Abstract:
A lifting mechanism is disclosed for a bed deck having a top surface where a user may lie thereon and a bottom surface. The bed deck is rotatably mounted to a bed platform having a recessed storage area. The bed deck can be moved from a horizontal to a non-horizontal position. The lifting mechanism is at least partially disposed in the recessed storage area and includes a torsion bar having a first end and a second end; a cam follower rigidly mounted to the torsion bar proximal to the first end; an anchor arm rigidly mounted to the torsion bar proximal to the second end; a mechanism for mounting the torsion bar with the bed platform; and a cam mounted to the bottom surface of the bed deck.

Description:
RELATED APPLICATIONS  
       [0001]     This application is a non-provisional patent application of U.S. patent application Ser. No. 60/473,630, Filed May 27, 2003, entitled “Lifting Mechanism For A Bed Deck” and is a continuation-in-part of U.S. patent application Ser. No. 10/391,091, filed Mar. 18, 2003, which is a continuation-in part of U.S. Pat. No. 6,611,973, issued Sep. 2, 2003 the disclosures of which are incorporated herein by reference. 
     
    
     BACKGROUND  
       [0002]     U.S. Application Ser. No. 10/146,153 (the &#39;153 application), filed May 15, 2002, for a “Bed Structure with Storage Area”, and assigned to the same assignee as that of the present invention, is incorporated herein by reference. The &#39;153 application discloses a bed structure with a platform having a recessed storage area and a deck hingedly mounted to the platform such that the same may serve as a surface upon which a user may lie (e.g., for sleeping), and may be rotated upward for access to the storage area.  FIG. 1  shows one embodiment of a bed structure  10  having one or more platforms  12  disposed in spaced relation to one another by a set of end frames  14 . Each platform  12  has a recessed storage area  16  formed therein by sidewalls  18  of the platform  12 . A deck  20  is rotatably mounted to the platform  12  to alternately cover the recessed storage area  16  and provide access to the storage area  16 .  
         [0003]     Depending on the construction of the deck  20 , it may have a weigh well over 100 pounds, and in one embodiment of the bed structure  10  the deck  20  weights over 190 pounds. Not only does this make it difficult to manually rotate the deck  20  upward, but also presents a serious danger of the deck accidentally falling downward if the deck is “propped-up” to hold open the access to the recessed storage area  16 . Although lifting mechanisms for such decks  20 , such as gas springs  22 , have been proposed for assisting in deck lifting, the high forces needed for upward rotation of the deck  20  from the most downward position would require a very strong gas spring arrangement. Further, gas springs  22  often require maintenance over time and typically wear out within a certain number of cycles. Additionally, these types of lifting mechanisms often do not support holding up the deck  20  at a selected angle of rotation other than a fully “open” position.  
