an electric vehicle, comprising a rotor body, several permanent magnets which are arranged in a circumferential direction on the rotor body, wherein each permanent magnet is arranged in a magnet receiving recess of the rotor body.

[0002] Such rotors of an electric machine, in particular of permanent magnet synchronous machines, are generally known from the prior art. For example, DE 10 2020 121 864 A1 discloses an electric machine with a stator and a rotor, wherein the rotor has a rotor body and several permanent magnets arranged circumferentially on the rotor body. The rotor body has several magnet-receiving recesses to accommodate the permanent magnets, which are fixedly arranged in angular positions defined by the magnet-receiving recesses.

[0003] In an electromotive operating state, the magnetic fields of the permanent magnets interact with the magnetic fields of the stator winding in a known manner, causing rotation of the rotor. In other operating states, such as in drag operation, where no direct connection between the rotor and the stator is desired, the permanent magnets lead to undesirable losses due to their constantly present magnetic fields.

[0004] The object of the invention is therefore to provide a rotor which enables low-loss operation of the electrical machine in different operating states.

[0005] The problem is solved by the features of claim 1.

[0006] According to the invention, at least one permanent magnet is arranged in a cylindrical magnet carrier sleeve, which together with the permanent magnet is rotatably arranged in a cylindrical magnet receiving recess of the rotor base body, wherein the magnet carrier sleeve and / or the associated permanent magnet are connected to an adjusting device, such that the magnet carrier sleeve and the associated permanent magnet can be rotated between different angular positions by the adjusting device within the magnet receiving recess.

[0007] The magnet support sleeve is designed such that its outer diameter is slightly smaller than the diameter of the cylindrical magnet receiving recess. This allows the magnet support sleeve to rotate within the receiving recess without creating a gap between its outer surface and the inner surface of the cylindrical magnet receiving pocket, which would otherwise lead to undesirable radial and / or tangential displacement of the permanent magnet. Furthermore, the magnet support sleeve is made of a material that does not significantly influence the magnetic field lines of the permanent magnet and exhibits a low coefficient of friction with the rotor body material. The magnet support sleeve can preferably be axially secured by a positive locking mechanism to prevent axial displacement of the permanent magnet and the magnet support sleeve.

[0008] The permanent magnets extend over the entire length of the rotor body and can have different cross-sections. The permanent magnet, located in the magnet carrier sleeve, is firmly connected to the respective magnet carrier sleeve by a positive, material, and / or frictional connection. For example, the permanent magnet may be bonded to the magnet carrier sleeve. Alternatively, a cavity between the permanent magnet and the inner circumferential surface could be filled with a plastic injection molding, or the magnet carrier sleeve could have retaining elements by which the permanent magnet can be positively and / or frictionally connected to the magnet carrier sleeve.

[0009] The adjustment device is arranged, in particular, on at least one of the two end faces. The connection between the adjustment device and the magnetic carrier sleeve can be positive-locking, force-locking, or material-locking. This connection can be created simply and in various ways by linking the adjustment device to the magnetic carrier sleeve.

[0010] When the adjusting device is actuated, the magnet carrier sleeve and the permanent magnet rigidly connected to it are rotated between different angular positions. Preferably, several permanent magnets are arranged in each magnet carrier sleeve, with the magnet carrier sleeves and / or the associated permanent magnets being connected to the adjusting device. By adjusting the magnet carrier sleeves and / or the associated permanent magnets, different angular positions of the permanent magnets can be set, thus enabling the appropriate or optimal orientation of the permanent magnets to be set for different operating conditions. This ensures optimal operation of the electric machine under various operating conditions.

[0011] Preferably, the magnet carrier sleeves are rotatable at least between an electromotive operating position and a short-circuit position, in which a magnetic short circuit exists in the rotor. In the electromotive operating position, the resulting magnetization direction of the permanent magnets or the permanent magnet arrangement is radially oriented, and in the short-circuit position, the resulting magnetization direction of the permanent magnets is tangentially oriented. The electromotive operating position exists when the rotor rotates due to the interaction of the energized stator winding and the permanent magnets. In an electric vehicle, this is the state when one or more vehicle wheels are driven by the electric motor. In this case, the magnetic field lines of the permanent magnets pass through the radial gap between the rotor and the stator.In the short-circuit position, the magnetic field lines of all permanent magnets essentially pass through the rotor body, and therefore there is no or only minimal interaction with the stator. Such a short-circuit position is particularly useful in towing operation, i.e., when the rotor only moves along with the vehicle wheel(s) due to the wheels rolling on the road. For example, the electric machine is used solely for boost operation on one of the axles, and when no boost operation is present, the magnet carrier sleeves are arranged in the short-circuit position.

