DE102021214732A1 - Electrical machine with a multi-part coupling device - Google Patents

Abstract

An electric machine (1; 1') comprises: a stator (10; 10'); a rotor (11; 11') rotatable relative to the stator (10; 10'); a shaft (12) rotatable relative to the stator (10; 10'); and a coupling device (13; 13'; 13'') with at least one first connecting part (130; 130'; 130'') fixed to the rotor (11; 11') and at least one second connecting part ( 131; 131'; 131''), which are connected to one another via a plurality of elastic sleeves (132).

Description

The present disclosure relates in particular to an electric machine and a vehicle with such an electric machine.

In the case of electric motors and other electrical machines, the aim is to continuously improve the target parameters of energy efficiency, power-to-weight ratio, reliability and service life. A low weight of the drives is also important for low energy consumption in mobile applications (e.g. in vehicle construction). The requirements described apply in particular to use in aircraft. External forces can also act. In an aircraft, for example, crosswinds or the like can exert axial or radial forces on a propeller driven by an electric motor on a shaft connecting the electric motor to the propeller. A correspondingly stiff bearing of the shaft is therefore regularly provided in order to absorb these forces. However, such bearings often have a relatively high weight. In addition, the forces mentioned can lead to wear of the corresponding components.

The object of the present invention is to provide an improved electrical machine.

According to one aspect, an electric machine is provided, e.g. for a vehicle, in particular for an aircraft. The electric machine includes a stator; a rotor rotatable relative to the stator; a shaft rotatable relative to the stator; and a coupling device. The coupling device comprises at least one first connecting part fastened to the rotor and at least one second connecting part fastened to the shaft, which are connected to one another via a plurality of elastic sleeves.

This configuration of the coupling device allows the shaft to move axially and radially relative to the stator. The elastic sleeves allow this movement. At the same time, a torque can be transmitted between the rotor and the shaft with the coupling device. The coupling device elastically decouples the rotor from the shaft in the axial and radial directions. No lubricant is required for this, and the electric machine can therefore be used particularly well as a direct drive unit without the need for a lubrication system. The electrical machine is, for example, an electric motor.

The shaft can be arranged and aligned concentrically to the rotor. Viewed in the axial direction, the shaft and rotor can overlap. This enables a compact design.

The stator can be arranged so that it surrounds the shaft on the outside. The shaft can therefore extend into the stator. This also allows for a compact design.

It can be provided that the rotor surrounds the stator on the outside. The electrical machine can therefore be designed as an external rotor. The coupling device enables an efficient and robust coupling of the external rotor to the shaft.

For example, the coupling device is mounted on an annular first attachment area on the rotor and/or mounted on an annular second attachment area on the shaft. This allows a particularly secure connection. It can be provided that the coupling device is in contact with the rotor at the (entire) first fastening area and/or that the coupling device is in contact with the shaft at the (entire) second fastening area.

The first attachment area may have a diameter that is larger than the diameter of the second attachment area. For example, an internal shaft can be connected to the electrical machine designed as an external rotor. A distance can be bridged in a direction perpendicular to a direction of rotation of the shaft relative to the stator.

Optionally, the coupling device includes at least or exactly three elastic sleeves. This enables a particularly secure coupling.

The elastic sleeves are made of rubber, for example. This enables sufficient elasticity with good torque transmission at the same time.

The coupling device can have a plurality of socket connections, with each of the socket connections comprising one of the respective elastic sleeves. This enables a particularly secure connection, which holds the connection parts securely together even if one or more of the elastic sleeves fails.

The coupling device can have multiple arms. At least one (e.g. exactly one, exactly two or more than two) of the elastic sleeves can be held on each of the arms. For example, a space is formed between the arms. A particularly low weight of the coupling device is thus possible.

At least one of the arms can have a fork. The fork can grip the elastic sleeve of the corresponding arm. This enables particularly secure mounting in both axial directions.

Optionally, exactly one first connection part and exactly one second connection part are provided. Provision can be made for the first connecting part and/or the second connecting part (each) to have a flange. This enables secure attachment.

