DE102022125700A1 - Rotor for an electrical machine with improved holding elements for the axial fixation of a rotor laminated core - Google Patents

Abstract

A rotor (3a, 3b) for an electrical machine (1, 1a, 1b) is specified, which comprises a rotor lamination stack (12, 12a, 12b) with several rotor laminations (14, 14a..14d) stacked axially on top of one another, which have recesses that form a hole (15a..15c, 15..15''') leading axially through the rotor lamination stack (12, 12a, 12b). The rotor (3a, 3b) also comprises a holding element (16, 16a..16f) extending axially in the hole (15a..15c, 15..15''') for holding the rotor laminations (14, 14a..14d) together, which is made of fiber-reinforced plastic or has a fiber-reinforced plastic. Furthermore, the invention relates to an electrical machine (1, 1a, 1b) with a rotor (3a, 3b) of the type mentioned, a vehicle (22) with such an electrical machine (1, 1a, 1b), and a manufacturing method for such a rotor (3a, 3b).

Description

TECHNICAL AREA

The invention relates to a rotor for an electrical machine, which comprises a rotor lamination stack with a plurality of rotor laminations stacked axially on top of one another, wherein the rotor laminations have recesses that form a hole leading axially through the rotor lamination stack. The rotor laminations form a rotor lamination stack as part of the rotor lamination stack, which has a first end face and an axially opposite second end face. The rotor further comprises a holding element extending axially in the hole for holding the rotor laminations together. The invention also relates to an electrical machine with a rotor of the above-mentioned type and a vehicle with such an electrical machine.

STATE OF THE ART

A rotor, an electrical machine and a vehicle of the type mentioned are basically known from the prior art. The rotor laminations are stacked on top of one another to form a rotor lamination stack, and the rotor lamination stack is then axially fixed on both sides using holding elements that are guided through the holes in the rotor lamination stack. This counteracts the rotor lamination stack from drifting apart during operation of the electrical machine.

As a rule, screws or threaded pins made of steel are used as holding elements for this purpose. However, these holding elements influence a magnetic field generated by the rotor magnets or rotor windings of the rotor and therefore also the magnetic flux within the rotor lamination stack. This also has a negative impact on the performance and efficiency of the electrical machine.

In addition, axial securing is usually carried out using screw nuts that are screwed onto the screws or threaded pins. As is well known, means for holding or turning the screws or nuts must be provided on both sides of the rotor core. Axial fixing is therefore relatively complex and requires comparatively complex devices for mechanical production of the rotor core.

DISCLOSURE OF THE INVENTION

One object of the invention is therefore to provide an improved rotor, an improved electrical machine and an improved vehicle for a rotor of an electrical machine. In particular, the axial securing of the rotor laminated core should be made possible without impairing the performance and efficiency of the electrical machine and, if possible, in a simpler manner.

The object of the invention is achieved with a rotor of the type mentioned above, in which the holding element is made of fiber-reinforced plastic or comprises a fiber-reinforced plastic.

Furthermore, the object of the invention is achieved by an electrical machine with a rotor of the above-mentioned type. The rotor can in particular have a rotor shaft on which the rotor core is mounted, as well as several rotor magnets or rotor windings arranged in the rotor core. The electrical machine can in particular comprise a housing and a stator arranged in the housing, as well as the rotor of the above-mentioned type arranged in the stator and mounted so as to be rotatable about a rotor axis in the housing.

Furthermore, the object of the invention is achieved by a vehicle which has an electric machine of the above-mentioned type, which is intended to drive the vehicle.

The proposed materials for the holding element have little or no influence on the magnetic field generated by the rotor magnets or rotor windings and therefore also on the magnetic flux within the rotor lamination stack. Therefore, the axial securing of the rotor lamination stack can be achieved with no or no significant impairment of the rotor magnetic field and thus with no or no significant impairment of the performance and efficiency of the electrical machine.

It is particularly advantageous if the holding elements and holes are arranged in the same radial area as the rotor magnets or rotor windings of the rotor. Between the rotor magnets, as seen from the front side of the rotor laminated core, there is a triangular or trapezoidal area for the arrangement of the holding elements and holes. The axial fixation of the rotor laminated core is particularly successful due to the holding elements being located far outwards in the radial direction.

Glass fibers, aramid fibers, Kevlar fibers or carbon fibers are particularly suitable as fibers in the fiber-reinforced plastic. Composite materials in which the above-mentioned materials are used in combination are also conceivable.

