Sofa bed

Abstract

A sofa bed has a seat portion, a backrest portion and a hinge mechanism including a first section, a second section and a third section sequentially and pivotably connected. The first section is fixed to a side of the seat portion. The second section is fixed to a side of the backrest portion. A protruding portion is provided at a position where the first section is connected with the second section. Each of the armrest frames is formed with a slideway for receiving and guiding the protruding portion. An end of the third section opposite to the second section is pivotally connected to the armrest. The first section and the second section are be lockable to place the main body frame into a sofa configuration. The sofa bed can be easily switched between sofa and bed positions

I claim: 
     
         1 . A sofa bed, comprising:
 a plurality of elastic modules each comprising a conical spring and a spring bracket that holds the conical spring;   a main body frame formed with a plurality of slide rails engageable with a bottom portion of each of the spring brackets so that the plurality of elastic modules can slide on the slide rails,   the plurality of the elastic modules configured to be mounted on the slide rails;   two slide rail beams forming each slide rail, each slide rail beam having a first snap-fitting structure extending along an entire length of the slide rail beam, a bottom portion of the spring bracket formed with a second snap-fitting structure;   the first snap-fitting structure and the second snap-fitting structure snap-fitted to each other to allow the elastic module to slide along the slide rail, when an elastic module is mounted on the slide rail.   
     
     
         2 . The sofa bed according to  claim 1  wherein the first snap-fitting structure is configured to simultaneously engage with the second snap-fitting structures of the two elastic modules on both sides of the rail beam, and wherein, when engaged, the two elastic modules on both sides of the rail beam are slidable along their respective slide rails independently of each other. 
     
     
         3 . The sofa bed according to  claim 1  wherein the first snap-fitting structure comprises a groove formed on a top surface of the slide rail beam and extends along the slide rail beam, and the second snap-fitting structure comprises a protrusion protruding toward the groove outwardly from a top surface of a base of the elastic module. 
     
     
         4 . The sofa bed according to  claim 3  wherein the first snap-fitting structure comprises a bottom surface of the slide rail beam, the second snap-fitting structure comprises an extension structure extending downward from the base, wherein a bottom portion of the extension structure is provided with a snap hook protruding outward, and the snap hook is configured to be snap-fit on the bottom surface of the slide rail beam. 
     
     
         5 . The sofa bed according to  claim 4  wherein the base is a rectangular structure, and a side of the base engaged with the slide rail beam is provided with two extension structures and a protrusion located between the two extension structures. 
     
     
         6 . The sofa bed according to  claim 3  wherein a width of the groove is set to accommodate two protrusions arranged side by side, such that respective protrusions of the two elastic modules on both sides of each of the slide rail beams are slidable in the groove independently of each other. 
     
     
         7 . The sofa bed according to  claim 3  wherein a bottom surface of the rail beam is provided with a groove, and the snap fitting structure is configured to hook into the groove. 
     
     
         8 . The sofa bed according to  claim 7  wherein the groove formed on the bottom surface and the groove formed on the top surface of the rail beam are arranged symmetrically. 
     
     
         9 . The sofa bed according to  claim 8  wherein left and right sides of the rail beam are convex arc surfaces, and portions of a base of the elastic modules are concaved arc surfaces. 
     
     
         10 . The sofa bed according to  claim 1  wherein the first snap-fitting structure comprises a protrusion formed on a top surface of the slide rail beam and extending along the slide rail beam, and the second snap-fitting structure comprises a groove disposed at an edge of the top surface of a base of the elastic module facing towards the protrusion. 
     
     
         11 . The sofa bed according to  claim 1  wherein the main body frame is rectangular, and the slide rails extend in a longitudinal direction of the main body frame. 
     
     
         12 . The sofa bed according to  claim 11  further including first and second arm rests, each having a slideway facing a hinge mechanism, so that movement of the hinge mechanism is guided by the slideway;
 the sofa bed configured to lock the backrest portion relative to the seat portion at a predetermined angle when the backrest portion and the seat portion pivot relative to each other about the hinge mechanism, and the armrest frame connected with the main body frame through the hinge mechanism, so that in a locked state, a partial structure of the hinge mechanism can move the main body frame guided by the slideway. 
 
     
     
         13 . The sofa bed according to  claim 12  wherein the hinge mechanism comprises:
 a seat portion connecting rod attached to a transverse side edge of the seat portion and extending along the transverse side edge; 
 a backrest portion connecting rod attached to a transverse edge of the backrest portion on the same side as the transverse side edge of the seat portion and extending along the transverse edge of the backrest portion; 
 a pivot connecting the seat portion connecting rod with the backrest portion connecting rod such that the backrest portion and the seat portion can pivot relative to each other. 
 
     
     
         14 . The sofa bed according to  claim 13  wherein the main body frame is configured to release locking between the seat portion connecting rod and the backrest portion connecting rod when the seat portion is operated in the locked state to pivot toward the backrest portion. 
     
     
         15 . The sofa bed of  claim 1  wherein the plurality of elastic modules are configured to be pressed and mounted on the side rails in a direction perpendicular to a plane jointly defined by extension directions of two slide rail beams, and in a direction perpendicular to a plane jointly defined by extension directions of two slide rail beams. 
     
     
         16 . The sofa bed of  claim 8  wherein the rail beam is configured to be symmetrical about a plane perpendicular to a symmetrical plane vertically symmetrical with the rail beam. 
     
     
         17 . The sofa bed of  claim 8  wherein left and right sides of the rail beam are planes.