Rotor hub for aircraft with a propeller drive, and assembly comprising a rotor hub of this kind

Abstract

The invention relates to a rotor hub, in particular for aircraft with a propeller drive, having a bore for receiving a drive shaft, wherein the bore comprises an internal thread which is designed to interact with an external thread of the drive shaft and to releasably connect the rotor hub to the drive shaft. The invention makes provision for the bore to have an annular groove for receiving an O-ring which is suitable for inhibiting a relative movement between the rotor hub and the drive shaft.

Description

[0001] Rotor hub for propeller-driven aircraft and assembly comprising such a rotor hub

[0002] The present invention relates to a rotor hub according to the preamble of independent claim 1.

[0003] A generic rotor hub has a bore for receiving a drive shaft, wherein the bore comprises an internal thread which is designed to cooperate with an external thread of the drive shaft and to detachably connect the rotor hub to the drive shaft.

[0004] Generic rotor hubs are primarily used in the field of unmanned aerial vehicles. The connection between the rotor hub and the drive system is an important aspect and can generally be designed as detachable or non-detachable. With detachable connections, for example, the rotor hub can be attached directly to the drive shaft using a central thread. The thread direction is usually designed such that the rotor hub tightens during acceleration of the drive shaft, thus supporting the frictional connection between the drive shaft and rotor hub. Alternatively, detachable connections that tighten during rotor operation can be realized using fastening elements in the form of two- or three-dimensional shapes that are complementary to the rotor hub and shaft and interact via a suitable fit connection.

[0005] A rotor hub according to the preamble of independent claim 1 is known from DE202014010962. This document describes various embodiments of the attachment of a rotor hub to a drive shaft.

[0006] However, the fastening methods known from the state of the art are not optimal, since the fastening of the rotor hub to the shaft is designed to be self-tightening during operation, but such connections without additional safety features can become loose due to external influences such as vibrations or abrupt load changes, thus endangering the functional reliability of the drive.

[0007] The object of the present invention is therefore to provide a rotor hub which is characterized by increased operational reliability while maintaining a consistently compact design.

[0008] The problem is solved by the features of independent claim 1. Accordingly, the problem is solved according to the invention if the bore has an annular groove for receiving an O-ring suitable for inhibiting the relative movement between the rotor hub and the drive shaft. Advantageous embodiments of the present invention are the subject of the dependent claims.

[0009] The invention is particularly relevant for propeller-driven unmanned aerial vehicles. These include, for example, drones with horizontal propeller arrangements, but also fixed-wing aircraft with vertically aligned propellers.

[0010] According to an advantageous embodiment of the present invention, the bore has a first bore section, wherein the first bore section comprises the annular groove, and the bore has a second bore section, wherein the second bore section comprises the internal thread and wherein the internal diameter of the first bore section is larger than the nominal diameter of the internal thread. The design of the diameters of the bore sections depends on how the two bore sections are arranged relative to a screw-in direction. It is therefore also conceivable that the nominal diameter of the internal thread is larger than the diameter of the first bore section comprising the annular groove.

[0011] According to a further advantageous embodiment of the present invention, the annular groove and the internal thread are designed to be spaced apart from one another in the axial direction. Advantageously, the annular groove is therefore not located within the internal thread. However, embodiments are also conceivable in which the annular groove and an O-ring arranged within the annular groove are arranged in the region of the internal thread.

[0012] According to a further advantageous embodiment of the present invention, the bore has a screw-in direction, and the annular groove is arranged in front of the internal thread in the screw-in direction. This arrangement offers the advantage that a centering means can be provided within the first bore section comprising the annular groove, simplifying the screw-in process step.

[0013] According to a further advantageous embodiment of the present invention, the rotor hub is a propeller hub and has at least one receiving element for attaching a rotor blade. However, the rotor hub can also have two, three, or even more receiving elements for a rotor blade, depending on the type of aircraft to be equipped and the required number of rotor blades.

[0014] According to a particularly advantageous embodiment of the present invention, the rotor hub is part of an assembly comprising an O-ring, wherein the O-ring is arranged in the annular groove, a drive shaft, wherein the drive shaft has a drive shaft axis and an external thread which is configured to cooperate with the internal thread of the rotor hub and to detachably connect the drive shaft to the rotor hub.

