Abstract:
A seat structure with latching-unlatching mechanism for enabling smoothly operating releaseable locking and unlocking actions between a seat-base and an inclinable seat-back hinged to the seat-base in the seat structure. Two interengageable arcs of gear teeth forming part of the mechanism engage and release selectively under rocker-lever seat-occupant control to lock and unlock the seat-back for inclinational fixation and adjustment, and, as determined by tooth-pitch in the arcs, enable positive locking to take place in a large number of specific, small-angular-difference, seat-back inclinations.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION  
         [0001]    This invention relates to adjustable seat structure, and more particularly to mechanism for selectively adjusting, and for releasably gear-locking, the inclination of a seat-back sub-structure (seat-back) in relation to a seat-base frame (seat-base) to which the seat-back is pivoted. While the invention has utility in many applications, it is described and illustrated herein in the setting of an aircraft passenger seat—a setting with respect to which its utility has been found to be especially well suited.  
           [0002]    As will be seen, the mechanism of this invention includes a unique, combined lever, gear and cam arrangement which operates smoothly, and bi-directionally positively, to free and anchor a seat-back selectively at a plurality of different inclinations relative to the associated seat-base.  
           [0003]    According to a preferred and best mode embodiment of the invention which is specifically illustrated and described herein, three spaced, substantially parallel hinge, or pivot, axes play cooperative roles in the structure and operation of the invention. One of these axes (the seat-back rock axis) is that with respect to which the seat-back swings, inclines, rocks, etc., reciprocally relative to the seat-base. A special rocker gear, which possesses an arc of gear teeth, is pivoted on this same axis. The rocker gear is anchored to the seat-back for movement as a unit therewith, and its arc of gear teeth follows a circular, chordal path (approximately 30°) which is radially centered on the seat-back rock axis.  
           [0004]    A second axis is one on which a rockable latch element, which also possesses an arc of gear teeth, is pivoted for reciprocal rocking relative to the seat-base. The teeth in this latch element confrontingly face the teeth in the rocker gear, are distributed along a chordal, circular arc (about 20°) which has a radius of curvature substantially the same as that of the arc of teeth in the rocker gear, and, because both sets of teeth have the same (common) tooth-pitch, are freely meshable and de-meshable with the rocker gear teeth. The arc of teeth in the latch element are not fixedly centered on any of the mentioned, three pivot axes. Rather, the teeth in this second-mentioned arc swing, with rocking of the latch element, about the mentioned “second” axis. The latch element, within its perimeter, is formed with a specially shaped void space which functions, as will be explained, to furnish special cam-follower dwell and drive surfaces (structures) that play roles in the operation of the invention.  
           [0005]    The third axis defines a rock/pivot axis for a cam, or cam structure, which is specially shaped, and disposed operatively within the latch element&#39;s void space for interaction therein with the mentioned cam-follower dwell and drive surfaces. This cam structure is anchored to a rock-axis-sharing elongate shaft which carries, near one (or both of its) end(s), a user (seated person) manipulable lever which is employable to operate the mechanism of the invention. This shaft and lever, per se, are not part of the present invention.  
           [0006]    Various other features and advantages of the invention will become more fully apparent as the description which now follows is read in conjunction with the several drawing figures. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIGS. 1-3, inclusive, are very simplified, schematic side elevations of an aircraft passenger seat having a seat-base, and pivoted thereto, a reciprocally inclinable seat-back which is pivoted to the seat-base, with this seat employing the preferred and best mode embodiment of the present invention. In solid lines in FIGS. 1 and 2, the seat-back is shown in a fully forward inclination, and in FIG. 3, in a fully rearward inclination. A dash-double-dot line in FIG. 3 helps visually to relate the fully forward and fully rearward inclinations.  
         [0008]    [0008]FIGS. 4-6, inclusive, show, on a larger scale, isolated side elevations picturing profile details of the preferred plural-component inclination adjustment mechanism which is constructed in accordance with the invention, and which is employed by the seat shown in FIGS. 1-3, inclusive. The relative positions of these components as they appear in FIGS. 4, 5, and  6 , relate to the seat “conditions” illustrated, respectively, in FIGS. 1, 2, and  3 .  
