Abstract:
A quiet, non-binding articulatable spring mechanism for resiliently supporting a mattress includes a system of articulatable, sinuous springs, each having hooked ends for silencing the mechanism during use or collapse, as well as central offset portions for enabling the sinuous springs to compress to a greater extent than heretofore. Both rigid and yieldable support structures connect the spring mechanism to an item of furniture.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to furniture having a spring mechanism for resiliently supporting a person during use, but being collapsible for compact storage, and, more particularly, to improvements in the structure, function, operation and assembly of such spring mechanisms.  
         [0003]     2. Description of the Related Art  
         [0004]     It is generally known that foldaway or foldable beds are attractive bedding options for persons with restricted living space, such as are commonly found in recreational vehicles, trailers, boats, studio apartments, and the like. A Murphy-style bed includes a mattress that can be swung or folded into a wall-mounted cabinet or closet when not being used for sleeping. A convertible foldable bed folds upon itself, either one or two times, for compact storage and to serve as a sofa or seating area, and then is unfolded into a bed for sleeping. The convertible sofa-bed includes a mattress that is sufficiently flexible to fold upon itself, and that is supported and deployed by an articulated bed frame.  
         [0005]     Although generally satisfactory for their intended purposes, the known foldable beds have exhibited some drawbacks. For maximum sleeping comfort the mattress is desired to be relatively firm and thick. However, a thick, firm-mattress is not readily foldable, and certainly not in furniture of contemporary style where a low seat height and small dimensions are aesthetically desirable. In foldaway beds, a thick mattress requires a deeper cabinet or closet, thereby encroaching on the already limited living space. Where style and space requirements are paramount, a thin, foldable, soft and easily crushable mattress is employed; however, the result is often an unsatisfactory sleeping surface.  
         [0006]     To solve the aforementioned problems, I have developed several spring mechanisms within mattresses, the mechanisms being collapsible for compact storage and being expandable for resiliently supporting a person during use. Reference can be made, for example, to my earlier patents, namely, U.S. Pat. No. 4,489,450; U.S. Pat. No. 4,654,905; U.S. Pat. No. 4,620,336; U.S. Pat. No. 5,184,809; U.S. Pat. No. 5,431,376; U.S. Pat. No. 5,535,460; U.S. Pat. No. 5,539,940; U.S. Pat. No. 5,539,944; U.S. Pat. No. 5,540,418; U.S. Pat. No. 5,524,305; U.S. Pat. No. 5,642,536 and U.S. Pat. No. 5,655,240.  
         [0007]     As exemplified by these patents, each mechanism has an upper wire grid located below an upper mattress face, a lower wire grid located above a lower mattress face, and a system of generally planar, collapsible springs pivotably connected at opposite ends to the grids. When the mattress is in the body-supporting use position, the collapsible springs are upright in parallel planes generally parallel to head and foot end faces of the mattress. However, as the mattress is moved to the storage position, the collapsible springs pivot about the grids; and the upper and lower grids shift longitudinally and are drawn closer together, thereby decreasing the distance between the upper and lower mattress surfaces and decreasing the thickness of the mattress so that it can be compactly stored.  
         [0008]     Experience has shown, however, that the collapsible spring mechanisms of these patents have certain shortcomings. One is the expense of production which is relatively high, primarily due to the requirement for special wire forming machinery. Another is the tendency of the collapsible springs to rotate beyond their upright position. Still another is the extent to which each collapsible spring can be compressed. Limited compression of collapsible springs render the mattress less comfortable for sleeping. Yet another is mechanical contact between adjacent portions of the collapsible springs which, when the mattress is repeatedly compressed, can be noisy and undesirable for a sleeping occupant. Also related to this noise issue is the tendency of the ends of the collapsible springs to suddenly snap off helical interconnecting coils that interconnect the collapsible springs transversely along the mattress. The sudden snapping of these spring ends is not only quite noisy, but also disconcerting to the occupant who may fear that the mattress is about to imminently collapse. An additional shortcoming is the complex, labor-intensive, clip-type connection between longitudinal grid wires and a border wire on each grid.  
       SUMMARY OF THE INVENTION  
     OBJECTS OF THE INVENTION  
       [0009]     Accordingly, it is a general object of this invention to improve the operation and assembly of collapsible spring mechanisms used in furniture, especially for mattresses.  