[0012] Additionally or alternatively, the adjustment device is designed to rotate the magnet carrier sleeves and the permanent magnets in such a way that different numbers of pole pairs can be set. By switching between different numbers of pole pairs, the appropriate number of pole pairs can be set for different operating conditions. For example, with four adjustable permanent magnets, it is possible to switch between a single pole pair (i.e., 2-pole) and two pole pairs (i.e., 4-pole).

[0013] Preferably, the adjusting device comprises a planetary gear set, wherein at least some of the magnet carrier sleeves and / or the associated permanent magnets are rotationally fixed to the planet gears, a sun gear is rotationally fixed to the rotor body, and a ring gear is rotationally fixed to an actuator. During operation of the electric machine and when the rotor rotates, the sun gear rotates with the rotor body. The ring gear is connected to an actuator and can be driven by the actuator, causing the ring gear to rotate relative to the sun gear. Due to the relative rotational movement between the sun gear and the ring gear, the planet gears, which are operatively connected to the ring gear and the sun gear, necessarily rotate, and the rotationally fixed coupling of the planet gears to the magnet carrier sleeves and / or the associated permanent magnets also causes these to rotate.In this way, the magnet carrier sleeves and the associated permanent magnets can be rotated between different angular positions. The actuator is controlled depending on the current or desired operating state, thereby setting the angular position of the magnet carrier sleeves and the associated permanent magnets that is advantageous for the corresponding operating state.

[0014] Alternatively, at least some of the magnet carrier sleeves and / or the associated permanent magnets are non-rotatably connected to the planetary gears, the sun gear is non-rotatably connected to the actuator, and the ring gear is non-rotatably connected to the rotor body. The operating principle described here corresponds to the previously described operating principle, except that the sun gear and the ring gear have their functions reversed.

[0015] In a preferred embodiment, a planetary gear set is arranged at each axial end of the rotor body, wherein the planet gears of the planetary gear sets are rotationally fixed to differing magnet carrier sleeves and / or associated permanent magnets. The magnet carrier sleeves and / or the associated permanent magnets connected to one planetary gear set can preferably be rotated in different directions relative to the magnet carrier sleeves and / or the associated permanent magnets connected to the other planetary gear set, and / or rotated between the different angular positions at different angles and / or speeds.In this system, the planetary gears are driven by the actuators in such a way that the magnet carrier sleeves and / or the associated permanent magnets driven by one planetary gear are rotated in opposite directions, with differing angles of rotation and / or with differing rotational speeds, compared to the magnet carrier sleeves driven by the other planetary gear. This allows the angular positions of the magnet carrier sleeves and / or the associated permanent magnets to be set to the advantageous values ​​for the respective operating condition.

[0016] The problem is also solved by an electric machine of an electric vehicle, comprising a stator and a rotor according to any one of claims 1 to 7. For the advantages, reference is made to the preceding claims.

[0017] An embodiment of the invention is explained in more detail with reference to the drawings. Fig. Figure 1 schematically shows an electric machine in longitudinal section, and Fig. Figure 2 schematically shows a rotor of the electric machine made of Fig. 1 in cross-section.

[0018] The Fig. Figure 1 shows an electric machine 10, which is designed as a permanent magnet excited synchronous machine and serves as a traction motor of an electric vehicle.

[0019] The electric machine 10 comprises a stator 20, the stator having a stator winding (not shown in the figures). The stator winding is electrically connected to a control device (also not shown), the stator winding being controlled depending on the drive power to be provided by the electric machine 10.

[0020] The electric machine 10 further comprises a rotor 30, which has a rotor shaft 32, a rotor base body 34 connected to the rotor shaft 32 in a rotationally fixed manner and several permanent magnets 381, 382, ​​383, 384.

