DE102020214193A1 - Drive device for a propeller of a multicopter - Google Patents

Abstract

The invention relates to a drive device for a propeller of a multicopter with a drive shaft 2 which can be driven in rotation by a first electric motor 16 and by which an output shaft carrying the propeller can be driven in rotation directly or indirectly. The drive shaft 2 can also be driven in rotation by a second electric motor 25 in the same direction of rotation as the first electric motor 16, with the first electric motor 16 and the second electric motor 25 driving the drive shaft 2 in rotation via a differential gear and in a first electric motor 16 having and a first freewheel 42 driving the differential gear and a second freewheel 43 in a second drive train having the second electric motor (25) and driving the differential gear.

Description

The invention relates to a drive device for a propeller of a multicopter with a drive shaft that can be driven in rotation by a first electric motor, from which a drive shaft carrying the propeller can be driven in rotation directly or indirectly.

A multicopter is an aircraft that uses multiple rotors or propellers arranged in a plane, working vertically downwards, to generate lift. Propulsion can also be generated by tilting the rotor plane.

Multicopters take off and land primarily in the vertical direction (vertical take-off and landing -vTOL) and are used, among other things, to transport people.

In such a drive device, it is known that an electric motor rotatably drives an output shaft, which carries a propeller, via a planetary gear set.

If a multicopter has only a few drive devices for propellers, the flight of the multicopter can become unstable in the event of a defect in the electric motor of the drive devices and thus failure of a propeller.

The object of the invention is to create a drive device for a propeller of a multicopter of the type mentioned at the outset, which enables stable flight of the multicopter even if the motor is defective.

This object is achieved according to the invention in that the drive shaft can also be driven in rotation by a second electric motor in the same direction of rotation as by the first electric motor, the first electric motor and the second electric motor driving the drive shaft in rotation via a differential gear and in a motor having the first electric motor and a first freewheel is arranged in the first drive train driving the differential gear and a second freewheel is arranged in a second drive train having the second electric motor and driving the differential gear.

If one of the two electric motors fails, the propeller can still be operated by the other electric motor, so that there is no instability in the flight of the multicopter. No additional actuators are required for this.

The differential gear can be a bevel gear differential or a spur gear differential.

In the case of a bevel gear differential, the bevel gear differential can have a first axle shaft bevel gear that can be driven in rotation by the first drive train and from which a first differential bevel gear can be driven in rotation, which is rotatably mounted about a first differential axle that is fixed to a differential housing and is firmly connected to the drive shaft and with a second axle shaft bevel gear which can be driven in rotation by the second drive train and from which a second bevel gear can be driven in rotation, which is rotatably mounted about a second compensating axle which is fixedly arranged on the differential housing and is rigidly connected to the drive shaft. The first and second side gears preferably have the same number of teeth. Furthermore, the first differential gear preferably has the same number of teeth as the second differential gear.

In a spur gear differential that can be produced inexpensively, the spur gear differential can have a first spur gear that can be driven in rotation by the first drive train, in which a first spur planetary gear engages, which is rotatably mounted about a first axis arranged on a planet carrier, and with a second sun spur gear rotatably drivable by the second drive train, in which engages a second planetary spur gear, which is rotatably mounted about a second axis arranged on a planetary carrier, the planetary carrier being fixedly connected to the drive shaft and the first planetary spur gear and the second planetary spur gear meshing with one another.

The second sun wheel can preferably have the same number of teeth as the first sun wheel.

In order to achieve a translation of the speed of the output shaft relative to the input shaft in a space-saving and compact manner, the output shaft can be rotatably driven by the input shaft via a planetary gear set.

Preferably, the drive shaft carries a sun gear of the planetary gearset in a rotationally fixed manner, on which one or more planetary gears are arranged, which engage both in the sun gear and in a fixed ring gear enclosing the planetary gears, the planetary gears each being rotatably mounted about planetary carrier axes of a planetary carrier and the planetary carrier has a driven axle which carries the propeller and forms the driven shaft.

A compact and therefore space-saving design is achieved if the first drive train has a first drive tube which encloses the drive shaft at a radial distance and is connected to a rotor of the first electric motor by which the differential gear can be driven in rotation and in that the second drive train has a second drive tube which encloses the drive shaft at a radial distance, which is connected to a rotor of the second electric motor and by which the differential gear can be driven in rotation.