[0015] According to a further advantageous embodiment of the present invention, the annular groove of the rotor hub has a width and a depth and the O-ring is designed and positioned in the annular groove in such a way as to bring the rotor hub and the drive shaft into frictional contact when installed.

[0016] The advantage of the rotor hub according to the invention is primarily evident in its installation with an O-ring and a drive shaft. Due to the position of the O-ring in the ring groove and its corresponding dimensioning, the O-ring is in frictional contact with the drive shaft and in positive contact with the rotor hub when the drive shaft and rotor hub are installed. The frictional contact of the O-ring with the drive shaft ensures that the relative movement between the rotor hub and drive shaft is inhibited. The advantage of using an O-ring is that the O-ring inhibits the relative movement between the rotor hub and the drive shaft in all operating states, but does not limit or prevent the relative movement. Furthermore, the rotor hub and drive shaft can be assembled and disassembled even when the O-ring is installed.

[0017] According to a further advantageous embodiment of the present invention, the drive shaft comprises a functional section that forms a clearance fit with the first bore section of the rotor hub. The clearance fit between the first bore section of the rotor hub and the functional section of the drive shaft ensures proper centering and alignment of the drive shaft with the rotor hub during screwing. This minimizes imbalance and ensures smooth operation of the assembly.

[0018] According to a further advantageous embodiment of the present invention, the rotor hub has a rotor axis and a rotor hub rotation direction corresponding to the driven state, and the thread direction of the rotor hub and drive shaft is designed such that when accelerated by a drive system in the rotor hub rotation direction, the rotor hub is tightened on the drive shaft.

[0019] According to a further advantageous embodiment of the present invention, the O-ring is made of a polymer. The advantage of a polymer is that the material is flexible and deformable. The O-ring is arranged in the annular groove of the rotor hub and designed to inhibit the relative movements between the rotor hub and the drive shaft. This requires frictional contact between the O-ring and the drive shaft. The O-ring and the annular groove are therefore advantageously dimensioned such that the O-ring has a greater radial extension than the annular groove. However, the width of the annular groove, i.e. the extension in the axial direction, should be greater than the width of the O-ring. When the drive shaft is screwed into the rotor hub, the drive shaft presses the O-ring radially outward, whereby the O-ring is deformed and the material of the O-ring expands in the direction of the width of the annular groove.The O-ring is therefore positively connected to the rotor hub and frictionally connected to the drive shaft.

[0020] According to a particularly advantageous embodiment of the present invention, the assembly comprises at least one rotor blade which is mounted in the receiving element so as to be rotatable about a rotor blade axis, the rotor blade axis being aligned substantially parallel to the drive shaft axis, the rotor blade having an operating position and the rotor blade in the operating position being aligned substantially radially to the drive shaft axis and radially to the rotor blade axis, and the rotor blade having a storage position and the rotor blade in the storage position being rotated about the rotor blade axis relative to the operating position. The rotor blade can be mounted so as to be rotatable such that the rotor blade can be folded into the storage position and that the rotor blade can be brought into the operating position, for example as a result of the centrifugal force caused by the rotation of the rotor hub.

[0021] The fact that the rotor blade axis is aligned substantially parallel to the drive shaft axis means, in the context of the described embodiment, that the axes have an offset of at most 5°, preferably at most 1° and particularly preferably not more than 0.1° from one another.

[0022] Rotatably mounted rotor blades have the advantage that they can be folded into a storage position when not in use, thus saving space. This arrangement also allows the rotor blades to move into the operating position automatically due to centrifugal force, rather than having to be manually moved into the operating position before flight.

[0023] During takeoff, however, the inertia of the rotor blades can cause them to over-rotate, causing them to rotate from their storage position beyond their operating position. At high accelerations, this over-rotation is only limited when the rotor blade hits the rotor hub. Depending on the design of the rotor hub, this can cause damage to both components. In unfavorable cases, this creates a notch in the rotor blade where the rotor can jam, disrupting or even preventing the rotor blades from aligning to their operating position.

