DE102021123696A1 - Electrical axial flow machine - Google Patents

Abstract

The invention relates to an electrical axial flow machine (1), comprising a stator (2) and a rotor (3), the rotor (3) having a rotor shaft (30) with at least a first disc-shaped design which can rotate on the rotor shaft (30). and non-displaceably arranged, rotor body (31), wherein the stator (2) comprises at least one first annular disc-shaped stator body (21) which is arranged coaxially to the rotor shaft (30), and being between the first annular disc-shaped stator body (21) and the rotor (3) a first air gap is formed at a distance in the axial direction, the axial flow machine (1) also having a cylindrical motor housing (4) which in the axial direction encloses at least the first stator body (21) in the form of a ring disk and the rotor (3), wherein an inner lateral surface (41) of the motor housing (4) at least in sections has a first knurling (42) which is so in the outer lateral surface (22) of the first stator body ers (21) of the stator (2) engages in that the first stator body (21) is non-rotatably and axially fixed in the cylindrical motor housing (4).

Description

The present invention relates to an electrical axial flow machine, comprising a stator and a rotor, the rotor having a rotor shaft with at least one first disk-shaped rotor body arranged on the rotor shaft in a rotationally and non-displaceably fixed manner, the stator comprising at least one first annular disk-shaped stator body which is arranged coaxially to the rotor shaft, and wherein a first air gap is formed between the first annular disk-shaped stator body and the rotor, spaced apart in the axial direction, the axial flux machine also having a cylindrical ring-shaped motor housing that encloses at least the first annular disk-shaped stator body and the rotor in the axial direction .

Electric motors are increasingly being used to drive motor vehicles in order to create alternatives to internal combustion engines that require fossil fuels. Significant efforts have already been made to improve the suitability for everyday use of electric drives and also to be able to offer users the driving comfort they are accustomed to.

A detailed description of an electric drive can be found in an article in the ATZ magazine, volume 113, 05/2011, pages 360-365 by Erik Schneider, Frank Fickl, Bernd Cebulski and Jens Liebold with the title: Highly integrative and flexible electric drive unit for electric Vehicles. This article describes a drive unit for an axle of a vehicle, which includes an electric motor that is arranged concentrically and coaxially with a bevel gear differential, with a switchable 2-speed planetary gear set being arranged in the power train between the electric motor and the bevel gear differential, which is also is positioned coaxially to the electric motor or the bevel gear differential or spur gear differential. The drive unit is very compact and allows a good compromise between climbing ability, acceleration and energy consumption due to the switchable 2-speed planetary gear set. Such drive units are also referred to as e-axles or electrically operable drive train.

In addition to purely electrically operated drive trains, hybrid drive trains are also known. Such drive trains of a hybrid vehicle usually include a combination of an internal combustion engine and an electric motor, and allow - for example in urban areas - a purely electric mode of operation with simultaneous sufficient range and availability, especially for cross-country trips. In addition, there is the possibility, in certain operating situations, to be driven simultaneously by the internal combustion engine and the electric motor.

An axial flux machine is a dynamo-electric machine in which the magnetic flux between the rotor and stator runs parallel to the axis of rotation of the rotor. Often, both the stator and the rotor are largely disc-shaped. Axial flow machines are particularly advantageous when the space available axially is limited in a given application. This is often the case, for example, with the electric drive systems for electric or hybrid vehicles described at the outset.

In addition to the shortened axial length, another advantage of the axial flow machine is its comparatively high torque density. The reason for this is the larger air gap area compared to radial flux machines, which is available for a given installation space. Furthermore, a lower iron volume is required compared to conventional machines, which has a positive effect on the efficiency of the machine.

As a rule, an axial flux machine includes at least one stator that has windings for generating the axially aligned magnetic field. At least one rotor is equipped with permanent magnets, for example, whose magnetic field generates a drive torque via an air gap in interaction with the magnetic field of the stator windings.

It is fundamentally known to design such stators for axial flow machines with a multilayer circuit board. A multi-layer circuit board or multi-layer circuit board is to be understood as meaning a printed circuit board that has a number of superimposed levels, each of which is equipped with conductor tracks.

From the EP 2863524 A1 a stator for an axial flow machine is known, which is designed in the form of a printed circuit board (PCB). The PCB is designed as a multilayer circuit board, ie it includes several layers with conductor tracks on top of each other. This allows the windings of a coil to be distributed over these multiple layers.

