Rotor for an electric machine

Abstract

The invention relates to a rotor (1) for an electric machine, in particular an electric machine for a motor vehicle, comprising a rotor shaft (2) and a laminated core (3) arranged on the rotor shaft (2), wherein the rotor shaft (2) comprises at least one tubular body (4) made of an electrically non-conductive material, in particular a fiber composite material, wherein at least one sleeve (5-7) is arranged on the tubular body (4).

Description

[0001] ZF Friedrichshafen AG File 305970 Friedrichshafen 2025-11-19

[0002] Rotor for an electric machine

[0003] The invention relates to a rotor for an electric machine, in particular an electric machine for a motor vehicle, comprising a rotor shaft and a laminated core arranged on the rotor shaft.

[0004] Rotors for electric machines, especially electric machines for motor vehicles, which have a rotor shaft and a laminated core mounted on the rotor shaft, are generally known from the prior art. The rotor shaft is usually made of a metal, for example, steel, so that it can fulfill the properties required for the operation of the electric machine, particularly with regard to torque transmission and bending stiffness. The laminated core, for example, axially adjacent laminations, is attached to the rotor shaft, for example, by being pressed onto it.

[0005] Due to the typically metallic construction of the rotor shaft, its manufacture is comparatively complex, especially if it is to be designed as a hollow shaft. Furthermore, the metallic construction usually results in a higher weight and potentially undesirable electrical conductivity compared to other materials.

[0006] The invention is based on the objective of providing an improved rotor for an electric machine, in which the rotor shaft in particular is improved.

[0007] The problem is solved by a rotor having the features of claim 1. Advantageous embodiments are the subject of the dependent claims.

[0008] As described, the invention relates to a rotor for an electric machine, specifically an electric machine for a motor vehicle. The electric machine can, in particular, be designed as a drive unit for the motor vehicle. This means that the electric machine can generate or provide torque for driving the motor vehicle. The rotor comprises a rotor shaft, on which a laminated core, specifically axially aligned laminated lamellae, is arranged.

[0009] The invention is based on the finding that the rotor shaft comprises at least one tubular body made of an electrically non-conductive material, in particular a fiber-reinforced composite material, wherein at least one sleeve is arranged on the tubular body. The invention thus proposes providing a tubular body made of an electrically non-conductive material, specifically consisting of or comprising a fiber-reinforced composite material. This allows for weight and manufacturing cost savings compared to a conventional metallic rotor shaft.

[0010] To ensure sufficient stability, particularly to achieve a certain bending stiffness or to transmit the required torque from the rotor to an output, at least one sleeve is arranged on the tube body. The sleeve can thus be considered a reinforcement or stiffener for the at least one tube body. Specifically, the sleeve is also made of an electrically non-conductive material, for example, a fiber-reinforced composite. In particular, a fiber matrix of glass fibers impregnated and cured with a resin material, such as epoxy resin, can be used as the fiber-reinforced composite.

[0011] Advantageously, the rotor shaft can therefore be manufactured in a simplified manner, specifically from semi-finished products that can be joined together. The tube body and the at least one sleeve can be provided separately and then joined together, so that they do not have to be manufactured in a single production process, nor does the entire rotor shaft have to be manufactured in a single production process. This also makes it possible, in particular, to selectively reinforce areas of the tube body with at least one sleeve, so that reinforcement only needs to be applied in those areas where it is necessary. Specifically, the use of the at least one sleeve allows for targeted reinforcement in different areas. (ZF Friedrichshafen AG File 305970 Friedrichshafen 2025-11-19)

[0012] Different properties are implemented in different areas, which will be described in more detail below.

[0013] In a further development of the rotor, at least one sleeve can be arranged on an outer surface and / or an inner surface of the tube body. As described, more than one sleeve, for example two or three sleeves, can be used and arranged on the tube body to form the rotor shaft, i.e., attached to it. At least one sleeve can be arranged on an outer surface of the tube body. The at least one sleeve arranged on the tube body thus causes a "thickening" of the tube body at the location or over the axial area where the sleeve is arranged. In particular, more than one sleeve can be arranged on an outer surface of the tube body, especially in different axial areas, for example, in the axial end regions of the tube body.

