Rotor, method for manufacturing a rotor and electrically driven compressor

Abstract

The invention relates to a rotor (19) for an electric machine (9), with a magnetic section (20) arranged in an axial direction between two rotor end sections. In order to improve the functionality and / or manufacturing of the rotor (19), the rotor end sections are held axially together with the magnet section (20) arranged in the axial direction between them by means of a tie rod which extends axially through the magnet section (20) and has an external thread at at least one end.

Description

[0001] The invention relates to a rotor for an electric machine, comprising a magnetic section arranged axially between two rotor end sections. The invention further relates to a method for manufacturing such a rotor. The invention also relates to an electrically driven compressor with such a rotor. State of the art

[0002] German patent application DE 10 2015 016 607 A1 discloses a turbomachine for an energy converter with a compressor for compressing air supplied to the energy converter, with a housing and with a rotor rotatable about an axis of rotation relative to the housing.German patent application DE 10 2016 211 251 A1 discloses an electric machine with a magnetically anisotropic rotor, wherein the electric machine has a stator arranged around the rotor, wherein the electric machine has a two-part shaft with a first and second shaft part, wherein the rotor is arranged between the two shaft parts and connected to the two shaft parts, in particular rigidly connected, wherein the electric machine has a first and second impeller and a connecting rod which is passed through a passage in the rotor and through passages in the two shaft parts, wherein the first and second impellers are arranged opposite each other at the ends of the connecting rod, and the shaft parts are clamped to the rotor, in particular by clamping elements. Disclosure of the invention

[0003] The object of the invention is to improve the functionality and / or manufacturing of a rotor for an electric machine, comprising a magnetic section arranged in an axial direction between two rotor end sections.

[0004] The problem with a rotor for an electric machine, with a magnetic section arranged axially between two rotor end sections, is solved by holding the rotor end sections and the axially arranged magnetic section together axially by means of a tie rod that extends axially through the magnetic section and has an external thread at at least one end. In addition to the rotor, the electric machine includes a stator in which the rotor can rotate about an axis of rotation. The term "axial" refers to this axis of rotation of the rotor. "Axial" means in the direction of or parallel to the axis of rotation of the rotor. Similarly, "radial" means perpendicular to this axis of rotation. During operation of the electric machine, the rotor rotates at very high speeds, sometimes exceeding one hundred thousand revolutions per minute.The electric machine is, for example, a permanent magnet synchronous machine. The electric machine is preferably integrated into a turbomachine, in particular an electrically driven air compressor. The turbomachine or air compressor advantageously serves to provide compressed air in a fuel cell system. The rotor is preferably of a multi-part construction. At least one magnet is arranged in the magnet section, which, due to the very high rotor speeds occurring during operation and the associated centrifugal forces, is advantageously banded, for example, by means of a sleeve made of a suitable material.In the specified rotor design with the tie rod, an additional component is required. However, the tie rod, with its external thread at at least one end, ensures high rotor stability and very high rotational speed capability during operation. The tie rod can have an external thread at only one end if, for example, a screw head is formed at the opposite end. Depending on the design, the tie rod can also have external threads at both ends, onto which a corresponding nut is screwed to create the desired tension. When tightening or clamping the threaded connection, an axial preload should be applied. This allows the desired clamping force to be precisely defined. Undesired torsion of the relatively long tie rod is thus avoided.

[0005] A preferred embodiment of the rotor is characterized in that the tension rod comprises a tension rod shaft that extends axially through a central recess in the magnet section. The central recess is, for example, designed as a central through-hole in the magnet assembly. The central recess in the magnet section is relatively easy to manufacture.

[0006] Another preferred embodiment of the rotor is characterized in that the tie rod is screwed with its external thread into a complementary internal thread, which is provided for this purpose in one of the rotor end sections. This significantly simplifies the stable fastening of the tie rod in the rotor end section and the clamping of the tie rod. According to a further preferred embodiment, the complementary internal thread is formed in an additional nut that bears against the rotor end section or the impeller. In this case, the complementary internal thread is independent of the rotor end section and the impeller.

