Abstract:
Mechanisms designed to facilitate movement of tray tables or other platforms are addressed. Internal flexible sleeves provide more constant pressure on linearly-moving shafts associated with the tables, reducing or cancelling possible lateral misalignments of the shafts. Outer cases maintain the flexible sleeves in position, and positive stopping features may be employed to prevent extension or retraction of the shafts beyond desired amounts.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 61/005,994 entitled Expansion and Retraction Mechanisms for Moveable Tray Tables filed on Dec. 10, 2007, the contents of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to tray tables commonly used for food service and other purposes on-board passenger aircraft or other vehicles and more particularly, although not necessarily exclusively, to expansion and retraction mechanisms associated with such tables. 
     BACKGROUND OF THE INVENTION 
     Commonly-owned U.S. Pat. No. 6,742,840 to Bentley illustrates various tray table assemblies of the type frequently used on-board commercial aircraft. These tray tables, at times, are constructed so as to latch to the rear surfaces of back rests of seats forward of the users of the tables. Unlatching the tray tables permits their deployment into generally horizontal orientations for use as supporting platforms (for food trays or other items). 
     Also depicted in the Bentley patent are arms to which a tray table may be connected. These arms are attached to each side of the seat and are configured to pivot when the table is deployed or returned to its stowage position.  FIGS. 7A and 7B  of the Bentley patent, for example, detail locations of the arms when the tray table is stowed.  FIGS. 7C and 7D , by contrast, illustrate positioning of the arms when the table is deployed. 
     U.S. Pat. No. 4,526,421 to Brennan, et al. details another tray table assembly for aircraft use. FIG. 7 of the Brennan patent shows one tray table, together with corresponding arms, deployed for use by the depicted passenger. A second tray table is stowed in contact with the rear surface of the back rest of the seat in which the passenger is seated. 
     Although food service tray tables for passenger vehicles usually are connected to or stowed in passenger seats (including sometimes in arm rests thereof), they need not always be so connected or stowed. U.S. Pat. No. 5,340,059 to Kanigowski describes tray tables instead extending from cabinet assemblies. These cabinet assemblies are attached to rear walls of aircraft cabin bulkheads, with each tray table apparently made of energy-absorbing material and additionally functioning to dissipate kinetic energy over its area when impacted by a passenger during a rapid deceleration of the aircraft. 
     Each of the tray tables of the Bentley, Brennan, and Kanigowski patents conceivably could be configured to move linearly when deployed. Depending upon the distance between rows of seats (seat pitch) in the vehicle cabin, the nominal distance between the deployed table and its user may be more or less than optimal. Permitting the tray table to move in the generally-horizontal plane toward or away from the passenger thus may be advantageous. 
     SUMMARY OF THE INVENTION 
     The present invention provides mechanisms or assemblies designed to facilitate movement of tray tables in the generally-horizontal plane. For tray tables connected to moveable shafts, the invention furnishes internal flexible sleeves intended to provide constant pressure on the shafts and reduce, if not cancel, possible misalignments. Outer casings function to maintain the flexible sleeves in position; they may assist in cancelling possible misalignments as well. Positive stopping features also may be employed to prevent extension or retraction of the shafts beyond preferred amounts. 
     Presently-preferred versions of the invention incorporate one or more flexible sleeves as part of the assemblies. Such sleeves may, if desired, resemble the Greek letter “π” in cross-section, with two outwardly-flared legs depending from a flanged base. The sleeves may, of course, have other cross-sectional shapes if appropriate or desired, however. 
     Beneficially, though, the flared, depending legs of a first sleeve are positioned in contact with, and so as to place pressure on, a (typically cylindrical) shaft. Legs of a second sleeve are positioned in contact with the shaft at locations opposite those of the legs of the first sleeve. As the shaft moves linearly, the opposing sleeves resist lateral movement of the shaft, effectively reducing the opportunity for lateral misalignment of the shaft. The flexibility of the sleeves effectively allows the shaft to self-align, reducing (if not cancelling) any manufacturing misalignment. After each shaft is inserted inside a corresponding sliding mechanism, the sleeves maintain lateral shaft positioning by applying constant pressure (e.g. spring effect) to the shaft. Linear ribs within the outer casings of the mechanisms may receive the flanged bases of the sleeves to limit their lateral movement. 