It is also known in principle to fix such printed circuit boards of a stator in a motor housing by means of a press fit. However, this requires a high machining accuracy and tight workpiece tolerances, which are difficult to guarantee in practice and if so, only with a high and cost-intensive manufacturing effort.

It is therefore the object of the invention to provide an electrical axial flow machine, wel che reduces or completely avoids the disadvantages known from the prior art and allows the stator to be fixed in the motor housing in a cost-effective and secure manner.

This object is achieved by an electrical axial flow machine, comprising a stator and a rotor, the rotor having a rotor shaft with at least one first disk-shaped rotor body arranged on the rotor shaft in a rotationally fixed and non-displaceable manner, the stator comprising at least one first annular disk-shaped stator body , which is arranged coaxially to the rotor shaft, and wherein a first air gap is formed between the first annular disk-shaped stator body and the rotor, spaced apart in the axial direction, the axial flux machine also having a cylindrical motor housing that in the axial direction contains at least the first annular disk-shaped stator body and the Framed rotor, wherein an inner surface of the motor housing has at least partially a first knurling, which engages in such a way in the outer surface of the first stator body of the stator that the first stator body in the cylindrical Mo gate housing is non-rotatable and axially fixed.

Due to the sharp edges present in knurling, the knurling cuts into the material of the stator body and correspondingly displaces the material of the stator body.

As a result, a press fit can be realized between the stator body and the motor housing, which has only very low accuracy and tolerance requirements, so that it can be produced inexpensively. In particular, the accuracy of the diameter of the stator body can preferably be +−100 μm. In this case, no post-processing of the stator body is then necessary, which has a further positive effect on the production costs. The knurling is designed and configured in such a way that the stator body is secured against twisting and is axially clamped relative to the motor housing in accordance with the motor forces acting on it.

First, the individual elements of the claimed subject matter of the invention are explained in the order in which they are mentioned in the set of claims, and particularly preferred configurations of the subject matter of the invention are described below.

The magnetic flux in an electrical axial flux machine (AFM) according to the invention is directed axially in the air gap between the stator and rotor to a direction of rotation of the rotor of the axial flux machine. There are different types of axial flow machines. A known type is a so-called I-arrangement, in which the rotor is arranged axially next to a stator or between two stators. Another known type is a so-called H-arrangement, in which two rotors are arranged on opposite axial sides of a stator. The axial flux machine according to the invention can be configured as an I or H type. In principle, it is also possible for a plurality of rotor-stator configurations to be arranged axially next to one another as an I-type and/or H-type. It would also be possible in this context to arrange both one or more I-type rotor-stator configurations and one or more H-type rotor-stator configurations next to one another in the axial direction. In particular, it is also preferable that the rotor-stator configuration of the H-type and/or the I-type are each configured essentially identically, so that they can be assembled in a modular manner to form an overall configuration. Such rotor-stator configurations can in particular be arranged coaxially to one another and can be connected to a common rotor shaft or to a plurality of rotor shafts.

The rotor of an electrical axial flow machine can preferably be designed at least in parts as a laminated rotor. A laminated rotor is formed in layers in the axial direction. Alternatively, the rotor of an axial flow machine can also have a rotor carrier or rotor body, which is designed to be fitted with magnetic sheets and/or SMC material and with magnetic elements designed as permanent magnets.

A rotor body preferably has an inner part, via which the rotor can be connected to a shaft in a rotationally fixed manner, and an outer part, which outwardly delimits the rotor in the radial direction. The rotor body can be designed with several rotor struts between the inner part and the outer part, via which the inner part and the outer part are connected to one another and which, together with the radial outer surface of the inner part and the radial inner surface of the outer part, form a receiving space for accommodating the magnetic elements and the flux-guiding elements of the rotor forms. As an alternative to the receiving space, the magnetic elements can be arranged or placed on the rotor carrier.

A magnet element can be in the form of a permanent magnet in the form of a bar magnet or in the form of smaller magnet blocks designed as blocks. The magnetic elements are usually arranged in, on or on a rotor carrier. The magnetic element of a rotor of an axial flow machine, designed as a permanent magnet, is in Interaction with a rotating magnetic field which is generated by the stator winding coils, which are usually charged with a three-phase current.