[0024] According to a further advantageous embodiment of the present invention, a locking device is provided to hold the rotor blades in the operating position or in the storage position. The locking device is provided on the rotor hub and on the rotor blades. The locking device comprises, for example, a recess on the rotor hub and a knob-like element on the rotor blade. The recess can be arranged, for example, as a bore between the rotor axis and the rotor blade axis on the rotor hub. The recess can also be arranged as a cutout on the opposite side of the rotor axis, towards the rotor blade, on the rotor hub. The rotor blade can have a raised or knob-like element. The knob-like element is arranged on the rotor blade at the end near the rotor hub. The recess and the knob-like element interact in a form-fitting manner and hold the rotor blade in the operating position.By locking the knob-like element and the recess into place, the rotor blade is secured to the rotor hub in the operating position. However, with sufficient force, it can be released again and, for example, folded into the storage position. This locking device allows the rotor blades to be unfolded and secured in a suitable position, as well as folded into the storage position. Thus, the use of pivoting rotor blades, which can be folded or folded into a storage position when not in use, enables space-saving storage of the rotor blades.

[0025] According to a further advantageous embodiment of the present invention, a further embodiment of the locking device is provided. The locking device consists, for example, of an end of the rotor hub that tapers towards the rotor blade. The rotor blade has at least two raised or knob-like elements that rest against the surfaces of the tapered end of the rotor hub in an operating position. These knob-like elements enclose the tapered end of the rotor hub on both sides and thus achieve a locking effect of the rotor blades in the operating position, which can be released again with appropriate force. This locking device enables the rotor blades to be unfolded and secured in the operating position, as well as to be folded or folded into the storage position when not in use.

[0026] According to a particularly advantageous embodiment of the present invention, it is therefore provided that the rotor blade has a first rotor direction of rotation about the rotor blade axis and a second rotor direction of rotation opposite to the first rotor direction of rotation, and that the rotor blade has an end near the rotor hub and an end remote from the rotor hub, and wherein the rotor hub has a stop surface which cooperates with the end of the rotor blade near the rotor hub in such a way that a deflection of the rotor blade in the second rotor direction of rotation is limited to a maximum of 90° and preferably to a maximum of 85° relative to the operating position of the rotor blade.

[0027] The design of the stop surface ensures that the rotor blades are stopped by a defined stop when they over-rotate. The contact between the stop surface and the end of the rotor blade closest to the rotor hub is configured in such a way that neither component sustains damage. The end of the rotor blade closest to the rotor hub refers to the area of ​​the rotor blade that is closer to the rotor hub when installed, while the end farther from the rotor hub refers to the other area, further away from the rotor hub. The design of the stop surface is therefore essential for the safe operation of the rotor hub according to the invention.

[0028] According to a further advantageous embodiment of the present invention, the stop surface is designed such that a deflection of the rotor blade in the second rotor rotation direction of at least 75° and preferably of at least 80° relative to the operating position of the rotor blade is permitted.

[0029] The stop surface allows the rotor blade to be folded into a storage position, even in the second rotor rotation direction. The movement of the rotor blade in the first rotor rotation direction is not restricted by the stop surface, so the maximum angle of rotation of the rotor blade around the rotor blade axis and relative to the operating position is greater in the first rotor rotation direction than in the second rotor rotation direction.

[0030] When the assembly is not in use, it may be advantageous to pivot the rotor blades so that they are aligned approximately parallel to each other, thus saving space when storing the assembly. This requires that the rotor blades be allowed sufficient deflection in both directions of rotor rotation.

[0031] The particular advantage of the described design of the rotor hub is that the stop surface ensures secure contact between the rotor hub and the rotor blade when the rotor blade is over-rotated and at the same time ensures sufficient freedom of rotation of the rotor blade for space-saving storage.

