Abstract:
A vibration isolation fastener insert comprising: a rigid cylindrical hub having an externally extending flange and a through longitudinal opening to receive a fastener. An elastomeric bushing around the hub has a slot therein receiving the external flange. An upper housing is disposed around the side of the bushing and has a flange over the top of the bushing. A lower housing is disposed around the external side of the upper housing and has a flange extending below a lower surface of the bushing.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a vibration isolation insert device that serves the purpose of dampening vibrations while fastening structures/assemblies together or installing assemblies to a vibrating structure. This insert device can be installed on a monument, assembly, panel, plate or in a composite panel to assemble or install a component part on an aircraft, moving vehicle, or vibrating structure. 
     The effects of vibrations are a problem in commercial aircraft. For example, vibration is transmitted by the structural beams which support the floor panels. These floor panels are typically made of an aluminum honeycomb, or other rigid, lightweight material and vibration causes the panels to vibrate which creates sound. This background sound can be unpleasant and interfere with ordinary conversation, disturb sleep and the like. Other structures or monuments normally found in aircraft interiors such as seats, galleys, bulkheads, etc. supported by the base airframe structure are also subject to vibration and the creation of unwanted sound and noise. 
     All of the effects are undesirable and reduce the flying customer&#39;s comfort and satisfaction. 
     The practice of using isolators on vehicles is longstanding. They are used to reduce noise and eliminate the transfer of isolating frequencies to the passenger cabin, thereby reducing perceived noise and reducing passenger fatigue. It has been common practice to isolate monuments (e.g., furnishings) and/or added components on an aircraft or vehicles with the use of external isolator mounts (i.e., isolating devices mounted to the aircraft or vehicle structure). These isolator mounts generally require additional brackets, fasteners and other adapters in order to make isolation functional in a vibrating environment. 
     U.S. Pat. No. 6,443,679 issued to Schwarz on Sep. 3, 2002 shows a vibration-dampening connecting arrangement for the detachable connection of two components with a releasing part, which can be moved on a bolt guided by a bush. U.S. Pat. No. 7,179,039 issued to Schwartz et al. on Feb. 20, 2007 shows a vibration-damping ring insert arrangement and component connection arrangement incorporating the same. U.S. Pat. No. 5,876,023 issued to Hain et al. on Mar. 2, 1999 and companion U.S. Pat. No. 5,876,024 shows a vibration isolation insert for aircraft floor panels and the like. U.S. Pat. Nos. 6,065,742, 6,138,980, 6,216,833 B1, 6,394,432 B1, 6,715,746 and Enidine GmbH U.S. Pat. No. 7,131,786 B2 are also patents in this field. 
     SUMMARY OF THE INVENTION 
     A vibration isolation fastener insert structure adapted to be partially or wholly snugly received in a hole in a panel comprising: 
     a rigid cylindrical hub having an externally extending flange and a central through longitudinal opening adapted to receive a fastener element; 
     an elastomeric bushing snugly carried or formed around said hub and having a slot therein receiving said externally projecting flange; 
     an upper housing; 
     a lower housing; 
     the upper housing being disposed around the side of said bushing and having a flange over the top of said bushing and the lower housing disposed around the external side of said upper housing and having a flange extending below a lower surface of said bushing. 
     A vibration isolation fastener insert structure adapted to be partially or wholly snugly received in a hole in a panel comprising: 
     a rigid cylindrical hub having an externally extending flange and a central through longitudinal opening adapted to receive a fastener element; 
     an elastomeric bushing snugly carried or formed around said hub and having a slot therein receiving said externally projecting flange; 
     an upper housing; 
     a lower housing; 
     the upper housing being disposed around the side of said bushing and having a flange over the top of said bushing and the lower housing disposed around the external side of said upper housing and having a flange extending below a lower surface of said bushing, said lower housing being externally threaded. 
     A panel assembly having a through hole, at least partially snugly received in said hole a vibration isolation fastener insert comprising: 
     a rigid cylindrical hub having an externally extending flange and a central through longitudinal opening adapted to receive a fastener element; 
     an elastomeric bushing snugly carried or formed around said hub and having a slot therein receiving said externally projecting flange; 
     an upper housing; 
     a lower housing; 
     the upper housing being disposed around the side of said bushing and having a flange over the top of said bushing and the lower housing disposed around the external side of said upper housing and having a flange extending below a lower surface of said bushing, 
     the upper housing being disposed around the side of said bushing and having a flange over the top of said bushing and the lower housing disposed around the external side of said upper housing and having a flange extending below a lower surface of said bushing, said lower housing being externally threaded. 
     A panel assembly, said panel having a through hole, and upper and lower flanges, the upper flange having a cylindrical element being snugly received in said through hole and the lower flange having a cylindrical element being threadably received in said upper flange and carrying inwardly projecting threads, 
     a vibration isolation fastener insert structure partially or wholly inserted in said hole in said panel and comprising:
         a rigid cylindrical hub having an externally extending flange and a central through longitudinal opening adapted to receive a fastener element;   an elastomeric bushing snugly carried or formed around said hub and having a slot therein receiving said externally projecting flange;   an upper housing;   a lower housing;   the upper housing being disposed around the side of said bushing and having a flange extending over the top of said bushing and the lower housing disposed around the external side of said upper housing and having a flange extending below a lower surface of said bushing, said lower housing being externally threaded,
 
said external threads on said lower housing being made up with the inwardly projecting threads on said lower flange.
       