As a rule, a single retaining element is not sufficient for the axial fixation of a Rotor lamination package. Therefore, in one embodiment, a rotor can be provided with several holes corresponding to the hole and with several holding elements corresponding to the holding element, each of which extends axially in one of the holes. For example, the holes and holding elements can be arranged at the same radial distance from a rotor axis and thus on a circle.

Further advantageous embodiments and developments of the invention emerge from the subclaims and from the description in conjunction with the figures.

The holding element can have a thread. For example, the holding element can be designed as a screw or threaded pin onto which a nut is screwed. However, it is also conceivable that the holding element is designed as a (smooth) pin and is fixed in another way.

The holding element can have a circular cross-section, which makes it easy to manufacture. However, the holding element can also have a non-circular cross-section, in particular a polygonal, hexagonal, square, triangular, oval, toothed or star-shaped cross-section. In this way, it can be well protected against twisting. In this context, it is particularly advantageous if the hole corresponds to the cross-section of the holding element. For example, the hole can have the same shape as the cross-section of the holding element. However, it is also conceivable that the cross-section of the holding element and the shape of the hole are different and interact in a different way, for example in that the hole is smaller than at least parts of the holding element. For example, a star-shaped cross-section of the holding element can be arranged in a hole that is slightly too small. The proposed measures prevent the holding element from twisting when it is inserted into the hole. This also eliminates the need to fix the holding element separately with a tool, which means that screw nuts can be easily screwed onto a thread of the holding element. This simplifies the production of a rotor lamination stack and the necessary equipment for machine production.

It is particularly advantageous if the holding element passes through an end plate arranged on an axial side of the rotor lamination stack. The provision of an end plate ensures that the rotor lamination stack is secured axially particularly well. The end plate has holes that correspond to the holes in the rotor lamination stack. This means that in this case the holes pass through the rotor laminations of the rotor lamination stack and through the end plate. It is also conceivable that an end plate is arranged on each of the axial sides of the rotor lamination stack. The second end plate then also has holes that correspond to the holes in the rotor lamination stack.

In one variant, the holding element can have a screw head arranged outside the rotor laminated core. The screw head creates a positive connection between the holding element and the rotor laminated core. In this context, it is also advantageous if a truncated cone-shaped, toothed section is provided axially adjacent to the screw head. In this way, the screw or the screw head can be particularly well secured against twisting. The teeth of the toothed section dig into the rotor laminated core.

As an alternative to the screw head, the holding element can have another type of thickening which is arranged outside the rotor core and creates a positive connection between the holding element and the rotor core.

It is also advantageous if the holding element has a metal sleeve with an external thread at one axial end or at both axial ends, which is attached to the holding element in a form-fitting or force-fitting manner. In this way, the risk of damaging a thread when tightening a screw or nut is avoided or reduced. A form-fitting connection between the metal sleeve and the part of the holding element made of fiber-reinforced plastic can be achieved in particular with an internal thread on the metal sleeve. In order to avoid or reduce the risk of the metal sleeve tearing out, it can be provided that the metal sleeve has a length that is at least three times greater than its external diameter.

SHORT DESCRIPTION OF THE CHARACTERS

• 1 eine schematisch im Halbschnitt dargestellte, beispielhafte elektrische Maschine;
• 2 eine schematisch im Halbschnitt dargestellte, beispielhafte elektrische Maschine mit axialen Endplatten auf dem Rotorblech-Stapel;
• 3 einen beispielhaften polygonförmigen Querschnitt eines Lochs und eines Haltelements;
• 4 einen beispielhaften sternförmigen Querschnitt eines Lochs und eines Haltelements;
• 5 einen beispielhaften ovalen Querschnitt eines Lochs und eines Haltelements;
• 6 einen beispielhaften sternförmigen Querschnitt eines Haltelements in einem kreisförmigen Loch;
• 7 eine Schraube mit einem Schraubenkopf und einem daran angrenzenden kegelstumpfförmigen, gezahnten Abschnitt;
• 8 eine Metallhülse mit einem Außengewinde an einem axialen Ende des Halteelements;
• 9 eine Vorderansicht eines Rotorblechpaktes mit radial außen angeordneten Löchern für die Halteelemente und
• 10 ein beispielhaftes Fahrzeug mit einer elektrischen Maschine der vorgeschlagenen Art.