[0032] According to a further advantageous embodiment of the present invention, sensors are provided for detecting the rotor position and / or the motor temperature. In order to ensure a suitable position of the rotor blades when the device is switched off, a sensor can be used to determine the exact position of the drive shaft or motor and to align the rotor blades accordingly to protect them from damage. For example, when a fixed-wing aircraft lands, the rotor blades can be damaged by an unintentional vertical position of the rotor blades, whereas when the propeller is in a horizontal position, the rotor blades are protected. Furthermore, in the case of a multicopter, the alignment of the propellers after landing can, for example, automatically cover the multicopter in a charging station, whereby the alignment of the rotor blades prevents damage.The sensor for determining the rotor position can be, for example, a Hall sensor or an optical sensor. It is also possible to detect the rotor position using the commutation control. The rotor can be actively braked in this case. In the event of such an abrupt load change, the propeller may become detached from the rotor hub. Therefore, in this embodiment, securing the rotor hub with an O-ring, which is positively connected to the rotor hub and frictionally connected to the drive shaft, is advantageous. A temperature sensor can be provided to prevent damage to the O-ring. A temperature sensor can also be used to monitor the condition of the motor.

[0033] An embodiment of the present invention is explained in more detail below with reference to drawings.

[0034] They show:

[0035] Fig. 1 : the sectional view of a rotor hub according to the invention,

[0036] Fig. 2: a perspective view of a rotor hub according to the invention,

[0037] Fig. 3: the cross-sectional view of an assembly

[0038] Fig. 4: a rotor hub according to the invention with rotor blade,

[0039] Fig. 5: a rotor hub according to the invention with two rotor blades in operating position,

[0040] Fig. 6: a rotor hub according to the invention with two rotor blades in storage position,

[0041] Fig. 7: a rotor hub according to the invention with two rotor blades in operating position,

[0042] Fig. 8: a locking device of a rotor blade on the rotor hub in a first

[0043] Embodiment, Fig. 9: a locking device of a rotor blade on the rotor hub in a second embodiment,

[0044] Fig. 10: a locking device of a rotor blade on the rotor hub in a third

[0045] embodiment,

[0046] Fig. 11 : a schematic representation of an assembly which includes sensors for detecting the rotor position and / or motor temperature.

[0047] In the following embodiments, identical parts are designated by identical reference numerals. If a figure contains reference numerals that are not further explained in the corresponding figure description, reference is made to the preceding or subsequent figure descriptions.

[0048] Fig. 1 shows the sectional view of a rotor hub 1 according to the invention with a bore 2. The bore 2 is provided with an internal thread 4 and, for this purpose, has an annular groove 6. The annular groove 6 is formed in the first bore section 8, whereas the internal thread 4 is introduced into the second bore section 9. It can also be clearly seen that the annular groove 6 and the internal thread 4 are spaced apart from one another in the axial direction and that the internal diameter of the first bore section 8 is somewhat larger than the nominal diameter of the internal thread 4. Furthermore, the embodiment of the rotor hub 1 according to the invention shown here has two receiving elements 11, each with a rotor blade axis 20, each for a rotor blade 12.For screwing the rotor hub 1 according to the invention to a drive shaft 3, a screwing direction 10 is provided, wherein the first bore section 8 with the annular groove 6 is formed in front of the second bore section 9 in the screwing direction 10.

[0049] Fig. 2 shows a spatial representation of the rotor hub 1 according to the invention. The two stop surfaces 18 formed on the rotor hub 1 according to the invention can be clearly seen.

[0050] Fig. 3 shows an assembly 14 comprising the rotor hub 1 according to the invention, an O-ring 7, a drive shaft 3 with a drive shaft axis 21, which in the embodiment shown corresponds to the rotor axis 19, and two rotor blades 12. The drive shaft 3 is screwed to the rotor hub 1 according to the invention, wherein the O-ring 7 is installed in the annular groove 6 and is in frictional contact with the functional section 13 of the drive shaft 3. The first bore section 8 and the functional section 13 of the drive shaft form a clearance fit. In each of the two receiving elements 11, a rotor blade 12 is mounted so as to be rotatable about the rotor blade axis 20. It can be clearly seen that the rotor blade axis 20 is aligned parallel to the rotor axis 21 and parallel to the drive shaft axis 19.The design of the rotor hub 1 according to the invention enables a repeatable and precise assembly of the drive shaft 3 in the rotor hub 1 thanks to the existing clearance fit between the drive shaft 3 and the rotor hub 1. A further contribution to safe operation is the installed O-ring 7, which counteracts the loosening of the rotor hub 1 and drive shaft 3 in any operating condition.