[0014] At least one sleeve can be arranged on an inner surface of the tube body. In this embodiment, the tube body is designed, at least in sections, as a hollow body or hollow shaft. Combinations are possible such that, in the same axial section or over the same axial region, or overlapping in the axial direction, at least one sleeve can be arranged on the outer surface and at least one sleeve on the inner surface of the tube body. As already described, the properties, especially the mechanical properties, of the tube body can be improved by the targeted arrangement of sleeves over certain axial regions. For example, the ability of the rotor shaft to transmit torque can be improved by at least one sleeve on the tube body. Furthermore, the stiffness, especially the bending stiffness, can be positively influenced by the at least one sleeve.

[0015] Furthermore, the rotor may be provided with a first sleeve on an output side of the tube body on an inner surface of the tube body and / or a second sleeve on an output side of the tube body on an outer surface of the tube body and / or a third sleeve on a sensor side of the tube body opposite the output side on an outer surface of the ZF Friedrichshafen AG File 305970 Friedrichshafen 2025-11-19

[0016] is arranged in the pipe body. Specifically, a drive side can be formed on the pipe body, at which torque is transmitted from the rotor, namely from the pipe body, for example via a drive element connected to the pipe body and / or one of the sleeves, for example made of a metal, in particular steel, for example to a drive of the drive train to which the electric machine is assigned.

[0017] On the side opposite the axial direction, a sensor side can be formed on which a sensor element is arranged, for example, a speed sensor and / or a rotor position sensor or the like. For this purpose, the pipe body and / or the at least one sleeve connected to or arranged on the pipe body can be connected to a sensor element. The sensor element can interact with a detector so that the electric machine or some associated control device is configured to evaluate a sensor signal from the sensor element.

[0018] As previously described, by arranging the different sleeves in different areas of the tube body, the mechanical properties can be adapted or adjusted to the respective function of that section. For example, the rotor shaft can be designed for torque transmission on the output side by arranging the first sleeve on the inner surface of the tube body and / or the second sleeve on the outer surface. Specifically, this increases the stability on the output side of the rotor shaft, particularly compared to the tube body alone.

[0019] On the sensor side opposite the output side, for example, the third sleeve can be positioned on the outer surface in such a way that the (bending) stiffness of the rotor shaft on the output side is increased, for example, compared to the tube body alone. This stabilizes and thus improves the detection of the sensor element and its rotational movement. The designation of the individual sleeves and their numbering, i.e., the terms "first," "second," and "third," can be changed or interchanged as desired. ZF Friedrichshafen AG File 305970 Friedrichshafen 2025-11-19

[0020] The manufacturing of the tube body and / or the at least one sleeve from the electrically non-conductive material can, in principle, be carried out using any method, for example, resin transfer molding (RTM). This allows, in particular, a comparatively fast and inexpensive manufacturing process for the tube body and / or the at least one sleeve. To subsequently ensure a proper fit between the individual components of the rotor, the tube body and / or the at least one sleeve can be machined in at least one section.

[0021] Specifically, it may be provided that at least one inner surface and / or one outer surface of the tube body and / or the at least one sleeve is mechanically machined, in particular by machining. Specifically, the tube body and sleeve, or the tube body or sleeve, may only be mechanically machined in those areas where the fit between the tube body and the lamination stack or between the tube body and the sleeve is to be achieved. For example, the machining may extend to the axial areas, such as those sections of the inner and outer surfaces where the lamination stack or a sleeve is to be arranged on the tube body.

[0022] As already described, the individual manufacturing parameters for the tube body and the at least one sleeve are, in principle, arbitrarily selectable. In one embodiment of the rotor, the tube body can have the same or a different wall thickness than the at least one sleeve, and / or it can be provided that at least two sleeves have the same and / or a different wall thickness. Therefore, it is fundamentally possible for the tube body and all sleeves to have the same wall thickness, or for the tube body and the sleeves to have different wall thicknesses. For example, the sleeves can each have the same wall thickness, or at least two sleeves can have different wall thicknesses. Specifically, all sleeves can have different wall thicknesses.This results in corresponding combinations where the tube body can have a wall thickness of one dimension, and the first, second, and third sleeves can each have any desired wall thickness. The selection or specification is documented in ZF Friedrichshafen AG file 305970, Friedrichshafen, November 19, 2025.

