Patent Publication Number: US-8973187-B2

Title: Bed frame assembly with a lift system having a translatable carriage

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part application of application Ser. No. 12/967,440 filed Dec. 14, 2010 which claims priority to provisional application no. 61/369,337 filed Jul. 30, 2010, each of which is incorporated by reference herein in their entirety. 
    
    
     TECHNICAL FIELD 
     The subject matter described herein relates to beds having a base frame and an elevatable frame and particularly to the lift system used to govern the vertical elevation of the elevatable frame relative to the base frame. 
     BACKGROUND 
     Beds used in hospitals, other health care facilities and home care settings may have a base frame and an elevatable frame. Such beds also include a lift mechanism for adjusting the height of the elevatable frame relative to the base frame between a maximum elevation and a minimum elevation. It is desirable for the lift mechanism to be compact in order to make efficient use of the limited space between the base frame and the elevatable frame. Compactness may also assist the bed designer in achieving a sufficiently low minimum elevation of the elevatable frame. Compactness and the architecture or layout of the lift system may also provide space that bulky interframe components can occupy, particularly when the vertical separation between the frames is small, thereby further enhancing the ability to achieve a satisfactorily low minimum elevation of the elevatable frame. 
     SUMMARY 
     The present disclosure comprises one or more of the features recited in the appended claims and/or the following features which, alone or in any combination, may comprise patentable subject matter: 
     A bed frame assembly includes a base frame, an elevatable frame, and a lift system. The lift system includes a carriage, longitudinally translatably mounted on the base frame, and a lift arm mounted to the carriage at a pivotable joint A and connected to the elevatable frame by a lift arm connector. The lift system also includes an actuator mounted on the carriage at a juncture B and connected to the lift arm such that operation of the actuator rotates the lift arm about a crank axis. The lift system also includes a part span connector pivotably connected to the lift arm at a joint D and pivotably connected to the base frame at a joint C. 
     Additional features and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of illustrated embodiments exemplifying the best mode of carrying out the invention as presently perceived. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features of the various embodiments of the bed frame assembly described herein will become more apparent from the following detailed description and the accompanying drawings in which: 
         FIG. 1  is a perspective view of a hospital bed having a base frame, an elevatable frame and a segmented deck, the bed being shown in a horizontal configuration. 
         FIG. 2  is a perspective view of the bed of  FIG. 1  in a chair configuration. 
         FIG. 3  is a schematic, right side elevation view of a first embodiment of a bed frame assembly described herein with a lift system and the elevatable frame shown in a first position (solid lines) and a second position (broken lines). 
         FIG. 4  is a right side perspective view of a prototype of the first embodiment of the bed frame assembly described herein as seen by an observer looking from a location above the bed. 
         FIG. 5  is a view similar to that of  FIG. 4  as seen by an observer looking from a location below the bed. 
         FIG. 6  is a close-up view of the bed frame assembly seen in  FIGS. 4-5  showing part of a foot end lift system including a remote end of a foot end lift arm and a lift arm connector in the form of a pivotable joint. 
         FIG. 7  is a view similar to that of  FIG. 4  showing components of the head end lift system in more detail. 
         FIGS. 8-10  are a sequence of views similar to that of  FIG. 4  showing, in combination with  FIG. 4 , the elevatable frame of the bed frame assembly at a relatively high elevation, a moderately high elevation, a moderately low elevation and a fully lowered elevation respectively. 
         FIG. 11  is a schematic, left side elevation view of a second embodiment of the bed frame assembly described herein showing the foot end lift system and elevatable frame in a first position. 
         FIGS. 12-13  are views similar to that of  FIG. 11  showing the lift system and the elevatable frame in the first position of  FIG. 11  (solid lines) in a second position (broken lines of  FIG. 12 ) and in a third position (broken lines of  FIG. 13 ). 
         FIG. 14  is a left side perspective view of a prototype of a second embodiment of the bed frame assembly described herein. 
         FIG. 15  is a view similar to that of  FIG. 14  showing the foot end lift system from a different perspective to render links  146  and  148  more readily visible. 
         FIG. 16  is a side view of another embodiment of a bed frame assembly having head end lift mechanism that is fixed in its location relative to a base frame and a foot end lift mechanism that translates relative to the base frame. 
         FIG. 17  is a view similar to the view of  FIG. 16 , the bed frame assembly having an elevatable frame lowered in  FIG. 17 . 
         FIG. 18  is a view similar to the view of  FIG. 16 , the bed frame assembly having an elevatable frame lowered to a position lower than that shown in  FIG. 17 . 
         FIG. 19  is a view similar to the view of  FIG. 16 , the bed frame assembly having an elevatable frame lowered in  FIG. 18  and a head end of the elevatable frame slightly higher than a foot end of the elevatable frame, the bed frame assembly positioned in a chair configuration. 
