EP3827503A1

EP3827503A1 - Rotor, electric motor, method for producing a rotor and use of a rotor and electric motor

Info

Publication number: EP3827503A1
Application number: EP19742735.4A
Authority: EP
Inventors: Mathias Schröder; Roland BUOL
Original assignee: ThyssenKrupp AG
Current assignee: ThyssenKrupp AG; Thyssenkrupp Dynamic Components GmbH
Priority date: 2018-07-25
Filing date: 2019-07-19
Publication date: 2021-06-02
Also published as: WO2020020787A1; CN112470366A; DE102018212431A1; US20210273510A1

Abstract

The present invention relates to a rotor (R), comprising a shaft (1) having a longitudinal axis (L) and a rotor stack (2) connected at least in a rotationally secure manner to the shaft (1), wherein the rotor stack (2) is composed of individual sheet-metal laminates (21), wherein the rotor stack (2) is provided with an opening (22) for receiving the shaft (1), wherein the shaft (1) is a hollow shaft with a wall (11), wherein the wall (11) of the shaft (1) is provided on its side facing the opening (22) with recesses (12) running in the longitudinal direction, to an electric motor, in particular a synchronous or hybrid synchronous machine, comprising a rotor (R) and a stator (S), characterized by a rotor (R) according to at least one of the preceding claims, to a method for producing a rotor (R) according to at least one of the preceding claims, wherein the recess (12) is produced by machining processes, in particular milling, or forming processes, in particular pressing, and to a use of a rotor (R), in particular an electric motor having a rotor, according to at least one of the preceding claims, wherein the circumferential stiffness is reduced by way of the recesses (12), and/or wherein the recesses (12) are used as flux barriers for directing a magnetic field, and/or wherein the recesses (12) are supplied with a cooling medium.

Description

Rotor, electric motor, method for producing a rotor and use of a

Rotor or electric motor

The present invention relates to a rotor according to the preamble of claim 1, an electric motor according to the preamble of claim 9, a method for producing a rotor according to the preamble of claim 10, and use of a rotor according to the preamble of claim 11, 12 or 15 ,

A rotor, comprising a shaft and a rotor assembly attached to the shaft, is mostly used in electric motors. The rotor package is usually a laminated core composed of individual laminations. The individual sheet metal lamellae are arranged one behind the other in the axial direction. However, the laminations as such can also be composed of individual laminated segments which are arranged and connected one behind the other in the circumferential direction.

The rotor package is non-rotatably connected to the shaft. As a rule, this is done using a press network.

Particularly at high speeds, there are considerable centrifugal forces that act on the rotor components. This can lead to problems with rotor assemblies that are attached using a press connection. As a rule, the rotor assemblies have larger masses compared to the shaft with a greater distance from the axis of rotation. Furthermore, the rotor packs experience higher centrifugal forces due to their mass distribution which is further away from the axis of rotation. In this respect, the rotor package threatens to lift off the shaft at high speeds or the effective overlap and thus the still transmitted torque is reduced.

From DE 102014216905 A1, for example, a rotor package with an internal thread has become known, which is screwed onto a shaft provided with an external thread. Although this measure can be used to improve the connection between the shaft and the rotor assembly, there is still a need for an improved rotor, in particular a connection between the shaft and the rotor assembly, which represents a secure connection even at high speeds. Preferably, the rotor should also be easy to manufacture. According to the invention, this object is achieved by a rotor with the characterizing features of claim 1. Due to the fact that the shaft is a hollow shaft with a wall, the wall of the shaft on its side facing the opening being provided with recesses running in the longitudinal direction, the circumferential rigidity can be reduced. As a result, a higher compression of the shaft provided with recesses compared to a normal hollow shaft can be achieved with the same pressing force. The shaft acts as a compressed spring and can follow the pre-compressed path when the rotor assembly is expanded. Due to the centrifugal forces also acting on the shaft (albeit lower centrifugal forces than with the rotor package), the shaft is also expanded beyond the normal diameter.

Further advantageous refinements of the proposed invention result in particular from the features of the subclaims. The subjects or features of the various claims can in principle be combined with one another as desired.

In an advantageous embodiment of the invention it can be provided that the recesses are aligned parallel to the longitudinal axis of the shaft and / or parallel to one another.