[0023] The wall thickness and the design of the pipe body and the at least one sleeve, each with a defined wall thickness, can be determined, for example, based on the load and / or the rotor concept and / or a simulation.

[0024] In a further embodiment of the rotor, it can be provided that the tube body has the same or a different fiber orientation as the at least one sleeve and / or that at least two sleeves have the same and / or a different fiber orientation, in particular the first sleeve has a fiber orientation of + 45° or - 45° and / or the tube body has a fiber orientation of + 45° or - 45° and / or the second sleeve has an orthogonal fiber orientation or a fiber orientation of + 45° or - 45° and / or the third sleeve has a parallel fiber orientation with respect to the axis of rotation of the rotor.

[0025] In principle, a defined fiber orientation can be selected or specified for the pipe body and each of the at least one sleeve. For example, the pipe body and each of the at least one sleeve can have a fiber orientation of +45° or -45°, an orthogonal fiber orientation, or a parallel fiber orientation. In particular, the fiber orientation of the pipe body and the at least one sleeve can be determined based on their function. A fiber orientation of +45° or -45°, i.e., "diagonal," typically improves torque transmission. An orthogonal fiber orientation improves the press fit between the components, and a parallel fiber orientation improves stiffness, especially bending stiffness.

[0026] Specifically, the first and second sleeves can be designed for torque transmission and may have a fiber orientation of +45° or -45°. The third sleeve, designed to increase stiffness on the sensor side, may advantageously have a parallel fiber orientation. The tube body may, for example, have a fiber orientation of + / -45° or an orthogonal fiber orientation. In particular, it is also possible for the individual components, i.e., the tube body and / or the at least one sleeve, to have different fiber orientations in different layers of the fiber-reinforced composite material. Corresponding combinations are possible. ZF Friedrichshafen AG File 305970 Friedrichshafen 2025-11-19

[0027] In a further embodiment, the pipe body and at least one sleeve can each have at least one corresponding temperature control medium opening. In other words, a temperature control medium channel, for example, a channel for oil, can extend through corresponding temperature control medium openings formed in the pipe body and the at least one sleeve. For example, the pipe body and the at least one sleeve can be joined together in a defined orientation so that the temperature control medium openings align, allowing the temperature control medium to flow through the channel via the individual temperature control medium openings in the pipe body and the at least one sleeve. Alternatively, the at least one temperature control medium opening can be introduced into the pipe body after the at least one sleeve has been joined. For this purpose, for example, a temperature control medium channel can be drilled diagonally through the pipe body and the at least one sleeve.

[0028] Furthermore, the rotor may be provided with an adhesive between the tube body and the laminated core and / or between the tube body and the at least one sleeve. This adhesive may be in liquid form as a lubricant and in solid form to bond the tube body and the laminated core and / or the tube body and the at least one sleeve. The adhesive may be specifically formulated to match the material from which the tube body and the at least one sleeve are made. As described, the surfaces of the tube body and the at least one sleeve may be machined, particularly in the axial areas where they are to be joined.

[0029] When joining the tube body and at least one sleeve, or the tube body and the lamination stack, the adhesive can be applied so that, in liquid form, it acts as a lubricant to reduce pressing forces during the insertion process of the lamination stack onto the tube body or the sleeve onto or into the tube body. After the adhesive has cured, it bonds the lamination stack to the tube body or the sleeve to the tube body. The surfaces of the sleeve and / or tube body can also be pretreated in other ways, for example, with plasma pretreatment. ZF Friedrichshafen AG File 305970 Friedrichshafen 2025-11-19

[0030] As already described, the tube body and the at least one sleeve are made of an electrically non-conductive material, in particular a fiber-reinforced composite. In one embodiment, the tube body and / or the at least one sleeve can comprise a fiber matrix, in particular glass fibers, and a resin material, in particular epoxy resin, that impregnates the fiber matrix. In principle, any fibers can be selected as long as they are not electrically conductive. The material of the tube body and / or the at least one sleeve is, in particular, resistant to media, especially to the oil used as a temperature control medium, and / or temperature-resistant.

