Rotor blade retention system

Claim 2

A rotor blade retention system comprising a rotor hub rotatable about a central axis, at least one sustaining blade, and retention means connecting said blade to said rotor hub with said blade normally extending generally radially from said hub for rotation therewith about said central axis, said retention means including a pair of arcurate shaped elastomeric bearing means comprising a plurality of radially alternating and bonded layers of rigid and elastomeric material operatively connected in series along a longitudinal axis with said layers oriented to have a component normal to said axis, said serially arranged bearings mounted between said blade and rotor hub coincident with the longitudinal axis of said blade for restraining said blade against the centrifugal load imposed thereon by compression loading of each of said bearings at least partially normal to said layers while permitting and sharing pivotal movement of said blade about its longitudinal axis by loading said bearings torsionally along the layers, said radially alternating layers of each bearing being concentrically disposed about the longitudinal axis of said blade and defining therealong an effective elastic center, the elastic centers of said bearings being coincident.

Claim 3

A rotor blade retention system, according to claim 1, wherein one of said elastomeric bearings is spherical shaped to also permit lead-lag and flapping movement of said blade relative to said rotor hub.

Claim 4

A rotor blade retention system, according to claim 1, wherein both of said elastomeric bearings are spherical shaped to also permit and share lead-lag and flapping movement of said blade relative to said rotor hub.

Claim 5

A rotor blade retention system, according to claim 1, including means for precompressing each of said elastomeric bearings along the longitudinal axis of said blade during non-rotation of said rotor hub.

Claim 6

A rotor blade retention system, according to claim 4, wherein said blade and rotor hub axially engage to precompress each of said elastomeric bearings along the longitudinal axis of said blade during non-rotation of said rotor hub and disengage during rotation of said rotor hub as a result of the axially compression of said bearings due to the centrifugal load imposed on said blade.

Claim 7

A rotor blade retention system comprising a rotor hub rotatable about a central axis, at least one sustaining blade and retention means connecting said blade to said rotor hub with said blade normally extending generally radially from said hub for rotation therewith about said central axis, said retention means including a pair of arcurate shaped elastomeric bearing means comprising a plurality of radially alternating and bonded layers of rigid and elastomeric material operatively connected in series along a longitudinal axis with said layers oriented to have a component normal to said axis, each of said bearings having a passage extending centrAlly therethrough coincident with said longitudinal axis, one of said blade and rotor hub being received through the passages of said bearings, said serially arranged bearings mounted between said blade and rotor hub coincident with the longitudinal axis of said blade for restraining said blade against the centrifugal load imposed thereon by compression loading of each of said bearings at least partially normal to said layers while permitting and sharing pivotal movement of said blade about its longitudinal axis by loading said bearings torsionally along the layers, said radially alternating layers of each bearing being concentrically disposed about the longitudinal axis of said blade and defining therealong an effective elastic center, the elastic center of said bearings being coincident.

Claim 8

A rotor blade retention system comprising a rotor hub rotatable about a central axis, at least one sustaining blade and retention means connecting said blade to said rotor hub with said blade normally extending generally radially from said hub for rotation therewith about said central axis, said retention means including a pair of arcurate shaped elastomeric bearing means comprising a plurality of radially alternating and bonded layers of rigid and elastomeric material operatively connected in series along a longitudinal axis with said layers oriented to have a component normal to said axis, each of said bearings having a passage extending centrAlly therethrough coincident with said longitudinal axis, one of said blade and rotor hub being received through the passages of said bearings, said serially arranged bearings mounted between said blade and rotor hub coincident with the longitudinal axis of said blade for restraining said blade against the centrifugal load imposed thereon by compression loading of each of said bearings at least partially normal to said layers while permitting and sharing pivotal movement of said blade about its longitudinal axis by loading said bearings torsionally along the layers, said radially alternating layers of each bearing being concentrically disposed about the longitudinal axis of said blade and defining therealong an effective elastic center, the elastic center of said bearings being coincident.

Claim 9

A rotor blade retention system, according to claim 6, including a housing carried by said rotor hub, said housing having an opening therein facing radially outward from said rotor hub, said bearings being disposed within said housing, said blade having an inboard end received through the opening in said housing and passage of both of said bearings, and said serially arranged bearings being mounted between the inboard end of said blade and the outboard end of said housing adjacent said opening therein.

Claim 10

A rotor blade retention system comprising a rotor hub rotatable about a central axis, at least one sustaining blade, and retention means connecting said blade to said rotor hub with said blade normally extending generally radially from said hub for rotation therewith about said central axis, said retention means including a bearing housing carried by one of said rotor hub and the inboard end of said blade, said housing having an opening in the end thereof facing the other of said blade and rotor hub, a pair of arcurate shaped elastomeric bearing means comprising a plurality of radially alternating and bonded layers of rigid and elastomeric material disposed within said housing, each of said bearings having a passage extending centrally therethrough aligned with each other and the opening in said housing, the other of said rotor hub and the inboard end of said blade extending through said opening in said housing and the passages of each of said bearings, said bearings being mounted in series with each other between said housing and the inboard end of said blade with said layers of each bearing oriented to be loaded at least partially in compression normal thereto and restrain said blade against centrifugal forces imposed in response to rotation of said hub while being loaded torsionally to permit and share pivotal movement of said blade about its longitudinal axis, said radially alternating layers of each bearing being concentrically disposed about the longitudinal axis of said blade and defining therealong an effective elastic center, the elastic center of said bearings being coincident.

