Rotor body with a rotor sleeve for a rotor of an electrical machine

Abstract

A rotor body (1) for a rotor (10) of an electrical machine (21) has a rotor lamination stack (3) composed of a plurality of axially stacked rotor laminations, each having a central recess, wherein the recesses form an axial first through-opening (4). In addition, the rotor body (1) has a rotor sleeve (5) which extends through the first through-opening (4) and has an axial second through-opening (6) for a rotor shaft (11). The invention further relates to a rotor (10) having such a rotor body (1), an electrical machine (21) having such a rotor (10), a vehicle (20) having such an electrical machine (21), and a method for producing such a rotor (10).

Description

The invention relates to a rotor body for a rotor of an electric machine, having a laminated rotor core which is composed of a plurality of axially stacked rotor laminations which each have a central cutout, the cutouts forming an axial first through opening. The invention further relates to a rotor for an electric machine, an electric machine having a rotor, a vehicle having an electric machine and a method for producing a rotor for an electric machine.A rotor for an electric machine according to the prior art has a laminated rotor core with a plurality of axially stacked laminated rotor cores, wherein the axial direction runs parallel to the axis of rotation of the rotor. A rotor winding can be fastened to the laminated core, which serves to generate a rotor magnetic field. Alternatively, a plurality of permanent magnets can be accommodated in the rotor laminated core, which permanent magnets serve for generating a rotor magnetic field.When producing a rotor with a rotor winding, the rotor laminated core is first fastened on the rotor shaft in order to stabilize the rotor laminated core for a subsequent winding process. Thereafter, during the winding process, the rotor winding is fastened to the rotor laminated core by winding a winding wire with an automated winding tool around the rotor laminated core or around projections of the rotor laminated core.In the winding process, the rotor shaft restricts the spatial range in which the winding tool can be moved, which makes the winding process complicated and complicated. A disturbing factor is in particular a rotor shaft end which protrudes far beyond an axial side of the laminated rotor core. In addition, the additional mass of the rotor shaft, which must be moved or rotated together with the rotor laminated core during the winding process, requires a particularly robust design of the winding tool.The object of the invention is to simplify the winding process for a rotor winding of an electric machine.The object is achieved with a rotor body according to the invention, which has a rotor sleeve which extends through the first through-opening of the laminated rotor core and has an axial second through-opening which is provided for receiving a rotor shaft. In other words, the rotor sleeve is guided through the first through-opening of the laminated rotor stack.The rotor laminated core can be fastened or stabilized on the rotor sleeve for a winding process without requiring a rotor shaft for this purpose. This makes it possible to arrange the rotor laminated core on the rotor shaft only after the winding process, as a result of which the winding process can be carried out without the rotor shaft. As a result, the spatial region in which the winding tool is movable is not restricted by the rotor shaft, which simplifies the winding process. A further advantage is that, due to the lack of mass of the rotor shaft during the winding process, the winding tool can be designed to be less robust.The stabilization of the laminated rotor core with a rotor sleeve is also advantageous in the case of a rotor with permanent magnets. As a result, the permanent magnets can be cast with a casting compound already before the rotor laminated core is arranged on a rotor shaft. Thus, the heat generated during casting cannot impair the hardened surface of the rotor shaft.The object is furthermore achieved with a rotor which has a rotor body according to the invention and a rotor shaft arranged in the second through-opening. That is, the rotor shaft is guided through the second through-opening of the rotor sleeve. The entire rotor body is arranged, for example fastened, on the rotor shaft by the rotor sleeve.The object is further achieved with an electric machine comprising a rotor according to the invention and a stator with respect to which the rotor is rotatable. The machine may be, among other things, a separately excited synchronous motor (EESM), a permanent magnet synchronous motor (PMSM), or a generator.The object is further achieved with a vehicle having an electric machine according to the invention, which is configured to drive the vehicle. The vehicle can be, inter alia, a road vehicle, a watercraft, a rail vehicle or an aircraft.The object is furthermore achieved with a method for producing a rotor for an electric machine according to the invention, in which the rotor sleeve is arranged in the first through-opening before the rotor shaft is arranged in the second through-opening.It should be noted that the rotor sleeve can be designed in particular in the form of a cylinder jacket.In an embodiment of the rotor body