Alternatively or additionally, the second connecting part has, for example, a polygonal connecting section, for example a cuboid pin. This allows a positive connection and reliable torque transmission.

The rotor drives a propeller, for example. This allows, for example, the generation of thrust.

According to one aspect, a vehicle is specified, in particular an aircraft. The vehicle, in particular an aircraft, includes the electric machine according to any configuration described herein. In the case of a vehicle, in particular an aircraft, the advantages described above come into play to a particular extent.

• 1 ein Luftfahrzeug mit mehreren elektrischen Maschinen zum Antrieb mehrerer Propeller;
• 2 eine Prinzipskizze einer der elektrischen Maschinen des Luftfahrzeugs gemäß 1 mit einem Stator, einem Rotor und einer Kopplungsvorrichtung;
• 3 eine elektrische Maschine des Luftfahrzeugs gemäß 1 in einer perspektivischen Ansicht mit Blick auf die Kopplungsvorrichtung;
• 4 die Kopplungsvorrichtung der elektrischen Maschine gemäß 3;
• 5 eine Detailansicht einer Buchsenverbindung der Kopplungsvorrichtung gemäß 3;
• 6 eine aufgeschnittene Ansicht der Buchsenverbindung der Kopplungsvorrichtung gemäß 5;
• 7 eine aufgeschnittene Ansicht der elektrischen Maschine mit der Kopplungsvorrichtung gemäß 3;
• 8 eine elektrische Maschine für das Luftfahrzeug gemäß 1 in einer perspektivischen Ansicht mit Blick auf eine Kopplungsvorrichtung;
• 9 eine elektrische Maschine für das Luftfahrzeug gemäß 1 in einer perspektivischen Ansicht mit Blick auf eine Kopplungsvorrichtung;
• 10A-10D verschiedene Schritte in der Herstellung der elektrischen Maschine gemäß 8; und
• 11 eine aufgeschnittene Ansicht der elektrischen Maschine mit der Kopplungsvorrichtung gemäß 8 mit einer demgegenüber anders ausgestalteten Anbindung an eine Welle.

Exemplary embodiments will now be described with reference to the figures; show in the figures:

• 1 an aircraft with multiple electrical machines for driving multiple propellers;
• 2 according to a schematic diagram of one of the electrical machines of the aircraft 1 with a stator, a rotor and a coupling device;
• 3 according to an electrical machine of the aircraft 1 in a perspective view looking at the coupling device;
• 4 according to the coupling device of the electrical machine 3 ;
• 5 a detailed view of a socket connection of the coupling device according to FIG 3 ;
• 6 a cut-away view of the socket connection of the coupling device according to FIG 5 ;
• 7 a cut-away view of the electric machine with the coupling device according to FIG 3 ;
• 8th according to an electrical machine for the aircraft 1 in a perspective view looking at a coupling device;
• 9 according to an electrical machine for the aircraft 1 in a perspective view looking at a coupling device;
• 10A-10D various steps in the manufacture of the electric machine according to 8th ; and
• 11 a cut-away view of the electric machine with the coupling device according to FIG 8th with a different connection to a shaft.

1 shows an aircraft 2 in the form of an air taxi. The aircraft 2 includes a cabin 20 and several, here four, electrical machines 1, each in the form of an electric motor. Each of the electrical machines 1 drives a propeller 22 . For this purpose, each of the propellers 22 is operatively connected to a rotor of the respective electrical machine 1 (eg attached to it). A battery 21 supplies electrical power to operate the electrical machines 1. In the present case, the electrical machines 1 are direct drives.

2 illustrates the basic structure of the example according to 1 mutually identical electrical machines 1.

