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 main body frame comprising a seat portion and a backrest portion movable so that the main body frame can be switched between a bed configuration and a sofa configuration;   an armrest frame disposed on each side of the main body frame;   a bottom supporting structure disposed under the main body frame, the armrest frame mounted on the bottom supporting structure, the bottom supporting structure comprising a bracket configured to support a junction portion of the seat portion and the backrest portion when the main body frame is in the bed configuration; and to support the seat portion and the backrest portion simultaneously when the main body frame is in the sofa configuration.   
     
     
         2 . The sofa bed according to  claim 1  wherein the seat portion and the backrest portion are formed into a rectangular structure, and a longitudinal edge of the seat portion is joined with a longitudinal edge of the backrest portion. 
     
     
         3 . The sofa bed according to  claim 2  wherein the bracket includes a first bracket section extending substantially in a transverse direction below the seat portion, a bracket second section bent upwardly from an end of the first bracket section, and a third bracket section bent from an end of the second bracket section to extend substantially in the transverse direction, the first bracket section configured to abut against and support a bottom surface of the seat portion when the main body frame is in the sofa configuration, the second bracket section being configured to abut against and support a surface of the backrest portion away from the seat portion when the main body frame is in the sofa configuration. 
     
     
         4 . The sofa bed according to  claim 2  wherein the bracket comprises a support block disposed on a surface of the bracket facing towards the seat portion, and the support block is configured to support the junction portion of the seat portion and the backrest portion when the main body frame is in the bed configuration. 
     
     
         5 . The sofa bed according to  claim 4  wherein the seat portion comprises a plurality of longitudinal beams extending in a longitudinal direction of the sofa bed, and the support block is in front of one of the longitudinal beams of the seat portion, thereby restricting forward slide of the seat portion, when the main body frame is in the sofa configuration. 
     
     
         6 . The sofa bed according to  claim 4  wherein when the main body frame is in the bed configuration, a longitudinal beam of the backrest portion closest to the seat portion and a longitudinal beam of the seat portion closest to the backrest portion are abut against each other, and a support block contacts and supports the two longitudinal beams. 
     
     
         7 . The sofa bed according to  claim 5  wherein two ends of the bracket are respectively provided with a U-shaped portion opening downward, and the U-shaped portions are capable of snapping onto two beams of the bottom supporting structure extending in the longitudinal direction. 
     
     
         8 . The sofa bed according to  claim 4  wherein the support block is welded or riveted to a main body of a support pipe. 
     
     
         9 . The sofa bed according to  claim 1  wherein the main body frame is configured to release locking between a seat portion connecting rod and a backrest portion connecting rod when the seat portion is operated to pivot toward the backrest portion in a locked state. 
     
     
         10 . The sofa bed according to  claim 9  wherein one of the seat portion connecting rod and the backrest portion connecting rod is provided with a ratchet, and the other of the seat portion connecting rod and the backrest portion connecting rod is provided with a pawl, wherein the ratchet and the pawl engage with each other so that the backrest portion is locked at a predetermined angle relative to the seat portion. 
     
     
         11 . The sofa bed according to  claim 10  wherein an outer edge of the ratchet is provided with a recessed portion that is inwardly recessed in a radial direction of the ratchet, and the pawl is provided with a protruding portion corresponding to the recessed portion, wherein the protruding portion is configured so that the protruding portion engages the recessed portion when the backrest portion and the seat portion are at the predetermined angle, thereby locking the backrest portion and the seat portion. 
     
     
         12 . The sofa bed of  claim 1  wherein the bottom supporting structure comprising a bracket extends in a transverse direction of the sofa bed.