In a further advantageous embodiment of the invention it can be provided that the recess is designed as an elongated hole in the wall of the hollow shaft. The design of the recess as an elongated hole can advantageously be produced in terms of production technology, for example by milling the elongated hole out of the wall of a hollow shaft. However, other manufacturing processes are also conceivable.

In a further advantageous embodiment of the invention it can be provided that the elongated hole extends over a section of the shaft, in particular over a section which is received in the opening of the rotor assembly. As a result, only that area is reduced in terms of its circumferential rigidity that is essentially necessary for the improved connection between the shaft and the rotor assembly.

In a further advantageous embodiment of the invention it can be provided that the recess is designed as a groove. The configuration of the recess as a groove differs from the configuration as an elongated hole essentially in that the groove has a groove bottom. Such a structure can preferably by profiling the wall of the Hollow shaft can be made. The wall preferably has a constant wall thickness.

Furthermore, if the recesses are designed as elongated holes or grooves, it advantageously results that the shaft is equipped with contact surfaces which abut the inner surface of the opening, the recesses being arranged between the contact surfaces.

In a further advantageous embodiment of the invention, it can be provided that the shaft is formed from a soft magnetic material. By using the shaft as a magnetic conductor, material in the rotor package can be saved.

In a further advantageous embodiment of the invention, it can be provided that the rotor package has cutouts, in particular triangular cutouts, which in particular directly adjoin the cutouts, so that the cutouts and cutouts together form a continuous flow barrier. As a result, the magnetic material can be used more effectively and material in the rotor package can be saved. In particular, magnetically weakly used areas are cut out radially below magnets, so that the weight of the rotor can be reduced

Another object of the present invention is to propose an improved electric motor.

According to the invention, this object is achieved by an electric motor with the characterizing features of claim 9. Because the rotor is a rotor proposed according to the invention, an improved connection between the shaft and the rotor assembly can be provided, which can ensure a reliable connection between the shaft and the rotor assembly even at high speeds.

Another object of the present invention is to propose an advantageous production method for a rotor according to the invention.

According to the invention, this object is achieved by a method having the characterizing features of claim 10. The fact that the recess or the recesses is produced by material-separating processes, in particular milling or punching, or shaping processes, in particular pressing or hammering, depending on which Embodiment is selected for the recess or the recesses, the recesses are made in a manner that is advantageous in terms of production technology.

Another object of the present invention is to propose an advantageous use of a rotor according to the invention, in particular an electric motor according to the invention with a rotor according to the invention.

According to the invention, this object is achieved by use with the characterizing features of claim 11. Because the shaft acts as a compressed spring, the shaft can follow the pre-compressed path when the rotor package is expanded.

According to the invention, this object is achieved by use according to the characterizing features of claim 12. Because the shaft serves to guide a magnetic flux, the recesses being used as flow barriers for guiding this magnetic flux, the recesses can have a multiple function accordingly, in particular as a function of an improved connection between the shaft and the rotor package, and also as flow barriers for steering of a magnetic field.

The recesses in the shaft can be designed as a groove or as an elongated hole. For this purpose, the shaft is also made of soft magnetic material, so that the shaft serves as a magnetic conductor, in particular for the magnetic short-circuiting of two poles of two magnets of a rotor package having magnets. This can save material in the rotor, in particular for reducing the rotor yoke.

The rotor assembly preferably has further flow barriers in the form of cutouts, in particular essentially triangular cutouts. These cutouts directly adjoin the cutouts, so that the cutouts and cutouts each form a coherent flow barrier. This can further save material in the rotor package. The number of recesses is preferably an integer multiple n (n = 1, 2, 3, ...) of the number of poles; the number of recesses and poles are particularly preferred equal (n = 1). Another object of the present invention is to propose an advantageous use of a rotor according to the invention, in particular an electric motor according to the invention with a rotor according to the invention.

According to the invention, this object is achieved by use according to the characterizing features of claim 15. Effective cooling of the rotor can be carried out by applying a cooling medium to the recesses. In addition, the recesses can be assigned the functions already outlined above, so that, for example, three functions are combined in one recess, which in turn can contribute to a compact construction of the rotor or electric motor.