[0051] Fig. 5 and Fig. 7 show a rotor hub 1 according to the invention with two rotor blades 12 in operating position 22. The rotor blades 12 are aligned radially with respect to the drive shaft axis 21 and the rotor blade axis 20 pointing in the blade plane, with the two rotor blades 12 again being aligned approximately 180° to each other and, in the examples shown, pointing vertically upwards and vertically downwards, respectively. It is also clearly visible that the stop surface 18 does not interact with the end 24 of the rotor blade 12 near the rotor hub in the operating position 22.

[0052] Fig. 4 shows the interaction of the stop surface 18 with the end 24 of the rotor blade 12 near the rotor hub. This situation arises, for example, when the rotor hub 1 accelerates around the rotor axis 19. The rotor hub 1 then rotates in the rotor hub rotation direction 15, and the rotor blade 12, due to its inertia, rotates in the direction of the second rotor rotation direction 17, whereby the end 24 of the rotor blade 12 near the rotor hub strikes the stop surface 18 and is prevented from over-rotating by it. The angle of rotation of the rotor hub a relative to the operating position 22 is approximately 80° in the embodiment shown.

[0053] Another example of the contact or abutment of the end 24 near the rotor hub against the stop surface 18 is shown in Fig. 4. It can be advantageous if both rotor blades 12 are aligned parallel to one another in the storage position 23. In this folded position, the rotor blades can be stored in a space-saving manner, while at the same time the rotor can be quickly reinserted. For this purpose, it is necessary that both rotor blades 12 have sufficient freedom of rotation in both rotor rotation directions 16, 17. One of the rotor blades 12, the upper one in the example shown, is rotated in the second rotor rotation direction 17, whereas the other rotor blade 12, the lower one in the example shown, is rotated in the first rotor rotation direction 16. It is also clearly visible that due to the design of the rotor hub 1 and in particular due to the contact surface 18, the angle of rotation α in the first rotor rotation direction 16 is greater than in the second rotor rotation direction 17.As a result, a parallel alignment of the two rotor blades 12 could also be achieved in that the upper rotor blade 12 in the illustration in Fig. 6 has a smaller angle of rotation α and consequently no longer rests against the stop surface 18, and at the same time the lower rotor blade 12 in Fig. 6 is deflected even further in the first rotor rotation direction 16 until both rotor blades 12 are aligned approximately parallel to one another. Figs. 8-10 show locking devices of a rotor blade 12 on the rotor hub 1 in various embodiments. By means of a locking device, the rotor blades 12 are aligned in a defined position relative to the rotor hub 1. The locking device can be designed in various ways. The locking device has, for example, a knob-like element 26 and a recess 27. The locking device can also have a bulge 28 and two knob-like elements 26.In all embodiments, the rotor blade 12 is held in an operating position 22 by the locking device. With a certain force tangential to the rotor blade axis 20, the rotor blade 12 can be folded into the storage position. The locking devices can be designed or arranged such that the rotor blades 12 are also held in the storage position relative to the rotor hub 1.

[0054] Fig. 8a-c show a first embodiment of a locking device. The locking device has a recess 27 on the rotor hub 1. The recess 27 is a cutout. On a straight line passing through the center of the rotor axis 19 and the rotor blade axis 20, the recess has its deepest point on the rotor hub 1. When the rotor blade 12 is in the operating position 22, the rotor blade 12 has a knob-like element 26 at the same location as the recess in the rotor hub 1. Figure 8a shows the locking device in a plan view. Figures 8b and c in a side sectional view, wherein in Figure 8b the rotor blade 12 has a knob-like element 26 only on one side, while in Figure 8c the rotor blade 12 has a knob-like element 26 on both sides of the cross section through the rotor blade 12.

