Rotor

Abstract

The invention relates to a rotor (1) for an electric machine, in particular for an internal permanent magnet motor. The rotor (1) comprises a shaft (2) and a rotor body (3), wherein a circumferential cavity (8) is formed between the shaft (2) and the rotor body (3). Furthermore, the rotor (1) comprises two support rings (6a, 6b), wherein at least two channels (12) fluidically connected to the cavity (8) are formed between one of the support rings (6a) and the rotor body.

Description

[0001] The invention relates to a rotor for an electric machine, in particular for an internal permanent magnet motor, comprising a shaft and a rotor body according to the preamble of claim 1.

[0002] The rotor of an internal permanent magnet motor typically consists of magnets and a rotor assembly attached to a non-magnetic core. The non-magnetic core is mounted on the shaft and supports the magnets and rotor assembly. Torque is transmitted from the shaft, through the core, to the magnets and rotor assembly. The non-magnetic core adds complexity to the manufacturing and assembly process and increases the rotor's weight.

[0003] The object of the invention is therefore to provide an improved or at least alternative embodiment for a rotor of the generic type, in which the described disadvantages are overcome.

[0004] This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0005] The rotor according to the invention is designed for an electric machine, in particular for an internal permanent magnet motor. The rotor comprises a shaft with a longitudinal central axis and an annular rotor body. The rotor body is arranged coaxially and radially at a distance from the shaft, such that an annular cavity is formed between the shaft and the rotor body, and the shaft rotates circumferentially around the longitudinal central axis. The rotor further comprises a first annular support ring and a second annular support ring. The support rings are aligned coaxially with the shaft, and the rotor body is arranged axially between and attached to the support rings. The first support ring includes at least two projections that extend axially from the first support ring to the rotor body and are arranged circumferentially around the longitudinal central axis.The first support ring is supported by its projections on the rotor body, so that at least two fluid-flowable channels are formed between the rotor body and the first support ring, which are fluidically connected to the cavity.

[0006] In the rotor according to the invention, the rotor body is arranged at a distance from the shaft, so that the shaft and the rotor body can be cooled by air via the cavity. Furthermore, an axial-radial fan is formed on the rotor body through the channels between the rotor body and the first support ring, which enables air circulation in the cavity and improves the cooling of the rotor body and the shaft. In addition, the weight of the rotor is reduced by the cavity. Furthermore, the number of components in the rotor can be reduced, which also means a reduction in costs and assembly effort.

[0007] The cavity can extend over the entire axial length of the rotor body. This allows the shaft and rotor body to be cooled along their entire axial length within the cavity. The support rings can be attached to the shaft, for example, by means of an interference fit. The support rings can, and in particular should, be made of a non-magnetic material. The support rings can support the rotor body, and torque can be transmitted to the support rings via the rotor body.

[0008] The second support ring can have at least one recess fluidically connected to the cavity. This recess can then be fluidically connected to the channels across the cavity, thereby forming a flow-through cooling path within the rotor. The shaft and rotor body can then be actively cooled via this cooling path. As the rotor rotates, air can be drawn into the cavity through the recesses of the second support ring and expelled from the cavity to the outside via the channels between the first support ring and the rotor body, or via the axial-radial fan formed by this channel.

[0009] The features of the first support ring can be radially oriented, allowing radial airflow through the channels formed between the rotor body and the first support ring. This enables particularly efficient airflow from the cavity to the outside.

[0010] The rotor body of the electric motor can have several magnets arranged around the longitudinal center axis of the shaft. The magnets can be radially aligned and spaced apart from each other. In other words, the magnets can be arranged in a star-like pattern around the longitudinal center shaft. The magnets of the rotor body can, in particular, be magnetized tangentially to the circumferential direction of the rotor body. The respective magnets of the rotor body can, in particular, be arranged such that their south poles and their north poles are each aligned in the circumferential direction or are arranged opposite each other in the circumferential direction. The rotor body or the rotor can, in particular, be used in a so-called "spoke-type" internal permanent magnet motor.

[0011] The rotor body can have multiple rotor segments and multiple magnets. The rotor segments and magnets can be arranged around the shaft, alternating in the circumferential direction. The rotor segments can be spaced apart from each other in the circumferential direction and arranged without contact. This prevents, in particular, a magnetic bridge between the rotor segments. The individual magnets of the rotor body can be arranged such that their south poles and north poles are aligned in the circumferential direction or are positioned opposite each other in the circumferential direction. The rotor body or rotor can be used, in particular, in a so-called "spoke-type" internal permanent magnet motor.