Further features and advantages of the present invention will become clear from the following description of preferred exemplary embodiments with reference to the accompanying figures. Show in it

1 shows an electric motor according to the invention with a rotor according to the invention in a schematic cross-sectional illustration;

2a shows a shaft of a rotor according to the invention in a perspective view;

2b shows a shaft of a rotor according to the invention in a top view;

3 shows a rotor according to the invention in a perspective view;

4 shows a rotor according to the invention in a front view;

5 shows an exemplary comparison of the transmissible torque as a function of the rotational speed for different rotor packet / shaft constellations;

6a shows a further embodiment of a shaft for a rotor according to the invention in a first perspective illustration;

6b shows an embodiment of a shaft according to FIG. 6a for an inventive one

Rotor in another perspective view;

7 shows a rotor according to the invention with a shaft according to FIGS. 6a and 6b in a perspective illustration;

8 shows a schematic illustration of magnetic flux lines in a rotor according to the invention;

9 shows a schematic illustration of magnetic flux lines in a rotor according to the invention.

First, reference is made to FIG. 1.

A rotor R according to the invention essentially comprises a shaft 1 and a rotor package 2.

The rotor assembly 2 is twisted, but preferably also axially fixed, attached to the shaft 1.

The shaft 1 is a hollow shaft with a corresponding wall 11. The shaft 1 has a corresponding longitudinal axis or axis of rotation L. The rotor assembly 2 has at least one, preferably a plurality of annular sheet-metal laminations 21, which are assembled to form a hollow cylindrical rotor assembly 2. Correspondingly, the lamellae 21 are lined up one behind the other in the axial direction. But also the sheet metal lamellae 21 as such can be composed of individual sheet metal lamella segments (not shown) which are arranged and connected one behind the other in the circumferential direction.

The rotor assembly 2 has an opening 22 through which the shaft 1 is inserted or in which the shaft 1 is received. This opening 22 has a surface facing the shaft, which is referred to below as the inner surface.

Correspondingly, the shaft 1 or its wall 11 has a surface facing the opening 22.

According to the invention it is provided that the surface of the shaft 1 facing the inner surface of the opening 22 is provided with recesses 12 running in the longitudinal direction L. The recesses 12 are preferably aligned parallel to the longitudinal axis L of the shaft 1 and / or parallel to one another.

In a first embodiment, which is shown, for example, in FIGS. 6, the recesses 12 can be designed as elongated holes in the wall 11 of the hollow shaft. The elongated hole 12 preferably penetrates the wall 11 completely and is preferably produced by material-separating processes, such as milling or punching. In this respect, the recesses 12 of this embodiment preferably do not extend over the entire length of the shaft 1, but generally over the part of the shaft 1 which is located in the opening 22 of the rotor assembly 2. Alternatively, it can also be provided that the elongated holes 12 are open on one side. All openings on one side of the elongated holes can be arranged on one side of the shaft 1, but also alternately or alternately in a pattern with respect to the side of the shaft 1.

In a further embodiment, the wall 11 can be designed in a profiled manner, ie the recesses 12 are designed as grooves. The groove 12 accordingly has a groove bottom, ie, in contrast to the elongated holes, the groove 12 does not completely penetrate the wall 11. The groove or the profile is preferably produced by means of reshaping processes, such as presses. In both embodiments, there are ultimately contact surfaces 13 between the recesses 12 of the shaft 1, which bear against the inner surface of the opening 22. These contact surfaces 13 are preferably separated from one another in the circumferential direction by the recesses 12.

As a result, a rotor shaft 1 with reduced circumferential rigidity is proposed, onto which a rotor package 2 is pressed directly. The circumferential rigidity can be reduced by means of recesses 12, for example in the form of elongated holes and / or grooves.

To clarify this effect, transmissible torque versus rotor speed are plotted in FIG. 5 using various examples. The number I refers to an unprofiled hollow shaft, the number II to a hollow shaft with four grooves as recesses and the number III to a hollow shaft with eight grooves as recesses (Fig. 2 to 4).

In a further development of the invention or with regard to an advantageous use, the recesses 12 can at the same time be used as flow barriers for guiding a magnetic field, particularly in synchronous or hybrid synchronous machines. The number of recesses 12 is advantageously an integer multiple n (n = 1, 2.3 ...) of the number of poles. To illustrate this effect, magnetic flux lines 3 and the cutouts 12 acting as flow barriers 4 in FIG. 8 (with the same number of poles and cutouts, ie n = 1) and FIG. 9 (with double the number of cutouts, ie n = 2) shown.