     The invention is directed to aircraft having fastener inserts incorporated in a member which can be a honeycomb or composite or metal panel forming composite part of the floor, seat, overhead locker, etc. or sheet metal or plate component to support avionic equipment or the like. This invention can also be applied directly to the airframe metal structure as a swaged insert on to the metal structure in similar manner as to plate or sheet metal. 
     In one preferred embodiment, a thru hole is cut in the panel, the upper and lower flanges are pressed in and the flanges are also bonded on the skins of the panel with adhesive then potting material is injected to form the “desification”. 
     Separately, the upper and lower housing with the “C” cross-section shaped elastomeric bushing and hub are assembled. An elastomeric spacer ring can be dropped into place if spacing is desired. Then the above described assembly is threaded into place, female threads on the lower housing engaging the inwardly projecting male threads on the lower flange. The assembly can be advanced as desired. 
     The purpose of the elastomeric bushing is to provide a vibration dampener between the two structural parts. The nut, bolt and seat track do not form part of the invention but do show how the insert is used. 
     The “potted-in” embodiment is preferred but not a limitation since the fastener inserts can be held in, for example, a metal sheet or directly to the airframe panel by force or interference fit, viz., swaging or bonded-on. 
     In case of application directly to sheet metal, plate or airframe metal structure, isolator insert will be swaged to metal in similar manner as a rivet or clinch nut. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention incorporates a vibration isolation insert as a permanent component of the monument, panel, assembly, plate and/or composite panel (hereafter collectively called monument). This insert device is assembled with an internal elastomer with dampening characteristics that can be modulated to accommodate different frequencies. Its various embodiments allow for an infinite number of permutations. 
     For example, the fastener inserts are used in floor panels to fasten the floor panel to a structural floor track or beam. Other uses are to fasten seats, galleys, overhead lockers, bulkheads, lavatories and the like. 
     The invention includes an elastomeric part within the fastener insert, to isolate, for example, the floor from structural vibration within the main structural framework of the aircraft and thereby make the passenger compartment more comfortable and pleasing to the passenger. 
    
    
     
       THE DRAWINGS 
       The basic design of one embodiment of a panel assembly with the vibration isolation insert in place is as shown in cross-section in  FIG. 1 . 
         FIG. 2   a  is a top perspective view of upper flange  16 ,  116 . 
         FIG. 2   b  is a perspective view of the upper flange  16 ,  116  in the inverted position. 
         FIG. 2   c  is the elastomeric bushing  24 ,  124  carried on hub  26 ,  126 . 
         FIG. 2   d  is a perspective view of lower flange  18 ,  118 . 
         FIG. 2   e  is a perspective view in partial section of hub  26 ,  126 . 
         FIG. 2  shows another embodiment of the invention in cross-section. 
         FIG. 3  shows one application of the vibration isolation insert of  FIG. 2 . 
         FIG. 4  shows another application of the vibration isolation insert of  FIG. 3 . 
     
    
    