[0012] The first support ring can have enough features such that each of the multiple rotor segments is assigned at least one feature, and each of the multiple magnets is assigned at least one feature. The first support ring can then be axially supported by the at least one feature assigned to each rotor segment against that segment and by the at least one feature assigned to each magnet against that magnet. This allows the first support ring to press the rotor body axially against the second support ring, thus securely fixing the rotor body between the support rings and to the shaft. Furthermore, this allows for the formation of multiple channels between the first support ring and the rotor body, thereby intensifying the extraction of air from the cavity during rotor rotation.

[0013] The magnet can be designed as a separate, single-piece or multi-piece element. The magnet can, for example, be made of a ferritic material. The rotor segment can be designed as a separate element consisting of several sheet metal segments bonded together. The rotor segment can, for example, be made of an electrically conductive material.

[0014] The at least one shape of the first support ring associated with each rotor segment and the at least one shape of the first support ring associated with each magnet can differ from one another. In particular, the shapes in a plane oriented transversely to the longitudinal center axis can differ from one another in their shape and / or their size and / or their orientation.

[0015] The rotor body can be attached to the first and second support rings by means of several screws or rivets. These screws or rivets can penetrate the support rings and the rotor segments, fastening the support rings to each other and the rotor body to the support rings. In particular, the screws or rivets can act as tie rods, axially pulling the two support rings and the rotor body positioned between them together. For this purpose, corresponding openings can be provided in the support rings and the rotor segments. The screws or rivets can penetrate the first support ring through the recesses associated with the respective rotor segments. This ensures secure fastening of the rotor body between the support rings, and the airflow through the channels formed between the first support ring and the rotor body is not obstructed by the screws or rivets.

[0016] The second support ring can have a radially inner inner ring and a radially outer outer ring. The second support ring can also have several radially oriented ribs connecting the inner and outer rings.

[0017] Each rib of the second support ring can be assigned to one of the rotor segments and rest on that segment. This ensures secure attachment of the rotor body between the support rings. The recesses leading into the cavity, as described above, can be located between the ribs and / or in the inner ring.

[0018] The first support ring can have an annular, closed body, and the at least two projections can be integral to the ring body and axially projecting from it. In other words, the ring body can be axially closed, so that the channels formed between the first support ring and the rotor body are only open to radial or transverse flow to the longitudinal axis of the shaft.

[0019] In connection with the present invention, the terms "axial", "coaxial", "radial", and "circumferential" always refer to the longitudinal center axis of the shaft. During operation of the rotor or the electric machine, the longitudinal center axis of the shaft corresponds to a rotational axis of the shaft.

[0020] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0021] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0022] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0023] They show, each schematically Fig. 1 a sectional exploded view of a rotor according to the invention in a section plane aligned parallel to the longitudinal center axis; Fig. 2 a sectional view of the rotor according to the invention in a section plane aligned parallel to the longitudinal center axis; Fig. 3 a view of the rotor according to the invention; Fig. 4 a view of the rotor according to the invention without its shaft; Fig. 5 a sectional view of the rotor according to the invention without its shaft in a section plane aligned parallel to the longitudinal center axis; Fig. 6 a sectional view of the rotor according to the invention without its shaft in a section plane oriented perpendicular to the longitudinal center axis; Fig. 7 a top view of a first support ring of the rotor according to the invention; Fig. 8 a top view of a second support ring of the rotor according to the invention.

[0024] Fig. Figure 1 shows a sectional exploded view of a rotor 1 according to the invention for an electric machine, in particular for an internal permanent magnet motor. Fig. Figure 2 shows a sectional view of the rotor 1 according to the invention. The rotor 1 comprises a shaft 2 with a longitudinal center axis LMA and an annular rotor body 3. The rotor body 3 and the shaft 2 are aligned coaxially with each other, the shaft 2 being arranged in the rotor body 3. Fig. 1 and in Fig. 2 the cutting plane is aligned parallel to the longitudinal center axis LMA of the rotor 1.

[0025] The rotor body 3 comprises several – here eight – rotor segments 4 and several – here eight – magnets 5. The rotor segments 4 and the magnets 5 are arranged around the shaft 2 in a circumferential direction UR around the longitudinal center axis LMA and alternate in this circumferential direction UR. The rotor segments 4 and the magnets 5 are each designed as separate elements and their side surfaces, arranged transversely to the circumferential direction UR, abut each other. The rotor segments 4 and the magnets 5 can be bonded together at their facing side surfaces – for example, by adhesive.