Embodiments of the invention are shown by way of example in the attached schematic figures. They show:

• 1 an exemplary electrical machine shown schematically in half section;
• 2 an exemplary electrical machine with axial end plates on the rotor lamination stack, shown schematically in half section;
• 3 an exemplary polygonal cross-section of a hole and a retaining element;
• 4 an exemplary star-shaped cross-section of a hole and a holding element;
• 5 an exemplary oval cross-section of a hole and a retaining element;
• 6 an exemplary star-shaped cross-section of a retaining element in a circular hole;
• 7 a screw having a screw head and an adjacent frustoconical, toothed portion;
• 8th a metal sleeve with an external thread at an axial end of the retaining element;
• 9 a front view of a rotor lamination package with radially outwardly arranged holes for the holding elements and
• 10 an exemplary vehicle with an electric machine of the proposed type.

DETAILED DESCRIPTION OF THE INVENTION

To begin with, it should be noted that identical parts in the different embodiments are provided with identical reference symbols or identical component designations, possibly with different indices. The disclosure of a component contained in the description can be transferred analogously to another component with the same reference symbol or identical component designation. The position information chosen in the description, such as "top", "bottom", "back", "front", "side" and so on, also refer to the figure directly described and shown and, if the position changes, are to be transferred analogously to the new position.

1 shows a half-section through a schematically illustrated electrical machine 1a. The electrical machine 1a comprises a rotor shaft 2 as part of a rotor 3a, wherein the rotor shaft 2 is mounted so as to be rotatable about a rotor axis or axis of rotation A relative to a stator 5 with the aid of (rolling) bearings 4a, 4b. Specifically, the first bearing 4a is located in a first front bearing plate 6 and the second bearing 4b in a second, rear bearing plate 7. The electrical machine 1a also comprises a middle housing part 8, which connects the front bearing plate 6 and the rear bearing plate 7 and accommodates the stator 5. The front bearing plate 6, the rear bearing plate 7 and the housing part 8 form the housing 9 of the electrical machine 1a in this example. The stator 5 comprises a stator laminated core 10 with several stator laminates (not shown in detail) and stator windings 11 arranged therein.

The rotor 3a comprises a rotor lamination stack 12a with a rotor lamination stack 13, wherein the rotor lamination stack 12a is mounted on the rotor shaft 2. The rotor lamination stack 13 comprises a plurality of rotor laminations 14 stacked axially on top of one another in a stacking direction, wherein the rotor laminations 14 have recesses which together form a plurality of holes 15a leading through the rotor lamination stack 13 and aligned in the stacking direction (or parallel to the rotor axis A). The rotor lamination stack 13 also has a first end face B1 and an axially opposite second end face B2, wherein the holes 15a in this exemplary embodiment each have a first axial end on the first end face B1 and a second axial end on the second end face B2. In addition, the rotor lamination stack 12a comprises a plurality of holding elements 16 for holding the rotor laminations 14 together, wherein one of the holding elements 16 is guided through one of the holes 15a. In addition, the rotor core 12a comprises several screw nuts 17, which in this example are screwed onto the holding elements 16. The rotor core 12a can be axially secured with the help of the holding elements 16 and the screw nuts 17. The rotor 3a also comprises rotor windings or rotor magnets arranged in the rotor core 12a, which are not shown in detail (see also 9 ). For example, the holding elements 16 and the holes 15a can be arranged at the same radial distance from the rotor axis A and thus on a circle.

Specifically, the holding elements 16 can have a thread and as shown in the 1 be designed as a screw or as a threaded pin onto which the nut 17 is screwed. A screw head is arranged outside the rotor lamination stack 12a or outside the rotor lamination stack 13. However, it is also conceivable that the holding element 16 is designed as a smooth pin and is connected to the rotor lamination stack 12a in another way.

Generally, the holding elements 16 are made of fiber-reinforced plastic or have a fiber-reinforced plastic. As a result, a magnetic field or magnetic flux within the rotor lamination stack 13 is not or only slightly influenced, and the axial securing of the rotor lamination stack 12a can take place without significantly affecting the performance and efficiency of the electrical machine 1a. In particular, glass fibers, aramid fibers, Kevlar fibers or carbon fibers come into consideration as fibers in the fiber-reinforced plastic. Composite materials in which the above-mentioned materials are used in combination are also conceivable.

2 shows an electrical machine 1b, which is 1 is very similar to the electrical machine 1a shown. In contrast, the rotor lamination stack 12b has two end plates 18a, 18b, which are arranged on the end faces B1, B2 of the rotor lamination stack 13.