       SUMMARY  
       [0004]     A lifting mechanism  100  for a bed deck  200  rotatably mounted on a bed platform  202  is provided in the form of a torsional assembly. The lifting mechanism  100  includes a cam  102  mounted on the bed deck  200  and a cam follower  104  mounted with a torsion bar  106  that is itself preferably mounted with the bed platform  202  in a recessed storage area  204  thereof. The cam  102  is configured such that the force generated by torsion of the torsion bar  106  and applied by the cam follower  104  to the cam  102  as a lifting force is reduced as the bed deck  200  is rotated upward from the horizontal position. This reduction in the lifting force value is due to the center of gravity of the rotating bed deck  200  moving into a more favorable position closer to the location where the beck deck  200  is mounted with the bed platform  202 . In this way, the position of the bed deck  200  may be maintained in force equilibrium at any angle of rotation (e.g., slightly open, fully open, etc.). 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  is a side elevational view of a bedding assembly having a lifting assembly using gas springs;  
         [0006]      FIG. 2  is a perspective view of the lifting mechanism in accordance with an embodiment of the present invention;  
         [0007]      FIG. 3  is an exploded view of the lifting mechanism of the present invention;  
         [0008]      FIG. 4  is a perspective view of the cam assembly in accordance with an embodiment of the present invention;  
         [0009]      FIG. 5  is a cross-sectional view of the platform and deck of the present invention showing the deck in horizontal position and having a side wall cut-away to show the lifting mechanism in the platform;  
         [0010]      FIG. 6  is a side elevational of the platform and deck of the present invention showing the deck in a non-horizontal position and having a side wall cut-away to show the lifting mechanism in the platform;  
         [0011]      FIG. 7  is a side elevational of the platform and deck of the present invention showing the deck in a non-horizontal position and having a side wall cut-away to show the lifting mechanism in the platform;  
         [0012]      FIG. 8  is a perspective view of the platform with lifting assembly of the present invention with the deck removed;  
         [0013]      FIG. 9  is a perspective view of the platform with lifting assembly of the present invention with the deck removed;  
         [0014]      FIG. 10  is a perspective view of one side of the lifting mechanism as mounted to the bed platform within the recessed storage area;  
         [0015]      FIG. 11  is a perspective view of the other side of the lifting mechanism as mounted to the bed platform within the recessed storage area; and  
         [0016]      FIG. 12  is a perspective view of the bed platform with the lifting mechanism removed. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0017]      FIG. 2  shows the lifting mechanism  100  without the cam  102  and removed from mounting within the recessed storage area  204  of the bed platform  202 . The lifting mechanism  100  comprises generally the torsion bar  106  with the cam follower  104  rigidly mounted to a first end  108  thereof and an anchor arm  110  rigidly mounted to a second end  112  thereof. When mounted with the bed platform  202 , the torsion bar  106  axis extends generally in the horizontal plane and defines a lateral direction.  
         [0018]     Despite the fact that the mounting of the cam follower  104  with the torsion bar  106  is rigid, the cam follower  104  is able to rotate about the axis of the torsion bar due to the twisting of the bar  106  in torsion; the twisting of the torsion bar  106  is at a maximum at the first end  108  thereof where the cam follower  104  is mounted. In the embodiment shown in  FIG. 1 , the rotational force applied by the cam follower  104  is in a clockwise direction around the axis of the torsion bar  106 . The anchor arm  110  provides a brace to prevent the torsion bar  106  from untwisting at the second end  112  thereof and releasing the torque built up in the torsion bar  106  by rotation of the cam follower  104 .  
         [0019]     To anchor the torsional bar  106  and the cam follower  104  and anchor arm  110  mounted thereon to the bed platform  202 , a pair of mounting blocks  114  and a mounting plate  116  are fit onto the cam follower  104  and the anchor arm  110 , respectively, and generally surround the torsion bar  106  through central holes  117  therein, as seen in  FIGS. 1 and 2 . The mounting blocks  114  are preferably mirror-images of one another and have abutting mating surfaces  118 . Bores  120  extend laterally through the mounting blocks  114  through which fasteners may be inserted to secure the blocks  114  together and to the bed platform  202 , as explained more fully herein. In this way, the mounting blocks  114  laterally sandwich a base  122  of the cam follower  104  therebetween while circumferentially surrounding bosses  124  of the base  122  through which the torsion bar first end  110  extends. Similarly, the mounting plate  116  is configured to circumferentially surround a boss  126  of the anchor arm  110  through which the torsion bar second end  112  extends. Bores  128  extend laterally through the mounting plate  116  through which fasteners extend to secure the plate  116  to the bed platform  202 . Additionally, sleeve bearings  130  are press fit into the central holes  117  of the mounting blocks  114  and the mounting plate  116  and are configured to surround the bosses  124 ,  126  to carry the torsional on the cam follower  104  and the anchor arm  110  while allowing relatively free rotation of the follower  104  and arm  110  with respect to the blocks  114  and the plate  116 , respectively.  