         [0010]     More particularly, it is an object of the present invention to provide a collapsible spring that can be compressed to a greater depth or extent than is currently available for such springs of the prior art.  
         [0011]     Still another object of the present invention is to provide a reliable means to effectively prevent the collapsible springs from rotating past their upright position.  
         [0012]     It is yet another object of the present invention to reduce, if not eliminate, noise generated during compression of the collapsible springs, as well as during shifting or rolling by the occupant.  
         [0013]     A still further object of the present invention is to strengthen the upper and lower grids for firmer support.  
         [0014]     A still further object of the present invention is to provide grid wires that can easily be connected to a border wire via automated equipment.  
         [0015]     A still further object of the present invention is to provide a mattress collapsible to minimal dimensions for compact storage to conserve living space.  
         [0016]     A concomitant object of the present invention is to construct a spring mechanism of the above type so as to be relatively simple in construction, inexpensive to manufacture, easy to use, and yet reliable in operation.  
       FEATURES OF THE INVENTION  
       [0017]     In keeping with the above objects and others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a furniture item, for example, a foldaway or foldable bed, convertible sofa-bed, or like motion furniture, comprising a support and a movable mattress mounted thereon for movement between a storage position and a body-supporting use position. In a currently preferred application, the furniture item is a Murphy-style bed, and the support is a wall-mounted cabinet in which the mattress is stored in an internal storage compartment.  
         [0018]     In further accordance with this invention, a spring assembly is used for resiliently supporting the mattress in the use position. The spring assembly includes an upper wire grid, a lower wire grid, and a system of collapsible springs pivotably connected to the grids for movement from a collapsed position in which the grids are adjacent one another in close proximity when the mattress is in the storage position for compact storage, along an opening direction, to an upright position in which the grids are resiliently held and spaced apart by the collapsible springs when the mattress is in the use position, for example, for sleeping.  
         [0019]     The spring assembly is mounted on the support by a support structure having a pair of spaced-apart upper and lower support elements to which the upper and lower wire grids are pivotably mounted. The support elements are either rigidly or resiliently held apart. In the case of a rigid support structure, it is mounted away from the main sleeping surface of the mattress, for example, in the cabinet, for user comfort. In the case of a yieldable support structure, it is mounted either away from, or within, the main sleeping surface of the mattress. For example, the yieldable support structure can be mounted on an articulated frame which is used for folding or unfolding the mattress.  
         [0020]     One feature of the present invention relates to the structure and operation of the collapsible springs. Each collapsible spring is sinuously formed of a single length of wire with multiple runs and arcuate portions or turns, and roughly resembles the letter “S” repeated a number of times without interruption. Each spring has upper and lower linear runs having hooked ends for hookingly engaging respective interconnecting coils that are arranged in mutual parallelism transversely across both the upper and lower wire grids. This type of sinuous spring has not heretofore been provided with hooked ends and, as a result, the ends of the prior art springs tend to withdraw from the interconnecting coils with concomitant sudden, undesirable popping sounds.  
         [0021]     Each sinuous spring of this invention also has at least one offset, and preferably a pair of offsets, formed in central regions of intermediate runs of the spring. Hence, the spring enables the runs adjacent the offset(s) to bypass each other to a greater extent than heretofore during compression of the spring for greater user comfort. The runs of each spring therefore lie in different spaced-apart planes.  
         [0022]     Still another feature of this invention resides in ensuring that each interconnecting coil encircles the upper and lower linear runs of each sinuous spring along their entire lengths thereof for improved strength and mattress support. In the known sinuous springs of the prior art, these upper and lower linear runs had stops for resisting movement of the collapsing springs along the opening direction past the upright position. These stops were offset from the remainder of the linear upper and lower runs and, hence, the interconnecting coils could not encircle these offset stops, thereby leading to an overall weakening of the assembly.  
         [0023]     The function of resisting over-rotation of the collapsible springs is, in accordance with this invention, not performed by means within the spring assembly, for example, by the aforementioned offset stops, but instead, by means outside the spring assembly and remote from the collapsible springs. Such means are aided by the aforementioned support structure mounted on a stationary support, the support structure insuring that the upper and lower wire grids are held apart. Also, the mattress is supported on a platform which is pivotably connected to the support by hinges, and is bordered by an upright board extending across a longitudinal or transverse dimension of the mattress. The board is pivotably connected by support links to the support. The board and/or the hinges are operative to prevent over-rotation of the platform, the spring assembly, and the collapsible springs therein.  