[0021] The rotor body 34 has four circumferentially distributed magnet receiving recesses 341, 342, 343, 344, which are designed as cylindrical bores and extend from one end face of the rotor body 34 to the other end face. A magnet carrier sleeve 361, 362, 363, 364 and a permanent magnet 381, 382, ​​383, 384 are arranged in each of the magnet receiving recesses 341, 342, 343, 344. The permanent magnets 381, 382, ​​383, 384 are arranged within the magnet carrier sleeves 361, 362, 363, 364 and are rigidly connected to the magnet carrier sleeves 361, 362, 363, 364. For example, the permanent magnets 381, 382, ​​383, 384 are bonded to the inner circumferential surface of the corresponding magnet carrier sleeves 361, 362, 363, 364. The magnet carrier sleeves 361, 362, 363, 364 and the permanent magnets 381, 382, ​​383, 384 extend over the entire length of the rotor base body 34.The magnet carrier sleeves 361, 362, 363, 364 lie with their outer circumferential surface against the circumferential surface of the corresponding magnet receiving recesses 341, 342, 343, 344 in such a way that the magnet carrier sleeves 361, 362, 363, 364 together with the permanent magnets 381, 382, ​​383, 384 are rotatable within the magnet receiving recesses 341, 342, 343, 344.

[0022] The rotor 30 also has an adjusting device 39, which comprises two planetary gear sets 40, 60. Each planetary gear set 40, 60 has a sun gear 42, 62, two planet gears 44, 64, and a ring gear 46, 66. The sun gears 42, 62 are non-rotatably connected to the rotor shaft 32. The ring gears 46, 66 are each connected to an actuator 50, 70, wherein the actuators 50, 70 are designed as an electric motor and each has a stator 52, 72 and a rotor 54, 74. The stator 52, 72 is connected to the sun gear 42, 62 in each case. The rotor 54, 74 is connected to the ring gear 46, 66 in each case. The planet gears 46 of one planetary gear set 40 are non-rotatably connected to the magnetic carrier sleeves 361, 362. The planet gears 64 of the other planetary gear set 60 are non-rotatably connected to the magnetic carrier sleeves 363, 364.

[0023] In the Fig. 2a and Fig. Figure 2b shows two different positions of the magnet carrier sleeves 361, 362, 363, 364 and the permanent magnets 381, 382, ​​383, 384.

[0024] Fig. Figure 2a shows an electromotive position of the magnet carrier sleeves 361, 362, 363, 364 and the permanent magnets 381, 382, ​​383, 384, which is present when an interaction between the stator windings of the stator 20 and the permanent magnets 381, 382, ​​383, 384 is desired and the electric machine is intended to propel the electric vehicle. In this position, the magnetization directions of the permanent magnets 381, 382, ​​383, 384 are radially aligned and two pole pairs are present.

[0025] Fig.Figure 2b shows the short-circuited position of the magnet carrier sleeves 361, 362, 363, 364 and the permanent magnets 381, 382, ​​383, 384, which occurs when no interaction between the stator windings of the stator 20 and the permanent magnets 381, 382, ​​383, 384 is desired and the electric machine 10 is in towing mode, i.e., the rotor 30 rotates only with the vehicle wheel(s) due to the wheels rolling on the road. In this position, the magnetization directions of the permanent magnets 381, 382, ​​383, 384 are tangentially aligned in the same direction.

[0026] The adjustment of the magnet carrier sleeves 361, 362, 363, 364 and the permanent magnets 381, 382, ​​383, 384 between the electromotive position and the short-circuit position is carried out by the two planetary gear sets 40, 60, wherein the magnet carrier sleeves 361, 362 and the associated permanent magnets 381, 382 are rotated by 90° in a first direction of rotation due to a corresponding control of the actuator 50, and the magnet carrier sleeves 363, 364 and the associated permanent magnets 383, 384 are rotated by 90° in a second direction of rotation opposite to the first direction of rotation due to a corresponding control of the actuator 70. In another embodiment of the rotor 30, not shown, the number of pole pairs could be adjusted by a corresponding rotation of the magnet carrier sleeves 361, 362, 363, 364 and the permanent magnets 381, 382, ​​383, 384.For example, the electric machine 10 could be switched between 2-pole and 4-pole operation. For this purpose, the planetary gears 44 of the planetary gear set 40 would need to be connected to the two adjacent permanent magnets 381, 382, ​​383, 384, while the other two permanent magnets 381, 382, ​​383, 384 could be fixed. Alternatively, each magnet carrier sleeve 361, 362, 363, 364 or each permanent magnet 381, 382, ​​383, 384 could be independently adjustable by an actuator, thus allowing both the number of pole pairs to be varied and a short-circuit position to be achieved. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2020 121 864 A1