The electric machine 1 comprises a stator 10, a rotor 11 that can be rotated about an axis of rotation A relative to the stator 10, a shaft 12 that can be rotated about the axis of rotation A relative to the stator 10, and a coupling device 13 with a first connecting part 130 fixed to the rotor 11 and a second connection part 131 fixed to the shaft 12. The connection parts 130, 131 are connected to one another via a plurality of socket connections V. In concrete terms, the connecting parts 130, 131 are connected to one another via a plurality of elastic sleeves at the socket connections V, as will be explained in more detail below.

This allows relatively high torques to be transmitted and radial mobility at a relatively low weight. The coupling device 13 allows a radial movement (perpendicular to the axis of rotation A) of the shaft 12 relative to the rotor 11. In particular, vibrations can be decoupled. Torque can be transmitted in both directions. The coupling device 13 allows a particularly simple construction of the electric machine 1. Furthermore, the coupling device 13 is essentially wear-free and can be adapted to different engine designs.

The electrical machine 1 is designed as an external rotor. The rotor 11 surrounds the stator 10. The stator 10 is arranged inside the rotor 11. The stator 10 is fixed to a supporting structure 17 . The supporting structure 17 is attached to the aircraft 2 . The shaft 12 is rotatably mounted on the supporting structure 17 (alternatively or additionally on the stator 10). The shaft 12 is arranged coaxially and concentrically with the rotor 11 and the stator 10 .

The stator 10 is thus arranged between the rotor 11 and the shaft 12 . There is a clearance between the rotor 11 and the shaft 12 . The coupling device 13 bridges this distance.

The propeller 22 is operatively connected to the shaft 12, namely fastened to the shaft 12 in the present case. The propeller 22 can be rotated via the shaft 12 by rotating the rotor 11 relative to the stator 10 .

3 shows the electrical machine 1. As can be seen, the coupling device 13 is connected to the outer rotor 11. The first connecting part 130 is fixed to the rotor 11 with a flange F1. The flange F1 touches the rotor 11 at an annular attachment area B1. Here, the second connecting part 131 is fixed to the shaft 12 (specifically, at an axial end thereof) with a flange F2. In this case, that flange F2 touches the shaft 12 at an annular (second) attachment area B2. The first connecting part 130 has a diameter D1 larger than the diameter D2 of the second connecting part 131. The flange F1 of the first connecting part 130 has a larger diameter than the flange F2 of the second connecting part 131. The first connecting part 130 forms a circular one outer edge. The second connection part 131 forms a circular opening.

The connecting parts 130, 131 are arranged offset to one another in the axial direction (with respect to the axis of rotation A). The flange F2 is arranged inside the stator 10 and the rotor 11 .

Further details of the geometry of the coupling device 13 are in particular based on the 3 until 7 apparent.

It can be seen in particular that the second connecting part 131 has a plurality of arms 137A, namely three in this case. The arms 137A are equidistant from each other. About the axis of rotation A, the arms 137A are offset from one another by 120 degrees. The arms 137A of the second connecting part 131 each narrow outwardly from the flange F2. In plan view along axis of rotation A, arms 137A are generally triangular. The arms 137A each have a plurality of openings. As a result, a particularly low weight can be achieved despite the high torque that can be transmitted.

A female connection V is provided at the end of each of the arms 137A remote from the flange F2. The female connections V are each formed by a retaining cylinder 139 and a bolt 133 (or other elongate element) housed therein, with the interposition of an elastic sleeve 132. The bolt 133 is in two openings one at the opposite end of the flange F2 of each fork 138 provided on arms 137A. The elastic sleeves 132 are each made of rubber here. In the present case, the elastic sleeves 132 are made of a (much) more elastic material than the connecting parts 130, 131. The latter are made of steel, for example. In the present case, the elastic sleeves 132 have a hollow-cylindrical shape. It should be noted that in the 4 and 7 the elastic sleeve 132 and the bolt 133 are shown on only one of the socket connections V for the purpose of illustration.