         [0024]     Still another feature of this invention is embodied in the connection of the spring assembly to upper and lower border wires in the upper and lower wire grids. A plurality of upper grid wires extends in mutual parallelism along the longitudinal direction between the upper support element of the support structure and a transverse section of the upper border wire. Another plurality of lower grid wires extends in mutual parallelism along the longitudinal direction between the lower support element and a transverse section of the lower border wire. Each of these grid wires has a bow tie formation having two mirror-symmetrical loops. A plurality of ties each extends through one of these loops and around the border wire. The tie is configured as a ring and is easily fitted in place by automated machinery.  
         [0025]     The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]      FIG. 1  is a perspective view of a foldaway wall bed having a mattress stored in a storage position in accordance with this invention;  
         [0027]      FIG. 2  is a perspective view of the bed of  FIG. 1  depicting a hidden compartment for storage of extra items;  
         [0028]      FIG. 3  is a perspective view of the bed of  FIG. 1  in the storage position, but with base cabinets and cushions to form a couch;  
         [0029]      FIG. 4  is a perspective view of the couch of  FIG. 3 , but with one base cabinet open to stow the cushions therein;  
         [0030]      FIG. 5  is a perspective view of the couch of  FIG. 3 , but with the cushions positioned in front of the base cabinets preparatory to folding down the bed;  
         [0031]      FIG. 6  is a perspective view of the bed of  FIG. 5  folded down over the base cabinets and the cushions;  
         [0032]      FIG. 7  is a broken-away, enlarged, vertical sectional view taken on line  7 - 7  of  FIG. 1  depicting the mattress in the storage position in solid lines, and depicting the folding down of the bed in phantom lines;  
         [0033]      FIG. 8  is a broken-away, perspective view of a corner of one embodiment of the mattress after being folded down to a body-supporting use position;  
         [0034]      FIG. 9  is a top plan view of a collapsible spring used in the mattress of  FIG. 8 ;  
         [0035]      FIG. 10  is a side elevational view of the spring of  FIG. 9  in an upright, uncompressed position;  
         [0036]      FIG. 11  is an end elevational view of the uncompressed spring of  FIG. 10 ;  
         [0037]      FIG. 12  is a side elevational view of the spring used in the mattress of  FIG. 8  during compression;  
         [0038]      FIG. 13  is a view analogous to  FIG. 8 , but of another embodiment of the mattress;  
         [0039]      FIG. 14  is a view analogous to  FIG. 12 , but depicting a non-rigid, yieldable support structure for mounting the mattress to a support;  
         [0040]      FIG. 15  is a perspective view of another non-rigid, yieldable support structure for mounting the mattress to a support;  
         [0041]      FIG. 16  is a view analogous to  FIG. 15 , but depicting the non-rigid, yieldable support structure in a collapsed position; and  
         [0042]      FIGS. 17-18  are enlarged plan views of a detail of the spring mechanism.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0043]     The present invention is related to furniture, particularly motion furniture in which a body-supporting component thereof, for example, a mattress, a cushion, a pad or the like, is moved, typically from a storage position in which the body-supporting component is stored, to a use position in which the body-supporting component resiliently supports a human body. For ease of illustration and description, this invention is described for use in a foldaway or foldable bed in which the mattress is generally horizontal in its unfolded position to serve as a support for a sleeping occupant, and is generally vertical for compact storage in a Murphy-style foldaway bed, or folded over itself at least once, again for compact storage, in a sofa-bed convertible item of furniture. However, it will be expressly understood that this invention, especially as it relates to the structure, function and operation of a collapsible spring mechanism associated with the mattress can be used in other items of furniture which are not beds, such as fold-down seats. It should also be understood that the term furniture is not restricted to items found in one&#39;s house, but can equally well apply to items on recreational vehicles, trailers, boats and the like.  