[0055] Figures 9a-c show a second embodiment of a locking device in a plan view and in two side sectional views, wherein in Figure 9b the rotor blade 12 has a knob-like element 26 only on one side, while in Figure 9c the rotor blade 12 has a knob-like element 26 on both sides of the cross-section through the rotor blade 12. In the second embodiment shown in Figure 9, the knob-like element 26 is arranged between the rotor axis 19 and the rotor blade axis 20. The recess 27 on the rotor hub 1 is designed as a bore in the rotor hub 1.

[0056] Figures 10a-c show a third embodiment of a locking device in a plan view and in two side sectional views. In Figure 10b, the rotor hub 1 has a bulge 28 in the form of a narrowly tapered end on only one side, whereas in Figure 10c, the rotor hub 1 has the bulge 28 in the form of a narrowly tapered end on both sides of the cross-section through the rotor hub 1. The bulge 28 lies on a straight line that runs on the rotor hub 1 through the center of the rotor axis 19 and the rotor blade axis 20. When the rotor blade 12 is in the operating position, the rotor blade 12 has a knob-like element 26 on each side of the bulge 28 of the rotor hub 1.

[0057] Figure 11 shows a schematic representation of part of an assembly 14, which includes sensors for detecting the rotor position 30 and / or the motor temperature 31. The sensors for detecting the rotor position 30 can be, for example, Hall sensors or optical sensors. The sensors 30, 31 can be connected to a controller 32 for the motor of the drive shaft 3 or to the controller 32 of the aircraft. Further relevant signals and information for the operation of the aircraft can be processed in the controller 32.

[0058] The position sensors 30 can, for example, detect the position of a rotor drive such as an electric motor and can, for example, be integrated into the electric motor or engine. The position sensors 30 can also detect the position of the drive shaft 3 and / or the rotor hub 1 and / or the rotor blades 12. Using the position sensors 30, for example in the case of a fixed-wing aircraft, the rotor blades 12 can be brought into a horizontal position or stopped in a horizontal position when landing. This can protect the rotor blades 12 from contact with the ground when landing. The rotor blades 12 must be stopped in a certain predetermined position. The O-ring 7 in the rotor hub 1 prevents the rotor hub 1 from becoming detached from the drive shaft 3 due to rapid, abrupt braking of the drive shaft 3 in the certain position. The temperature sensor 31 can also, for example, provide information on the operating state of the engine, which can, for example,it can be determined whether landing the aircraft is appropriate or necessary.

[0059] List of reference symbols:

[0060] 1 rotor hub

[0061] 2 holes

[0062] 3 drive shaft

[0063] 4 internal threads

[0064] 5 external threads

[0065] 6 ring groove

[0066] 7 O-ring

[0067] 8 first drilling section

[0068] 9 second drilling section

[0069] 10 Screwing direction

[0070] 11 Receiving element

[0071] 12 rotor blades

[0072] 13 Functional section

[0073] 14 Assembly

[0074] 15 Rotor hub rotation direction

[0075] 16 first rotor rotation direction

[0076] 17 second rotor rotation direction

[0077] 18 Stop surface

[0078] 19 Rotor axis

[0079] 20 Rotor blade axis

[0080] 21 Drive shaft axis 22 Operating position of the rotor blade

[0081] 23 Storage position of the rotor blade

[0082] 24 End of the rotor blade near the rotor hub in folded state

[0083] 25 End of the rotor blade remote from the rotor hub in the folded state 26 Knob-like element

[0084] 27 recess

[0085] 28 bulge

[0086] 30 Rotor position sensor

[0087] 31 Temperature sensor 32 Control a Rotor blade twist angle

Claims

Claims 1. Rotor hub (1), in particular for propeller-driven aircraft, comprising a bore (2) for receiving a drive shaft (3), wherein the bore (2) comprises an internal thread (4) which is designed to cooperate with an external thread (5) of the drive shaft (3) and to detachably connect the rotor hub (1) to the drive shaft (3), characterized in that the bore (2) has an annular groove (6) for receiving an O-ring (7) which is suitable for preventing a relative movement between the rotor hub (1) and the drive shaft (3) to inhibit.