         [0009]    [0009]FIGS. 7-11, inclusive, are larger scale views of the adjustment mechanism of the invention illustrating several stages in the operation of this mechanism relating to inclination of the seat-back shown in FIGS. 1, 2 and  3  from a fully forwardly inclined disposition to a fully rearwardly inclined disposition. The views presented in these five figures of the mechanism of the invention have a point of view which is slightly rotated relative to the point of view employed in FIGS. 4-6, inclusive. Specifically the mechanism components shown in FIGS. 7-11, inclusive, are rotated (as a group) clockwise relative to how they appear in FIGS. 4-6, inclusive.  
         [0010]    [0010]FIG. 12 isolates the several individual components of the adjustment mechanism of this invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0011]    Turning now to the drawings, and referring first of all to FIGS. 1-3, inclusive, indicated generally at  13  is an aircraft passenger seat which includes a seat-base (or seat-base frame structure)  14 , and a seat-back (or seat-back structure)  15 . The seat-back is pivotally connected to the seat for reciprocal inclination about an axis (which is normally a horizontal axis, and which is also called herein a rock axis)  16 , back and forth through a limited angle as indicated by double-headed curved arrow  18  in FIGS. 1 and 3. The specific size for this angle, which is not critical, and as illustrated herein, is about 15°. In seat  13 , the operative size of this angle is controlled essentially by the structure of the present invention. This will become clear shortly. Seat-base  14  is appropriately secured to the frame of an aircraft which is not shown in the drawings Indicated generally at  20  is latch-release mechanism, also called a latching-unlatching mechanism, which is constructed in accordance with a preferred and best mode embodiment of the invention. Mechanism  20  is located adjacent one lateral side of seat  13 , and this side is referred to hereinafter as the mechanism side of the seat. Mechanism  20  accommodates selective, releasably lockable, reciprocal, angular-positional adjustment of seat-back  15  relative to seat-base  14  through the angle just mentioned above. To effect such an adjustment, a person seated in seat  13  manipulates an exposed rocker lever  22  which is illustrated schematically by a dash-dot, downwardly projecting line in FIGS. 1, 2, and  3 . Lever  22  is secured near one end of, and to, an elongate, transverse shaft  24  that is appropriately journaled (or pivoted) on base  14  to turn about an axis  25  which coincides with its own (the shaft&#39;s) long axis  24   a . Lever  22  is exposed and accessible at one, outer side of seat  13 . It is shaft  24 , under the control of lever  22 , which introduces operative rotation (or rocking) into mechanism  20 . With regard to this just-described lever and shaft structure, it should be understood that other specific kinds of structural arrangements may be provided for allowing operation of mechanism  20 , and in particular for enabling a seat occupant to introduce rocking rotation into this mechanism. In the embodiment of mechanism  20  herein illustrated, and now to be described, and including focus now on all of the drawing figures, there are three, principal interactive components (also called rock structures). These include a rocker cam  26  (also called a person-manipulable rocker cam), a latch, or latch element,  28  which includes a cut-out void space  30  that furnishes internal surfaces  30   a ,  30   b , and  30   c  that function, as will be explained, as dwell, cam-follower (or cam-follower structure), and drive, surfaces, respectively, and a rocker gear  31 . Two other internal surfaces,  30   d ,  30   e , in void space  30  should be mentioned here. Surface  30   d  forms one “lateral” side of the void space.  
         [0012]    Surface  30   e  furnishes herein what is later referred to as a reception surface. Rocker cam  26  includes two angularly opposite “lateral” sides  26   a ,  26   b , and another surface  26   c  which functions as a dwell surface that cooperates, as will later be explained, with dwell surface  30   a  in void space  30 . Surfaces  30   a ,  30   e  are curved, have substantially the same radious of curvature, and are referred to herein as twin, like-radius follower surfaces.  
         [0013]    Rocker cam  26 , which is suitably joined, as by welding, to that end of shaft  24  which is adjacent the mechanism side of seat  13 , is somewhat pie-shaped, with rounded corners. The rocker cam flairs angularly outwardly from shaft  24  along previously mentioned sides  26   a ,  26   b , toward curved dwell surface  26   c . Surface  26   c  herein is a surface of revolution curving about previously mentioned axis  25 . The rocker cam is operatively disposed within void space  30 .  
         [0014]    Latch element  28  has the perimetral shape clearly illustrated for it in the drawings, and includes an extension arm  28   a  which is pivoted to seat-base  14  for reciprocal rocking about an axis  32 . Axis  32  is spaced from, and disposed substantially parallel to, axes  16 ,  25 . The preferred arrangement of these three spaced, generally parallel axes, relative to seat-base  14 , is such that axes  25 ,  32  are below axis  16 , with axis  25  being located rearwardly of axis  16 , and axis  32  being located forwardly of axis  16 .  