[0031] In addition to the rotor, the invention relates to an electric machine comprising a rotor as previously described. As described, the electric machine is specifically designed as a drive unit for a motor vehicle and is thus capable of transmitting torque for propelling the motor vehicle or absorbing torque during operation of the motor vehicle, for example, for recuperation. The invention further relates to a drive train, in particular an electric axle drive, comprising an electric machine and / or a rotor as previously described. It also relates to a motor vehicle comprising such a drive train and / or an electric machine and / or a rotor as previously described.

[0032] In addition, the invention relates to a method for manufacturing a rotor for an electric machine, in particular an electric machine for a motor vehicle, comprising a rotor shaft and a laminated core arranged on the rotor shaft, wherein the rotor shaft comprises at least one tube body made of an electrically non-conductive material, in particular a fiber composite material, wherein at least one sleeve is arranged on the tube body.

[0033] The described process can be used, in particular, to manufacture a previously described rotor, or the previously described rotor can be manufactured by the process described herein. All advantages, details, and features described with respect to the rotor are fully transferable to the electric machine, the drive train, the motor vehicle, and the process, and vice versa. ZF Friedrichshafen AG File 305970 Friedrichshafen 2025-11-19

[0034] The invention is explained below with reference to an exemplary embodiment and the figure. The figure is a schematic representation and shows a rotor for an electric machine.

[0035] The figure shows a rotor 1 for an electric machine (not shown in detail), specifically an electric machine for a motor vehicle. The rotor 1 comprises a rotor shaft 2 on which a laminated core 3, for example, axially arranged laminations, is mounted. In the illustrated embodiment, the rotor shaft 2 has a tubular body 4 on which, by way of example, three sleeves 5-7 are arranged. For the sake of simplicity and by way of example, sleeve 5 is referred to as "first sleeve 5", sleeve 6 as "second sleeve 6", and sleeve 7 as "third sleeve 7". These designations are therefore interchangeable and can be modified as desired.

[0036] By way of example, the first sleeve 5 is arranged on an inner surface of the tube body 4, namely on an output side 8, to which an output element 9 is connected. The output element 9 can be made of metal and can also be referred to as a "shaft stub". The second sleeve 6 is arranged on an outer surface of the tube body 4, namely also on the output side 8, for example, on a first side with respect to the laminated core 3 on the rotor shaft 2 of the rotor 1. The third sleeve 7 is arranged on the axially opposite second side, namely on a sensor side 10, and also on the outer surface of the tube body 4. A sensor element 11 is arranged on the sensor side 10, namely, like the output element 9, inserted or pressed into the cavity of the tube body 4.

[0037] For the manufacture of the rotor 1, for example, the tube body 4 and the sleeves 5-7 can be provided as semi-finished products. The outer surface of the tube body 4 can be machined, in particular by machining, to create or prepare a precise fit for the lamination stack 3 and / or the sleeves 6, 7. ZF Friedrichshafen AG File 305970 Friedrichshafen 2025-11-19

[0038] The sheet metal stack 3 can then be pressed onto the tube body 4, or the tube body 4 can be pressed into the sheet metal stack 3. Independently of the joining of the sheet metal stack 3, the first sleeve 5 can be pressed into the tube body 4. For this purpose, the inner surface of the tube body 4 is machined, particularly by machining. Additionally, the inner surface of the sleeves 6 and 7, or the outer surface of the first sleeve 5, can be machined to improve the fit with the tube body 4.

[0039] An adhesive (not shown) can be applied between the tube body 4 and the sheet metal stack 3 and / or between the tube body 4 and the sleeves 5-7. In liquid form, this adhesive acts as a lubricant to reduce forces during the pressing-in process or the joining process in general. Once cured, the adhesive bonds the tube body 4 to the sheet metal stack 3 and / or the sleeves 5-7 to the tube body 4.