For this purpose, the shaft 1 is made of soft magnetic material, so that a magnetic path leads through one or more elevations 13 of the shaft. As a result, the shaft short-circuits two poles of two magnets 16. By using the shaft 1 as a magnetic conductor, material in the rotor package 2 can be saved.

The rotor package has further flow barriers in the form of cutouts 15, here essentially triangular cutouts 15. These cutouts 15 directly adjoin the cutouts 12, so that the cutouts 12 and cutouts 15 together form a continuous flow barrier 4. As a result, the magnetic material can be used more effectively and material in the rotor assembly 2 can be saved. In particular are magnetically weakly used areas are cut out radially below magnets 16, so that the weight of the rotor can be reduced.

In a further development of the invention or in view of an advantageous use, the recesses 12 can also serve as channels for a cooling medium which can come into direct contact with the rotor assembly.

Features and details apply, which are described in connection with the method of course also in connection with the rotor or electric motor according to the invention and vice versa, so that with respect to the disclosure of the individual aspects of the invention, reference can always be made to one another. In addition, the method according to the invention can be carried out with the rotor or electric motor according to the invention.

The following reference symbols are used in the figures:

S stator

R rotor

L longitudinal axis / axis of rotation

1 wave

2 rotor package

3 magnetic flux lines

4 river barrier

11 wall / surface

12 recess

13 contact surface

15 recess

16 magnet

21 sheet metal fins

22 opening / inner surface

Claims

Expectations

1. A rotor (R) comprising a shaft (1) with a longitudinal axis (L) and an at least rotation test connected to the shaft (1) rotor package (2), wherein

- The rotor assembly (2) is composed of individual laminations (21), wherein - the rotor assembly (2) is equipped with an opening (22) for receiving the shaft (1), characterized in that

- The shaft (1) is a hollow shaft with a wall (11)

- The wall (11) of the shaft (1) on its side facing the opening (22) with in

Longitudinally extending recesses (12) is equipped.

2. Rotor according to claim 1, characterized in that the recesses (12) parallel to

Longitudinal axis (L) of the shaft (1) and / or aligned parallel to each other.

3. Rotor according to at least one of the preceding claims, characterized in that the recess (12) is designed as an elongated hole in the wall (11) of the shaft (1).

4. Rotor according to at least one of the preceding claims, characterized in that the elongated hole (12) extends over a section of the shaft (1), in particular over a section which is received in the opening (22) of the rotor assembly (2).

5. Rotor according to at least one of the preceding claims, characterized in that the recess (12) is designed as a groove.

6. Rotor according to at least one of the preceding claims, characterized in that the shaft (1) is equipped with contact surfaces (13) which bear against the inner surface of the opening (22), the recesses (12) between the contact surfaces (13) are arranged.

7. Rotor according to at least one of the preceding claims, characterized in that the shaft (1) is formed from a soft magnetic material.

8. Rotor according to at least one of the preceding claims, characterized in that the rotor assembly (2) has recesses (15), in particular triangular recesses (15), has, which in particular directly adjoin the recesses (12), so that the recesses (12) and recesses (15) together form a continuous flow barrier (4).

9. Electric motor, in particular synchronous or flybride synchronous machine, comprising a rotor (R) and a stator (S), characterized by a rotor (R) according to at least one of the preceding claims.

10. A method for producing a rotor (R) according to at least one of the preceding claims, characterized in that the recess (12) is produced by material-separating methods, in particular milling or punching, or reshaping methods, in particular pressing or flame.

11. Use of a rotor (R) or an electric motor with a rotor (R), according to at least one of the preceding claims, characterized in that the circumferential rigidity of the shaft (1) is reduced by the recesses (12).

12. Use of a rotor (R) or an electric motor with a rotor (R), according to at least one of the preceding claims, characterized in that the shaft (1) serves to conduct a magnetic flux, the recesses (12) serving as flow barriers ( 4) can be used to control this river.

13. Use according to claim 12, characterized in that the rotor assembly (2) has recesses (15), in particular triangular recesses (15), which in particular directly adjoin the recesses (12), so that the recesses (12) and Recesses (15) together form a continuous flow barrier (4).

14. Use according to claim 12 or 13, characterized in that the number of recesses (12) is an integer multiple of the number of poles.

15. Use of a rotor (R) or an electric motor with a rotor (R), according to at least one of the preceding claims, characterized in that the recesses (12) are acted upon by a cooling medium.