according to the invention, the rotor body has a rotor winding, wherein the rotor winding can be attached to the laminated rotor core. In this case, the rotor may be a separately excited synchronous motor (EESM). In this type of machine, the rotor laminations may be star-shaped so as to have radial projections around which the rotor winding is wound.Alternatively, the rotor body may include a plurality of permanent magnets. In this case, the rotor may be a permanent magnet synchronous motor (PMSM). In this type of machine, the rotor laminations can be circular.In a further embodiment of the rotor body according to the invention, the rotor body has two rotor end plates which each cover an axial side of the laminated rotor core and surround the rotor sleeve. For this purpose, each rotor end plate has a through-opening through which the rotor sleeve is at least partially guided. The rotor laminated core can be axially compressed and stabilized by the rotor end plates. While the rotor end plates in a separately excited synchronous motor (EESM) can be star-shaped, the rotor end plates in a permanent magnet synchronous motor (PMSM) can be circular.In a further embodiment of the rotor body according to the invention, the laminated rotor core is connected to the rotor sleeve in a rotationally fixed manner by means of a press fit, a toothing, a tongue / groove connection or cross sections of the first through-opening and the rotor sleeve which differ from the circular shape. As a result, a torque can be transmitted in an optimum manner from the rotor laminated core to the rotor sleeve, from which torque can be transmitted further to the rotor shaft."Rotationally fixed" here means that the rotor laminated core cannot be rotated about the axis of rotation with respect to the rotor sleeve. In addition, the connection of the rotor laminated core to the rotor sleeve can have the effect that the rotor laminated core is axially fixed on the rotor sleeve. The latter applies in particular during the press fit. In addition to the aforementioned types of connection of the laminated rotor core to the rotor sleeve, any desired combination of a plurality of these types is also possible.In a further embodiment of the rotor body according to the invention, the rotor sleeve has a radial thickening which abuts an axial side of the laminated rotor core. The thickening prevents the thickened rotor sleeve section from being inserted into the laminated rotor core, whereby the axial position of the rotor sleeve in the laminated rotor core can be adjusted in a simple manner.Optionally, the thickening is at least partially axially covered by a rotor end plate. As a result, the rotor end plate can extend as far as the rotor shaft and be fastened on the rotor shaft for a higher stability, for example with a press fit.In a further embodiment of the rotor body according to the invention, the laminated rotor core has a plurality of laminated core segments, each of which has a plurality of rotor laminations and a plurality of magnetic poles, wherein the magnetic poles of one laminated core segment are rotated about the axis of rotation of the rotor body with respect to the magnetic poles of another laminated core segment. Such a rotor body is used for a so-called skewed rotor, which is distinguished by an improved rotational behavior.In one embodiment of the rotor according to the invention, the rotor sleeve is connected to the rotor shaft in a rotationally fixed manner by means of a press fit, a toothing, a tongue / groove connection or cross sections of second through-opening and rotor shaft deviating from the circular shape. As a result, a torque can be transmitted optimally from the rotor sleeve to the rotor shaft."Rotationally fixed" here means that the rotor sleeve (and thus the rotor body) cannot be rotated about the axis of rotation with respect to the rotor shaft. In addition, the connection of the rotor sleeve to the rotor shaft can cause the rotor sleeve to be axially fixed on the rotor shaft. The latter applies in particular during the press fit. In addition to the aforementioned types of connection of the rotor sleeve to the rotor shaft, any combination of several of these types is also possible.In one embodiment of the method for producing a rotor according to the invention, the rotor sleeve is fastened in the first through-opening by means of an interference fit, wherein the interference fit is reinforced when the rotor shaft is arranged in the rotor sleeve.For this purpose, a second press fit between the rotor sleeve and the rotor shaft can be provided, among other things. The second interference fit may be established by cooling the rotor shaft, reducing the diameter of the rotor shaft. Thereafter, the rotor shaft is inserted into the rotor sleeve and heated, so that the diameter of the rotor shaft increases. This leads to a widening and thus an enlargement of the outer diameter of the rotor sleeve and thus to a reinforcement of the press fit between the rotor sleeve and the rotor laminated core. This press fit can thereby reliably transmit the torque generated during operation of the electric machine.The described reinforcing of the press fit between the rotor sleeve and the rotor laminated core has the further advantage: the press fit can initially be implemented as a slight press fit, which is not