[0040] The tube body 4 and the sleeves 5-7 are made of an electrically non-conductive material, in particular a fiber-reinforced composite material. For example, they are made of a fiber matrix, in particular glass fibers, which is impregnated with a resin material, in particular epoxy resin, and cured. The tube body 4 and the sleeves 5-7 can be manufactured with different or the same wall thicknesses in any combination. For example, the tube body 4 has a different wall thickness than the sleeves 5-7. Alternatively, at least one of the sleeves 5-7 can have the same wall thickness as the tube body 4. The sleeves 5-7 can have different wall thicknesses. Alternatively, at least one sleeve 5-7 can have the same wall thickness as at least one of the other sleeves 5-7. Accordingly, any combination of wall thicknesses is possible.

[0041] The same applies to the fiber orientation of the fiber material comprising the tube body 4 and the sleeves 5-7. In principle, the tube body 4 and each of the sleeves 5-7 can have any diagonal, orthogonal, or parallel fiber orientation with respect to a rotation axis 12 of the rotor 1. In addition, any other fiber orientations beyond those listed are also possible. (ZF Friedrichshafen AG File 305970 Friedrichshafen 2025-11-19)

[0042] Fiber orientations can also differ. The fiber orientations can, for example, be combined to improve the function of the individual components of rotor 1.

[0043] For example, the output side 8 of the rotor shaft 2 can be designed for transmitting torque from the rotor 1 to an output, which can be coupled to or connected to the output element 9, and this transmission can be enhanced by the properties of the tube body 4 and / or the first sleeve 5 and / or the second sleeve 6. To improve torque transmission, the first sleeve 5 and / or the second sleeve 6 can, for example, have a diagonal fiber orientation, i.e., a fiber orientation of ±45°. The same applies to the tube body 4. Alternatively, the tube body 4 and / or the first sleeve 5 and / or the second sleeve 6 can have an orthogonal fiber orientation to improve the press fit. For example, a combination can be formed in which the first sleeve 5 and the tube body 4 have a diagonal fiber orientation and the second sleeve 6 has an orthogonal fiber orientation, or any other combination.

[0044] On the transmitter side 10, the third sleeve 7 can have a parallel fiber orientation to improve the stiffness, especially the bending stiffness, of the rotor shaft 2 in this area. This can particularly improve the evaluation of a sensor signal by a detector generated by the sensor element 11.

[0045] Furthermore, the figure shows temperature control openings 13-16, for example, any number of temperature control openings 13-16 distributed circumferentially around the axis of rotation 12. The temperature control openings 13 are provided in the first sleeve 5, the temperature control openings 14 are provided in the tube body 4, the temperature control openings 15 are provided in the second sleeve 6, and the temperature control openings 16 are provided in the third sleeve 7. The tube body 4 obviously has two groups of temperature control openings 14, the first group of temperature control openings 14, which faces the output side 8, corresponding to the temperature control openings 13 of the first sleeve 5 ZF Friedrichshafen AG File 305970 Friedrichshafen 2025-11-19 and the temperature control openings 15 in the second sleeve 6.The second group of temperature control openings 14, which faces the sensor side 10, corresponds to the temperature control openings 16 in the third sleeve 7.

[0046] For example, the individual temperature control openings 13-16 can be inserted into the tube body 4, thus allowing the sleeves 5-7 to be inserted and aligned during assembly. Alternatively, it is also possible to insert the temperature control openings 13-16 into the tube body 4 after the sleeves 5-7 have been joined, for example by drilling them diagonally to ensure accessibility to the sheet metal stack 3.

[0047] As described, the rotor 1 can be a component of an electric machine (not shown in detail), in particular the drive system of a motor vehicle. The electric machine can be part of a drive train, for example an electric axle drive, for such a motor vehicle. Such a motor vehicle thus comprises such a drive train or an electric machine and / or a rotor 1 as shown.

[0048] The method described herein can be used to manufacture the rotor 1 shown, as described, or the rotor 1 shown has been manufactured using the method described herein.

[0049] All the advantages, details and features described in relation to Rotor 1 are fully transferable to the electric machine, the drive train, the motor vehicle and the method.