     Preferred stopping features of the invention include pins, ribs, and detents, although other stopping elements may be utilized instead. In embodiments using pins, ribs, and detents, when a shaft is fully extended, an associated pin is configured to be received by a detent in a first end cap of the outer casing. Reception of the pin by the detent prevents further extension of the shaft yet allows subsequent retraction thereof. By contrast, when the shaft is fully retracted, it may snap into (or otherwise be frictionally received by) ribs in a second end cap of the outer casing. This action prohibits further retraction of the shaft yet allows subsequent extension thereof. 
     In general, two parallel shafts, each positioned at least partially within an outer casing, will be used in connection with each tray table associated with the present invention. Typically, although not necessarily, the shafts and outer casings will extend within or along a table at or adjacent its opposing edges. One or more rods extending laterally between, and connected to, the shafts frequently may be employed. 
     It thus is an optional, non-exclusive object of the invention to provide assemblies facilitating movement of platforms. 
     It is an additional optional, non-exclusive object of the present invention to provide assemblies facilitating generally-horizontal movement of tray tables for deployment or stowage. 
     It is another optional, non-exclusive object of the present invention to provide assemblies enhancing lateral stability of tray tables by reducing, or cancelling, lateral misalignments thereof otherwise likely to occur during deployment for use. 
     It is a further optional, non-exclusive object of the present invention to provide assemblies including one or more flexible sleeves designed to pressure a shaft associated with a tray table. 
     It is, moreover, an optional, non-exclusive object of the present invention to provide assemblies in which opposing sleeves inhibit lateral motion of a shaft as it is extended and retracted linearly. 
     It is yet another optional, non-exclusive object of the present invention to provide assemblies in which further linear movement of shafts is prevented past certain defined stopping points. 
     It is also an optional, non-exclusive object of the present invention to provide assemblies in which pins, ribs, and detents may be employed to stop undesired linear movement of shafts. 
     Other objects, features, and advantages of the present invention will be apparent to those skilled in the appropriate field with reference to the remaining text and drawings of this application. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an assembly of the present invention with a shaft retracted. 
         FIG. 2  illustrates the assembly of  FIG. 1  with the shaft extended. 
         FIG. 3  illustrates a flexible sleeve of the assembly of  FIG. 1 . 
         FIG. 4  illustrates an outer casing of the assembly of  FIG. 1 . 
         FIG. 5A-B  illustrate a longitudinal cross-sectional view of the assembly of  FIG. 1 . 
         FIG. 6  illustrates a transverse cross-sectional view of the assembly of  FIG. 1 . 
         FIG. 7A-B  illustrate a first end cap of the assembly of  FIG. 1 . 
         FIG. 8  illustrates a second end cap of the assembly of  FIG. 1 . 
         FIG. 9  illustrates assemblies of  FIG. 1  (without shafts) for incorporation into a tray table (portions of which have been removed to show interior channels). 
         FIGS. 10-11  illustrate the tray table of  FIG. 9  together with shafts and ancillary components. 
     
    
    
     DETAILED DESCRIPTION 
     Detailed in  FIGS. 1-2  is an exemplary assembly  10  of the present invention. Assembly  10  may include outer casing  14  together with first and second end caps  18  and  22 , respectively. Also shown in  FIGS. 1-2  is shaft  26 , portions of which may be fitted within casing  14 . 
     Shaft  26  may be similar or identical to those presently used with aircraft tray tables and preferably is made of metal or other relatively rigid material. Shaft  26  likewise preferably is generally cylindrical in shape.  FIG. 2  illustrates that shaft  26  may be elongated; advantageously (although not necessarily), the length of shaft  26  exceeds the length L of casing  14 . 
       FIG. 3  shows a version of sleeve  30  of assembly  10 . Sleeve  30  preferably is made of flexible material, such as (but not limited to) plastic or natural or synthetic rubber, and of length less than L. Sleeve  30 , furthermore, is configured for placement within casing  14  in contact with shaft  26 . 
     In the embodiment of sleeve  30  depicted in  FIG. 3 , the sleeve  30  comprises legs  34  depending from base  38 . Dependency locations of legs  34  effectively create flanges  42  for base  38 . Moreover, legs  34  may flare outward from base  38 ; collectively, the configuration of legs  34  and base  38  causes sleeve to have cross-sectional shape resembling the Greek letter “π.” Those skilled in the requisite art will, however, recognize that sleeve  30  may be shaped or configured other than as shown in  FIG. 3 . 
