embodiments shown in the drawings and described herein provide an actuation system for an articulating bed which simplifies the drive components and actuation requirements while preventing torsional effects which might otherwise create binding of the actuation mechanism . sufficient torsional support for the movable portions of the bed is also provided for rigidity with minimal structural weight or complexity . referring to fig1 , bed 10 incorporates a frame having side rails 12 a and 12 b . for the embodiment shown in the drawings corner posts 14 are present at the end of the side rails and receive end rails 16 a and 16 b to complete the frame . and actuating mechanism 20 provides for elevation of a selected portion of a mattress as will be described in greater detail subsequently . the actuating mechanism may be driven by a single actuator 22 , which for the embodiment shown is a linear actuator having a telescoping rod 24 extending from a barrel 26 . a motor 28 provides rotation of the barrel for extension and retraction of the rod . in alternative embodiments , multiple actuators may be employed for each movable section . as best seen in fig2 , telescoping rod 24 incorporates an end fitting 30 which receives a torque tube 32 through a bore 31 ( best seen in fig4 b ) for rotational motion . a pinion gear 34 a is attached to a first end of the torque tube and rides on a rack 36 a attached to a lower flange 38 a of side rail 12 a . as shown in fig3 , a second end of torque tube 32 carries a pinion gear 34 b which rides on a rack 36 b attached to a lower flange 38 b of the second side rail 12 b . elevation bars 40 a and 40 b are carried by end fittings 42 a and 42 b . end fittings 42 a and 42 b incorporate bores 44 a and 44 b respectively to receive the torque tube 32 which rotates within the bores . extension and retraction of actuator rod 24 causes the torque tube to translate in a direction perpendicular to its axis 33 and parallel to rails 12 a and 12 b . pinion gears 34 a and 34 b riding on racks 36 a and 36 b create rotation in the torque tube thereby maintaining alignment . translation of the torque tube results in angular rotation of the elevation bars to raise and lower a support plate for the mattress portion being elevated as will be described in greater detail subsequently . the structural support by the multiple elevation bars supported from the torque tube provides good torsional stability for the elevating head portion of the bed without requiring excessive structural weight or complexity . actuation mechanism 20 allows a single actuator to uniformly position the symmetrical elevation bars without any torsional binding which could occur based on the flexibility of the support plate and mattress . the use of the pinion gears at each end of the torque tube allows non - symmetrical positioning of the linear actuator thereby allowing attachment of the actuator and motor to a single side rail without additional cross - rail structural elements . the actuator may be located at any position along the torque tube which may be most convenient based on the available mounting structure . additional details of an exemplary embodiment for elements of actuation mechanism 20 are shown in fig4 a , 4 b and 4 c . an end cap 50 is attached to the outboard surface 52 of the pinion gear 34 a . the end cap has a diameter 54 , greater than diameter 56 of the pinion gear , which extends over an outer edge 58 of rack 36 a to prevent motion of the pinion gear and attached torque tube along the axis of the torque tube . this additionally maintains engagement of the pinion on the rack by preventing the pinion from jumping off the rack due to the proximity of the cap to the upper flange 72 a of the side rail and prevents the pinion from abraiding the side rail . lock rings 60 and 62 are received over the torque tube inboard and outboard , respectively , of end fittings 44 a and 30 to avoid canting of those fittings with respect to the torque tube thereby avoiding binding . attachment of the locking rings and pinion gear to the torque tube may be accomplished using diametric pins 64 or set screws . a shank 66 extending from pinion gear 34 a is received within a central bore of the torque tube and is pinned using a common diametric pin with lock ring 62 for the embodiment shown . a plastic shield 68 , also shown in fig5 , incorporates a top plate 70 which rides on an upper flange 72 a of side rail 12 a . an aperture 74 in side plate 76 receives torque tube 32 . as torque tube 32 translates along the rails , shield 68 is drawn along the side rail thereby providing complete shielding of the rotating interface between the pinion gear and rack to avoid any pinching hazard . the configuration of side rails 12 a and 12 b with plates 78 a and 78 b extending between the top and bottom flanges of each side rail shields the actuation mechanism from the exterior of the bed . the configuration of the actuation mechanism with use of a single actuator allows simple configuration for multiple portions of the mattress to be separately elevated . as shown in fig6 a and 6 b , a first actuation mechanism 20 a may be incorporated for elevation of a head portion