Abstract:
The present invention is for a method of converting a standard jack knife hinge into a new hinge, which allows access to a storage area underneath the seat bottom while retaining the ability to be used as a sofa and a bed. The new hinge is created by removing the seat bottom frame from the seat bottom bracket, fixably attaching a first attachment bracket to the seat bottom frame, pivotally attaching the first attachment bracket to a second attachment bracket, and fixably attaching the seat bottom bracket and the second attachment bracket to the seat base frame. The present invention also claims the finished combined hinge as well as a convertible sofa utilizing the new hinge.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to a convertible sofa and, more particularly, to a convertible sofa or seat for use on recreational vehicles which can be converted from a seat to a bed.  
         BACKGROUND OF THE INVENTION  
         [0002]    In many recreational vehicles today, it is common to have a convertible sofa or seat bed, which can function as a seat, a sofa, or a bed. Such seats are typically employed on recreational vehicles, but can also be used in extended cab pickups, vans, and minivans. The seat is often configured to fold into a flat, planar configuration for use as a bed, and then fold at a juncture between the seat bottom and the seat back so as to form a seat or sofa. The prior art seats have accomplished this versatility by the use of a standard jack knife hinge, which is shown in FIGS. 1 and 2 and will be discussed in detail below.  
           [0003]    It is also common in recreational vehicles today to optimize the available space therein for maximum possible usage. Given the economic and fuel efficiency drawbacks of increasing the size of the vehicle, manufacturers are continually redesigning vehicle ergonomics to take maximum advantage of available interior space. One prior art device comprises a seat wherein the seat bottom can be folded parallel to the seat back to increase the storage space of the vehicle and to access a space provided below the seat. However, this prior art design has several limitations. It does not allow the seat back to fold over the seat bottom to allow greater access behind the seat back or to allow more room for storage. This prior art design also requires the use of a hinge plate between the seat and the seat back making the construction relatively complex and, possibly, allowing accidental insertion of fingers, which can cause serious injury. This prior art design also cannot be easily retrofitted, as it requires replacement of the standard jack knife design.  
         SUMMARY OF THE INVENTION  
         [0004]    The convertible sofa of this invention provides a simple seat bottom hinge and seat back hinge, which are designed to be used in combination with a standard jack knife hinge. The new invention will allow the seat bottom to be rotated upwards and generally parallel to the seat back in order to increase the storage space of the vehicle and to provide access to a space provided below the seat. The new invention will also allow normal operation of the standard jack knife hinge, which allows the sofa to be converted into a bed when the seat bottom is down.  
           [0005]    These and other advantages are provided by a method of making an improved convertible sofa hinge from a standard convertible sofa jack knife hinge. The jack knife hinge connects a seat back frame and a seat bottom frame to a seat base frame including a side rail. The jack knife hinge has a seat back bracket fixably connected to the seat back frame, a seat bottom bracket fixably connected to the seat bottom frame, the seat back bracket pivotally connected to the seat bottom bracket, a first pivot arm pivotally connected to the side rail and the seat back bracket, a second pivot arm pivotally connected to the side rail and the seat bottom bracket, and the cross bar arm pivotally attached to the first pivot arm and the second pivot arm. The method of making the an improved convertible sofa hinge comprises the steps of: a) removing the seat bottom frame from the seat bottom bracket; b) fixably attaching a first attachment bracket to the seat bottom frame; c) pivotally attaching the first attachment bracket to a second attachment bracket; and d) fixably attaching the seat bottom bracket and the second attachment bracket to the seat base frame.  
           [0006]    These and other advantages are also provided by a hinge assembly for a convertible sofa, wherein the hinge connects a seat back frame and a seat bottom frame to a seat base frame including a side rail. The hinge for a convertible sofa comprises a seat back bracket fixably connected to the seat back frame, a seat bottom bracket pivotally connected to the seat back bracket, a first pivot arm pivotally connected to the side rail and the seat back bracket, a second pivot arm pivotally connected to the side rail and the seat bottom bracket, a cross bar arm pivotally attached to the first pivot arm and the second pivot arm, a first attachment bracket fixably attached to the seat bottom frame, and a second attachment bracket pivotally attached the first attachment bracket. The seat bottom bracket and the second attachment bracket are fixably attached to the seat base frame.  
