Hub structure for a rotary wing aircraft

• US 5,228,834 A
• Filed: 04/16/1991
• Issued: 07/20/1993
• Est. Priority Date: 04/27/1990
• Status: Expired due to Term

• Current Assignee: Japan As Represented By Director General Technical Research and Development Institute Japan Defense Agency
• Original Assignee: Japan As Represented By Director General Technical Research and Development Institute Japan Defense Agency, Kawasaki Jukogyo Kabushiki Kaisha
• Inventors: Yamamoto, Keizou, Ichihashi, Takahiro, Wakatsuki, Tadashi, Hanayama, Kanehiro, Bandoh, Shunichi, Kakinuma, Asao
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): Mattingly, Todd
• Application Number:
  US07/685,646
• Time in Patent Office: 826 Days
• Field of Search: 416/131, 416/134 R, 416/134 A, 416/141 R, 416/142, 416/140 A, 416/143, 384/203, 384/204, 384/221
• US Class Current: 416/131
• CPC Class Codes: B64C 27/33 having flexing arms
• CPC Class Codes: B64C 27/50 Blades foldable to facilitate stowage of aircraft
• CPC Class Codes: B64C 27/51 Damping of blade movements

Abstract

A bearingless hub structure for a rotary-wing aircraft is provided, the structure including a hub body adapted to be securely connected to a rotor mast, a plurality of flexible beam members provided integrally with the hub body to extend radially outwardly, a pitch housing encircling each of the flexible beam members, and having a radially outward end portion which is rigid with a radially inward end portion of a rotor blade, a spherical bearing positioned adjacent to a radially inward end portion of the flexible beam member for supporting the pitch housing, a lead-lag damper positioned between the flexible beam member and the pitch housing, and the flexible beam members each having a flexible plate portion which is of a low bending rigidity in a flapping direction, a flexible portion provided radially outwardly of the flexible plate portion having a low bending rigidity in the lead-lag direction, and a twist-flex portion provided radially outwardly of the flexible portion. The flexible portion has two beam sections which have radially outward end portions integrally connected with a radially inward end portion of a twist-flex portion, with the radially inward end portions of the beam sections being removably connected to a radially outward end portion of the flexible plate portion at a plurality of circumferentially spaced positions.

Claims

1. A bearingless hub structure of a rotary wing aircraft including a hub body which is adapted to be connected with a rotor mast, a plurality of flexible beam members provided integrally with the hub body to extend radially outward, a pitch housing encircling each of said flexible beam members with a spacing therebetween, said pitch housing having a radially outward end portion which is rigid with a radially inward end portion of a rotor blade, spherical bearing means provided adjacent to a radially inward end portion of said flexible beam member for supporting a radially inward end portion of said pitch housing, lead-lag damper means provided between said flexible beam member and said pitch housing for providing a damping function in a lead-lag direction, the improvement comprising that said flexible beam member includes a flexible plate portion which is of a low bending rigidity in a flapping direction, a flexible portion provided radially outward said flexible plate portion and of a low bending rigidity in the lead-lag direction and a twist-flex portion provided radially outward said flexible portion, said flexible portion being consisted of two beam sections which have radially inward end portions spaced apart in the lead-lag direction with a spacing which decreases toward radially outward, said beam sections having radially outward end portions integrally connected with a radially inward end portion of said twist-flex portion, said radially inward end portions of said beam sections being formed with lug means removably connected through bolt means with correspondingly formed lug means in a radially outward end portion of said flexible plate portion oat a plurality of positions spaced apart in the lead-lag direction, said damper means including upper and lower elastomeric dampers attached respectively to upper and lower surface portions of said spherical bearing means, said upper elastomeric damper having a support plate attached to an upper surface portion of said upper elastomeric damper and extending in the lead-lag direction, said lower elastomeric damper having a support plate attached to a lower surface portion of said lower elastomeric damper and extending in the lead-lag direction, said support plates of said upper and lower elastomeric dampers being connected to said flexible beam member at said lug means through said bolt means, and said pitch housing being provided with support means having a radially inwardly extending pivot shaft which is inserted into said spherical bearing means.

2. A hub structure in accordance with claim 1 in which said damper means is disposed in a space between said beam sections.

3. A hub structure in accordance with claim 1 in which said damper means includes a plurality of plates with a sheet of elastomeric material interposed between each adjacent two of said plates.

4. A hub structure in accordance with claim 3 in which said spherical bearing means is located between adjacent two of said plates of said damper means with a sheet of elastomeric material interposed between each one of said plates and said spherical bearing means.