[0050] ZF Friedrichshafen AG File 305970 Friedrichshafen 2025-11-19

[0051] Reference mark

[0052] 1 Rotor

[0053] 2 Rotor shaft

[0054] 3 sheet metal package

[0055] 4 pipe bodies

[0056] 5-7 Sleeve

[0057] 8 Output side

[0058] 9 Output element

[0059] 10 Sensor page

[0060] 11 Sensor element

[0061] 12 Rotation axis

[0062] 13-16 Tempering agent opening

Claims

ZF Friedrichshafen AG File 305970 Friedrichshafen 2025-11-19 Patent claims 1. Rotor (1) for an electric machine, in particular an electric machine for a motor vehicle, comprising a rotor shaft (2) and a laminated core (3) arranged on the rotor shaft (2), characterized in that the rotor shaft (2) comprises at least one tubular body (4) made of an electrically non-conductive material, in particular a fiber composite material, wherein at least one sleeve (5-7) is arranged on the tubular body (4).

2. Rotor (1 ) according to claim 1 , characterized in that the at least one sleeve (5-7) is arranged on an outer surface and / or on an inner surface of the tube body (4).

3. Rotor (1 ) according to claim 1 or 2, characterized in that a first sleeve (5) is arranged on an output side (8) of the tube body (4) on an inner surface of the tube body (4) and / or a second sleeve (6) is arranged on an output side (8) of the tube body (4) on an outer surface of the tube body (4) and / or a third sleeve (7) is arranged on an outer surface of the tube body (4) on a sensor side (10) opposite the output side (8) of the tube body (4).

4. Rotor (1 ) according to one of the preceding claims, characterized in that at least one inner surface and / or one outer surface of the tube body (4) and / or the at least one sleeve (5-7) is machined mechanically, in particular by machining.

5. Rotor (1 ) according to one of the preceding claims, characterized in that the tube body (4) has the same or a different wall thickness as the at least one sleeve (5-7) and / or that at least two sleeves (5-7) have the same and / or a different wall thickness.

6. Rotor (1) according to one of the preceding claims, characterized in that the tube body (4) has an identical or ZF Friedrichshafen AG File 305970 Friedrichshafen 2025-11-19 has a different fiber orientation and / or that at least two sleeves (5-7) have the same and / or a different fiber orientation, in particular the first sleeve (5) has a fiber orientation of +45° or -45° and / or the tube body (4) has a fiber orientation of +45° or -45° and / or the second sleeve (6) has an orthogonal fiber orientation and / or the third sleeve (7) has a parallel fiber orientation with respect to the axis of rotation (12) of the rotor (1 ).

7. Rotor (1 ) according to one of the preceding claims, characterized in that the tube body (4) and at least one sleeve (5-7) have at least one corresponding temperature control medium opening (13-16).

8. Rotor (1 ) according to one of the preceding claims, characterized in that an adhesive is provided between the tube body (4) and the laminated core (3) and / or between the tube body (4) and the at least one sleeve (5-7), which is designed in liquid form as a sliding aid and in solid form to connect the tube body (4) and the laminated core (3) and / or the tube body (4) and the at least one sleeve (5-7).

9. Rotor (1 ) according to one of the preceding claims, characterized in that the tube body (4) and / or the at least one sleeve (5-7) comprises a fiber matrix, in particular glass fibers, and a resin material, in particular epoxy resin, which impregnates the fiber matrix.

10. Electric machine comprising a rotor (1 ) according to any of the preceding claims.

11. Drive train, in particular axle drive, comprising an electric machine according to the preceding claim and / or a rotor (1) according to any one of claims 1 to 9. ZF Friedrichshafen AG File 305970 Friedrichshafen 2025-11-19 12. Motor vehicle comprising a drive train according to the preceding claim and / or an electric machine according to claim 10 and / or a rotor (1 ) according to any one of claims 1 to 9.

13. Method for manufacturing a rotor (1 ) for an electric machine, in particular an electric machine for a motor vehicle, comprising a rotor shaft (2) and a laminated core (3) arranged on the rotor shaft (2), characterized in that the rotor shaft (2) comprises at least one tubular body (4) made of an electrically non-conductive material, in particular a fiber composite material, wherein at least one sleeve (5-7) is arranged on the tubular body (4). 16

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