           [0007]    These and other advantages are also provided by a convertible sofa comprising a seat back frame, a seat bottom frame, and a seat base frame including a side rail on opposite sides of the seat base frame wherein the seat base frame encloses a storage area. The sofa further comprises a pair of hinges connecting the seat back frame and the seat bottom frame to the seat base frame. Each hinge comprises a seat back bracket fixably connected to the seat back frame, a seat bottom bracket pivotally connected to the seat back bracket, a first pivot arm pivotally connected to the side rail and the seat back bracket, a second pivot arm pivotally connected to the side rail and the seat bottom bracket, a cross bar arm pivotally attached to the first pivot arm and the second pivot arm, a first attachment bracket fixably attached to the seat bottom frame, and a second attachment bracket pivotally attached the first attachment bracket. The seat bottom bracket and the second attachment bracket are fixably attached to the seat base.  
           [0008]    These and other advantages of this invention will become apparent upon a reading of the following description. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0009]    A preferred embodiment of the invention has been depicted for illustrative purposes wherein:  
         [0010]    [0010]FIG. 1 is a side elevational view of a prior art convertible sofa utilizing a standard jack knife hinge assembly shown in the seat position with portions shown in section and the cushions shown in broken lines for purposes of illustration.  
         [0011]    [0011]FIG. 2 is a perspective view of the prior art convertible sofa of FIG. 1 shown in the bed position;  
         [0012]    [0012]FIG. 3 is an exploded perspective view of a seat bottom hinge assembly of the present invention;  
         [0013]    [0013]FIG. 4 is an assembled perspective view of the seat bottom hinge assembly shown in FIG. 3;  
         [0014]    [0014]FIG. 5 is a partially exploded perspective view of the seat bottom hinge assembly attached to the seat bottom frame assembly over top of a seat frame assembly including a jack knife hinge assembly;  
         [0015]    [0015]FIG. 6 is a perspective view of the seat bottom hinge assembly attached to the seat bottom frame assembly;  
         [0016]    [0016]FIG. 7 is a perspective view of an embodiment of the convertible sofa utilizing the seat bottom hinge assembly of the present invention shown in a sofa or seat configuration;  
         [0017]    [0017]FIG. 8 is a perspective view of an embodiment of the convertible sofa utilizing the seat bottom hinge assembly of the present invention shown in a lifted seat bottom configuration;  
         [0018]    [0018]FIG. 9 is an exploded perspective view of a seat back hinge assembly of an embodiment of the present invention;  
         [0019]    [0019]FIG. 10 is an assembled perspective view of the seat back hinge assembly shown in FIG. 9;  
         [0020]    [0020]FIG. 11 is a perspective view of the seat back hinge assembly as shown in FIG. 9 attached to a seat back frame assembly;  
         [0021]    [0021]FIG. 12 is a partially exploded perspective view of the seat back hinge assembly attached to the seat bottom frame assembly displaced over a seat frame assembly including a jack knife hinge assembly;  
         [0022]    [0022]FIG. 13 is a perspective view of an embodiment of the convertible sofa utilizing the seat bottom hinge assembly and utilizing the seat back hinge assembly of the present invention in a sofa or seat configuration;  
         [0023]    [0023]FIG. 14 is a perspective view of an embodiment of the convertible sofa utilizing the seat bottom hinge assembly and the seat back hinge assembly of the present invention shown in a lowered seat back configuration;  
         [0024]    [0024]FIG. 15 is an exploded perspective view of an alternate embodiment of a seat bottom hinge assembly of the present invention;  