     Turning to  FIG. 1  in more detail, the insert  10  is adapted to be received in a hole  12  drilled in panel  14 , typically a honeycomb panel. In use, the upper and lower flanges  16  and  18  are inserted into hole  12  and held by an interference or press fit, i.e., swaged. Alternatively, the flanges  16  and  18  can be potted in by a liquid potting compound or glue, injected via potting holes  17 , which, after injection, hardens and adheres to surfaces of upper flange  16  and lower flange  18  and to exposed cells within the honeycomb panel  14 , holding the flanges in place. The flanges are usually bonded on first with an adhesive and then potted-in with a potting compound. 
     Next, the upper housing  20 , lower housing  22  having external male threads, elastomeric bushing  24 , hub  26  are pre-assembled with the external flange  27  on hub  26  being received in slot  25  in elastomer bushing  24  and the so sub-assembly threaded into the female threads on upper flange  16 . The elastomer can be over-molded onto hub  26  whereby the holes on hub are used for anti-rotation and increased bonding surface for the elastomer. Finally, a nut  28  and bolt  30  are inserted and made up to join the panel  14  to the structural track  32 . 
     Turning to  FIGS. 2   a,    2   b  and  2   c  of  2 , the drawings, in this embodiment the upper flange  116  and the lower flange  118  are press fit, screwed or swaged to each other and capture components. The elastomeric bushing  124  and hub  126  (elastomer/metal hub assembly) are positioned as shown. The dimensions and materials for flange  116  and flange  118  will depend on the type and size of fasteners (e.g., screw, anchor, etc.) used to secure the monument to the vehicle structure and the material into which it will be installed. Flange  116  and flange  118  will accommodate different applications whereby the overlying elements  119  on flanges  116  and  118  may be omitted and the balance of the flanges  116  and  118  are flush with the surface of the panel  110  or may overlap the surface(s) of the panel  110  to increase the strength of the insert under various tensile, shear or torsion loading conditions. The holes  117  are for the injection of potting material and venting of air as potting is carried out. 
     Hub  126  is to be cylindrical in shape with a circular “T” flange  127  intersecting the cylinder. The flange  127  component on hub  126  are larger than the clearance hole openings on flanges  116  and  118  such that it is retained if pulled axially, even if elastomeric bushing  124  would fail. Hub  126  may be threaded internally to accept any size screw or it can remain unthreaded or through-drilled to act as a bushing, either with/without a countersink on either end to accommodate a flat-head screw. Hub  126  may also be threaded externally at its exposed end to accept adapters of different sizes. The diameter dimensions and finishes of hub  126  may vary to accommodate various size screws, and to accommodate strength requirements. 
     Elastomeric bushing  124  may have ribs or projections  130  to provide anti-rotation elements which can engage slots  128 . 
     Flange  118  may have a snap ring  131  to facilitate engagement with snap groove  129  on flange  116 . 
     Elastomeric bushing  124  may or may not be bonded to hub  126  such as by molding and will have the required characteristics to provide the optimum dampening under the loads for each condition. Various dampening effects can be achieved by modifying the material characteristics and dimensions of elastomeric bushing  124 . 
     Optionally, flange  116  may have an anti-rotation knurled ring or area  133 . 
     Hub  126  may have holes  132  in flange  127  to allow for over-molding of elastomer and thereby prevent relative rotation. Hub  126  as shown, for example, in  FIG. 2   c  may have self-locking internal threads. The external threads may also be self-locking. Hub  126  may also be double ended, that is, have a flange at both of its ends. 
     As shown in  FIG. 3 , two honeycomb panels can also be joined and held in spaced apart relationship using a stand off  134 . 
       FIG. 4  shows the vibration isolation fastener in a panel used to join to another panel with separation provided by standoff  134 . 
     As shown in  FIGS. 3 and 4 , the assembly can be secured by anti-rotation hex nut  135 . 
     This invention lends itself to include the development of a family of insert types that will address many applications and uses. This family of inserts may be viewed in two general categories: Potted Isolator Inserts and swaged Isolator Inserts. The Potted Isolator Insert category would typically be installed through a honeycomb panel attached to (or part of) the monument, and would be secured via the application of a potting compound in the panel cavity surrounding the installed insert and possibly via bonding to flanges of components  116  and  118 . The swaged Isolator Insert embodiment would typically be installed in a panel attached to (or part of) the monument by crimping its outer flange(s) after the Insert is installed in a receiving hole on the panel. A panel could be a plate, a group of stacked plates or the web of an extrusion of any type of material depending on the application. Honeycomb panels are panels manufactured with two rigid skins and a lightweight core. Generally, honeycomb panels come in many thicknesses and vary in core material, core density, skin materials, skin thickness, and adhesive type. 
     The installation and application of these inserts include many fastening methods for us with the various fastener types and sizes commonly used in aircraft and other vehicles. The family of Isolator Inserts of this invention will accommodate typical metric and Imperial fastener sizes, and will address derivatives that include studs, through fasteners, threaded fasteners, and additional attachments. 
     The Potted Isolator Insert category will include, among other embodiments: 
     1. Adjustable threaded hub w/an assembled outer ring assembly. 
     2. Adjustable threaded hub w/an un-assembled 2-piece plug/sleeve assembly for adjustability. 
     3. When addressing bulkhead or vertical panel applications the hub will have bi-directional extensions, extending on opposite directions. These may also be threaded or not internally and externally. 
     4. Inserts as noted: fully assembled and ready for installation; or an un-assembled insert in three or five parts (i.e., flanges and elastomeric bushing/hub assembly) to be assembled and installed by customer. 
     The swaged Isolator Insert category will include, among other embodiments: 
     1. Adjustable threaded hub w/an assembled outer ring assembly to be press fit into a panel hole. 
     2. Adjustable threaded hub w/an un-assembled 2-piece flanges assembly to be press fit or threaded upon installation. 
     3. Inserts as noted: fully assembled and ready for installation; or an un-assembled insert in three or five parts (i.e., flanges and elastomer bushing/hub assembly) to be assembled and installed by customer.