[0002]

Claims

[1] Rotor of an electric machine for an electric vehicle, comprising a rotor body (34), several permanent magnets (381, 382, ​​383, 384), wherein each permanent magnet (381, 382, ​​383, 384) is arranged in a magnet receiving recess (341, 342, 343, 344) of the rotor body (34), characterized by, that at least one permanent magnet (381, 382, ​​383, 384) is arranged in a cylindrical magnet carrier sleeve (361, 362, 363, 364), which together with the permanent magnet (381, 382, ​​383, 384) is rotatably arranged in a cylindrical magnet receiving recess (341, 342, 343, 344) of the rotor base body (34), wherein the magnet carrier sleeve (361, 362, 363, 364) and / or the associated permanent magnet (381, 382, ​​383, 384) are connected to an adjusting device (39) such that the magnet carrier sleeve (361, 362, 363, 364) and the associated permanent magnet (381, 382, ​​383, 384) can be rotated between different angular positions by means of the adjusting device (39) within the magnet receiving recess (341, 342, 343, 344). [2] Rotor according to claim 1, characterized by, that several permanent magnets (361, 362, 363, 364) are each arranged in a magnet carrier sleeve (361, 362, 363, 364) arranged in a magnet receiving recess (341, 342, 343, 344), wherein the magnet carrier sleeves (361, 362, 363, 364) and / or the associated permanent magnets (381, 382, ​​383, 384) are connected to the adjusting device (39). [3] Rotor according to claim 2, characterized by , that the magnet carrier sleeves (361, 362, 363, 364) and the associated permanent magnets (381, 382, ​​383, 384) are rotatable at least between an electromotive operating position and a short-circuit position, wherein in the electromotive operating position the resulting magnetization direction of the permanent magnets (381, 382, ​​383, 384) is radially oriented and in the short-circuit position the resulting magnetization direction of the permanent magnets (381, 382, ​​383, 384) is tangentially oriented. [4] Rotor according to claim 2 or 3, characterized by, that the adjusting device (39) is designed to rotate the magnet carrier sleeves (361, 362, 363, 364) and the permanent magnets (381, 382, ​​383, 384) in such a way that different numbers of pole pairs can be set. [5] Rotor according to any one of the preceding claims, characterized by, that the adjusting device (39) has a planetary gear (40), wherein at least a part of the magnet carrier sleeves (361, 362, 363, 364) and / or the associated permanent magnets (381, 382, ​​383, 384) are non-rotatably connected to the planet gears (44), a sun gear (42) is non-rotatably connected to the rotor body (34) and a ring gear (46) is non-rotatably connected to an actuator (50), or at least a part of the magnet carrier sleeves (361, 362, 363, 364) and / or the associated permanent magnets (381, 382, ​​383, 384) are non-rotatably connected to the planet gears (44), the sun gear (42) is non-rotatably connected to the actuator (50) and the ring gear (46) is non-rotatably connected to the rotor body (34). is connected in a rotationally fixed manner. [6] Rotor according to claim 5, characterized by, that a planetary gear set (40, 60) is arranged at each axial end of the rotor body (34), wherein the planet gears (44, 64) of the planetary gear sets (40, 60) are connected in a rotationally fixed manner to differing magnet carrier sleeves (361, 362, 363, 364) and / or the associated permanent magnets (381, 382, ​​383, 384). [7] Rotor according to claim 6, characterized by , that the planetary gears (40, 60) can be driven by the actuators (50, 70) in such a way that the magnet carrier sleeves (361, 362, 363, 364) driven by one planetary gear (40) and the associated permanent magnets (381, 382, ​​383, 384) are rotated in the opposite direction of rotation to the magnet carrier sleeves (361, 362, 363, 364) driven by the other planetary gear (60) and the associated permanent magnets (381, 382, ​​383, 384). [8] Electric machine of an electric vehicle, comprising a stator and a rotor according to claims 1 to 7.

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