         [0044]     Thus, by way of non-limiting example,  FIGS. 1-6  depict a foldaway Murphy-style bed  10  having a wall-mounted closet or cabinet  12  which frames an interior storage compartment  14  ( FIG. 6 ) in which a mattress  20  is received in a storage position depicted in  FIG. 1 . As will be described herein, the mattress  20  is collapsed in the storage position and can fit into the cabinet  12  whose depth is on the order of 3-4 inches as measured with respective to a rear wall  16  on which the bed is mounted. However, as also described herein, the mattress  20  expands to a thickness on the order of nine inches when it has been unfolded to a body-supporting use position as depicted in  FIG. 6 . The increased thickness of the mattress in the use position provides increased sleeping comfort. The decreased thickness of the mattress in the storage position provides increased compact storage which is of particular benefit in applications, such as recreational vehicles, which have limited living space.  
         [0045]     Reference numeral  18  depicts a planar platform on which the mattress is supported in the use position. A planar board  22  is co-planar with the platform  18  in the storage position, and is pivoted by support links  19  to be perpendicular to the platform to support the platform above the ground in the use position. A handle  24  on the board  22  enables the user to open and close the bed. A latch  26  on the cabinet holds the bed in the storage position until the latch is manually released. The board may extend across the side, foot or head of the mattress to serve as a sideboard, footboard, or headboard, respectively.  
         [0046]     As best shown in  FIGS. 1-2 , a lower panel  28  provided underneath the platform  18  is pivotable outwardly to expose a lower compartment  30  for storage of miscellaneous items. As best shown in  FIGS. 3-4 , a pair of base cabinets  32 ,  34  is situated in front of the folded bed, and a set of cushions  36  is placed on the cabinets to serve as a couch or seating area. Each cabinet is operable to receive the cushions therein, or to store additional items. The cushions may even be placed in front of the cabinets  32 ,  34  as shown in  FIG. 5 . When the bed is unfolded, as shown in  FIG. 6 , the cabinets and the cushions are accommodated underneath the platform  18 .  
         [0047]     The various furniture configurations of  FIGS. 1-6  is of particular utility in cramped quarters. Comfort is not compromised. A great deal of storage area is available. The folded bed occupies a minimal amount of space and, of course, a couch and a bed are readily available for use.  
         [0048]     Turning now to  FIGS. 7-8 , the mattress  20  includes a padding  38  of a soft, cushioned material encased in a sheath or mattress cover  40 . The cabinet  12  includes a stationary planar support shelf  42  to which the platform  18  is pivotably connected by means of hinges  44 . In the use position, the platform  18  is co-planar with the shelf  42 .  
         [0049]     A rigid, non-yielding support structure is mounted on the shelf  42  and includes a lower cross rail  44  fixedly connected by non-illustrated screws to the shelf  42 , an upper cross rail  46  parallel to the lower rail  44 , and a plurality of rigid elements  48  having lower  50  and upper  52  flanges screwed into the rails  44 ,  46 , the flanges being spaced apart by a spacer  54  for holding the rails apart by a fixed spacing. The rigid support structure is advantageously covered by the padding  38  and the cover  40  as shown, but need not be. The rigid support structure is entirely accommodated in the storage compartment  14  and does not extend out over the platform  18  where it might otherwise present an unforgiving, uncomfortable location upon which to sleep.  
         [0050]     A spring mechanism is mounted underneath the padding  38 , and preferably within the mattress  20 . The spring mechanism includes an upper wire grid  58 , a lower wire grid  60 , and a system of collapsible springs  62  pivotably connected to the grids for movement from a collapsed position (see  FIG. 7 ) in which the grids are closely adjacent one another when the mattress is in the storage position, to an upright position (see  FIG. 8 ) in which the grids are resiliently held and spaced apart by the collapsible springs when the mattress is in the use position.  FIGS. 9-11  show a representative collapsible spring  62  unstressed in its upright position.  FIG. 12  depicts the representative collapsible spring  62  stressed under a compressive load.  
         [0051]     The upper grid  58  includes a rigid, thick, border wire  64  of U-shaped configuration in top plan view and having opposite ends  66  hooked through staples  68  for pivoting movement relative to the upper rail  46 . Likewise, the lower grid  60  includes a rigid, thick, border wire  70  of U-shaped configuration and having opposite ends  72  hooked through staples  74  for pivoting movement relative to the lower rail  44 .  
