US-12617525-B2 - Drive unit for a rotary-wing aircraft, and rotary-wing aircraft

US12617525B2US 12617525 B2US12617525 B2US 12617525B2US-12617525-B2

Abstract

A drive unit for a rotary-wing aircraft has a first and second propeller, which rotates in the opposite direction to, and are axially spaced apart from, the first propeller. A first and second drive shaft are arranged coaxially with the first drive shaft, for the propellers, wherein the propellers are each rigid and mounted to be tiltable relative to the axis of rotation of their drive shafts. The tilt axis of each propeller extends in a plane perpendicular to the axis of rotation of the drive shafts and is oriented at an angle different from 90° relative to the longitudinal axis of the propeller. An electric drive module has at least two rotors which are coupled to one of the drive shafts, wherein the ratio of the diameter of the propellers to the axial distance between the propellers is between 4:1 and 12:1.

Inventors

Peter Außerlechner
Jürgen Greil
Markus Kampitsch
Jens Steingräber

Assignees

FLYNOW AVIATION GMBH

Dates

Publication Date: 20260505
Application Date: 20211028
Priority Date: 20201102

Claims (14)

1 . A drive unit for a rotary-wing aircraft, comprising: a first propeller and a second propeller, which rotates in the opposite direction to, and is axially spaced apart from, the first propeller, a first drive shaft and a second drive shaft, arranged coaxially with the first drive shaft, for the first and second propellers, wherein the first and second propellers are each rigid and are mounted so as to be tiltable relative to an axis of rotation of their drive shafts, wherein a tilt axis of each propeller extends in a plane perpendicular to the axis of rotation of the drive shafts and is oriented at an angle different from 90 degrees relative to a longitudinal axis of the propellers, an electric drive module having at least two rotors which are coupled to a respective one of the drive shafts, wherein the ratio of a diameter of the propellers to an axial distance between the propellers is between 4:1 and 12:1; wherein the drive unit comprises a bearing unit connecting the drive unit to a cabin of a rotary-wing aircraft so as to be pivotable relative to a pivot bearing point, wherein the unit formed of the electric drive module and the drive shafts is connected to the bearing unit using a universal joint, and wherein a bearing for an inner one of the drive shafts is arranged on a side of the universal joint facing away from the propellers.
2 . The drive unit according to claim 1 , wherein the tilt axis extends at an angle of +30° to +50° or −30° to −50° relative to the longitudinal axis of the propellers.
3 . The drive unit according to claim 1 , wherein at least one pin extends along the tilt axis and connects a hub of the propellers to the drive shaft in an articulated manner.
4 . The drive unit according to claim 3 , wherein an intermediate piece is arranged coaxially with the hub of the propellers and is detachably connected to the hub and on which the pin is mounted and which is adapted to be connected to the hub in various angular positions.
5 . The drive unit according to claim 3 , wherein the propellers have a connecting surface in which a multitude of holes is provided, and an intermediate piece on which the pin is mounted has a contact surface corresponding to the connecting surface, wherein the contact surface has a hole pattern provided therein which is configured such that the propellers can be connected to the intermediate piece in various angular positions.
6 . The drive unit according to claim 1 , wherein the electric drive module includes two electric motors which are accommodated coaxially with each other in a shared housing.
7 . The drive unit according to claim 1 , wherein an adjusting device acts between the bearing unit and a unit formed of the electric drive module and the drive shafts in order to be able to adjust an orientation of the drive shafts relative to the bearing unit.
8 . The drive unit according to claim 7 , wherein one end of the adjusting device engages the electric drive module.
9 . A rotary-wing aircraft comprising a drive unit according to claim 1 , wherein the rotary-wing aircraft includes a cabin which constitutes a passenger compartment and/or a payload compartment.
10 . The rotary-wing aircraft according to claim 9 , wherein the rotary-wing aircraft comprises a carrier for the drive unit, wherein an adjusting device is fixed to a bearing unit and is configured such that it can pivot a unit formed of the electric drive module and the drive shafts in relation to the carrier.
11 . The rotary-wing aircraft according to claim 10 , wherein the drive unit is arranged above the cabin, wherein the cabin constitutes the carrier.
12 . A rotary-wing aircraft comprising a drive unit according to claim 2 , the rotary-wing aircraft includes a cabin which constitutes a passenger compartment and/or a payload compartment.
13 . The rotary-wing aircraft according to claim 12 , wherein the rotary-wing aircraft comprises a carrier for the drive unit, wherein an adjusting device is fixed to a bearing unit and is configured such that it can pivot a unit formed of the electric drive module and the drive shafts in relation to the carrier.
14 . A drive unit for a rotary-wing aircraft, comprising: a first propeller and a second propeller, which rotates in the opposite direction to, and is axially spaced apart from, the first propeller, a first drive shaft and a second drive shaft, arranged coaxially with the first drive shaft, for the first and second propellers, wherein the first and second propellers are each rigid and are mounted so as to be tiltable relative to an axis of rotation of their drive shafts, wherein a tilt axis of each propeller extends in a plane perpendicular to the axis of rotation of the drive shafts and is oriented at an angle different from 90 degrees relative to a longitudinal axis of the propellers, an electric drive module having at least two rotors which are coupled to a respective one of the drive shafts, wherein the ratio of a diameter of the propellers to an axial distance between the propellers is between 4:1 and 12:1, wherein at least one pin extends along the tilt axis and connects a hub of the propellers to the drive shaft in an articulated manner, and wherein the propellers have a connecting surface in which a multitude of holes is provided, and an intermediate piece on which the pin is mounted has a contact surface corresponding to the connecting surface, wherein the contact surface has a hole pattern provided therein which is configured such that the propellers can be connected to the intermediate piece in various angular positions.