A likewise compact and therefore space-saving design is achieved if the first drive train has a first drive tube which encloses the drive shaft at a radial distance, which is connected to a rotor of the first electric motor and through which the differential gear can be driven in rotation, and that the second drive train incorporates the drive shaft having a second drive tube enclosing it at a radial distance, which is connected to a rotor of the second electric motor and through which the differential gear can be driven in rotation.

To cool the components of the drive device and/or lubricate the gears of the drive device, a coolant and/or lubricant can flow through the differential gear and/or the planetary gearset and/or the rotors and stators of the first and second electric motors.

The coolant and/or lubricant can also be supplied to other components such as seals, bearings and freewheels.

For this purpose, without additional components and thus saving size and weight, the drive shaft can be a hollow shaft into which the coolant and/or lubricant can be conveyed and which has radial openings distributed over its length.

The coolant and/or lubricant is thrown radially outwards to the gears and/or the rotors and stators of the first and second electric motors via the rotating hollow shaft and the radial openings.

If the hollow shaft has a conical inner wall, the end of the inner wall of the hollow shaft with the smaller diameter protruding into a sump of coolant and/or lubricant and the end of the hollow shaft with the larger diameter is closed, the coolant and/or lubricant is automatically switched off sucked in from the sump and pulls up along the inner wall of the hollow shaft to the radial openings, so that no delivery unit for the coolant and/or lubricant is required to save space and weight.

If the drive device has a housing that encloses its components and from which the end of the output shaft that carries the propeller protrudes, the coolant and/or lubricant can be thrown until it rests against the inner wall of the housing and along the inner wall to the one below of the electric motors and gears in the housing.

If cooling elements through which air can flow are arranged on the outer wall of the housing, the coolant and/or lubricant located on the inner wall of the housing is simultaneously cooled as it drains.

Preferably, the cooling elements are cooling fins, through which an air stream flows axially to the drive shaft, which is generated by the propeller or a component connected to the propeller.

• 1 eine Prinzipdarstellung einer Anbtriebseinrichtung mit einem Kegelrad-Differentialgetriebe
• 2 eine Prinzipdarstellung einer Anbtriebseinrichtung mit einem Stirnrad-Differentialgetriebe.

Exemplary embodiments of the invention are shown in the drawing and are described in more detail below. Show it

• 1 a schematic representation of a drive device with a bevel gear differential
• 2 a schematic representation of a drive device with a spur gear differential.

The drive devices shown have a closed housing 1 in which a drive shaft 2 is mounted so as to be rotatable about an axis of rotation 10 and aligned vertically. The drive shaft 2 is designed as a hollow shaft whose inner wall 3 is conical. The end of the inner wall 3 of the hollow shaft with the smaller diameter is directed towards the lower area of the container 1 and the end of the inner wall 3 of the hollow shaft with the larger diameter is directed towards the upper area of the housing 1 .

The lower end of the drive shaft 2 designed as a hollow shaft is open and the upper end of the drive shaft 2 designed as a hollow shaft is closed.

In the upper end area of the drive shaft 2, the latter carries a sun gear 4 of a planetary gearset 5, in which several planetary gears 6 engage, in a rotationally fixed manner. The planetary gears 6 are rotatably mounted about planetary gear axles 7 which are fixedly connected to a planetary carrier 8 at their ends.

The planetary carrier 8 has a tubular extension 9 which is coaxial with the axis of rotation 10 and protrudes through an opening in an upper end wall 11 of the housing 1 at its upper end from the housing 1 and forms an output shaft. Outside of the housing 1 of Rohrfortsart 9 is closed and carries a propeller mount 12 which carries a propeller, not shown.

A first bearing 13 for the rotatable mounting of the tubular extension 9 and thus of the planetary carrier 8 is arranged in the opening of the upper end wall.

At the ends facing away from the planetary carrier 8 , the planetary carrier axles 7 are firmly connected to a carrier disk 14 , which is rotatably mounted in the housing 1 about the axis of rotation 10 .

The planetary gear set 5 also has a ring gear 15 which is fixed to the inner wall 3 of the housing 1 and encloses the planetary gears 6 and into which the planetary gears 6 engage.

A first electric motor 16 is arranged below the planetary gear set 5 in the housing 1 , the first electric motor 16 of which is fixedly connected to the housing 1 .

The first rotor 18 of the first electric motor 16, which is arranged radially inside the first stator 17, is firmly connected via a first web 19 projecting radially inwards to a first drive tube 20 coaxially enclosing the drive shaft 2 at a radial distance. The upper end of the first drive tube 20 is rotatably mounted with a second bearing 21 in a central opening of the carrier disk 14 . The lower end 24 of the first drive tube 20 leads to a differential gear which is 1 as a bevel gear differential 22 and in 2 is designed as a spur gear differential 23.