         [0025]    [0025]FIG. 16 is a perspective view of the seat bottom hinge assembly of FIG. 15 attached to the seat bottom frame assembly;  
         [0026]    [0026]FIG. 17 is a partially exploded perspective view of the seat bottom hinge assembly of FIG. 15 attached to the seat bottom frame assembly over top of a seat frame assembly including a jack knife hinge assembly;  
         [0027]    [0027]FIG. 18 is an exploded perspective view of another alternate embodiment of a seat bottom hinge assembly of the present invention;  
         [0028]    [0028]FIG. 19 is a perspective view of the seat bottom hinge assembly of FIG. 18 attached to the seat bottom frame assembly;  
         [0029]    [0029]FIG. 20 is a partially exploded perspective view of the seat bottom hinge assembly of FIG. 18 attached to the seat bottom frame assembly over top of a seat frame assembly including a jack knife hinge assembly;  
         [0030]    [0030]FIG. 21 is a perspective view of an embodiment of the convertible sofa utilizing the seat bottom hinge assembly shown in FIG. 18 of the present invention shown in a sofa or seat configuration;  
         [0031]    [0031]FIG. 22 is a perspective view of an embodiment of the convertible sofa utilizing the seat bottom hinge assembly shown in FIG. 18 of the present invention shown in a lifted seat bottom configuration;  
         [0032]    [0032]FIG. 23 is a perspective view of an unlocking strap assembly of the present invention used with a convertible sofa utilizing the seat bottom hinge assembly shown in FIG. 18 of the present invention shown in a lifted seat bottom configuration;  
         [0033]    [0033]FIG. 24 is a perspective view of the actuator strap loop of the unlocking strap assembly of FIG. 23 extending from a convertible sofa utilizing the seat bottom hinge assembly shown in FIG. 18 of the present invention shown in a lifted seat bottom configuration;  
         [0034]    [0034]FIG. 25 is an exploded perspective view of another alternate embodiment of a seat bottom hinge assembly of the present invention;  
         [0035]    [0035]FIG. 26 is a perspective view of the seat bottom hinge assembly of FIG. 25 attached to the seat bottom frame assembly; and  
         [0036]    [0036]FIG. 27 is a perspective view of an embodiment of the convertible sofa utilizing the seat bottom hinge assembly shown in FIG. 25 of the present invention shown in a lifted seat bottom configuration. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0037]    Referring to FIGS. 1 and 2 of the drawings, a prior art convertible sofa bed  10  utilizing a standard jack knife hinge  25  is shown. The convertible sofa bed  10  comprises generally a seat back cushion  24  attached to a seat back frame  22  and a seat bottom cushion  20  attached to a seat bottom frame  18 , both supported by seat frame  12  through a jack knife hinge  25 . The prior art jack knife hinge  25  comprises a seat bottom mounting bracket  26  secured to the rear of seat bottom frame  18  by bolts  29  and a seat back mounting bracket  28  secured to the lower end of seat back frame  22  by bolts  31 . Mounting brackets  26 ,  28  are secured to one another by a pivot bolt  27 . A first pivot arm  30  is connected at one end to seat bottom mounting bracket  26  by a fastener  16  and, at its other end, to frame  21  by a pivot pin  34 . A second pivot arm  36  is connected at one end to seat back mounting bracket  28  by fastener  38  and, at its other end, to frame  21  by pivot pin  40 . A cross pivot arm  42  is connected to first pivot arm  30  between its ends by fastener  44  and to second pivot arm  36  between its ends by fastener  46 . The jack knife hinge  25  allows the convertible sofa bed  10  to be configured in a sofa or seat configuration as shown in FIG. 1 or in a bed configuration as shown in FIG. 2.  