[0007] Another preferred embodiment of the rotor is characterized in that the tie rod with its external thread is screwed into a complementary internal thread, which is provided for this purpose in an impeller hub. This significantly simplifies the attachment of the impeller to the rotor. Furthermore, the corresponding end of the rotor end section can be made considerably shorter than in conventional rotors.

[0008] Another preferred embodiment of the rotor is characterized in that the tie rod is provided at one end with a screw head, with which an impeller hub of an impeller is attached to one of the rotor end sections. This embodiment also offers, among other advantages, that the corresponding end of the rotor end section can be made significantly shorter than in conventional rotors. Furthermore, the attachment of the impeller to the rotor end section is considerably simplified by using the tie rod with the screw head.

[0009] Another preferred embodiment of the rotor is characterized in that the impeller has a contact surface arranged transversely to the axial direction, with which the impeller rests against one of the rotor end sections in a clearly defined manner. This ensures unambiguous positioning and stable attachment of the impeller to the rotor in a simple way.

[0010] Another preferred embodiment of the rotor is characterized in that the magnetic section is radially surrounded on the outside by a sleeve which is clamped axially between the two rotor end sections by means of the tie rod. The combination of the tie rod and the sleeve allows the magnetic section to be held stably in its desired position even at extremely high rotational speeds, for example, more than one hundred thousand revolutions per minute.

[0011] Another preferred embodiment of the rotor is characterized in that the sleeve is provided with concentric grooves on its end faces facing the rotor end sections. This greatly simplifies the sealing between the rotor end sections and the sleeve, particularly against a gaseous fluid such as air.

[0012] In a method for manufacturing a previously described rotor, the problem stated above is solved alternatively or additionally by clamping the magnet section between the two rotor end sections using the tie rod. Depending on the design of the tie rod, at least one impeller is advantageously attached to the rotor using the tie rod, which then performs a dual function. The external thread at one end of the tie rod significantly simplifies the clamping process.

[0013] The invention further relates to at least one separately tradable component of the rotor described above, for example a tie rod and / or a sleeve, for the rotor described above.

[0014] The problem described above can also be solved by an electrically driven compressor with a previously described rotor. The electrically driven compressor is preferably an electrically driven air compressor for use in a fuel cell system.

[0015] Further advantages, features and details of the invention will become apparent from the following description, in which various embodiments are described in detail with reference to the drawing. Brief description of the drawing

[0016] They show: Fig. Figure 1 shows an electric machine with a three-part rotor shaft in longitudinal section; and the Fig. 2, Fig. 3 to Fig. 4 different embodiments of a rotor for the in Fig. 1. Electric machine shown with a pull armature extending axially through a magnetic section of the rotor. Description of the exemplary implementations

[0017] In Fig. Figure 1 shows a gas supply device designed as an electrically driven turbomachine 1, comprising a compressor wheel 2 and a turbine wheel 4, in longitudinal section. The compressor wheel 2 is arranged on a compressor side 3 of the turbomachine 1. The turbine wheel 4 is arranged on a turbine side 5 of the turbomachine 1.

[0018] The turbine wheel 4 is driven by the compressor wheel 2. The two wheels 2 and 4 belong to a rotating assembly 6. The rotating assembly 6 includes a motor shaft 7 to provide a rotationally fixed connection between the compressor wheel 2 and the turbine wheel 4. The motor shaft 7 is designed as a hollow shaft and is rotatable about a pivot axis 8.

[0019] For electric drive, the turbomachine 1 comprises an electric machine 9. The electric machine 9 is designed as an electric motor with a motor housing 10 and a motor winding 11. A magnet 12, designed as a permanent magnet, is arranged in the motor shaft 7, which is designed as a hollow shaft.

[0020] In operation within a fuel cell system, the compressor wheel 2 of the turbomachine 1 is driven firstly by the turbine wheel 4. Secondly, the compressor wheel 2 is driven by the electric motor 9.