The spur differential gear 23 has a first spur gear 51 that can be driven in rotation by the first drive tube 20 and in which a first spur planetary gear 52 engages, which is rotatably mounted about a first axis 54 arranged on a first planetary carrier 53 . A second spur gear 55 can be driven in rotation by the second drive tube 29, in which a second spur gear 56 engages, which is rotatably mounted about a second axis 58 arranged on a second planet carrier 57, the planet carriers 53, 57 being firmly connected to the drive shaft 2 and the first planetary spur gear 52 and the second planetary spur gear 56 mesh.

The end of the first drive tube 20 opposite the planetary gear set 5 carries coaxially, non-rotatably, a first side shaft bevel gear 34 of a bevel gear differential 22, by which a first differential bevel gear 36 can be rotatably driven, which is rotatably mounted about a first differential axle 38 fixedly arranged on a differential housing 37, which is firmly connected to the drive shaft 2.

The end of the second drive tube 29 facing away from the power electronics 33 carries coaxially and non-rotatably a second axle shaft bevel gear 39, from which a second differential bevel gear 40 can be rotatably driven, which is rotatably mounted about a second differential axle 41 fixed to the differential housing 37 and fixed to the drive shaft 2 connected is.

In both figures, the first electric motor 16 can drive the first drive tube 20 so that it can rotate in a driving direction of rotation.

A second electric motor 25 is arranged in the housing 1 below the first electric motor 16 , the second electric motor 25 of which is fixedly connected to the housing 1 .

The second rotor 27 of the second electric motor 25, which is arranged radially inside the second stator 26, is firmly connected via a second web 28 projecting radially inward to a second drive tube 29 coaxially surrounding the drive shaft 2 at a radial distance. The lower end of the second drive tube 29 is rotatably mounted in a third bearing 30 in a central opening of a second carrier disk 31 which extends radially and is firmly connected radially on the outside to the housing 1 . The upper end 32 of the second drive tube 29 also leads to the differential gear.

The second drive tube 29 can be driven by the second electric motor 25 to rotate in the specific driving direction of rotation.

The first electric motor 16 and the second electric motor 25 are 2×3-phase electric motors that can be controlled by power electronics 33 that are located in the lower area of the housing 1 .

The end of the first drive tube 20 opposite the planetary gear set 5 carries coaxially, non-rotatably, a first side shaft bevel gear 34 of a bevel gear differential 35, by which a first differential bevel gear 36 can be rotatably driven, which is rotatably mounted about a first differential axle 38 fixedly arranged on a differential housing 37, which is firmly connected to the drive shaft 2.

The end of the second drive tube 29 facing away from the power electronics 33 carries coaxially and non-rotatably a second axle shaft bevel gear 39, from which a second differential bevel gear 40 can be driven in rotation Equal housing 37 is rotatably arranged second balancing axle 41, which is firmly connected to the drive shaft 2. The first pinion gear 36 and the second pinion gear 40 mesh with the first side pinion gear 34 and the second side pinion gear 40, respectively.

A first freewheel 42 acts on the first drive tube 20 and allows the first drive tube 20 to rotate freely in the drive direction of rotation. The first drive tube 20 is prevented from rotating in the opposite direction to the driving direction of rotation.

A second freewheel 43 acts on the second drive tube 29, through which the second drive tube 29 can rotate freely in the driving direction of rotation. The second drive tube 29 is prevented from rotating in the opposite direction to the driving direction of rotation.

The drive shaft 1 is designed as a hollow shaft with a conical inner wall 44, the end of which has the smaller diameter of the inner wall 44 protrudes into a sump 45 on the lower end region of the housing 1, which is closed by a bottom 46.

In at least the first and second electric motor 16 and 25, the planetary gear set 5, the bevel gear differential 35 and the first and second freewheel 42 and 43 radially opposite areas, the drive shaft 2 has continuous radial openings, not shown.

When driven by the electric motors 16 and 25, the drive shaft 2, which is rotatably driven, causes a coolant and lubricant in the sump 45 to be pulled upwards on the conical inner wall 3 of the drive shaft 2 in the form of a film and can escape radially outwards at the radial openings and enter the first and second electric motor 16 and 25, the planetary gear set 5, the bevel gear differential 22 and the first and second freewheels 42 and 43 cool and lubricate.

