# US 9,751,623 B2 · Flexbeam unit for a hingeless or a hinge and bearingless multi-blade rotor of a rotary wing aircraft > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,751,623 B2 - Document ID: US9751623B2 - Status: Granted - Kind: B2 - Application number: 14/594,601 - Filed: 2015-01-12 - Published: 2015-07-16 - Granted: 2017-09-05 - Earliest claimed: 2014-01-14 - Assignees: Airbus Helicopters Deutschland GmbH - Applicants: Airbus Helicopters Deutschland GmbH - Inventors: Rupert Pfaller - Web page: https://patentgrep.com/patent/US9751623B2 ## CPC - B64C 27/33: having flexing arms - B64C: AEROPLANES; HELICOPTERS ## Abstract A flexbeam unit for a multi-blade rotor of a rotary wing aircraft, the flexbeam unit comprising a plurality of flexbeam elements that define a predetermined number of torsion elements and a ring-shaped connection zone for attachment to a rotor hub associated with a rotor shaft of the multi-blade rotor, each flexbeam element passing the ring-shaped connection zone in a tangential manner and uninterruptedly connecting a first torsion element to a second torsion element of the predetermined number of torsion elements, wherein each flexbeam element overlaps at least one in the circumferential direction of the ring-shaped connection zone immediately following flexbeam element and is overlapped by at least one in the circumferential direction of the ring-shaped connection zone immediately preceding flexbeam element. ## Claims ### Claim 1 A flexbeam unit for a multi-blade rotor of a rotary wing aircraft, the flexbeam unit comprising a plurality of flexbeam elements that define a predetermined number of torsion elements and a ring-shaped connection zone for attachment to a rotor hub associated with a rotor shaft of the multi-blade rotor, each flexbeam element passing the ring-shaped connection zone in a tangential manner and uninterruptedly connecting a first torsion element to a second torsion element of the predetermined number of torsion elements, wherein each flexbeam element overlaps at least one in a circumferential direction of the ring-shaped connection zone immediately following flexbeam element and is overlapped by at least one in the circumferential direction of the ring-shaped connection zone immediately preceding flexbeam element, wherein each flexbeam element comprises at least one lath-shaped beam member, and wherein the at least one lath-shaped beam member of each flexbeam element comprises at least one lateral projection projecting into the ring-shaped connection zone and defining at least one attachment point for attachment of the flexbeam element to the rotor hub. ### Claim 2 (depends on 1) The flexbeam unit according to claim 1, wherein the first torsion element is associated with a n-th rotor blade of the multi-blade rotor and the second torsion element is associated with a (n+2)-th rotor blade of the multi-blade rotor in the circumferential direction of the ring-shaped connection zone. ### Claim 3 (depends on 1) The flexbeam unit according to claim 1, having a number N of torsion elements, the first torsion element being a n-th torsion element and the second torsion element being a (n+2)-th torsion element in the circumferential direction of the ring-shaped connection zone, where 1≦(n+2)≦N. ### Claim 4 (depends on 1) The flexbeam unit according to claim 1, wherein each flexbeam element comprises at least one upper and one lower lath-shaped beam member, the upper lath-shaped beam member being laterally recessed in a region where the upper lath-shaped beam member is overlapped by an overlapping flexbeam element. ### Claim 5 (depends on 1) The flexbeam unit according to claim 1, wherein each flexbeam element comprises at least one upper and one lower lath-shaped beam member, the lower lath-shaped beam member being laterally recessed in a region where the lower lath-shaped beam member overlaps an overlapped flexbeam element. ### Claim 6 (depends on 1) The flexbeam unit according to claim 1, wherein at least one lateral projection has an increased thickness. ### Claim 7 (depends on 1) The flexbeam unit according to claim 1, wherein each flexbeam element is inclined by a given inclination angle with respect to the at least one in the circumferential direction of the ring-shaped connection zone immediately following flexbeam element. ### Claim 8 (depends on 1) The flexbeam unit according to claim 1, wherein each flexbeam element is at least partially S-shaped in its axial direction. ### Claim 9 (depends on 8) The flexbeam unit according to claim 8, wherein each flexbeam element has an inner lateral edge that is facing the ring-shaped connection zone and an outer lateral edge that is facing away from the ring-shaped connection zone, the inner lateral edge comprising a connection section that is substantially S-shaped in the axial direction. ### Claim 10 (depends on 9) The flexbeam unit according to claim 9, wherein the outer lateral edge is substantially straight. ### Claim 11 (depends on 10) The flexbeam unit according to claim 10, wherein the outer lateral edge comprises a kink of less than 7°. ### Claim 12 (depends on 1) The flexbeam unit according to claim 1, wherein at least one clamping element is arranged in the area of the ring-shaped connection zone to stick the plurality of flexbeam elements in a star-shaped configuration together. ### Claim 13 (depends on 12) The flexbeam unit according to claim 12, wherein at least one clamping element comprises a central part that substantially covers the ring-shaped connection zone. ### Claim 14 (depends on 12) The flexbeam unit according to claim 12, wherein at least one clamping element comprises a plurality of clamping arms. ### Claim 15 (depends on 14) The flexbeam unit according to claim 14, wherein each one of the plurality of clamping arms comprises an associated control cuff bearing. ### Claim 16 (depends on 14) The flexbeam unit according to claim 14, wherein each one of the plurality of clamping arms comprises associated fixation means for attaching each one of the plurality of clamping arms to an associated flexbeam element. ### Claim 17 A flexbeam unit for a multi-blade rotor of a rotary wing aircraft, the flexbeam unit comprising a plurality of flexbeam elements that define a predetermined number of torsion elements and a ring-shaped connection zone for attachment to a rotor hub associated with a rotor shaft of the multi-blade rotor, each flexbeam element passing the ring-shaped connection zone in a tangential manner and uninterruptedly connecting a first torsion element to a second torsion element of the predetermined number of torsion elements, wherein each flexbeam element overlaps at least one in a circumferential direction of the ring-shaped connection zone immediately following flexbeam element and is overlapped by at least one in the circumferential direction of the ring-shaped connection zone immediately preceding flexbeam element, wherein each flexbeam element comprises at least one lath-shaped beam member, and wherein each flexbeam element is at least partially S-shaped in its axial direction. ### Claim 18 A flexbeam unit for a multi-blade rotor of a rotary wing aircraft, the flexbeam unit comprising a plurality of flexbeam elements that define a predetermined number of torsion elements and a ring-shaped connection zone for attachment to a rotor hub associated with a rotor shaft of the multi-blade rotor, each flexbeam element passing the ring-shaped connection zone in a tangential manner and uninterruptedly connecting a first torsion element to a second torsion element of the predetermined number of torsion elements, wherein each flexbeam element overlaps at least one in a circumferential direction of the ring-shaped connection zone immediately following flexbeam element and is overlapped by at least one in the circumferential direction of the ring-shaped connection zone immediately preceding flexbeam element, wherein each flexbeam element comprises at least one lath-shaped beam member, and wherein at least one clamping element is arranged in the area of the ring-shaped connection zone to stick the plurality of flexbeam elements in a star-shaped configuration together, the at least one clamping element comprising a plurality of clamping arms, each one of the plurality of clamping arms comprising an associated control cuff bearing.