         [0038]    A first embodiment of the present invention utilizes a seat bottom hinge assembly  41  shown in an exploded and assembled view in FIGS. 3 and 4, respectively. Seat bottom hinge assembly  41  comprises first attachment bracket  43  and a rotatable second inner attachment bracket  45 . First attachment bracket  43  comprises a generally vertical portion  47  having a first and a second generally horizontally projecting fastener  48  and  50 , respectively. First attachment bracket  43  also comprises a generally horizontal portion  52  having a first and second generally vertically projecting fastener  54  and  56 , respectively. Second inner attachment bracket  45  comprises a generally horizontal portion  59  adapted for securing second inner attachment bracket  45  to a bottom seat frame assembly  80 . Second inner attachment bracket  45  also comprises a generally vertical portion  57  having a first slot  58  and second slot  60  through which first and second fasteners  48  and  50  extend through when second inner attachment bracket  45  is assembled onto first attachment bracket  43  and secured thereto by nuts  62 . First slot  58  is generally horizontal and provides a pivot point about which second inner attachment bracket  45  rotates with respect to first attachment bracket  43 . Rotation is controlled by second slot  60 , which generally comprises an arcuate portion  64  terminating into a horizontal portion  66 . Second inner attachment bracket  45  may also include a spring-loaded lock pin assembly  68 , which will prevent second inner attachment bracket  45  from rotating with respect to first attachment bracket  43 , as will be discussed in greater detail below.  
         [0039]    Referring now to FIG. 6, seat bottom hinge assembly  41  is shown attached to seat bottom frame assembly  80 . This attachment may be accomplished by utilizing fasteners, welding, or any other appropriate fastening means. In FIG. 5, seat bottom frame assembly  80  with attached seat bottom hinge assembly  41  is shown in a partially exploded view over top a seat frame assembly  90  including a jack knife hinge  100 . First and second vertically projecting fasteners  54  and  56  extend through apertures  102  in a seat bottom mounting bracket  104  of jack knife hinge  100  and attached thereto by nuts  62 . This attachment may be also be accomplished by welding, or any other appropriate fastening means.  
         [0040]    In FIG. 7, a convertible sofa bed  110  is shown including seat bottom hinge assembly  41  of the present invention attached to seat bottom frame assembly  80 , including a jack knife hinge  100  configured in a seat configuration. In FIG. 8, the convertible sofa bed  110  is shown with seat bottom frame assembly  80  in a raised configuration providing access to the area below seat frame assembly  90 . In order to move seat bottom frame assembly  80  into a raised position, seat bottom frame assembly  80  must be pulled generally horizontally in a direction away from seat back frame assembly  180  such that second fastener  50  of first attachment bracket  43  slides from the horizontal portion  66  of second slot  60  and into the arcuate portion  64  of second slot  60  as best shown in FIG. 6. This enables seat bottom frame assembly  80  to be lifted upwards about the pivot point  57  formed by first fastener  48  of the first attachment bracket  43  and the end of the generally horizontal first slot  58 . Attempting to lift seat bottom frame assembly  80  without first pulling outward horizontally away from seat back frame assembly  180  will not result in the seat bottom frame assembly  80  moving upward as the horizontal portion  66  of second slot  60  will prevent this movement. Once the seat bottom frame assembly  80  has been completely rotated upward, spring-loaded lock pin assembly  68  will engage an aperture  88  on first attachment bracket  43 , thereby locking seat bottom frame assembly  80  in an upright position. In order to return the convertible sofa bed  110  to the seat position configuration, the spring-loaded lock pin assembly  68  is disengaged, allowing seat bottom frame assembly  80  to rotate downward to its initial generally horizontal position. Returning seat bottom frame assembly  80  to the seat configuration will allow the convertible sofa bed  110  to work as a standard jack knife hinged sofa bed.  