while a second actuation mechanism 20 b may be incorporated for elevation of a foot portion . the embodiment shown in fig6 a and 6b employs symmetrical mounting of the actuators for the actuation mechanisms on opposite rails of the bed however in alternative embodiments the actuators may be mounted to a single rail . as best seen in fig6 b the side rails , end rails and associated corner blocks are supported by bed legs 77 for the embodiment shown but may be floor mounted . as shown in fig7 a and 7 b , a support plate 80 for the head portion of the mattress rests in the horizontal position on corner blocks 14 , or alternative extensions thereof as subsequently described with respect to fig9 a , 9 b , 10 and 11 , vertically spaced from the side rails and is rotated about a pivot 82 by the elevation rods which are angularly displaced as shown in phantom for a first retracted position 40 w and a second elevated position 40 x created by translation of the torque tube responsive to the first actuator 22 a . pinned connection of the elevation rods to the torque tube through end fittings 42 a and 42 b at their base , as previously described , and to the support plate at an end 41 a . as an example , distal from the base causes translation of the base with the torque tube and resultant angular rotation due to the compressional rigidity of the rods . similarly a second support plate 84 for a foot portion of the mattress is rotated about a pivot 86 by the elevation rods of the second actuation mechanism as shown for a first retracted position 40 y and , in phantom , a second elevated position 40 z . an alternative to the linear actuator described with respect to the previous embodiments is shown in fig8 a and 8b . torque tube 32 incorporates a first gear portion 90 which receives a mating toothed belt 92 . the belt is fixed at a first end 94 to the lower flange of the side plate . a second end 96 of the belt is drawn to a linear actuator 22 by rod 24 as shown in fig8 a or wound on a rotating sprocket 98 as shown in fig8 b resulting in translation of the torque tube . the sprocket may be driven by a standard rotating motor ( not shown ). while a toothed belt is shown for the embodiment of fig8 a chain of alternative engagement mechanism may be employed in alternative embodiments . pinion gear 34 a is shown on the end of the torque tube for symmetrical operation as in the previously described embodiment . however , in alternative embodiments , the separate pinion gear may be eliminated by relying on the toothed belt to create the rotation of the torque tube with the pinion gear at the opposite end of the torque tube assuring the matching rotational velocity and translation of that end of the torque tube . additional safety elements are incorporated in the embodiments , shown in the drawings as previously described , to prevent openings in the structure where , for example , the mattress and mounting plates may be fixed above the level of the side rails and other frame elements of the bed . as shown in fig9 a and 9b , 10 and 11 , a resilient member such as a flat coil spring 100 is provided extending upwardly from each corner block 14 . plate 80 supporting the mattress head portion , for example , rests on the top of the flat coil springs in the horizontal position . a skirting strip 102 which may be plastic , heavy - duty fabric , or other suitable material extends between the coil springs . a fabric skirt 104 is connected to the skirting strip and draped downwardly attaching to the side rail . the fabric skirt prevents insertion of objects or body parts into the aperture between the plate and side rail . additionally , attachment of the skirt and skirting strip to the flat coil springs allows resilient deformation should any object or body part be inserted over the skirting strip when the plate is rotated upwardly using the actuators as previously described and then trapped by a downward rotation of the plate . as shown in in fig9 b engagement by an intruding element 106 , such as an arm or hand , would result in depression of the skirting strip with a resultant inward deformation of the flat coil spring as noted by element 100 ′. this prevents any significant pressure on the intruding object . flat coil springs 100 provide additional vertical support for plate 80 supplementing support provided by the elevation bars . having now described various embodiments of the invention in detail as required by the patent statutes , those skilled in the art will recognize modifications and substitutions to the specific embodiments disclosed herein . such modifications are within the scope and intent of the present invention as defined in the following claims .
a mechanism for activation of an articulating bed incorporates at least one mattress support plate and a pair of side rails . a rack is attached to each side rail and a torque tube extends between the side rails with a pinion gear at each end engaging a respective one of the racks . an actuator imparts translational motion to the torque tube perpendicular to its axis . elevation bars connected to the torque tube and the support plate are angularly displaced by translation of the torque tube .