         [0052]     A plurality of helical, interconnecting coils  76  extends in mutual parallelism transversely across the mattress in a transverse direction lengthwise of and parallel to the rails. As described below, a group of these interconnecting coils in the upper grid pivotably interconnect upper runs of the collapsible springs  62  that are co-linear along the transverse direction, and another group of these interconnecting coils in the lower grid pivotably interconnects lower runs of the collapsible springs  62  that are co-linear along the transverse direction.  
         [0053]     A plurality of grid wires  78  extends in mutual parallelism longitudinally along the mattress in a longitudinal direction perpendicular to the transverse direction. An upper group of the grid wires  78  in the upper grid is connected to the group of interconnecting coils  76  therein, and a lower group of the grid wires  78  in the lower grid is connected to the group of interconnecting coils therein. The upper grid wires  78  have ends  80  hooked into staples  82  for pivoting movement relative to the upper rail  46 , and likewise, the lower grid wires are pivotably connected int the same manner to the lower rail  44 .  
         [0054]     As best seen in  FIGS. 17-18 , each grid wire  78  is provided with a succession of spaced-apart bow tie formations, each having mirror symmetrical loops  84 ,  86 . The loop that is closest to the border wire, for example upper border wire  64 , is connected thereto by a hog ring  88 .  FIG. 17  depicts the closer loop  84  with respect to a longitudinal section of the border wire  64 , whereas  FIG. 18  depicts the closer loop  86  with respect to a transverse section of the border wire. Each interconnecting coil  76  not only pivotably interconnects the upper runs of the collapsible springs  62  as mentioned above, but also passes through and around the loops  84 ,  86  to secure the grid wires  78  to the coils  76  and the collapsible springs  62 .  
         [0055]     As best seen in  FIGS. 9-11  for the representative collapsible spring  62 , the spring  62  is a single length of sinuous wire formed into an upper linear run  100 , a lower linear run  102 , an upper intermediate linear run  104  connected to the upper run  100  by an arcuate portion  106 , a lower intermediate linear run  108  connected to the lower run  102  by an arcuate portion  110 , an upper offset run  112  connected to the intermediate run  104  by an arcuate portion  114 , a lower offset run  116  connected to the intermediate run  108  by an arcuate portion  118 , and a central linear run  120  connected to the offset runs  112 ,  116  by arcuate portions  122 ,  124 .  
         [0056]     In contrast to the sinuous spring disclosed in U.S. Pat. No. 5,540,418, the spring  62  of the current invention has the following features. First, each end of the upper and lower runs  100 ,  102  is bent to form hooks  126 ,  128 . These hooked ends  126 ,  128  extend through spaces between adjacent windings of the upper and lower interconnecting coils  76  and affirmatively prevent the upper and lower runs  100 ,  102  from binding and/or snapping off the coils  76  with concomitant snapping or popping sounds when the user rolls over the mattress as schematically illustrated in  FIG. 12 . In the prior art, as exemplified by U.S. Pat. No. 5,540,418, the upper and lower runs of the sinuous spring have straight ends. As the springs  62  are compressed, the springs tend to pull on the interconnecting coils which stretches to accommodate such tension. Eventually, the upper and lower runs snap off their coils  76 , creating noise which, if the mattress is used with a lower platform  18 , is magnified since the platform acts as a sound board or drum. The hooked ends  126 ,  128  effectively prevent such mechanical binding and noise.  
         [0057]     Secondly, each of the sinuous springs  62  of this invention has center offsets  130 ,  132  in the offset runs  112 ,  116 . This permits a greater deflection of the springs  62  when under compression. As shown in  FIG. 12 , the arcuate portions  106 ,  122 ,  118 ,  114 ,  124 ,  110  bypass one another during compression. In the prior art as exemplified by U.S. Pat. No. 5,655,240, only the ends of the runs are offset, thereby limiting the extent to which the springs may be compressed.  
         [0058]     Thirdly, each of the sinuous springs of U.S. Pat. No. 5,655,240 has offset stops in the upper and lower runs thereof. These offset stops abut against opposing tongue portions in the grid wires to prevent over-rotation in the upright position. Without such stops, the springs have a tendency to rotate beyond their upright position during opening of the bed, or under a compressive load. Such rotation causes the mattress to shift or collapse.  
         [0059]     In accordance with this invention, offset stops are not provided in the collapsible springs, nor are abutting tongue portions provided in the grid wires. This generally simplifies the manufacture of the collapsible springs and the grid wires and allows them to be readily made and assembled by automated machinery.  