Claim 11

A rotor blade retention system comprising a rotor hub rotatable about a central axis, at least one sustaining blade, and retention means connecting said blade to said rotor hub with said blade normally extending generally radially from said hub for rotation therewith about said central axis, said retention means including a bearing housing carried by one of said rotor hub and the inboard end of said blade, said housing having an opening in the end thereof facing the other of said blade and rotor hub, a pair of arcurate shaped elastomeric bearing means comprising a plurality of radially alternating and bonded layers of rigid and elastomeric material disposed within said housing, each of said bearings having a passage extending centrally therethrough aligned with each other and the opening in said housing, the other of said rotor hub and the inboard end of said blade extending through said opening in said housing and the passages of each of said bearings, said bearings being mounted in series with each other between said housing and the inboard end of said blade with said layers of each bearing oriented to be loaded at least partially in compression normal thereto and restrain said blade against centrifugal forces imposed in response to rotation of said hub while being loaded torsionally to permit and share pivotal movement of said blade about its longitudinal axis, said radially alternating layers of each bearing being concentrically disposed about the longitudinal axis of said blade and defining therealong an effective elastic center, the elastic center of said bearings being coincident.

Claim 12

A rotor blade retention system comprising a rotor hub rotatable about a central axis, at least one sustaining blade, and retention means connecting said blade to said rotor hub with said blade normally extending radially from said hub for rotation therewith about said central axis, said retention means including a bearing housing carried by said rotor hub, said housing having an opening therein facing radially outward from said rotor hub, and defining internally thereof adjacent and circumscribing said opening a surface facing radially inward toward said rotor hub, a pair of arcurate shaped elastomeric bearing means comprising a plurality of radially alternating and bonded layers of rigid and elastomeric material disposed within said housing, each of said bearings having a passage extending centrally therethrough aligned with each other and the opening in said housing, the inboard end of said blade extending through said opening and the passage of each of said bearings and having means carried thereby extending transversely of said blade axis and defining a surface concentric to said blade axis facing radially outward from said rotor hub, said bearings being mounted in series with each other between said housing and blade surfaces with said layers oriented to have a component normal to the longitudinal axis of said blade to be loaded at least partially in compression normal to the layers and restrain said blade against centrifugal loads imposed in response to rotation of said hub while being loaded torsionally to permit and share pivotal movement of said blade about its longitudinal axis, said radially alternating layers of each bearing being concentrically disposed about the longitudinal axis of said blade and defining therealong an effective elastic center, the elastic center of said bearings being coincident.

Claim 13

A rotor blade retention system comprising a rotor hub rotatable about a central axis, at least one sustaining blade, and retention means connecting said blade to said rotor hub with said blade normally extending radially from said hub for rotation therewith about said central axis, said retention means including a bearing housing carried by said rotor hub, said housing having an opening therein facing radially outward from said rotor hub, and defining internally thereof adjacent and circumscribing said opening a surface facing radially inward toward said rotor hub, a pair of arcurate shaped elastomeric bearing means comprising a plurality of radially alternating and bonded layers of rigid and elastomeric material disposed within said housing, each of said bearings having a passage extending centrally therethrough aligned with each other and the opening in said housing, the inboard end of said blade extending through said opening and the passage of each of said bearings and having means carried thereby extending transversely of said blade axis and defining a surface concentric to said blade axis facing radially outward from said rotor hub, said bearings being mounted in series with each other between said housing and blade surfaces with said layers oriented to have a component normal to the longitudinal axis of said blade to be loaded at least partially in compression normal to the layers and restrain said blade against centrifugal loads imposed in response to rotation of said hub while being loaded torsionally to permit and share pivotal movement of said blade about its longitudinal axis, said radially alternating layers of each bearing being concentrically disposed about the longitudinal axis of said blade and defining therealong an effective elastic center, the elastic center of said bearings being coincident.

Claim 14

A rotor blade retention system, according to claim 9, wherein at least one of said elastomeric bearings is spherical shaped and including a universal centering bearing carried by said housing and supporting said blade relative to said housing against blade shear loads, the centers of said elastomeric bearings and centering bearing substantially coinciding with each other and cooperating to permit pivotal movement of said blade about a lead-lag and flapping axis as well as the pitch axis.

Claim 15

A rotor blade retention system, according to claim 10, wherein said centering bearing has a fixed center.

Claim 16

A rotor blade retention system, according to claim 10, wherein said universal centering bearing comprises a spherical socket fixed to said housing and a ball rotatably mounted in said socket, the center of said ball coinciding with the centers of said elastomeric bearings, the inboard end of said blade being disposed centrally through said ball for rotation therewith and longitudinally movable relative to said ball.

Claim 17

A rotor blade retention system, according to claim 9, wherein one of said elastomeric bearings is spherical shaped and the other is frustoconical shaped.

Claim 18

A rotor blade retention system, according to claim 9, wherein both of said elastomeric bearings are spherical shaped.