         [0015]    Formed on the upper side of element  28  is an elongate, circularly-curved arc of teeth  28   b . Arc  28   b  herein subtends an angle of about 15°, and curves about a non-illustrated axis which, because of the rocking capability that is intentionally provided for the latch element, is not fixed relative to seat-base  14 . The radius of curvature of arc  28   b  is made to be substantially the same as the radius for curvature designed for an arc of somewhat similar teeth  31   a  provided in rocker gear  31 . The term “somewhat similar” is employed to describe this arc relationship, inasmuch as arc  28   b  is concave, and arc  31   a  is matchingly convex. Arcs of teeth  28   b  and  31   a  are also referred to herein as row-sets of teeth.  
         [0016]    Reciprocal rocking motions which are permitted interactively between rocker cam  26  and latch  28  are produced by manipulation of lever  22  and shaft  24 . These motions are angularly limited, and the angular limit conditions/positions of these two elements can be seen especially well in FIGS. 7 and 11 in the drawings. These motions are independent of the condition/position of rocker gear  31 . The limit conditions pictured depend principally on the respective radii of rocking provided for these two mechanism components, and upon the relationship which exists between the perimetral outline of cam  26  and that of void space  30 .  
         [0017]    How the perimetral configurations of cam  26  and void space  30  specifically relate, in the embodiment of mechanism  20  which is now being described, are herein-below now more fully explored.  
         [0018]    In a reasonable manner of thinking, the perimetral outline of void space  30  can be viewed as resulting from the overlapping, combined, axial foot-printing of the perimetral outline of cam  26  onto the side surface of latch element  28  under the two relative angular limit conditions that are pictured in FIGS. 7 and 9. In the FIG. 7 condition, side  26   a  in the rocker cam seats substantially matchingly in confronting contact with lateral side surface  30   d  in void space  30 . Dwell surface  26   c  in the rocker cam seats substantially in matching confronting contact with dwell surface  30   a  in the void space. Dwell surface  30   a  has substantially the same radius of curvature as does dwell surface  26   c.    
         [0019]    In the FIG. 9 conditions, side  26   b  in the rocker cam seats substantially in confronting abutment with drive surface  30   c  in void space  30 . Dwell surface  26   c  now substantially seats in matching confronting relationship with similarly curved reception surface  30   e  in the void space.  
         [0020]    How various ones of the specifically identified surfaces in cam  26  and in void space  30  interact during reciprocal operation of mechanism  20  will be discussed shortly.  
         [0021]    Rocker gear  31 , suitably anchored to function as a unit with seat-back  15  herein, has the shape and configuration clearly pictured in the drawings. Arc  31   a  of teeth curves about axis  16 , and subtends an angle of about 300.  
         [0022]    The teeth in arc  31   a  are configured to intermesh and lock with the teeth in arc  28   b  to create a condition referred to herein as compressive engagement between the teeth. Such intermeshing is plainly shown in FIGS. 4 and 6- 8 , inclusive, and  11  in the drawings. Intermeshing of these two arcs of teeth creates an angular positional lock for seat-back  15 , pursuant to operation of the invention. Given the manner in which the opposite ends of arc  31   a  are structured, the absolute angular limits for relative, intermeshed locking between components  28 ,  31  is established substantially as the difference in angles that are respectively subtended by arcs  28   b ,  31   a —herein about 15°. Thus it is that mechanism  20  positively establishes the range of “lockable” angular inclining which is permitted seat-back  15  relative to seat-base  14 .  
         [0023]    Reviewing now the operation of mechanism  20 , this will be described with reference to all of the drawing figures. Within these figures, FIGS. 1-3, inclusive,  4 - 6 , inclusive, and  7 - 11 , inclusive, each (group) illustrates the events of unlocking seat-back  15  from seat-base  14 , and inclining the seat-back rearwardly from its full forward locked inclination (the condition of mechanism  20  shown in FIGS. 1, 2,  4 ,  5  and  7 - 9 , inclusive), to its full rearward locked inclination (the condition of mechanism  20  shown in FIGS. 3, 6 and  11 ). In each of these two seat-back inclination conditions, the cam and cam-follower structures are said to be in opposed-surface locking engagement. Throughout all relative positions between the cam and cam-follower structures, these two structures remain contactively engaged.  
