Light-weight, elastic teeter bearing for a rotor and aircraft housing such bearing
A passive elastic teeter bearing for an aircraft rotor, including, rotatably arranged on an rotational axis of said rotor, a teeter beam, configured for attaching the rotor which has rotor blades, with the teeter beam being configured for performing a teetering motion, and having two pairs of first lugs arranged at opposite ends thereof at a distance with respect to the rotational axis; and a hub piece located below the teeter beam, the hub piece having two arms that extend outwardly in a radial direction, each having a second lug arranged at a distance with respect to said rotational axis. Each second lug is located between the two lugs of a respective pair of first lugs, and respective connecting pins pass through the first and second lugs on either side of the rotational axis. A pair of elastic bushings are arranged on each connecting pin between a first one of the first lugs and the second lug and between a second one of said first lugs and the second lug, respectively.
1. An elastic teeter bearing ( 3 c ) for a rotor ( 3 b ) rotatably arranged on an rotational axis (RA) of said rotor ( 3 b ), the elastic teeter bearing comprising:
a teeter beam ( 3 d ), configured for attachment of the a rotor ( 3 b ) thereto, the rotor having at least two rotor blades ( 3 b 1 , 3 b 2 ), provided as separate blade parts or in one piece, said teeter beam ( 3 d ) being configured for performing a teetering motion with respect to said rotational axis (RA) and having at least two first lugs or two pairs of first lugs ( 3 j 1 , 3 j 2 ) arranged at opposite ends thereof at a distance with respect to said rotational axis (RA);
a hub piece ( 3 f ) located below said teeter beam ( 3 d ), said hub piece ( 3 f ) having at least two arms ( 3 g 1 , 3 g 2 ) that extend outwardly in a radial direction with respect to said rotational axis (RA), each of said arms ( 3 g 1 , 3 g 2 ) having a second lug ( 3 k ), in case said teeter beam ( 3 d ) has said two pairs of first lugs ( 3 j 1 , 3 j 2 ), or having a pair of second lugs, in case said teeter beam ( 3 d ) has said two first lugs, arranged at said distance with respect to said rotational axis (RA);
wherein each one of said second lugs ( 3 k ) is located between the two lugs of a respective said pair of first lugs ( 3 j 1 , 3 j 2 ) or wherein each one of said first lugs is located between the two lugs of a respective said pair of second lugs, and respective connecting pins ( 3 n ) pass through said first and second lugs ( 3 j 1 , 3 j 2 , 3 k ) on either side of said rotational axis (RA); and
a pair of elastic bushings ( 3 l 1 , 3 l 2 ) arranged on each of said connecting pins ( 3 n ) between a first one of said first lugs ( 3 j 1 ) and said second lug ( 3 k ) and between a second one of said first lugs ( 3 j 2 ) and said second lug ( 3 k ), respectively, or vice versa.
2. The bearing ( 3 c ) of claim 1 , wherein said hub piece ( 3 f ) is rotated relative to said teeter beam ( 3 d ) around said rotational axis (RA).
3. The bearing ( 3 c ) of claim 1 , wherein said connecting pins ( 3 n ) are obliquely oriented with respect to said rotational axis (RA).
4. The bearing ( 3 c ) according to claim 1 , wherein said first and second lugs ( 3 j 1 , 3 j 2 , 3 k ) are angled at 15° to 50° with respect to said rotational axis (RA), or wherein said first and second lugs ( 3 j 1 , 3 j 2 , 3 k ) are aligned with said rotational axis (RA) for an unpowered rotor ( 3 b ).
5. The bearing ( 3 c ) of claim 1 , wherein said hub piece ( 3 f ) is aligned with teeter beam ( 3 d ) for an unpowered rotor ( 3 b ).
6. The bearing ( 3 c ) according to claim 1 , wherein the connecting pins ( 3 n ) comprise means for compressing said bushings ( 3 l 1 , 3 l 2 ), including a screw head ( 3 o ), a threaded end portion opposite said screw head, and a screw nut ( 3 p ) engaging said threaded end.