         [0041]    A second embodiment of the present invention utilizes a seat back hinge assembly  141  shown in an exploded and assembled view in FIGS. 9 and 10, respectively. Seat back hinge assembly  141  comprises first attachment bracket  143  and a rotatable second attachment bracket  145 . First attachment bracket  143  comprises a first generally planar portion  146  having a first and a second generally perpendicularly projecting fastener  148  and  150 , respectively, and an aperture  188 . First attachment bracket  143  also comprises a second generally planar portion  152 , generally perpendicular to first planar portion  146 , including a first and a second projecting fastener  154  and  156 , respectively. Second attachment bracket  145  comprises a first planar portion  159  adapted for securing second attachment bracket  145  to a bottom seat frame assembly  180 . Second attachment bracket  145  also comprises a second generally planar portion  157  having a slot  158  and an aperture  160  through which first and second fasteners  148  and  150  extend through when second attachment bracket  145  is assembled onto first attachment bracket  143  and secured thereto by nuts  62 . Aperture  160  provides a pivot point about which second attachment bracket  145  rotates with respect to first attachment bracket  143 . Rotation is controlled by slot  158 , which is generally arcuate. Second attachment bracket  145  may also include a spring-loaded lock pin assembly  168 , which mates with aperture  188  in the first attachment bracket  143 , as best shown in FIG. 9. Spring-loaded lock pin assembly  168  engages aperture  188  to prevent second attachment bracket  145  from rotating with respect to first attachment bracket  143  when the seat back frame assembly  180  is in an upright position in a seat configuration. When the spring-loaded lock pin assembly  168  is disengaged, the seat back frame assembly  180  is free to rotate downward toward the seat bottom frame assembly  80 .  
         [0042]    Referring now to FIG. 11, seat back hinge assembly  141  is shown attached to seat back frame assembly  180 . This attachment may be accomplished by utilizing fasteners, welding, or any other appropriate fastening means. In FIG. 12, seat back frame assembly  180 , with attached seat back hinge assembly  141 , is shown in a partially exploded view displaced over a seat frame assembly  190 , including a jack knife hinge  100 . First and second perpendicularly projecting fasteners  154  and  156  extend through apertures  106  in a seat back mounting bracket  108  of jack knife hinge  100  and attached thereto by nuts  62 . This attachment may be also be accomplished by welding, or any other appropriate fastening means.  
         [0043]    In FIG. 13, a convertible sofa bed  210  is shown, including seat back hinge assembly  141  of the present invention, attached to seat back frame assembly  180  including a jack knife hinge  100 , configured in a seat configuration. In FIG. 14, the convertible sofa bed  210  is shown with seat back frame assembly  180  in a lowered configuration, providing access to the area behind seat frame assembly  90 . In order to move seat back frame assembly  180  into a lowered position, spring-loaded lock pin assembly  168  must be disengaged from aperture  188  such that the seat back frame assembly  180  is free to rotate downward toward the seat bottom frame assembly  80 . In order to return the convertible sofa bed  210  to the seat position configuration, seat back frame assembly  180  is rotated upward until the spring-loaded lock pin assembly  168  engages aperture  188 , locking the seat back frame assembly  180  into position.  
         [0044]    A third embodiment of the present invention utilizes a seat bottom hinge assembly  241  shown in an exploded view in FIG. 15, shown attached to a seat bottom frame assembly  280  in FIG. 16, and shown attached to a seat assembly  290  in FIG. 17. This embodiment is similar to the first embodiment except that the bottom seat frame assembly  280  is pushed inwards, then lifted, instead of pulled outward, then lifted.  
         [0045]    Seat bottom hinge assembly  241  comprises a first or lower attachment bracket  243  and a rotatable second or upper attachment bracket  245 . Lower attachment bracket  243  comprises a first planar portion  247  having a perpendicularly projecting front travel pin  248 , a main pivot pin  250 , a rear travel slot  270  and a locking aperture  272 . Lower attachment bracket  243  also comprises a second planar portion  252  generally perpendicular to first planar portion  247  having a first and second generally vertically projecting fastener  254  and  256 , respectively. Upper attachment bracket  245  comprises a first planar portion  259  adapted for securing upper attachment bracket  245  to a bottom seat frame assembly  280 . Upper attachment bracket  245  also comprises a second portion  257  generally perpendicular to first planar portion  259  having a first slot  258  and second slot  260  through which front travel pin  248  and main pivot pin  250  extend through when upper attachment bracket  245  is assembled onto lower attachment bracket  243  and secured thereto by nuts  62  (not shown). Second portion  257  of upper attachment bracket  245  also comprises a rear travel pin  274  which mates with rear travel slot  270 , and an aperture  260  (not shown) for mounting spring-loaded lock pin assembly  168 .  