Description

The invention relates to a drive unit for a rotary-wing aircraft and to a rotary-wing aircraft having a drive unit. Rotary-wing aircraft, often referred to as helicopters, typically comprise at least one propeller or rotor that is arranged on a top surface of the rotary-wing aircraft and generates lift when rotated. When a helicopter is not hovering but flying forward, the flow velocity resulting from the rotation of the rotor is superimposed at the rotor or propeller blades on the blade-tip velocity resulting from the forward movement of the helicopter. When observing a revolution of a rotor blade in forward flight, a sector can be seen in which the rotor blade moves backward. There, the relative blade-tip velocity of the rotor blade decreases by the oppositely directed flight velocity of the helicopter, so that in a position of the rotor blade of 90° relative to the direction of flight, the effective flow velocity is at the minimum. In the sector in which the rotor blade moves forward, the two velocities add up, so that in a position of the rotor blade of 90° relative to the direction of flight, the flow velocity is at the maximum. Thus, when observing a rotor having two rotor blades, in the condition in which the two rotor blades are exactly perpendicular to the direction of flight, a noticeable difference arises between the high lift that is generated by the forward-running rotor blade and the low lift that is generated by the rearward-running rotor blade. This effect is most pronounced in forward flight, since this is where the highest flight velocities are reached. However, the same effects are produced during sideways or backward flight, albeit at a lower level due to the lower flight velocities. In a rotor having rotor blades the angle of attack of which can be varied, this effect can be compensated by a cyclic change of the angle of attack. When the rotor blade moves forward, the angle of attack is decreased in order to counteract the increase in lift caused by the higher blade-tip velocity, and when the rotor blade moves backward, it is increased in order to compensate for the lower blade-tip velocity. However, the systems by which the angle of attack of the rotor blades can be changed cyclically (usually by means of a swashplate) are comparatively elaborate. Also, the rotors are quite complex. It is therefore an object of the invention to provide a drive unit for a rotary-wing aircraft which is as simple and cost-effective as possible. This object is achieved according to the invention by a drive unit for a rotary-wing aircraft, including a first propeller and a second propeller, which rotates in the opposite direction to, and is axially spaced apart from, the first propeller, including a first drive shaft and a second drive shaft, arranged coaxially with the first drive shaft, for the propellers, wherein the two propellers are each rigid and are mounted so as to be tiltable relative to the axis of rotation of their drive shafts, wherein the tilt axis of each propeller extends in a plane perpendicular to the axis of rotation of the drive shafts and is oriented at an angle different from 90 degrees relative to the longitudinal axis of the propeller, and including an electric drive module having at least two rotors which are coupled to a respective one of the drive shafts, wherein the ratio of the diameter of the propellers to the axial distance between the propellers is between 4:1 and 12:1. This drive unit allows a variety of advantages to be combined. Due to its orientation, the tilt axis causes the propeller, when pivoting about the tilt axis, to perform a rotation about its longitudinal axis. This rotation leads to a change in the angle of attack, namely in opposite directions in the case of a propeller having two propeller blades arranged oppositely to each other. In this way, the angle of attack of a forward-running propeller blade can be decreased while at the same time the angle of attack of a backward-running propeller blade is increased. This allows the use of rigid propellers, that is, propellers in which the propeller blades are connected to a hub rigidly and thus at an invariable angle of attack. This results in a simple structure and low costs, while it is nonetheless possible to cyclically change the angle of attack of the propeller blades during rotation. This is done passively, i.e. solely under the effect of the lift generated and any imbalance of lift. The tilt axis is oriented in such a way here that an increase in lift (for example, due to an increase in the blade-tip velocity during forward flight) tilts the propeller such that the angle of attack is reduced in the sector with higher lift. This automatically results in an increase in the angle of attack in that sector of the propeller in which the relative blade-tip velocity is lower. By being able to tilt about the tilt axis, the propellers can also react automatically, that is, passively, and in a self-regulating manner to