[0026] Furthermore, the rotor 1 comprises a first support ring 6a and a second support ring 6b, which are aligned coaxially with the shaft 2 and are attached to the shaft 2, for example, by means of an interference fit. The rotor body 3 is arranged axially between the two support rings 6a and 6b. The rotor body 3 is attached to the support rings 6a and 6b by means of several—here sixteen—rivets 7. In the embodiment shown here, each rotor segment 4 is assigned two rivets 7. The two rivets 7 are arranged radially apart from each other on the respective rotor segment 4. The rivets 7 extend axially through the support rings 6a and 6b and the respective assigned rotor segment 4.

[0027] This allows each rivet 7 to connect the two support rings 6a and 6b and to secure the rotor body 3 between the support rings 6a and 6b. Each rivet 7 thus acts as a tie rod.

[0028] The inner diameter of the rotor body 3 is larger than the outer diameter of the shaft 2. This creates a cavity 8 between the shaft 2 and the rotor body 3, circumferencing the longitudinal center axis LMA of the shaft 2. The cavity 8 extends over the entire axial length of the rotor body 3 and is filled with air. This reduces the weight of the rotor 1 and cools the shaft 2 and the rotor body 3 within the cavity 8.

[0029] The first support ring 6a comprises an annular ring body 9 and several axially projecting projections 10 and 11 extending from the ring body to the rotor body 3. The projections 10 and 11 are elongated and extend radially. The projections 10 are assigned to the respective rotor segments 4, and the projections 11 are assigned to the respective magnets 5. Each rotor segment 4 is assigned one projection 10, and each magnet 5 is assigned two projections 11. The rivets 7 pass through openings in the projections 10.

[0030] The first support ring 6a is axially supported by its projections 10 on the associated rotor segments 4 and by its projections 11 on the associated magnets 5. This creates several radially oriented, flow-through channels 12 between the rotor body 3 and the first support ring 6a. These channels 12 are fluidically connected to the cavity 8. When the rotor 1 rotates, the projections 10 and 11 act as a radial-axial fan, conveying air from the cavity 8 to the outside via the channels 12.

[0031] The second support ring 6b has a radially inner inner ring 13 and a radially outer outer ring 14. Furthermore, the second support ring 6b includes several – here eight – ribs 15. The number of ribs 15 corresponds to the number of rotor segments 4, and each rib 15 abuts the respective rotor segment 4. The rivets 7 pass through the ribs 15 and the outer ring 14. Between the ribs 15 and in the inner ring 13, several – here sixteen – recesses 16 are formed, which lead from the outside into the cavity 8. The recesses 16, the cavity 8, and the channels 12 form a flowable cooling path 17 in the rotor 1, through which air actively flows when the rotor 1 rotates. As the rotor 1 rotates, air can flow through the recesses 16 into the cavity 8 and through the cavity 8 to the channels 12. Air can then be conveyed out of the cavity 8 to the outside via the channels 12.

[0032] Fig. Figure 3 shows a view of the rotor 1 according to the invention and Fig. Figure 4 shows a view of the rotor 1 according to the invention without the shaft 2. Fig. 3 and in Fig. 4 is particularly evident that the recesses 16 lead axially from the outside into the cavity 8 and the channels 12 lead radially out of the cavity 8 to the outside.

[0033] Fig. Figure 5 shows a sectional view of the rotor 1 according to the invention without the shaft 2. Fig. 5 is the cutting plane aligned parallel to the longitudinal center axis LMA of shaft 2 and passes through the magnets 5. In Fig. Figure 5 shows in particular the cooling path 17, which includes the recesses 16 of the second support ring 6b, the cavity 8, and the channels 12. It is also evident that the magnets 5 are composed of several—here four—individual magnets bonded together. The magnets 5 can, for example, be made of ferrite. The rotor segments 4 can, for example, be made of an electrically conductive material and comprise several sheets bonded together.

[0034] Fig. Figure 6 shows a sectional view of the rotor 1 according to the invention without the shaft 2 in a section plane oriented perpendicular to the longitudinal center axis LMA of the shaft 2. Fig. Figure 6 clearly shows that the magnets 5 and the rotor segments 4 alternate in the circumferential direction UR. Appropriately, the number of rotor segments 4 and the number of magnets 5 correspond to this.