         [0046]    First slot  258  is generally horizontal and provides a pivot point about which upper attachment bracket  245  rotates with respect to lower attachment bracket  243 . Rotation is controlled by front travel slot  260 , which generally comprises an arcuate portion  264  terminating into a horizontal portion  266  and rear travel slot  261 , which generally comprises an arcuate portion  263  terminating into a horizontal portion  265 . Upper attachment bracket  245  may also include a spring-loaded lock pin assembly  168 , which will prevent upper attachment bracket  245  from rotating with respect to lower attachment bracket  243 , similar to that discussed in relation to the first embodiment.  
         [0047]    Referring now to FIG. 16, seat bottom hinge assembly  241  is shown attached to seat bottom frame assembly  280 . This attachment may be accomplished by utilizing fasteners, welding, or any other appropriate fastening means. In FIG. 17, seat bottom frame assembly  280  with attached seat bottom hinge assembly  241  is shown in a partially exploded view over top a seat frame assembly  290  including a jack knife hinge  100 . First and second vertically projecting fasteners  254  and  256  extend through apertures  102  in a seat bottom mounting bracket  104  of jack knife hinge  100  and attached thereto by nuts  62 . This attachment may be also be accomplished by welding, or any other appropriate fastening means.  
         [0048]    In order to move seat bottom frame assembly  280  into a raised position, seat bottom frame assembly  280  must be pushed generally horizontally in a direction toward seat back frame assembly  180  such that front travel pin  250  of lower attachment bracket  243  slides from the horizontal portion  266  of front travel slot  260  and into the arcuate portion  264 . Similarly, rear travel pin  274  of upper attachment bracket  245  slides from the horizontal portion  265  of rear travel slot  270  and into the arcuate portion  264 . This enables seat bottom frame assembly  280  to be lifted upwards about the pivot point formed by main pivot pin  248  of the lower attachment bracket  243  and the end of the generally horizontal first slot  258 . Attempting to lift seat bottom frame assembly  280  without first pushing inward horizontally toward seat back frame assembly  180  will not result in the seat bottom frame assembly  280  moving upward as the horizontal portion  266  of front travel slot  260  and the horizontal portion  265  of rear travel slot  270  will prevent this movement. Once the seat bottom frame assembly  280  has been completely rotated upward, spring-loaded lock pin assembly  168  will engage aperture  272  on lower attachment bracket  243 , thereby locking seat bottom frame assembly  280  in an upright position. In order to return to the seat position configuration, the spring-loaded lock pin assembly  168  is disengaged, allowing seat bottom frame assembly  280  to rotate downward to its initial generally horizontal position.  
         [0049]    A fourth embodiment of the present invention utilizes a seat bottom hinge assembly  341  shown in a disassembled view in FIG. 18. This embodiment is different from the first and third embodiments in that the seat bottom hinge assembly  341  is locked in both the upright and lowered, or seat configurations such that the seat bottom frame assembly  380  does not need to be either pulled or pushed to allow movement, but rather must be unlocked. Seat bottom hinge assembly  341  comprises first attachment bracket  343  and a rotatable second attachment bracket  345 . First attachment bracket  343  comprises a first generally planar portion  347  having a pivot point aperture  388  and a seated locking position aperture  348  and an open locked position aperture  350 . First attachment bracket  343  also comprises a second generally planar portion  352 , generally perpendicular to first planar portion  346 , including a first and a second projecting fastener  354  and  356 , respectively. Second attachment bracket  345  comprises a first planar portion  359  adapted for securing second attachment bracket  345  to a bottom seat frame assembly  380 . Second attachment bracket  345  also comprises a second generally planar portion  357  having a pivot point aperture  358  and a second aperture  360  for mounting spring-loaded lock pin assembly  168  (not shown). First attachment bracket  343  is attached to second attachment bracket  345  by a bolt  375  extending through pivot point apertures  388  and  358 , respectively, and secured thereto by nut  62 . Apertures  388  and  358  provide a pivot point about which second attachment bracket  345  rotates with respect to first attachment bracket  343 . Second attachment bracket  345  includes a spring-loaded lock pin assembly  168 , which mates with seated locking position aperture  348  when seat bottom frame assembly  380  is in a lowered, or seat position. Spring-loaded lock pin assembly  168 , also mates with open locked position aperture  350  when seat bottom frame assembly  380  is in a raised or open position. Spring-loaded lock pin assembly  168  engages apertures  350 ,  388  to prevent second attachment bracket  345  from rotating with respect to first attachment bracket  343  when the seat bottom frame assembly  380  is in an upright position or in a seat configuration. When the spring-loaded lock pin assembly  168  is disengaged, the seat bottom frame assembly  380  is free to rotate downward toward the seat frame assembly  390 , or upward to a raised position.  