         [0020]     As best seen in  FIG. 3 , the torsion rod  106  is preferably formed by affixing multiple elongate hexagonal rods  132  together along longitudinal surfaces thereof such that each rod contacts at least two other rods. Three hexagonal rods  132  are shown in the embodiment of  FIG. 2 , but any number could be used as a matter of design choice depending on the desired strength and torsional rigidity of the torsional rod  106 , as well as the force necessary to lift and rotate the bed deck  200  hingedly mounted with the bed platform  202 . The bosses  124 ,  126  of the mounting blocks  114  and the mounting plate  116 , respectively, are shaped with a cross-section configured to accept the torsion rod  106 .  
         [0021]     The cam follower  104  has a body section  134  from which the base  122  extends, a pair of flanged ears  134  on an end of the body section opposite of the base  112 , and a roller  136  rotatably mounted with the ears  134 . The roller  136  allows the follower  104  to pass along the engaging surface  138  of the cam  102  with minimal friction while transferring the torsional load generated by the torsion bar  106  as a point load onto the cam  102 .  
         [0022]      FIG. 4  shows one embodiment of the cam  102 . The engaging surface  138  is formed by a central convex region  140  that transitions into a lower concave region  142  which terminates in a stop  144 . As shown in  FIGS. 5 and 6 , the convex region  140  is contacted by the cam follower  104  when the bed deck  200  is in the horizontal position overlying the recessed storage area  204  of the bed platform  202  and as the deck  200  rotates upward about a hinge  205  for a distance. With continued upward rotation of the bed deck  200 , the roller  136  of the cam follower  104  enters the concave region  142  and continues therein until reaching the stop  144 , as shown in  FIG. 7 . The stop  144  forms the concave region  142  with a radius that lowers in value until the radius is as small as the radius of the roller  136 , effectively locking the roller  136  from continuing down the engaging surface and affixing the upward rotation limit for the bed deck  200 . The cam  102  has a set of laterally extending bores  146 , best seen in  FIG. 4 , for mounting of the cam  102  with fasteners to a bracket  148  affixed to the bed deck  200 , as seen in  FIGS. 5-7 . A flat upper surface  150  of the cam  102  is mounted against the deck  200  to transfer the point load applied by the cam follower  104  to the deck  200 .  
         [0023]     As seen in  FIGS. 5-7 , the anchor arm  110  has a lower surface  152  that contacts a force adjusting screw  154  and transfers the reactive torque at the second end  112  of the torsion bar  106  opposite of the torque on the cam follower  104  to the screw  154 . The screw  154  is threadingly mounted to a brace  156  on the bed platform  202  that is configured to spread the reactive torsion load in the torsion bar  106  across a reinforced surface area of the platform  202  such that the anchor arm  110  does not “blow-out” the base surface  206  of the platform  202 . The screw  154  may be rotated to change the angle of the anchor arm  110  about the torsion bar axis relative to the angle of the cam follower  104  about the torsion bar axis, which increases or decreases—depending on the direction of screw  154  rotation—the force applied by the follower  104  to the cam  102 .  
         [0024]      FIGS. 8 and 9  show views of one bed platform  202  with the deck removed  200  for better viewing of the lifting mechanism  100 . The mounting blocks  114  and mounting plate may, in one embodiment, be attached with fasteners to dividers  208 ,  210 , respectively, extending orthogonally with respect to the torsion bar  106  across the base surface  206  of the bed platform  202 .  