A rotatably mounted shaft of an electrical machine is referred to as a rotor shaft, with which the rotor or rotor body is coupled in a torque-proof manner.

The stator of an electrical axial flow machine preferably has a stator body with a plurality of stator windings arranged in the circumferential direction. Viewed in the circumferential direction, the stator body can be designed in one piece or in segments. The stator body can be formed from a laminated stator core with a plurality of laminated electrical laminations. Alternatively, the stator body can also be formed from a pressed soft magnetic material, such as the so-called SMC material (Soft Magnetic Compound).

The axial flow machine according to the invention has a motor housing. The motor housing encloses the electric machine. A motor housing can also accommodate the control and power electronics. The motor housing can also be part of a cooling system for the electric machine and can be designed in such a way that cooling fluid can be supplied to the electric machine via the motor housing and/or the heat can be dissipated to the outside via the housing surfaces. In addition, the motor housing protects the electrical machine and any electronics that may be present from external influences.

A motor housing can be formed in particular from a metallic material. Advantageously, the motor housing can be formed from a cast metal material, such as gray cast iron or cast steel. In principle, it is also conceivable to form the motor housing entirely or partially from a plastic. The motor housing particularly preferably has a cylindrical basic shape. The motor housing can be made in one piece or in several pieces.

According to an advantageous embodiment of the invention, it can be provided that a first annular disk-shaped stator body and/or a second annular disk-shaped stator body are designed as a printed circuit board, in particular as a printed circuit, which is also referred to as a printed circuit board PCB, which makes the stator body particularly compact and can be produced inexpensively. The winding of the stator body is designed in one piece with the printed circuit board. The printed circuit board is preferably a multilayer printed circuit board with a number of copper layers over which the stator windings extend. Another possible embodiment is the design of the stator body as a sandwich of several multilayer circuit boards. The circuit board is preferably formed from a composite of epoxy resin and glass fiber.

In a likewise preferred embodiment variant of the invention, it can also be provided that the first stator body in the form of a ring disk and/or the second stator body in the form of a ring disk are received in the motor housing in a rotationally fixed manner and are connected to it, so that separate spacer elements between the stators can be dispensed with, for example.

According to a further preferred embodiment of the subject matter of the invention, it can be provided that the motor housing is formed from a metallic material and/or ceramic and/or a plastic and/or from a composite material.

According to a further preferred further development of the invention, it can also be provided that at least the first stator body is designed as a multilayer PCB and/or a plurality of carrier plates are arranged stacked on one another in layers.

The knurling preferably has structures that protrude radially inwards from the inner lateral surface of the motor housing. For example, one of the structures can be selected from the group of knurls with axially parallel grooves, left-hand knurls, right-hand knurls, left-right knurls with raised tips (checkering), crossed knurls with raised tips and/or circular knurls. Of course, any combination of these structures is also conceivable with knurling. Sharp-edged structures that are suitable for cutting into the lateral surface of a stator body are particularly preferred in connection with the invention. It is also possible for the structures of the knurling to be shaped in such a way that they caulk or press the lateral surface of a stator body locally.

The knurling can be produced without cutting, for example by knurling. It is also possible to shape the knurling by means of machining manufacturing processes, for example by means of knurling.

According to an advantageous embodiment of the invention, it can be provided that the first knurling is formed via a closed circular path on the inner surface of the motor housing. The advantage of this configuration lies in the fact that a particularly large contact surface can be provided for the press fit, which leads to correspondingly high supporting forces and torques.

According to a further preferred development of the invention, it can also be provided that the first stator body of the stator is configured as a printed circuit board. It can hereby be achieved that the stator can be produced particularly compactly and inexpensively.

Furthermore, according to a likewise advantageous embodiment of the invention, provision can be made for the first stator body to have an annular fixing region which extends radially inwards from the outer lateral surface and into which the first knurling of the motor housing engages and/or which extends through the first knurling of the motor housing is deformed, wherein the fixing area of the first stator body is not penetrated by a stator winding. A kind of ring-shaped “sacrificial zone” is thus created in the stator body by the fixing area. This zone or the fixing area can be partially cut away by the knurling and/or severely deformed without affecting the electrical conductor tracks in the neighboring areas. For example, tooth-like knurling creates areas of high pressure in the fixing area, which enables the stator body to be held, with the resulting form fit of the knurling also being able to support torques acting on it well. Since the knurling only presses in sections and not over the entire surface, the pressing does not cause any deeper destruction in the stator body outside of the fixing area.