         [0024]    From the condition pictured in FIGS. 1, 4 and  7 , a seat occupant manipulates lever  22  to rotate shaft  24  and rocker cam  26  clockwise about coincident axes  24   a ,  25 . Throughout the first roughly 20°s of such rotation, dwell surfaces  26   c ,  30   a  slide past one another, with latch element  28  “dwelling” essentially unmoved (unrocked) from the position in which it is shown in FIGS. 1, 4,  7  and  8 . Contact of the dwell surfaces holds latch element  28  in place. This transition is seen especially well in FIGS. 7 and 8.  
         [0025]    Just as surfaces  26   c ,  30   a  “clear” one another, which is the state of things pictured in FIG. 8- a  state in which element  28  is no longer held in a fixed, dwell mode by these two surfaces, lateral side surface  26   b  in the rocker cam engages drive surface  30   c  in void space  30 . Continued clockwise rotation of rocker cam  26 , and by means of a driving engagement which now exists between surfaces  26   b ,  30   a , causes driven clockwise rotation (rocking) of latch  28  about axis  32 . As this driven rotation occurs, the radiused corner of intersection which exists between surfaces  26   a ,  26   c  in the rocker cam skirts in brushing contact substantially continuously along cam-follower surface  30   b  in void space  30 , which cam-follower surface “follows” this radiused corner downwardly because of the rocking action occurring in latch element  28 . This action is referred to herein as positive driving disengagement of the two arcs of gear teeth.  
         [0026]    There thus exists the very useful condition that the rocker cam and the latch element essentially remain in a kind of positive, co-captured, driver-follower engagement throughout rocking motion.  
         [0027]    Rocking continues until the rocking-motion limit condition pictured in FIGS. 2, 5.  9  and  10  occurs, wherein dwell surface  26   c  closely confrontingly engages reception surface  30   e  in void space  30 . At this point, a limit condition is reached because of the shapes of the interrelated structures of, and the natures of the surface engagements between, the rocker cam and latch element, and as a consequence, the rocker cam and the latch element can no further rotate clockwise about their respective rock axes  25 ,  32 , respectively.  
         [0028]    Under these circumstances, the two arcs of gear teeth are completely disengaged, and seat-back  15  is free to change inclination by rocking clockwise about axis  16  in the figures. FIG. 10 illustrates (by the changed position shown here for rocker gear  31  relative to the position shown for it in FIGS. 1, 4,  5  and  7 - 9 , inclusive, a situation where the seat-back has been inclined rearwardly about half way between its forward and rearward permitted-inclination limits. The direction of clockwise rotational inclining of the seat-back is indicated by arrows  34 ,  36 .  
         [0029]    When the seat-back has been adjusted to the inclination desired, and here, a full rearward inclination is being used as an example, the seat occupant again manipulates lever  22 , this time to produce counter-clockwise rocking, or rotation, of shaft  24  and rocker cam  26  about axes  24   a ,  25 . This counter, or reciprocal, rocking causes the cam to drive against cam-follower surface  30   b  to cause lifting, and counter-clockwise-driven rocking about axis  32 , of latch element  28 , thus to return the latch element to the position shown for it now in FIGS. 3, 6 and  11 , but with the arcs of teeth now intermeshing to lock seat-back  15  in its fully rearwardly inclined condition relative to seat-base  14 .  
         [0030]    Achieving “intermediate” seat-back inclinations is accomplished in a similar manner.  
         [0031]    Accordingly, a preferred embodiment of the adjustment mechanism of this invention have been fully described and illustrated herein. This is a mechanism which uniquely enables releasable-locking selectable-inclination between a seat-back and a seat-base. The mechanism illustrated produces very smooth operation, with appropriate positive driving and following and engagements occurring between cam element  26  and latching element  28 . The two selectively intermeshable arcs of teeth provided in the mechanism enable secure locking between a seat-back and a seat-base in a large number of different, small-angular-difference inclinations. These different inclinations are, of course, determined by the common tooth-pitch characteristics of the two employed arcs of gear teeth.  
         [0032]    Accordingly, while a preferred and best mode embodiment of the invention have been described and illustrated herein, it is appreciated that variations and modifications may be made without departing from the spirit of the invention.