[0035] Fig. Figure 7 shows a top view of the first support ring 6a of the rotor 1 according to the invention. As in Fig. As is particularly evident in Figure 7, the projections 10 and 11 extend axially from the ring body 9 and are radially oriented. In the plane shown, oriented transversely to the longitudinal center axis LMA, the projections 10 and 11 differ from each other in their shape and size.

[0036] Fig. Figure 8 shows a top view of the second support ring 6b of the rotor 1 according to the invention. Fig. 8 In particular, the recesses 16 are recognizable, which are designed to allow air to flow into the cavity 8.

Claims

[1] Rotor (1) for an electric machine, in particular for an internal permanent magnet motor, - wherein the rotor (1) has a shaft (2) with a longitudinal central axis (LMA) and an annular rotor body (3), - wherein the rotor body (3) is arranged coaxially and at a radial distance on the shaft (2), such that an annular cavity (8) is formed between the shaft (2) and the rotor body (3), and the shaft (2) is circumferentially circumferentially circumferentially (UR) around the longitudinal central axis (LMA), - wherein the rotor (1) has a first annular support ring (6a) and a second annular support ring (6b), - wherein the support rings (6a, 6b) are aligned coaxially to the shaft (2) and the rotor body (3) is arranged axially between the support rings (6a, 6b) and attached to them, - wherein the first support ring (6a) has at least two axially projecting forms (10, 11) to the rotor body (3) and arranged in the circumferential direction (UR) around the longitudinal central axis (LMA), and - wherein the first support ring (6a) is supported by the projections (10, 11) on the rotor body (3), such that at least two flowable channels (12) are formed between the rotor body (3) and the first support ring (6a) and are fluidically connected to the cavity (8). [2] Rotor (1) according to claim 1, characterized by , that the cavity (8) extends over the entire axial length of the rotor body (3). [3] Rotor (1) according to claim 1 or 2, characterized by , - that the second support ring (6b) has at least one recess (16) fluidically connected to the cavity (8), and - that at least one recess (16) of the second support ring (6b) is fluidically connected to the channels (12) via the cavity (8) and thereby a flowable cooling path (17) is formed in the rotor (1). [4] Rotor (1) according to any one of the preceding claims, characterized by , that the features (10, 11) of the first support ring (6a) and thereby the channels (12) formed between the rotor body (3) and the first support ring (6a) are radially aligned. [5] Rotor (1) according to any one of the preceding claims, characterized by , that the rotor body (3) has several rotor segments (4) and several magnets (5), wherein the rotor segments (4) and the magnets (5) are arranged around the shaft (2) and alternate in the circumferential direction (UR). [6] Rotor (1) according to claim 5, characterized by , that the rotor segments (4) are spaced apart from each other in the circumferential direction and are arranged without contact with each other. [7] Rotor (1) according to claim 5 or 6, characterized by , - that the first support ring (6a) has so many features (10, 11) that each of the several rotor segments (4) is assigned at least one of the features (10) and each of the several magnets (5) is assigned at least one of the features (11), and - that the first support ring (6a) is axially supported on the rotor segment (4) by at least one projection (10) associated with the respective rotor segment (4) and on the magnet (5) by at least one projection (11) associated with the respective magnet (5). [8] Rotor (1) according to any one of claims 5 to 7, characterized by , that the at least one shape (10) of the first support ring (6a) assigned to the respective rotor segment (4) and the at least one shape (11) of the first support ring (6a) assigned to the respective magnet (5) differ from each other. [9] Rotor (1) according to any one of claims 5 to 8, characterized by - that the rotor body (3) is attached to the first support ring (6a) and to the second support ring (6b) by means of several screws or rivets (7), and - that the screws or rivets (7) penetrate the support rings (6a, 6b) and the rotor segments (4) and fasten the support rings (6a, 6b) to each other and the rotor body (3) to the support rings (6a, 6b). [10] Rotor (1) according to claim 9, characterized by that the screws or rivets (7) penetrate the first support ring (6a) through the projections (10) assigned to the respective rotor segments (4). [11] Rotor (1) according to any one of claims 8 to 10, characterized by , - that the second support ring (6b) has a radially inner inner ring (13) and a radially outer outer ring (14), - that the second support ring (6b) has several radially oriented ribs (15) that connect the inner ring (13) and the outer ring (14), and - that each rib (15) of the second support ring (6b) is assigned to one of the rotor segments (4) and rests on that rotor segment (4). [12] Rotor (1) according to any one of the preceding claims, characterized by , that the first support ring (6a) has an annular closed ring body (9) and the at least two projections (10, 11) are integral to the ring body (9) and axially projecting from the ring body (9).

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