Furthermore, the coolant and lubricant comes to rest on the inside of a radially circumferential housing wall 48 of the housing 1 and can flow back down this to the sump 45 .

Cooling elements 49 in the form of cooling fins are arranged on the outside of the radially circumferential housing wall 48, through which an air stream flows that is generated by the propeller mount when it rotates.

This cools the housing wall 48 and cools the coolant and lubricant running along its inside.

• • Erzeugt der erste Elektromotor 16 kein Drehmoment, so wird dieser erste Elektromotor 16 durch den weiterhin antreibenden zweiten Elektromotor 25 so lange abgebremst, bis der erste Freilauf 42 klemmt. Der zweite Elektromotor 25 fährt währenddessen auf doppelte Drehzahl hoch. Der Propeller kann durch den zweiten Elektromotor 25 weiterhin noch angetrieben werden
• • Erzeugt der zweite Elektromotor 25 kein Drehmoment, so wird dieser zweite Elektromotor durch den weiterhin antreibenden ersten Elektromotor 16 so lange abgebremst, bis der zweite Freilauf 43 klemmt. Der erste Elektromotor 16 fährt auf doppelte Drehzahl hoch. Der Propeller kann durch den ersten Elektromotor 16 weiterhin noch angetrieben werden.
• • Ist keine Drehzahl des ersten Elektromotors 16 vorhanden, so klemmt der erste Freilauf 42. Der zweite Elektromotor 25 fährt auf doppelte Drehzahl hoch. Der Propeller kann durch den zweiten Elektromotor 25 weiterhin noch angetrieben werden
• • Ist keine Drehzahl des zweiten Elektromotors 25 vorhanden, so klemmt der zweite Freilauf 43. Der erste Elektromotor 16 fährtauf doppelte Drehzahl hoch. Der Propeller kann durch den ersten Elektromotor 16 weiterhin noch angetrieben werden
• • Dreht der erste Elektromotor 16 entgegen der Antriebsdrehrichtung, so klemmt der erste Freilauf 42. Der zweite Elektromotor 25 fährt auf doppelte Drehzahl hoch. Der Propeller kann durch den zweiten Elektromotor 25 weiterhin noch angetrieben werden
• • Dreht der zweite Elektromotor 25 entgegen der Antriebsdrehrichtung, so klemmt der zweite Freilauf 43. Der erste Elektromotor 16 fährt auf doppelte Drehzahl hoch. Der Propeller kann durch den ersten Elektromotor 16 weiterhin noch angetrieben werden
• • Dreht der Propeller entgegen der Antriebsrichtung, so klemmen der erste Freilauf 42 und der zweite Freilauf 43
• • Wenn der Propeller zu langsam dreht wird dies durch elektrisches Beschleunigen abgefangen.
• • Dreht der Propeller zu schnell, wird dies durch elektrisches Bremsen angefangen
• • Fällt ein elektrischer Strang aus Leistungselektronik einschließlich der dazugehörenden drei Phasen des dazugehörenden 2x3-phasigen Elektromotors 16, 25 aus, so kann der jeweilige Elektromotor 16, 25 noch über seinen zweiten elektrischen Strang angetrieben werden.

The following failure modes of the embodiment of 1 are possible:

• • If the first electric motor 16 does not generate any torque, then this first electric motor 16 is braked by the second electric motor 25, which continues to drive, until the first freewheel 42 jams. The second electric motor 25 meanwhile runs up to twice the speed. The propeller can still be driven by the second electric motor 25
• • If the second electric motor 25 does not generate any torque, then this second electric motor is braked by the first electric motor 16, which continues to drive, until the second freewheel 43 jams. The first electric motor 16 runs up to twice the speed. The propeller can still be driven by the first electric motor 16 .
• • If the first electric motor 16 is not rotating, the first freewheel 42 is jammed. The second electric motor 25 runs up to double the speed. The propeller can still be driven by the second electric motor 25
• • If the second electric motor 25 is not rotating, the second freewheel 43 is jammed. The first electric motor 16 runs up to double the speed. The propeller can still be driven by the first electric motor 16
• • If the first electric motor 16 rotates in the opposite direction to the direction of rotation of the drive, the first freewheel 42 jams. The second electric motor 25 runs up to twice the speed. The propeller can still be driven by the second electric motor 25
• • If the second electric motor 25 rotates in the opposite direction to the driving direction of rotation, the second freewheel 43 jams. The first electric motor 16 runs up to twice the speed. The propeller can still be driven by the first electric motor 16
• • If the propeller rotates in the opposite direction to the drive direction, the first freewheel 42 and the second freewheel 43 will jam
• • If the propeller rotates too slowly, this is compensated by electrical acceleration.
• • If the propeller turns too fast, this is started by electric braking
• • If an electrical strand of power electronics, including the associated three phases of the associated 2x3-phase electric motor 16, 25, the respective Electric motor 16, 25 are still driven via its second electrical strand.