7. The bearing ( 3 c ) according to claim 1 , wherein said teeter beam ( 3 d ) comprises a central portion ( 3 da ) arranged on said rotational axis (RA), said central portion ( 3 da ) having a least one fixing structure for attaching said rotor ( 3 b ), said teeter beam ( 3 d ) further comprising, departing from said central portion ( 3 da ), two arms ( 3 db ) that extend outwardly in opposite radial directions with respect to said rotational axis (RA), each of said arms ( 3 db ) comprising one of said pairs of first lugs ( 3 j 1 , 3 j 2 ) arranged at said distance with respect to said rotational axis (RA).
8. The bearing ( 3 c ) according to claim 1 , wherein the elastic bushings ( 3 l 1 , 3 l 2 ) are formed as truncated cones, with a respective base being in contact with said hub piece ( 3 f ).
9. The bearing ( 3 c ) according to claim 1 , wherein the elastic bushings ( 3 l 1 , 3 l 2 ) are pre-compressed by the connecting pins ( 3 n ).
10. The bearing ( 3 c ) to claim 1 , further comprising a fitted tubular spacer ( 3 m ) that passes through the two elastic bushings ( 3 l 1 , 3 l 2 ) for each pair of said first lugs ( 3 j 1 , 3 j 2 ) and bears on each of said two first lugs ( 3 j 1 , 3 j 2 ).
11. The bearing ( 3 c ) to claim 1 , wherein at least one of (a) said first lugs ( 3 j 1 , 3 j 2 ) or (b) said second lugs ( 3 k ) comprise a recessed portion or a protruding portion ( 3 ja ) surrounding a lug through-hole.
12. The bearing ( 3 c ) according to claim 1 , further comprising a central pin ( 3 i ) extending along said rotational axis (RA), through said hub piece ( 3 f ) and said teeter beam ( 3 d ), said central pin ( 3 i ) is configured to fix a relative position of said hub piece ( 3 f ) and said teeter beam ( 3 d ) on said rotational axis (RA).
13. The bearing ( 3 c ) according to claim 12 , further comprising an angled sleeve ( 3 r ) around said central pin ( 3 i ) extending through an opening ( 3 dc ) in said teeter beam ( 3 d ).
14. The bearing ( 3 c ) according to claim 13 , wherein said angled sleeve ( 3 r ) is formed as a truncated cone, a maximum diameter of which is in close clearance with an inner diameter of said opening ( 3 dc ), and said hub piece ( 3 f ) abuts on an end of said angled sleeve ( 3 r ).
15. The bearing ( 3 c ) according to claim 13 , further comprising a spacing sleeve ( 3 ic ) around said central pin ( 3 i ) extending through said opening ( 3 dc ) in said teeter beam ( 3 d ) inside and through said angled sleeve ( 3 r ).
16. The bearing ( 3 c ) according to claim 12 , further comprising a retainer piece ( 3 h ) arranged on said central pin ( 3 i ) at a first end thereof, said first end being located on a side of said teeter beam ( 3 d ) opposite from said hub piece ( 3 f ).
17. The bearing ( 3 c ) according to claim 1 , wherein a teeter axis (TA) is rotated by an angle φ, φ>0°, or φ<0° with respect to a normal axis (NA) of the rotor ( 3 b ), said normal axis (NA) being oriented at right angles with respect to a rotor axis (RA′).
18. A driving arrangement for driving a rotor ( 3 b ) in an aircraft ( 1 ), comprising:
the bearing ( 3 c ) according to claim 12 ,
a motor ( 3 a ) having a hollow drive shaft ( 3 aa ) that is connected to said hub piece ( 3 f ) for rotatably driving said hub piece, and said central pin ( 3 i ) extends coaxially through said drive shaft ( 3 aa ).
19. An aircraft ( 1 ), comprising:
at least one propulsion unit ( 3 ) including a rotor ( 3 b ) comprising the bearing ( 3 c ) according to claim 1 ,
wherein at least two rotor blades ( 3 b 1 , 3 b 2 ) of said rotor ( 3 b ) are attached to the teeter beam ( 3 d ) of said bearing ( 3 c ) on opposing sides thereof, and
said hub piece ( 3 f ) is connected to a drive shaft ( 3 aa ) of a motor ( 3 a ) of said at least one propulsion unit ( 3 ).
20. The aircraft of claim 19 , wherein the aircraft is a multi-rotor VTOL aircraft ( 1 ) with a plurality of the propulsion units that are distributed, electrically powered propulsion units ( 3 ), and at least some of the distributed electrically powered propulsion units ( 3 ) each include one of the rotors ( 3 b ) having the bearing ( 3 c ).