According to a further particularly preferred embodiment of the invention, provision can be made for the first knurling to be formed from a metallic or ceramic material. In this way, the effect can be achieved in particular that the knurling can be designed to be particularly dimensionally stable and abrasion-resistant. Furthermore, the invention can also be further developed in such a way that the first knurling is formed in one piece, in particular monolithically, with the motor housing, as a result of which production and assembly can be implemented particularly cheaply.

In a likewise preferred embodiment variant of the invention, it can also be provided that the fixing area of the first stator body is formed from a plastic, in particular from a fiber-reinforced epoxy resin. It can also be advantageous to develop the invention further such that the fixing area of the first stator body is designed in one piece, in particular monolithically, with the first stator body, which again promotes good manufacture and assembly.

According to a further preferred embodiment of the subject matter of the invention, it can be provided that a press fit is formed between the first stator body and the motor housing.

In this way it can be achieved that a particularly secure seat can be formed between the rotor body and the motor housing.

Finally, the invention can also be advantageously implemented in such a way that the inner lateral surface of the motor housing has a second knurling, at least in sections, which is configured to engage in an outer lateral surface of a second stator body of the stator, so that the second stator body of the stator is in the cylindrical Motor housing is rotatably and axially fixed. The advantage that results from this is, in particular, that a stator of an axial flux machine configured in an I design with two stator bodies can be securely accommodated and fixed in a motor housing. The first knurling and the second knurling are preferably of essentially identical design.

The invention will be explained in more detail below with reference to figures without restricting the general inventive idea.

• 1 eine Axialflussmaschine in einer Explosionsdarstellung und
• 2 ein Motorgehäuse in einer freigestellten, perspektivischen Ansicht.

It shows:

• 1 an axial flow machine in an exploded view and
• 2 a motor housing in an isolated, perspective view.

The 1 shows an electrical axial flow machine 1 in I-design, comprising a stator 2 and a rotor 3, the rotor 3 having a rotor shaft 30 with at least one first rotor body 31, which is designed in the shape of a disk and is arranged on the rotor shaft 30 in a rotationally and non-displaceably fixed manner.

The rotor 3 has a plurality of receiving slots 32 distributed equidistantly over the circumference and running radially through the rotor body 31, in each of which a rotor magnet 33 is fixed.

The stator 2 has a first annular disc-shaped stator body 21 which is arranged coaxially with the rotor shaft 30 . A first air gap is formed at a distance in the axial direction between the first annular disc-shaped stator body 21 and the rotor 3 . The first stator body 21 of the stator 2 is configured as a circuit board.

Like in the 1 is also shown, the first stator body 21 has an annular fixing region 23 which extends radially inwards from the outer lateral surface 22 and into which the first knurling 42 of the motor housing 4 engages and/or which through the first knurling 42 of the motor housing 4 is deformed. The fixing region 23 of the first stator body 21 is not penetrated by a stator winding, so that it is not mechanically deformed and/or electrically severed by the knurling 42, for example.

The fixing area 23 of the first stator body 21 is formed from a plastic, in particular a fiber-reinforced epoxy resin, the fixing area 23 of the first stator body 21 being formed in one piece, in particular monolithically, with the first stator body 21 .

The axial flow machine 1 also has a motor housing 4 in the form of a cylindrical ring, which encloses at least the first annular disc-shaped stator body 21 and the rotor 3 in the axial direction. In the embodiment shown 1 The axial flux machine 1 configured as an I-type also includes a cylindrical motor housing 4 that in the axial direction encloses the first annular disk-shaped stator body 21 , the rotor 3 and also the second annular disk-shaped stator body 25 .

An inner lateral surface 41 of the motor housing 4 has, at least in sections, a first knurling 42 which engages in the outer lateral surface 22 of the first stator body 21 of the stator 2 in such a way that the first stator body 21 is non-rotatably and axially fixed in the cylindrical motor housing 4. A press fit is formed between the first stator body 21 and the motor housing 4 , so that the stator body 21 is accommodated in the motor housing 4 in a rotationally fixed and axially secured manner.