         [0060]     Prevention of over-rotation of the collapsible springs past the upright position is aided in accordance with this invention by, in the case of the embodiment of  FIG. 8 , the rigid support structure wherein the stationary rigid elements  48  insure that the lower and upper rails  44 ,  46  as well as the upper and lower grids  58 ,  60  are held a fixed distance apart. Also, the hinges  44  and the upright floor-engaging board  22  insure that the platform  18  will not rotate past the plane of the shelf  42 . Thus, the over-rotation function has been transferred away from the spring mechanism.  
         [0061]     Still another advantage of the spring mechanism according to this invention over the prior art is that the interconnecting coils  76  run along the entire length of each upper  100  and lower  102  run of the collapsible springs. In the prior art, the offset portions used for over-rotation prevention were not surrounded by the interconnecting coils  76 , thereby weakening the spring mechanism.  
         [0062]     Rather than employing a rigid support structure, this invention also proposes using yieldable support structures such as depicted in the embodiment of  FIGS. 13-14  or the embodiment of  FIGS. 15-16 . The yieldable structure of  FIGS. 13-14  includes a pair of lower and upper beams  134 ,  136  analogous to rails  44 ,  46 , but held apart by yieldable elements  138 . Preferably, the beams  134 ,  136  are constituted of plastic, and each element  138  includes a pair of lower and upper living hinge portions  140 ,  142  connected to each other by living hinge  144  and to the lower and upper beams by living hinges  146 ,  148 .  
         [0063]     When subjected to a compressive load during use as a bed, the hinge portions  140 ,  142  collapse, as shown in  FIG. 14 . When the load is relieved, the hinge portions  140 ,  142  self return to their uncollapsed upright positions.  
         [0064]     The yielding characteristic of this support structure is advantageous in that it will be more comfortable for the user being supported by a yieldable structure than by a rigid structure. This is perhaps not that important when the yieldable or rigid structure is fully contained within the cabinet  12 , that is, at a location where the user cannot access readily. However, the yieldable structure need not be located within a cabinet, but could be located, for example, in the middle of the mattress which is to be folded over once, or can be located at spaced-apart locations of the mattress which is to be folded over twice. Despite the presence of padding  38 , a rigid support structure in the sleeping area of the mattress would be uncomfortable, but a yieldable structure would be acceptable.  
         [0065]     The use of a yieldable structure within the sleeping area of a mattress is recommended for convertible sofa-beds, or as a transition between different types of spring mechanisms. For example, the head and middle sections of a mattress may be supported by conventional Bonnell-type coil springs, but the foot section of the mattress may be supported by the collapsible spring mechanism of this invention. In that case, the yieldable support structure is positioned between the transition between the coil springs and the collapsible spring mechanism.  
         [0066]     Despite the yieldable nature of the support structure, the over-rotation function is still primarily performed by the hinges  44  and the upright board  22  which prevent the platform  18  from moving past the plane of the shelf  42 . Also, without a compressive load, the lower and upper beams  134 ,  136  are held apart due to the stiffness of the living hinges.  
         [0067]     The yieldable support structure of  FIGS. 15-16  is likewise mountable on the support shelf  42  within the cabinet, or preferably, in the sleeping area of the mattress in the transition between conventional Bonnell-type coil springs, as represented by coils  150 , and the collapsible spring mechanism of this invention. The yieldable structure of  FIGS. 15-16  includes lower and upper bars  152 ,  154  pivotably connected to lower and upper links  156 ,  158  which, in turn, are pivotably connected at pivot  160 . Spring retainers  162  on the bars  152 ,  154  capture lower and upper convolutions of the Bonnell-type coil springs  150 .  
         [0068]     When subjected to a compressive load during use as a bed, the links  156 ,  158  pivot, as shown in  FIG. 16 , thereby increasing a user&#39;s comfort. When the load is relieved, the links  156 ,  158  self return to their upright position by return springs located within the pivot  160 .  
         [0069]     It will be understood that each of the elements described above, or two or more together, also may find a useful application in other types of constructions differing from the types described above.  
         [0070]     While the invention has been illustrated and described as embodied in collapsible spring mechanisms for items of furniture, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.  
         [0071]     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.