[0021] The drive unit 6 with the motor shaft 7 is rotatably mounted in the motor housing 10 of the electric machine 9 by means of two radial bearings 13, 14. The radial bearings 13, 14 are advantageously designed as foil air bearings.

[0022] On compressor side 3, a compressor spiral casing 15 is attached to the motor housing 10. The compressor spiral casing 15 includes a compressor inlet 16, through which air to be compressed is supplied to the turbomachine 1.

[0023] On turbine side 5, a turbine spiral casing 17 is attached to the motor housing 10. The turbine spiral casing 17 includes a turbine outlet 18 through which expanded air exits. The energy generated during the expansion of the air is used to drive the compressor wheel 2.

[0024] The motor shaft 7 can also be called a rotor shaft because it serves to form a rotor 19 in the electric machine 9. The rotor 19 comprises a magnetic section 20 in which the magnet 12 is arranged. Two shaft sections 21, 22 are attached to the opposite ends of the magnetic section 20. The magnet 12 is surrounded within the magnetic section 20 by a bandage 23.

[0025] In the Fig. 2, Fig. 3 to Fig. Figure 4 shows three embodiments 31; 32; 33 of a rotor which is in Fig. 1 is designated with 19. To designate identical or similar parts of the rotor 31; 32; 33, the following are used in the Fig. 2, Fig. 3 to Fig. 4. The same reference symbols are used. First, the similarities are described. Then, the differences between the individual embodiments are discussed.

[0026] The rotor 31; 32; 33 is a type of shaft into which a magnetic assembly 34 is integrated. The magnetic assembly 34 comprises at least one permanent magnet. During operation of the rotor 31; 32; 33, it rotates about a rotor axis 24.

[0027] The magnetic assembly 34 is bounded axially by two magnetic end disks 35, 36. Radially, the magnetic assembly 34 with the two magnetic end disks 35, 36 is surrounded by a sleeve 37. The sleeve 37 has the shape of a straight circular cylindrical shell.

[0028] The magnetic assembly 34 represents a magnetic section 20 of the rotor 31; 32; 33. The sleeve 37 represents the bandage 23 for the magnetic assembly 34.

[0029] In the axial direction, the magnetic section 20 of the rotor 31; 32; 33 is clamped between two rotor end sections 25, 26 by means of a tension armature 40; 50; 60. At a point in the Fig. 2, Fig. 3 to Fig. A wheel 27 is attached to the left end of the rotor end section 25. On one of the Fig. 2, Fig. 3 to Fig. 4 At the right end of the rotor end section 26 a wheel 28 is attached.

[0030] The impellers 27, 28 are fastened using fasteners described below. Each impeller 27, 28 comprises an impeller hub 29, 30, which is equipped with an annular contact surface arranged transversely to the rotor axis of rotation 24. These contact surfaces, arranged transversely to the rotor axis of rotation 24, serve to correctly position the impellers 27, 28 with their impeller hubs 29, 30 on the respective associated rotor end sections 25, 26.

[0031] The tie rod 40; 50; 60 comprises a tie rod shaft 39 that extends through a central recess 38 provided for this purpose in the magnet assembly 34. The central recess 38 is, for example, configured as a central through-hole. The tie rod shaft 39 advantageously has the shape of a straight circular cylinder.

[0032] The tie rod 40; 50; 60 is particularly advantageous not only for clamping the magnet section 20 between the two rotor end sections 25, 26. Furthermore, the tie rod 40; 50; 60 is also particularly advantageous for attaching at least one of the impellers 27, 28 to the rotor 31; 32; 33.

[0033] At the in Fig. In the rotor 31 shown in section 2, both impellers 27, 28 are attached to the rotor 31 by means of the tie rod 40. The tie rod 40 has at its Fig. 2 right end 41 a screw head 43 on. From the screw head 43, the tie rod shaft 39 extends through the two rotor end sections 25, 26 and the magnet section 20 arranged between them into the impeller 27.