The bolt 133 is designed in the form of a fitted screw. A nut, for example a lock nut, secures the bolt 133 in the assembled state. How in particular based on the 6 As can be seen, each of the elastic sleeves 132 is arranged between an inner ring R1 and an outer ring R2. The outer ring R2 is surrounded by the holding cylinder 139. The bolt 133 is inserted into the inner ring R1. Here, the fork 138 encompasses the holding cylinder 139 with the elastic sleeve arranged therein. The fork 138 has two parallel sections between which a distance is formed. Two washers are engaged with bolt 133 on each side of elastic sleeve 132 .

Each of the holding cylinders 139 is fixed to a respective arm 137B of the first connecting part 130 . This arm 137B of the first link 130 is substantially smaller than the corresponding arm 137A of the second link 131. Each of the arms 137A of the second link 131 is J-shaped in cross-section (having a curvature in only one direction). Each of the arms 137A of the first connecting part 131 describes an S-shape (having two bends in opposite directions) in cross section.

So-called “shock mounts” can be used for the socket connections V. The Socket connections V serve as vibration absorbers.

As in particular in 7 As can be seen, the electric machine 1 in the example shown is designed in the form of a transverse flux motor. The rotor 11 has a magnet holder 110 on which several magnets 11 are fixed, here in the form of permanent magnets. The stator 10 has a coil holder 100 to which electrical coils are fixed. Electric current can be applied to the coils, for example an alternating current, in particular a three-phase alternating current. As a result, a rotating magnetic field is generated, through which a force is exerted on the magnets 11 , which then causes the rotor 11 to rotate about the axis of rotation A relative to the stator 10 . The magnetic fields act in the axial direction.

The stator 10 has ribs for cooling the coils. The rotor 10 is rotatably mounted on the stator 10 by means of at least one, in particular several, in this case two, bearings 15 . Also shown is an end of the shaft 12 on which the shaft 12 is supported by a bearing 16, here on a portion of the supporting structure on which the stator 10 is also mounted.

8th shows the electrical machine 1 with a slightly modified embodiment of the coupling device 13'. The 10A-10D show several steps in a method for producing the electrical machine 1 according to FIG 8th . In contrast to the coupling device 13 described above, the coupling device 13' according to FIG 8th and 10A-10D provided that in each of the socket connections V (also three in this example) the holding cylinder 139 with the elastic sleeve 132 arranged therein is formed on the respective arm 137A of the second connection part 131'. A fork is not provided here. An opening 136 through which the bolt 133 passes is formed on the corresponding arm 137B of the second connecting part 130'.

Furthermore, the second connecting part 131 ′ comprises a connecting section, in this case a polygonal connecting section 135 , for form-fitting engagement in a receptacle 120 of the shaft 12 . In the present case, the receptacle 120 is provided on the axial end of the shaft 12 . The polygonal connecting section 135 has a polygonal, here square, outer circumference.

10A Figure 12 illustrates the alignment of the parts of the coupling device 13' with the rotor 11 and stator 10 assembly prior to assembly thereon.

10B 13 shows a state in which the first connecting part 130` has already been applied to the rotor 11.

10C 12 shows a state in which the first connection part 130` is already partially assembled to the second connection part 131'.

10D Fig. 12 shows a state in which the first and second connecting members 130', 131 are fixed to the rotor 11 and the shaft 12 by means of bolts 14, respectively. The first connection portion 130' can be welded to the rotor 11 in general, fastened thereto by force fit or also with screws or the like. In the assembled state, the first connecting part 130 ′ is in contact with the rotor 11 on an end face of the rotor 11 .

The production of the coupling device 13' is particularly simple. It is also possible to use the coupling device 13' as an overload protection. Because clearances are provided between the arms 137A, 137B and openings are provided in the arms 137A, the stator can be cooled.

9 shows a further electric machine 1' with a coupling device 13''. In the electrical machine 1 'according to 9 the stator is fastened to the supporting structure 17 on a side facing away from the shaft.

The coupling device 13'' comprises a second connecting part 131'' with several, here five, arms and forks 138 each formed thereon . The first connecting parts 130'' each have a holding cylinder with an elastic sleeve 132 arranged therein. The second connection part 131'' is mounted on a shaft flange 121 of the shaft.