sufficient for the secure transmission of the torque mentioned, but for stabilizing the rotor laminated core for a winding process in which a rotor winding is attached to the rotor laminated core.In a further embodiment of the method for producing a rotor according to the invention, a rotor winding is attached to the laminated rotor core after the rotor sleeve has been arranged in the first through-opening and before the rotor shaft is arranged in the second through-opening. As a result, the spatial region in which the winding tool is movable is not restricted by the rotor shaft, which simplifies the winding process. A further advantage is that, due to the lack of mass of the rotor shaft during the winding process, the winding tool can be designed to be less robust.In a further embodiment of the method for producing a rotor according to the invention, permanent magnets accommodated in the rotor laminated core are cast with a casting compound after the rotor sleeve has been arranged in the first through-opening and before the rotor shaft is arranged in the second through-opening. As a result, the heat generated during casting cannot impair the hardened surface of the rotor shaft.Embodiments of the invention are explained in more detail below with reference to the following schematic figures. They show FIG. 1 is a sectional view of a rotor body according to the invention, FIG. 2 shows a section through a rotor with the rotor body from FIG. 1, FIG. 3 shows a vehicle according to the invention.FIG. 1 shows a section through a rotor body 1 according to the invention. The rotor body 1 belongs to a rotor of an electric machine, in particular to a separately excited synchronous motor (EESM). The machine also has a stator, relative to which the rotor is rotatably mounted. The section runs along a (virtual) axis of rotation 2 of the rotor body 1 or of the rotor.The rotor body 1 has a laminated rotor core 3 which is composed of a plurality of axially stacked rotor laminations. The rotor laminations each have a central recess, wherein the recesses form an axial first through-opening 4, through which the axis of rotation 2 runs. In addition, the rotor laminations are each star-shaped, so that they have radial projections through which the section runs.The laminated rotor core 3 is fastened with a slight press fit on a rotor sleeve 5, which extends through the first through-opening 4 and has an axial second through-opening 6 for a rotor shaft. The press fit is designed in such a way that the rotor laminated core 3 is thus sufficiently stabilized for a winding process.Furthermore, two star-shaped rotor end plates 7 a, 7 bare shown, each of which covers an axial side of the laminated rotor core 3 and surrounds the rotor sleeve 5. In particular, an axially inner section of a rotor end plate 7 a, 7 bsurrounds an axially outer section of the rotor sleeve 5. the rotor sleeve 5 has a radial thickening 8, which abuts an axial side of the laminated rotor stack 3 and is axially covered by a rotor end plate 7 a. For reasons of clarity, hatching of the rotor end plates 7 a, 7 bhas been dispensed with.Also shown is a rotor winding 9 attached to the laminated core, which is wound around projections of the rotor laminations and the rotor end plates 7 a, 7 bsuch that axial ends of the rotor winding 9 rest on radially outer sections of the rotor end plates 7 a, 7 b.It should be noted that the rotor body 1 shown in FIG. 1 has been produced with the rotor winding 9 without arranging the laminated rotor core 3 on the rotor shaft. That is, the rotor winding 9 was wound around the rotor core 3 and the rotor end plates 7 a, 7 b, while the rotor core 3 was not (yet) fixed to the rotor shaft.FIG. 2 shows a section through the rotor 10 with the rotor body 1 from FIG. 1 and a rotor shaft 11 which is guided through the second through-opening 6 of the rotor sleeve 5.The rotor 10 was produced by first providing the rotor body 1 from FIG. 1 including the rotor winding 9 as an intermediate product and then guiding the rotor shaft 11 through the second through-opening 6 of the rotor sleeve 5. Consequently, the rotor sleeve 5 was arranged in the first through hole 4 before the rotor shaft 11 was arranged in the second through hole (6).The rotor shaft 11 is connected to the rotor sleeve 5 in a rotationally fixed manner by means of a press fit. When the press fit was established, the press fit existing between the rotor sleeve and 5 and the rotor laminated core 3 was reinforced, so that it became from a slight to a strong press fit, with which the torque generated during operation of the electric machine can be transmitted reliably.FIG. 3 shows a vehicle 20 according to the invention. The vehicle 20 is equipped with the electric machine 21 to which the rotor 10 belongs. Furthermore, the machine 21 has a stator 22, in which the rotor 10 is rotatably arranged or fastened.The electric machine 21 is configured to propel the vehicle 20. For this purpose, a torque provided by the engine 21 is transmitted to the wheels thereof via a drive train (not shown) of the vehicle 20.List of reference characters1 Rotor body 2 Axis of rotation 3 Rotor laminated core 4 First through-opening 5 Rotor sleeve 6 Second through-opening 7 aRot end plate 7 bRot end plate 8 Thickening 9 Rotor winding 10 Rotor 11 Rotor shaft 20 Vehicle 21 Electric machine 22 Stator