The end plates 18a, 18b have holes 15b, 15c which correspond to the holes 15a in the rotor lamination stack 13. This means that the holes 15a..15c and the holding elements 16 lead in this case through the rotor laminations 14 of the rotor lamination stack 13 and through the end plates 18a, 18b. As a result, the end plates 18a, 18b exert axial pressure on the rotor lamination stack 13, which ensures that it is axially secured particularly well. It would be conceivable that instead of the nut 17, internal threads are provided in the holes 15b of the end plate 18a, into which the screws 16 are screwed. It would also be conceivable in particular that an end plate 18a is arranged only on the front side B1. The holding elements 16 would then be as in the 1 rest on the rotor lamination stack 13. In principle, it would also be conceivable that an end plate 18b is arranged only on the front side B2.

In general, the holding element 16 and the holes 15a..15c can have a circular cross-section. However, it is also advantageous if the holding element 16 and possibly the holes 15a..15c have a non-circular cross-section, as shown by some examples in the 3 to 6 Specifically, the 3 a holding element 16a with a polygonal (here hexagonal) cross-section in a corresponding hole 15. In this way, rotation of the holding element 16a in the hole 15 can be prevented. This eliminates the need to fix the holding element 16a separately with a tool, which means that screw nuts 17 can be easily screwed onto a thread of the holding element 16a. The manufacture of a rotor laminated core 12a, 12b and the necessary devices for machine production are thereby simplified. Of course, other polygonal cross-sections for the holding element 16a and the hole 15 are also conceivable in this context, for example square, triangular and octagonal cross-sections.

For the same or a similar purpose, the holding element 16b and the hole 15' may have a toothed or star-shaped cross-section, such as that shown in the 4 is shown. In the 4 The toothed or star-shaped cross-section has twelve points, but of course a different number of points would also be conceivable, for example eight, ten or even sixteen points.

For the same or a similar purpose, the holding element 16c and the hole 15" may also have an oval cross-section, such as that shown in the 5 The cross-section is not bound to the width/height ratio shown, but can also have a different shape.

6 finally shows an example of a toothed or star-shaped cross-section of a holding element 16d, which is arranged in a circular hole 15'''. In this embodiment, the teeth of the holding element 16d claw into the rotor laminated core 12a, 12b.

The toothed or star-shaped cross-section does not have to be provided over the entire length of the holding element 16d in order to achieve the specified effect. Instead, the cross-section can be limited to part of the length of the holding element 16d, with another part of the length having, for example, a circular cross-section. It is also conceivable that a truncated cone-shaped, toothed section C is provided axially adjacent to a screw head. In this way, the screw 16e or the screw head can also be particularly well secured against twisting. The teeth of the toothed section C grip into the rotor laminated core 12a, 12b.

8th shows a further embodiment variant for a holding element 16f, which has a metal sleeve 19 with an external thread at one axial end or at both axial ends, which is fastened in a form-fitting or force-fitting manner to the holding element 16f, specifically to the plastic shaft 20 of the holding element 16f made of fiber-reinforced plastic. With the help of the metal sleeve 19, the risk of damage to the thread when screwing into an internal thread of a hole 15a..15c, 15..15''' or when tightening a screw nut 17 can be avoided or reduced. A form-fitting connection between the metal sleeve 19 and the plastic shaft 20 can be achieved in particular with an internal thread on the metal sleeve 19, as in the 8th In order to avoid or reduce the risk of the metal sleeve 19 tearing out, the metal sleeve 19 can have a length L which exceeds its outer diameter D by at least three times.

Advantageously, the holding elements 16 and holes 15 are arranged in the same radial region C as rotor magnets 21 or rotor windings of the rotor 3a..3c. 9 shows an example, specifically a front view of a part of a rotor sheet pa kets 12, in which the rotor magnets 21 are arranged in a V-shape.

Between the rotor magnets 21, as seen from the front side B1, B2 of the rotor lamination stack 12, there are thus triangular or trapezoidal areas C for the arrangement of the holding elements 16 and holes 15. The axial fixation of the rotor lamination stack 12 is particularly successful due to the holding elements 16 located radially far outwards. The fact that the holding elements 16 comprise or are made of a fiber-reinforced plastic is particularly important here, since these materials have little or no influence on the magnetic field generated by the rotor magnets 21 or rotor windings and therefore also on the magnetic flux within the rotor lamination stack 13.