         [0025]      FIGS. 10 and 11  show close-up views of  FIGS. 8 and 9 , respectively, where the lifting mechanism  100  is seen mounted to the bed platform  202  within the recessed storage area  204 . A first C-shaped bracket  156  is affixed on edges thereof to a back wall  212  and the base surface  206  of the bed platform  202 , such that the mounting blocks  114  may be mounted to the bracket  156 —with fasteners through bores  120  in the blocks  114 —between the bracket  156  and the divider  208 . Likewise, a second C-shaped bracket  158  is affixed to the surfaces of the bed platform in the same configuration as the first bracket  156 , such that the mounting plate  116  may be mounted to the bracket  158 —with fasteners through bores  128  in the plate  116 —between the bracket  158  and the divider  210 . To further stabilize the first and second C-shaped brackets  156 ,  158 , a vertical brace  160  may be mounted to the base surface  206  to span the lateral dimension between the brackets  156 ,  158 . Also, a channel brace  162 , with a cross-section best seen in  FIGS. 5-7 , may be mounted to the back wall  212  of the bed platform  202  to abut the top of the brackets  156 ,  158  and provide further stabilization thereof.  
         [0026]     When initially loading the torsion bar  106  with the necessary torsion for lifting the bed deck  200 , the cam follower  104  should be secured in a “loaded” position. To accomplish this, a loading cam (not shown) with dimensions larger than the cam  102  is first mounted to the bed deck  200  mounted to the bed platform  202 . The bed deck  200  is then lowered to the horizontal position such that the weight of the bed deck  200  loads the bar  106  with torsion. Once the body section  134  of the cam follower  104  passes below an axis formed between bores  164  of adjacent loading brackets  166  (the loading cam being shaped not to block this axis as it is contacting the cam follower roller  136 ), a pin may be inserted through both holes to hold the loaded cam follower  104  in place. The bed deck  200  may then be lifted and the loading cam replaced with the cam  102  used for standard operation. At that point, the deck  200  is again lowered to the horizontal position, this time with the engaging surface  138  of the cam  102  contacting the cam follower roller  136 . Once contact is established and the load is taken off of the loading bracket pin, the pin can be removed and the bed deck  200  and bed platform  202  are ready for use.  
         [0027]      FIG. 12  is the same view as that of  FIG. 8 , but with the torsion rod  106 , the cam follower  104 , the anchor arm  110 , the mounting blocks  114  and the mounting plate  116  removed. The position of the loading brackets  166 , the C-shaped bracket  156 , the vertical brace  160  and the channel brace  162  is best seen in relation to the overall configuration of the bed platform  202  in  FIG. 12 .  
         [0028]     Observing the motion of the bed deck  200  in  FIGS. 5-7 , it may be seen that as the deck is rotated upward from the horizontal position, the center of gravity C G  of the deck  200  moves towards a vertical plane aligned with the hinge  205  axis about which the deck  200  rotates. Thus, less of a moment exists that must be overcome by the point load applied by the cam follower  104 . Consequently, when the deck is at or near the horizontal position, the cam follower  104  is rotated to a lower position corresponding to increased torsion in the torsion bar  106 . As the deck rotates upward,  FIGS. 6 and 7  show the cam follower  104  likewise rotating upward, because of the shape of the cam engaging surface  138 , decreasing the torsion in the torsion bar  106 ; the decreased torsion is desired because of the lower moment needed to support the bed deck  200  at the rotated position in force equilibrium. If the cam engaging surface  138  is properly dimensioned, and the weight of the bed deck  200  is known, the point load applied to the deck  200  by the cam follower  104  will equal the moment produced by the deck  200 , hence force equilibrium, and the deck  200  can be suspended at any angle of rotation without having to hold or brace the deck  200 . Even if additional items are placed on the deck  200 , increasing the moment, if the weight of these items is small compared to the weight of the deck  200 , only a small lifting force will be necessary to lift the deck and expose the recessed storage area  304 .  
         [0029]     It should also be understood that the key lifting components of the lifting mechanism  100  may be reversed in position. In this arrangement, the torsion rod  106  is mounted on the undersurface of the bed deck  200  with the cam follower  104  and anchor arm  110  affixed on the rod  106  and facing a direction opposite of that shown in  FIGS. 8-11 . Likewise, the flat upper surface  150  of the cam  102  becomes a bottom surface mounted against the platform base surface  206  such that the cam  102  faces upward for engagement with the cam follower  104  facing downward.