         FIG. 20  is a perspective view of a portion of the bed frame assembly of  FIGS. 16-19  with portions removed to show structural details not visible in  FIGS. 16-19 . 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show a hospital bed  20  having a head end  22 , a foot end  24  longitudinally spaced from the head end, a left side  26  and a right side  28  laterally spaced from the left side. The bed includes a bed frame assembly comprising base frame  32  with casters  34  extending to the floor  36 , and an elevatable frame  40  supported on the base frame. The elevation of the elevatable frame can be adjusted relative to the base frame. The bed also includes a deck  44  supported on the elevatable frame. The illustrated deck is a segmented deck comprising a torso or upper body section  46 , a seat section  48 , a thigh section  50  and a calf section  52 . The angular orientation of the upper body, thigh and calf sections can be adjusted to achieve a variety of desired bed profiles. A mattress, not shown, rests on the deck. The bed also includes a headboard  60  affixed to the elevatable frame and a footboard  62  affixed to the calf deck section. The bed also includes a left side head end siderail  64 , a left side foot end siderail  66 , a right side head end siderail, not shown, and a right side foot end siderail, also not shown. As is evident from  FIG. 2  the bed can be placed in at least one chair configuration which may or may not be suitable for facilitating occupant ingress or egress. 
     Referring  FIGS. 3-10  and principally to  FIGS. 3 and 4 , the bed frame assembly also includes a lift system  80  shown in a first position (solid lines of  FIG. 3 ) and a second position (broken lines of  FIG. 3 ). The lift system comprises a carriage  82  longitudinally translatably mounted on the base frame  32 , for example by sliders or rollers. The lift system also includes a lift arm  84  having a crank end  86  and a remote end  88 . The crank end of the lift arm is mounted to the carriage at a pivotable joint A so that the crank arm is pivotable about a laterally extending crank axis  100 . The remote end of the lift arm forms a junction J with a lift arm connector  102  thereby connecting the remote end  88  of the lift arm  84  to the elevatable frame. In the embodiment seen in  FIGS. 3-10 , the lift arm connector comprises an auxiliary link  104  having a lift arm end  106  and a frame end  108 . The lift arm end of auxiliary link  104  is pivotably connected to the remote end of the lift arm at a pivotable joint E; the frame end of the auxiliary link is pivotably connected to the elevatable frame at a pivotable joint F. In a variant of the lift system the connector is a single pivotable joint F. This is seen best in  FIG. 6  where frame  40  includes an extension  114  welded by weld  112 . 
     The lift system also includes an actuator  120  mounted on the carriage at a juncture B and connected to the lift arm such that operation of the actuator rotates the lift arm about crank axis  100 . In the embodiment of  FIGS. 3-10 , the actuator is a linear actuator, juncture B between the actuator and the carriage is a pivotable joint B, and the actuator is connected to the lift arm  84  at a pivotable joint G. Joint G is spaced or offset from crank axis  100  to provide a moment arm (the distance from G to A) allowing the actuator to easily rotate the lift arm as actuator piston  122  extends further out of or retracts into actuator housing  124 . 
     The lift system also includes a part span connector  130 . In the embodiment of  FIGS. 3-10  part span connector  130  is a single link  132  pivotably connected to the lift arm at a joint D and pivotably connected to the base frame at a joint C, which is at substantially the same elevation relative to the floor as joint A. Joint D is separated from junction J (as represented by joint E of  FIG. 3  or joint F of  FIG. 6 ) by a distance DJ, joints A and D are separated from each other by a distance AD, and joints C and D are separated from each other by a distance CD. Joints A and D and junction J (as represented by joint E of  FIG. 3  or joint F of  FIG. 6 ) lie on a straight line. The distances DJ, AD and CD are substantially equal to each other. 
     A commercially practical version of the bed frame assembly includes a head end lift system  80 H and a foot end lift system  80 L (as seen in  FIG. 4 ) with the head end lift system employing a lift arm connector in the form of auxiliary link  104  whose lift arm end is pivotably connected to the remote end of the lift arm at a pivotable joint E and whose frame end is pivotably connected to the elevatable frame at a pivotable joint F ( FIG. 5 ), and with the foot end lift system employing a lift arm connector in the form of a single pivotable joint F ( FIG. 6 ). Alternatively, the lift system with the auxiliary link could be used at the foot end of the frame and the lift system with the single-joint could be used at the head end. In yet another alternative, both lift systems could employ the lift arm connector having the auxiliary link. 