     Illustrated in  FIG. 4  is outer casing  14  of assembly  10 . Casing  14  preferably, although not necessarily, has generally rectangular cross-section and sufficient width to accommodate shaft  26 . Included in side walls  44  and  46  may be openings  50  for connection to end caps  18  and  22 . Incorporated into top and bottom walls  54  and  58 , respectively, may be centrally-located, inwardly-extending longitudinal protrusions  62  and  66 , which may serve to decrease the distance shaft  26  may move up or down relative to casing  14 . Longitudinally-extending ribs  70 , together with side walls  44  and  46 , define recesses  74  into which flanges  42  of bases  38  of sleeves  30  may be fitted. 
       FIG. 6  details placement of sleeves  30  within casing  14 . Shown in  FIG. 6  are two sleeves  30 , each positioned to an opposing side of centrally-located shaft  26 . Sleeve  30 A, for example, is placed between wall  44  and shaft  26 , whereas sleeve  30 B is placed between wall  46  and the shaft  26 . In each instance, flanges  42  are received by recesses  74  to minimize lateral motion of the sleeves  30 A-B. 
     As illustrated in  FIG. 6 , distal ends  78  of legs  34  bear against exterior  82  of shaft  26 . Further, end  78 A of sleeve  30 A is positioned approximately one hundred eighty degrees about the circumference of exterior  82  from end  78 B of sleeve  30 B, and end  78 C of sleeve  30 A is separated from end  78 D of sleeve  30 B by approximately one hundred eighty degrees. Legs  78  thus place approximately constant laterally-opposed pressure on shaft  26 , reducing ability of the shaft  26  to move laterally and become misaligned with respect to other portions of a tray table. 
     Casing  14  additionally appears, in cross section, in  FIGS. 5A-B . Likewise shown in these drawings are cross-sectional representations of end caps  18  and  22  and shaft  26 . Included with shaft  26  is pin  86 , which freely travels within casing  14  as shaft  26  moves—until shaft  26  is extended fully. When shaft  26  is fully extended, pin  86  is received in internal detent  90  of end cap  18 , thus preventing further extension of the shaft  26 . 
     Additionally included as part of end cap  18  are central opening  94  (see  FIGS. 7A-B ), side recesses  98 , and arms  102 . Inwardly extending from arms  102  are protrusions  106  designed to snap into openings  50  of side walls  44  and  46 , thereby retaining end cap  18  in position relative to outer casing  14 . Central opening  94  receives shaft  26  and thus preferably has diameter slightly larger than the diameter of the shaft  26 . 
     Recesses  98  of end cap  18  extend from central opening  94 . Such recesses  98  preferably are positioned approximately one hundred eighty degrees apart along the circumference of the central opening  94  but not in the horizontal plane. Instead, recesses  98  advantageously are angled from the horizontal plane. 
     Recesses  98  are present to accommodate initial insertion of shaft  26  into casing  14 . In this initial instance, pin  86  must pass through central opening  94 , which would not be possible absent inclusion of recesses  98 . After pin  86  passes beyond central opening  94 , shaft  26  may be rotated so that pin  86  is generally horizontal, both (1) preventing pin  86  from passing back through central opening  94  and (2) ensuring that pin  86  is engaged by detent  90  when shaft  26  subsequently is fully extended. 
       FIG. 8  details end cap  22  of assembly  10 . End cap  22  may include base  110  from which arms  114  depend, with arms  114  including inwardly-extending protrusions  118  engaging openings  50  near end  122  of casing  14  opposite end  126  at which cap  18  is positioned. Similarly depending from base  110  are ribs  130 ; when shaft  26  is fully retracted, its end  134  snaps into and may be retained within the ribs  130 . Such retention force applied by ribs  130  thereafter may be overcome by manual force exerted by the user of the associated tray table so that shaft  26  may be extended as needed. 
       FIGS. 9-11  depict exemplary placements of assemblies  10  within tray table  138 . Included within table  138  may be one or more channels  142  into which outer casings  14  may be inserted. Preferably, table  138  surrounds the major surfaces of each outer casing  14  (as in  FIG. 10 ) so as effectively to incorporate the outer casings  14  into the table  138 . However, table  138  need not necessarily do so if some other connection scheme is preferred. 
     As shown in  FIGS. 10-11 , shafts  26  may be inserted into outer casings  14 , with the shafts  26  also being connected to laterally-extending rod  146  at their ends  150 . Screws, bolts, or other fasteners or connectors  154  may attach ends  150  to rod  146 . Rod  146  additionally may attach to arms  158  conventionally used to connect tray tables to frames of seats. 
     The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of the present invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of the invention. The disclosures of the Bentley, Brennan, and Kanigowski patents are hereby incorporated herein in their entireties by this reference.