         [0050]    Referring now to FIG. 19, seat bottom hinge assembly  341  is shown attached to seat bottom frame assembly  380 . This attachment may be accomplished by utilizing fasteners, welding, or any other appropriate fastening means. In FIG. 20, seat bottom frame assembly  380 , with attached seat bottom hinge assembly  341 , is shown in a partially exploded view displaced over a seat frame assembly  390 , including a jack knife hinge  100 . First and second perpendicularly projecting fasteners  354  and  356  extend through apertures  102  in a seat bottom mounting bracket  104  of jack knife hinge  100  and attached thereto by nuts  62 . This attachment may be also be accomplished by welding, or any other appropriate fastening means.  
         [0051]    In FIG. 21, a convertible sofa bed  310  is shown, including seat bottom hinge assembly  341  of the present invention, attached to seat bottom frame assembly  380  including a jack knife hinge  100 , configured in a seat configuration. In FIG. 22, the convertible sofa bed  310  is shown with seat bottom frame assembly  380  in a raised configuration, providing access to the area below seat frame assembly  390 . In order to move seat bottom frame assembly  380  into a raised or lowered position, spring-loaded lock pin assembly  168  must be disengaged from aperture  350 ,  348  respectively, such that the seat bottom frame assembly  180  is free to rotate downward toward the seat frame assembly  390 . Once seat bottom frame assembly  380  is rotated to the selected position, spring-loaded lock pin assembly  168  automatically engages the corresponding aperture  350 ,  348  of the new position.  
         [0052]    In another embodiment of the present invention, the spring-loaded lock pin assemblies  168  on either side of convertible sofa bed  310  can be disengaged using an unlocking strap assembly  400  as best shown in FIG. 23. Strap assembly  400  comprises a first strap  402  extending between the spring-loaded lock pin assemblies  168  on either side of convertible sofa bed  310 . An actuator strap  404  is attached to a midportion of the first strap and extends from the rear to the front of seat bottom frame  380 . A loop  406 , or tab portion, extends from underneath seat bottom frame  380  as best shown in FIG. 24. Pulling on loop  406  causes tension on first strap  402  and disengages spring-loaded lock pin assemblies  168 . This allows the seat bottom frame  380  to rotate either to a raised position or a lowered seat configuration.  
         [0053]    In another embodiment of the present invention, a seat bottom hinge assembly  441  is shown in FIGS.  25 - 27 . Seat bottom hinge assembly  441  is similar to the first embodiment in that the actuation is identical; pull the seat bottom assembly  480  outward and rotate up until it locks. The difference between these embodiments is that the first attachment bracket  443  and second attachment bracket  445  extend downward instead of upward. FIG. 25 shows first attachment bracket  443  attached to seat bottom assembly  480 . FIG. 26 shows second attachment bracket  445  being attached to the first attachment bracket  443  on seat bottom assembly  480 . FIG. 27 shows the operation of seat bottom hinge assembly  441  in a raised configuration on a convertible sofa bed  410 .  
         [0054]    It is contemplated that any of the seat bottom hinge embodiments can be used with the seat top embodiment, or if appropriate, used in place of a seat top embodiment as well.  
         [0055]    Although the present invention has been described above in detail, the same is by way of illustration and example only and is not to be taken as a limitation on the present invention. Accordingly, the scope and content of the present invention are to be defined only by the terms of the appended claims.