In the embodiment of 1-2 first knurling 42 is formed via a closed annular path on the inner lateral surface 41 of the motor housing 4, the first knurling 42 being formed from a metallic or ceramic material and being formed in one piece, in particular monolithically, with the motor housing 4.

Based on 2 It is easy to see that the inner lateral surface 41 of the motor housing 4 has a second knurling 43, at least in sections, which is configured to engage in an outer lateral surface 24 of a second stator body 25 of the stator 2, so that the second stator body 25 of the stator 2 in the cylindrical motor housing 4 is rotatably and axially fixed. The second stator body 25 and the first stator body 21 are of essentially identical design. Correspondingly, the first knurling 42 and the second knurling 43 are also shaped essentially identically.

The invention is not limited to the embodiments shown in the figures. The foregoing description is therefore not to be considered as limiting but as illustrative. The following patent claims are to be understood in such a way that a mentioned feature is present in at least one embodiment of the invention. This does not exclude the presence of other features. If the patent claims and the above description define 'first' and 'second' feature, this designation serves to distinguish between two similar features without establishing a ranking.

reference list

1

axial flow machine

2

stator

3

rotor

4

motor housing

21

stator body

22

lateral surface

23

fusing area

24

lateral surface

25

stator body

30

rotor shaft

31

rotor body

32

receiving slots

33

rotor magnet

41

lateral surface

42

knurling

43

knurling

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 2863524 A1 [0009]

Claims (10)

Electrical axial flux machine (1), comprising • a stator (2), and • a rotor (3), wherein the rotor (3) has a rotor shaft (30) with at least a first disc-shaped design, on the rotor shaft (30) rotationally and non-rotatably arranged, rotor body (31), wherein • the stator (2) comprises at least one first annular disk-shaped stator body (21), which is arranged coaxially to the rotor shaft (30), and wherein between the first annular disk-shaped stator body (21) and the rotor ( 3) a first air gap is formed at a distance in the axial direction, • the axial flux machine (1) also having a cylindrical motor housing (4) which in the axial direction encloses at least the first annular disc-shaped stator body (21) and the rotor (3), thereby characterized in that an inner lateral surface (41) of the motor housing (4) has, at least in sections, a first knurling (42) which is inserted into the outer lateral surface (22) of the first St atorkörpers (21) of the stator (2) engages that the first stator body (21) in the cylindrical motor housing (4) is non-rotatably and axially fixed. Electrical axial flow machine (1) according to claim 1 , characterized in that the first knurling (42) is formed over a closed circular path on the inner lateral surface (41) of the motor housing (4). Electrical axial flow machine (1) according to one of the preceding claims, characterized in that the first stator body (21) of the stator (2) is configured as a circuit board. Electrical axial flow machine (1) according to one of the preceding claims, characterized in that the first stator body (21) has an annular fixing region (23) which extends radially inwards from the outer lateral surface (22) and in which the first knurling (42) of the Motor housing (4) engages and / or which is deformed by the first knurling (42) of the motor housing (4), wherein the fixing area (23) of the first stator body (21) is not penetrated by a stator winding. Electrical axial flow machine (1) according to one of the preceding claims, characterized in that the first knurling (42) is formed from a metallic or ceramic material. Electrical axial flow machine (1) according to one of the preceding claims, characterized in that the first knurling (42) is formed in one piece, in particular monolithically, with the motor housing (4). Electrical axial flow machine (1) according to any one of the preceding Claims 4 - 6 , characterized in that the fixing area (23) of the first stator body (21) is formed from a plastic, in particular from a fiber-reinforced epoxy resin. Electrical axial flow machine (1) according to any one of the preceding Claims 4 - 7 , characterized in that the fixing area (23) of the first stator body (21) is formed in one piece, in particular monolithically, with the first stator body (21). Electrical axial flow machine (1) according to one of the preceding claims, characterized in that a press fit is formed between the first stator body (21) and the motor housing (4). Electrical axial flow machine (1) according to one of the preceding claims, characterized in that the inner lateral surface (41) of the motor housing (4) has, at least in sections, a second knurling (43) which is configured in an outer lateral surface (24) of a second stator body (25) of the stator (2) so that the second stator body (25) of the stator (2) is non-rotatably and axially fixed in the cylindrical motor housing (4).

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