The 10 finally shows the electric machine 1 installed in a vehicle 22. The vehicle 22 has two axles, one of which is driven. Specifically, the electric machine 1 is connected to the half-axles 24 of the rear axle or front axle via an optional transmission 23. Finally, the driven wheels 25 are mounted on the half-axles 24. The electric machine 1, the transmission 23 and the half-axles 24 are part of the drive train of the vehicle 22. The vehicle 22 is driven at least partially or temporarily by the electric machine 1. This means that the electric machine 1 can serve to drive the vehicle 22 alone or, for example, can be provided in conjunction with an internal combustion engine (hybrid drive).

Finally, it is noted that the scope of protection is determined by the patent claims. However, the description and the drawings must be used to interpret the claims. The features contained in the figures can be exchanged and combined with one another as desired. In particular, it is also noted that the devices shown can in reality also comprise more or fewer components than shown. In some cases, the devices shown or their components can also be shown not to scale and/or enlarged and/or reduced.

List of reference symbols

1, 1a, 1b

electric machine

2

Rotor shaft

3a, 3b

rotor

4a, 4b

(Roller bearing

5

stator

6

front bearing shield

7

rear bearing plate

8th

(middle) housing part

9

Housing

10

Stator lamination package

11

Stator winding

12, 12a, 12b

Rotor lamination package

13a, 13b

Rotor sheet stack

14, 14a..14d

Rotor sheet

15a..15c, 15..15'''

Through hole

16, 16a..16f

Screw / threaded pin

17

Mother

18a, 18b

End plate

19

Metal sleeve

20

Plastic shaft

21

vehicle

22

transmission

23

Half-axis

24

Wheel

A

Rotation axis

B1, B2

Front side / axial side

C

truncated cone-shaped, serrated section

D

Diameter metal sleeve

L

Length metal sleeve

Claims (12)

Rotor (3a, 3b) for an electrical machine (1, 1a, 1b), comprising - a rotor laminated core (12, 12a, 12b) with a plurality of rotor laminated cores (14, 14a..14d) stacked axially on top of one another, which have recesses which form a hole (15a..15c, 15..15''') leading axially through the rotor laminated core (12, 12a, 12b), and - a holding element (16, 16a..16f) extending axially in the hole (15a..15c, 15..15''') for holding the rotor laminated cores (14) together, characterized in that - the holding element (16, 16a..16f) is made of fiber-reinforced plastic or has a fiber-reinforced plastic. Rotor (3a..3c) after Claim 1 , characterized in that the holding element (16, 16a..16f) has a thread. Rotor (3a..3c) after Claim 1 or 2 , characterized in that the holding element (16, 16a..16f) has a polygonal, hexagonal, square, triangular, circular, oval, toothed or star-shaped cross-section. Rotor (3a..3c) after Claim 3 , characterized in that a cross section of the hole (15a..15c, 15..15''') corresponds to the cross section of the holding element (16, 16a..16f). Rotor (3a..3c) according to one of the preceding claims, characterized in that the holding element (16, 16a..16f) leads through an end plate (18a, 18b) arranged on an axial side (B1, B2) of the rotor laminated core (12, 12a, 12b). Rotor (3a..3c) according to one of the preceding claims, characterized in that the holding element (16, 16a..16f) has a screw head arranged outside the rotor laminated core (12, 12a, 12b). Rotor (3a..3c) after Claim 6 , characterized by a frustoconical, toothed section (C) axially adjacent to the screw head. Rotor (3a..3c) according to one of the preceding claims, characterized in that the holding element (16, 16a..16f) has at one axial end or at both axial ends a metal sleeve (19) with an external thread, which is fastened to the holding element (16, 16a..16f) in a form-fitting or force-fitting manner. Rotor (3a..3c) according to one of the preceding claims, with a plurality of holes (15a..15c, 15..15''') corresponding to the hole (15a..15c, 15..15''') and a plurality of holding elements (16, 16a..16f) corresponding to the holding element (16, 16a..16f), each of which extends axially in one of the holes (15a..15c, 15..15'''). Rotor (3a..3c) according to one of the preceding claims, characterized in that the holding elements (16, 16a..16f) are arranged in the same radial region (C) as rotor magnets (21) or rotor windings of the rotor (3a..3c). Electric machine (1a..1c) with a rotor (3a..3c) according to one of the preceding claims. Vehicle (22) with an electric machine (1a..1c) according to Claim 11 which is intended to drive the vehicle (22).

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