Reference List

1

Housing

2

drive shaft

3

inner wall

4

sun gear

5

planetary gear set

6

planet gears

7

planetary gear axles

8th

planet carrier

9

tube extension

10

axis of rotation

11

upper end wall

12

propeller mount

13

first camp

14

first carrier disc

15

ring gear

16

first electric motor

17

first stator

18

first rotor

19

first jetty

20

first drive motor

21

second camp

22

Bevel gear differential

23

Spur gear differential

24

lower end of first drive tube

25

second electric motor

26

second stator

27

second rotor

28

second jetty

29

second drive tube

30

third camp

31

second carrier disc

32

upper end of second drive tube

33

power electronics

34

first side gear

36

first pinion gear

37

differential case

38

first balancing axis of rotation

39

second side gear

40

second pinion gear

41

second balancing axis

42

first freewheel

43

second freewheel

45

swamp

46

floor

48

housing wall

49

cooling elements

51

first solar wheel

52

first planetary gear

53

first planet carrier

54

first axis

55

second solar wheel

56

second planetary gear

57

second planet carrier

58

second axis

Claims (11)

Drive device for a propeller of a multicopter with a drive shaft (2) which can be driven in rotation by a first electric motor (16) and from which an output shaft carrying the propeller can be driven in rotation directly or indirectly, characterized in that the drive shaft (2) is also driven by a second electric motor (25) can be driven in rotation in the same direction of rotation as by the first electric motor (16), the first electric motor (16) and the second electric motor (25) driving the drive shaft (2) in rotation via a differential gear and the first electric motor (16 ) having and driving the differential gear a first freewheel (42) and in a second electric motor (25) having and driving the differential gear second drive train a second freewheel (43) is arranged. drive device claim 1 , characterized in that the differential gear is a bevel gear differential gear (22) or a spur gear differential gear (23). Drive device according to one of the preceding claims, characterized in that the output shaft can be driven in rotation by the drive shaft (2) via a planetary gear set (5). drive device claim 3 , characterized in that the drive shaft (2) has a sun gear (4) of the planetary gear set (5) non-rotatably, on which one or more planetary gears (6) are arranged, which engage both in the sun gear (4) and in a fixed ring gear (15) surrounding the planetary gears (6), the planetary gears (6) each rotating around planet carrier axes Planetary carrier (8) are rotatably mounted and the planetary carrier (8) has an output shaft which carries the propeller and forms the output shaft. Drive device according to one of the preceding claims, characterized in that the first drive train has a first drive tube (20) which encloses the drive shaft (2) at a radial distance and is connected to a rotor (18) of the first electric motor (16) and through which the differential gear can be driven in rotation and that the second drive train has a second drive tube (29) which encloses the drive shaft (2) at a radial distance, which is connected to a rotor (27) of the second electric motor (25) and through which the differential gear can be driven in rotation. Drive device according to one of the preceding claims, characterized in that the differential gear and / or the planetary gear set (5) and / or the rotors (18, 27) and stators (17, 26) of the first and second electric motors (16, 25) from a Coolant and / or lubricant can flow through. drive device claim 6 , characterized in that the drive shaft (2) is a hollow shaft into which the coolant and/or lubricant can be conveyed and which has radial openings (47) distributed over its length. drive device claim 7 , characterized in that the hollow shaft has a conical inner wall (44), the end with the smaller diameter of the inner wall (44) protruding into a sump (45) of the coolant and/or lubricant and the end with the larger diameter being closed. Drive device according to one of Claims 6 until 8th , characterized in that the drive device has a housing (1) enclosing its components, from which the end of the output shaft carrying the propeller protrudes. drive device claim 9 , characterized in that cooling elements (49) through which air can flow are arranged on the outer wall of the housing (1). Drive device according to one of the preceding claims, characterized in that the first electric motor (16) and/or second electric motor (25) is a 2x3-phase electric motor unit.

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