Claims

Rotor body (1) for a rotor (10) of an electric machine (21), having a laminated rotor core (3) which is composed of a plurality of axially stacked rotor laminations which each have a central cutout, the cutouts forming an axial first passage opening (4), and having a rotor sleeve (5) which extends through the first passage opening (4) and has an axial second passage opening (6) for a rotor shaft (11).Rotor body (1) according to claim 1, having a rotor winding (9) or a plurality of permanent magnets.Rotor body (1) according to one of Claims 1 and 2, having two rotor end plates (7a, 7b) which each cover an axial side of the laminated rotor core (3) and surround the rotor sleeve (5).Rotor body (1) according to one of the preceding claims, wherein the laminated rotor core (3) is connected to the rotor sleeve (5) in a rotationally fixed manner by means of - a press fit, - a toothing, - a tongue / groove connection or - cross sections of the first through-opening (4) and the rotor sleeve (5) deviating from the circular shape.Rotor body (1) according to one of the preceding claims, wherein the rotor sleeve (5) has a radial thickening (8) which bears against an axial side of the laminated rotor stack (3).Rotor body (1) according to Claim 5, wherein the thickening (8) is axially covered by a rotor end plate (7a).Rotor body (1) according to one of the preceding claims, wherein the rotor laminated core (3) has a plurality of laminated core segments which each have a plurality of rotor laminations and a plurality of magnetic poles, wherein the magnetic poles of one laminated core segment are rotated about the axis of rotation (2) of the rotor body (1) with respect to the magnetic poles of another laminated core segment.Rotor (10) for an electric machine (21), having a rotor body (1) according to one of the preceding claims and a rotor shaft (11) arranged in the second through-opening (6).Rotor (10) according to Claim 8, wherein the rotor sleeve (5) is connected to the rotor shaft (11) in a rotationally fixed manner by means of - a press fit, - a toothing, - a tongue / groove connection or - cross sections of second through-opening (6) and rotor shaft (11) which differ from the circular shape.Electric machine (21) comprising a rotor (10) according to any of claims 8 and 9, and a stator (22) with respect to which the rotor (10) is rotatable.Vehicle (20) having an electric machine (21) according to claim 10, which is configured to propel the vehicle (20).Method for producing a rotor (10) for an electric machine (21) according to one of Claims 8 and 9, wherein the rotor sleeve (5) is arranged in the first through-opening 4 before the rotor shaft (11) is arranged in the second through-opening (6).Method according to claim 12, wherein the rotor sleeve (5) is fastened in the first through-opening (4) by means of an interference fit, wherein the interference fit is reinforced when arranging the rotor shaft (11) in the rotor sleeve (5).Method according to Claim 12 or 13, wherein a rotor winding (9) is attached to the laminated rotor core (3) after the rotor sleeve (5) has been arranged in the first through-opening (4) and before the rotor shaft (11) is arranged in the second through-opening (6).Method according to Claim 12 or 13, wherein permanent magnets accommodated in the rotor laminated core (3) are cast with a casting compound after the rotor sleeve (5) has been arranged in the first through-opening (4) and before the rotor shaft (11) is arranged in the second through-opening (6).

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