2. Rotor hub (1) according to claim 1, characterized in that the bore (2) has a first bore section (8), wherein the first bore section (8) comprises the annular groove (6) and that the bore (2) has a second bore section (9), wherein the second bore section (9) comprises the internal thread (4) and wherein the internal diameter of the first bore section (8) is larger than the nominal diameter of the internal thread (4).

3. Rotor hub (1) according to one of claims 1 or 2, characterized in that the annular groove (6) and the internal thread (4) are designed to be spaced apart from one another in the axial direction.

4. Rotor hub (1) according to one of claims 1 to 3, characterized in that the bore (2) has a screwing direction (10) and that the annular groove (6) is arranged in front of the internal thread (4) in the screwing direction (10).

5. Rotor hub (1) according to one of claims 1 to 4, characterized in that the rotor hub (1) is a propeller hub and has at least one receiving element (11) for fastening a rotor blade (12).

6. Assembly (14) comprising a rotor hub (1) according to one of claims 1 to 5, an O-ring (7), wherein the O-ring (7) is arranged in the annular groove (6), a drive shaft (3), wherein the drive shaft (3) has a drive shaft axis (21) and an external thread (5) which is designed to cooperate with the internal thread (4) of the rotor hub (1) and to detachably connect the drive shaft (3) to the rotor hub (1).

7. Assembly (14) according to claim 6, characterized in that the annular groove (6) of the rotor hub (1) has a width and a depth and that the O-ring (7) is designed and positioned in the annular groove (6) in such a way as to bring the rotor hub (1) and the drive shaft (3) into frictional contact when installed.

8. Assembly (14) according to claim 6 or 7, characterized in that the drive shaft (3) comprises a functional section (13) which forms a clearance fit or a transition fit with the first bore section (8) of the rotor hub (1).

9. Assembly (14) according to one of claims 6 to 8, characterized in that the rotor hub (1) has a rotor axis (19) and a rotor hub rotation direction (15) about the rotor axis (19) corresponding to the driven state and that the thread direction of the rotor hub (1) and drive shaft (3) is designed such that when accelerated by a drive system in the rotor hub rotation direction (15), the rotor hub (1) is tightened on the drive shaft (3).

10. Assembly (14) according to one of claims 6 to 9, characterized in that the O-ring (7) consists of a polymer.

11. Assembly (14) according to one of claims 6 to 10, characterized in that the assembly (14) comprises at least one rotor blade (12) which is mounted in the receiving element (11) so as to be rotatable about a rotor blade axis (20), the rotor blade axis (20) being aligned substantially parallel to the drive shaft axis (21), the rotor blade (12) having an operating position (22) and the rotor blade (12) in the operating position (22) being aligned substantially radially to the drive shaft axis (21) and radially to the rotor blade axis (20), and the rotor blade (12) having a storage position (23) and the rotor blade (12) in the storage position (23) being rotated about the rotor blade axis (20) relative to the operating position (22).

12. Assembly (14) according to one of claims 6 to 11, characterized in that a locking device is provided to hold the rotor blades in the operating position (22) or in the storage position (23).

13. Assembly (14) according to one of claims 6 to 12, characterized in that the rotor blade (12) has a first rotor direction of rotation (16) about the rotor blade axis (20) and a second rotor direction of rotation (17) opposite the first rotor direction of rotation (16), and in that the rotor blade (12) has an end (24) near the rotor hub and an end (25) remote from the rotor hub, and wherein the rotor hub (1) has a stop surface (18) which cooperates with the end (24) of the rotor (12) near the rotor hub in such a way that a deflection of the rotor blade (12) in the second rotor direction of rotation (17) is limited to an angle α of at most 90° and preferably to at most 85° relative to the operating position (22) of the rotor blade (12).

14. Assembly (14) according to one of claims 6 to 13, characterized in that the stop surface (18) is arranged such that a deflection of the rotor blade (12) in the second rotor rotation direction (17) of at least 75° and preferably of at least 80° relative to the operating position (22) of the rotor blade (12) is permitted.

15. Assembly (14) according to one of claims 6 to 14, characterized in that the assembly (14) comprises at least one rotor position sensor (30) for detecting the rotor position and / or a temperature sensor (31) for detecting the motor temperature.

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