11 shows an alternative embodiment of the second connecting part 131, which in contrast to the electrical machine 1 according to 8th has no polygonal connecting portion 135.

It should be noted that forks 138 may be on the first connector instead of on the second connector.

It should be understood that the invention is not limited to the embodiments described above, and various modifications and improvements can be made without departing from the concepts described herein. Any of the features can be used separately or in combination with any other feature unless mutually exclusive, and the disclosure extends to and encompasses all combinations and sub-combinations of one or more features described herein.

Reference List

1; 1'

electric machine

10; 10'

stator

100

spool holder

11; 11'

rotor

110

magnetic mount

12

Wave

120

Recording

121

shaft flange

13; 13'; 13''

coupling device

130; 130'; 130''

first connector

131; 131'; 131''

second connector

132

elastic sleeve

133

bolt

134

disc

135

polygonal connecting section

136

opening

137A, 137B

poor

138

Fork

139

holding cylinder

14

screw

15

camp

16

camp

17

supporting structure

2

aircraft

20

cabin

21

battery

22

propeller

A

axis of rotation

B1, B2

mounting area

D1, D2

diameter

F1, F2

flange

R1

inner ring

R2

outer ring

V

socket connection

Claims (15)

Electrical machine (1; 1'), comprising: - a stator (10; 10'); - a rotor (11; 11') rotatable relative to the stator (10; 10'); - a shaft (12) rotatable relative to the stator (10; 10'); and - a coupling device (13; 13'; 13'') having at least one first connecting part (130; 130'; 130'') fixed to the rotor (11; 11') and at least one second connecting part (130; 130'; 130'') fixed to the shaft (12) 131; 131'; 131''), which are connected to one another via a plurality of elastic sleeves (132). Electrical machine (1; 1 ') after claim 1 , wherein the shaft (12) is arranged concentrically to the rotor (11; 11'). Electrical machine (1; 1 ') after claim 1 or 2 , wherein the stator (10) surrounds the shaft (12) on the outside. Electrical machine (1; 1') according to one of the preceding claims, wherein the rotor (11; 11') surrounds the stator (10; 10') on the outside. Electrical machine (1; 1') according to any one of the preceding claims, wherein the coupling device (13; 13'; 13'') is mounted on the rotor (11; 11') at an annular first attachment region (B1) and at an annular second Fastening area (B2) is mounted on the shaft (12). Electrical machine (1; 1 ') after claim 5 , wherein the first attachment area (B1) has a diameter (D1) which is larger than the diameter (D2) of the second attachment area (B2). Electrical machine (1; 1') according to one of the preceding claims, wherein the coupling device (13; 13'; 13'') comprises three elastic sleeves (132). Electrical machine (1; 1') according to one of the preceding claims, wherein the elastic sleeves (132) consist of rubber. Electrical machine (1; 1') according to one of the preceding claims, wherein the coupling device (13; 13'; 13'') has a plurality of socket connections (V), each of the socket connections (V) comprising one of the elastic sleeves (132). . Electrical machine (1; 1 ') according to any one of the preceding claims, wherein the coupling device (13; 13 ';13'') has a plurality of arms (137A, 137B), wherein on each of the arms (137A, 137B) at least one of the elastic sleeves (132) is held. Electrical machine (1) according to claim 10 wherein at least one of the arms (137A) has a fork (138) which engages around the respective elastic sleeve (132) of the respective arm (137). Electrical machine (1) according to one of the preceding claims, wherein exactly one first connection part (130; 130`) and exactly one second connection part (131; 131') is provided, the first connection part (130; 130') and the second connection part (131; 131') each have a flange (133, 134). Electrical machine (1) according to one of the preceding claims, wherein the second connecting part (131') has a polygonal connecting section (135). Electrical machine (1; 1') according to one of the preceding claims, wherein the rotor (11; 11') drives a propeller (22). Vehicle, in particular aircraft (2), comprising the electrical machine (1; 1') according to one of the preceding claims.

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