     In use, operation of actuators  120  changes the vertical separation of the elevatable frame relative to the base frame so that the elevatable frame can be elevated to a fully raised state or elevation, lowered to a fully lowered state or elevation, or positioned at a selected elevation between the fully raised and fully lowered elevations. For example, for the initial position shown in  FIG. 3  (solid lines) as the head end actuator piston extends out of its housing, the head end lift arm  84  rotates clockwise about its axis  100  at joint A. Head end link  132  constrains the position of head end joint D relative to head end joint C, thereby causing the head end carriage  82  to translate longitudinally in the direction of joint C with the result that joint E moves substantially perpendicularly relative to base frame  32 . For some initial positions other than the one shown in  FIG. 3 , (e.g. if link  132  is initially oriented at an angle below the horizontal) carriage  82  will initially move away from joint C and then later in the direction of joint C. The foot end lift system operates similarly but is oriented so that its lift arm rotates counterclockwise (when viewed from the same side of the bed) thereby causing its carriage  82  to translate longitudinally in the direction of its joint C. In other words during an increase in vertical separation the lift system carriages translate longitudinally toward their respective ends of the bed but, depending on the initial position of the linkages, may initially translate away from their respective ends of the bed. During an increase in vertical separation the carriages translate principally away from their respective ends of the bed. As the elevatable frame approaches its fully lowered elevation, the lift system carriages may undergo a small motion toward their respective ends of the bed. FIGS.  4  and  8 - 10  are a sequence of views showing the elevatable frame of the bed frame assembly at a relatively high elevation, a moderately high elevation, a moderately low elevation and a fully lowered elevation respectively. 
     As seen best in  FIGS. 4 ,  7  and  8 , the lift system comprises laterally spaced left and right lift arms  84 L,  84 H. The lift arms and crank axis  100  embrace a void  140  capable of receiving or accommodating the presence of components that vertically approach the base frame as the vertical separation between the elevatable frame and the base frame decreases. Examples of such components include actuators mounted on the underside of the elevatable frame for governing the angular orientation of the deck sections  46 ,  50 ,  52 . When the elevatable frame is at a relatively high elevation, for example as seen in  FIGS. 4 ,  7  and  8 , there is a large volume of space bounded by base frame  32 , elevatable frame  40  and the head and food end lift arms  84 . This space can be useful for accommodating equipment such as radiological equipment. 
     The operational demands on actuator  120  can be reduced by ensuring a long moment arm (distance AG) between joints A and G. However doing so can force the system designer to place joint A, and therefore joint C, at a high enough elevation that the fully lowered elevation of the elevatable frame is unsatisfactorily high. A second embodiment of the lift system, shown in  FIGS. 11-13  may be effective in overcoming such a limitation. 
     Referring to  FIGS. 11-13 , the part span connector  130  of the lift assembly of the second embodiment comprises a first link  144  extending from joint C, and a second link  146  extending from joint D. The first and second links are pivotably connected to each other at a common joint K. The lift assembly may also include a third link  148  extending from the common joint K to a joint I that pivotably joins the third link to carriage  82 . Joints I and C are at substantially equal elevations. Joints A, D, I and K define corners of a parallelogram. Joint D is separated from junction J (as represented by joint F) by a distance DJ, joints A and D are separated from each other by a distance AD, joints C and K are separated from each other by a distance CK and joints K and I are separated from each other by a distance KI. Distances DJ, AD, CK, and KI are substantially equal to each other. 
     The foot end lift mechanism  222  also includes a pair of ground links  244  that are each pivotably coupled to the base frame  32  at pivots  245  on opposite lateral sides with each link  244  pivotably coupled to a swing link  246  at a pivot  243 . The swing links  246  are each pivotably coupled to a respective lift arm  284  at a pivot  248 . Referring now to  FIG. 20 , the foot end lift mechanism  222  further includes a pair of link arms  249  each of which is pivotably coupled to the swing links  246  at the pivot  243 . The link arms  249  are coupled to the carriage  282  at pivots  252 . The link arms  249  and lift arms  284  cooperate as a parallelogram mechanism with the swing link connecting the lift arms  284  and link arms  249  at an upper end and a frame  264  of the carriage  284  connecting the lift arms  284  and link arms  249  at a lower end. 
     The foot end lift mechanism  222  includes a pair of lift arms  284  that are each pivotably coupled to a carriage  282  and pivotable relative to the carriage  282  about an axis  236 . The carriage  282  translates relative to the base frame  32  in a manner similar to that discussed with regard to carriage  82  above. As shown in  FIG. 16 , the when the foot end lift mechanism  222  is in a fully extended position, the carriage  282  is positioned in a configuration that causes the carriage  282  to be the nearest to the foot end  24  of the base frame  32  it achieves during movement of the foot end lift mechanism  222 . Activation of the foot end lift mechanism  222  to lower the foot end  24  of the elevatable frame  40  causes the carriage  282  to move toward the head end  22  of the base frame  32  of the bed  20 . 