[0034] At his in Fig. At its left end 42, the tie rod shaft 39 has an external thread 56, with which the tie rod 40 is screwed into a complementary internal thread 44 in the impeller hub 29. The internal thread 44 is represented, for example, by means of a threaded insert that is fastened in the impeller hub 29 of the impeller 27.

[0035] The in Fig. The 3 depicted tie rods 50 have at their in Fig. 3 right end 51 a screw head 53 on. On its in Fig. At its left end 52, the tie rod 50 has an external thread 56, with which the tie rod shaft 39 of the tie rod 50 is screwed into a complementary internal thread 54, which is provided for this purpose in the rotor end section 25 of the rotor 32. The impeller 28 is attached to the rotor end section 26 by means of the tie rod 50.

[0036] The impeller 27 is attached to the rotor end section 25 by a screw 55. The screw 55 has a screw head from which a screw shank with an external thread extends, with which the screw 55 is screwed into the internal thread 54 of the rotor end section 25.

[0037] At the in Fig. As illustrated in the embodiment shown in Figure 4, the tie rod 60 can also be used solely to clamp the magnet section 20 of the rotor 33 between the two rotor end sections 25, 26. The tie rod 60 is attached to a Fig. 4 right end 61 equipped with a kind of screw head which is recessed in a central recess of the rotor end section 26.

[0038] At his in Fig.At its left end 62, the tie rod 60 has an internal thread through which the tie rod shaft 39 is screwed into a corresponding threaded blind hole in the rotor end section 25. The impellers 27 and 28 are fastened to the rotor 33 by means of screws 65, 66. 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 2015 016 607 A1

[0002] DE 10 2016 211 251 A1

[0002]

Claims

[1] Rotor (19;31;32;33) for an electric machine (9), with a magnet section (20) arranged in an axial direction between two rotor end sections (25,26), characterized by , that the rotor end sections (25,26) are held axially together with the magnet section (20) arranged in the axial direction between them by means of a pull rod (40;50;60) which extends in the axial direction through the magnet section (20) and has an external thread (56) at at least one end (42;52). [2] Rotor (19;31;32;33) according to claim 1, characterized by , that the tension anchor (40;50;60) comprises a tension anchor shaft (39) which extends in an axial direction through a central recess (38) in the magnet section (20). [3] Rotor (19;31;32;33) according to any of the preceding claims, characterized by, that the tie rod (50) with the external thread (56) is screwed into a complementary internal thread (54) which is provided for this purpose in one of the rotor end sections (25). [4] Rotor (19;31;32,33) according to one of claims 1 to 2, characterized by , that the tie rod (40) with the external thread (56) is screwed into a complementary internal thread (44) which is provided for this purpose in a wheel hub (29) of a wheel (27). [5] Rotor (19;31;32;33) according to any of the preceding claims, characterized by , that the tie rod (40;50) is provided at one end (41;51) with a screw head (43;53) with which a wheel hub (30) of a wheel (28) is attached to one of the rotor end sections (26). [6] Rotor (19;31;32;32) according to claim 4 or 5, characterized by, that the impeller (27;28) has a contact surface arranged transversely to the axial direction, with which the impeller (27;28) is uniquely defined against one of the rotor end sections (25;26). [7] Rotor (19;31;32;33) according to any of the preceding claims, characterized by , that the magnet section (20) is surrounded radially outside by a sleeve (37) which is clamped in the axial direction between the two rotor end sections (25;26) by means of the pull rod (40). [8] Rotor (19;31;32;33) according to any one of the preceding claims, characterized by , that the sleeve (37) is provided with concentric grooves on its end faces facing the rotor end sections (25;26). [9] Method for manufacturing a rotor (19;31;32;33) according to any one of the preceding claims, characterized by , that the magnet section (20) is clamped between the two rotor end sections (25,26) using the pull armature (40;50;60). [10] Electrically driven compressor with a rotor (19;31;32;33) according to one of the preceding claims.

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