     The foot end lift mechanism  222  also includes a pair of ground links  244  that are each pivotably coupled to the base frame  32  at pivots  245  on opposite lateral sides with each link  244  pivotably coupled to a swing link  246  at a pivot  250 . The swing links  246  are each pivotably coupled to a respective lift arm  284  at a pivot  248 . Referring now to  FIG. 20 , the foot end lift mechanism  222  further includes a pair of link arms  249  each of which is pivotably coupled to the swing links  246  at the pivot  250 . The link arms  249  are coupled to the carriage  282  at pivots  251 . The link arms  249  and lift arms  284  cooperate as a parallelogram mechanism with the swing link connecting the lift arms  284  and link arms  249  at an upper end and a frame  264  of the carriage  284  connecting the lift arms  284  and link arms  249  at a lower end. 
     The lift arms  284  are each also pivotably coupled to the elevatable frame  40  on opposite lateral sides at pivot  257 . The lift arms  284  are interconnected by a torque tube  256  that is coupled to a flange  260  that extends from a body  258  of the lift arms  284 . The torque tube  256  supports the lift arms  284  and is pivotable relative to the flanges  260 . A pair of arms  262  are fixed to the torque tube  256 . An actuator  120  is pivotably coupled to the arms  262  so that extension and retraction of actuator  120  causes rotation of the torque tube  256  relative to the lift arms  284 . The actuator  120  is also pivotably coupled to the base frame  32  and causes all of the motion of the foot end lift mechanism  222  and the carriage  282  relative to the base frame  32 . 
     In operation, the retraction of actuator  120  causes torque tube  256  to rotate and allows lift arms  284  to pivot about axis  236  while links  249  pivot about the pivot  251 . The ground links  244  act on the swing links  246  to control movement of the lift arms  284  and carriage  282  to urge the carriage  282  toward the head end  22  of the base frame  32  while the actuator retracts. The head end lift mechanism  224  operates independently with a separate actuator  266  (best seen in  FIG. 20 ) to control elevation of the head end  22  of the elevatable frame  40 . 
     As shown in  FIGS. 16-18 , the calf section  52  has a fixed portion  270  that pivots relative to the thigh section  50  and a moving portion  272  that retracts onto the fixed portion  270  to reduce the length of the calf section  52  as the bed  220  moves to a chair position, such as the position shown in  FIG. 19 . 
     In addition, the bed  220  includes three covers secured to the base frame  32  including a main cover  250 , a head end cover  252 , and a moving cover  254 . The main cover  250  is secured to the base frame with two screws  256  and two washers  258  as suggested in  FIG. 20 . The head end cover  252  is coupled to the base frame  32  by a screw  256  as suggested in  FIG. 20 . The moving cover  254  is secured to the carriage  282  by two screws  256 . The moving cover  254  moves with the carriage  282  and telescopes or collapses relative to the main cover  250  as the carriage  282  moves relative to the base frame  32 . 
     As can be seen in the progression of  FIGS. 16-19 , retraction of the actuator  120  causes the lift arms  284  to rotate about axis  236 , lowering the foot end  24  of the elevatable frame  40 . The carriage  282  moves away from the foot end  24  toward the head end  22 , causing the entire head end lift mechanism  224  to move inboard. As the deck  44  moves toward a chair configuration, the movement of the carriage  282 , and thereby, the foot end lift mechanism  222  provides clearance for the calf section  52  to pivot relative to the elevatable frame  40  without any elements of the foot end lift mechanism  222  being in the way of the calf section  52 . Similarly, the moving cover  254  moves relative to the main cover  250 . This allows the moving cover  254  to cover certain moving parts of the foot end lift mechanism  222  while the lift system  280  operates. 
     As can be seen in  FIG. 19 , in a chair position, the head end lift mechanism  224  may lift a head end  22  of the elevatable frame  40  relative to the foot end  24  of the elevatable frame  40  to thereby improve the ability for an occupant to egress from the foot end  24  of the bed  220 . In addition, the reduction in the length of the calf deck section  52  by moving the moving portion  272  relative to the fixed portion  270  allows the overall height of the bed  220  to be lower in the chair position, reducing the potential for interference with the floor. 
     The independent movement of the foot end lift mechanism  222  and the head end lift mechanism  224  in conjunction with the movement of the carriage  282  to reduce the distance between the axes  226  and  236  results in improved clearance and a lower height of the elevatable frame  40  than could be achieved without movement of carriage  282 . In addition, the movement of carriage  282  permits the elevatable frame  40  to be lowered with the elevatable frame  40  maintaining a constant attitude relative to the floor. This configuration cooperates to improve the ability of the bed  220  to achieve an acceptable chair position, as shown in  FIG. 19 , than might be achieved without the cooperating elements. 
     Although this disclosure refers to specific embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the subject matter set forth in the accompanying claims.