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 relative to the seat portion;   an armrest frame on each side of the main body frame;
 a hinge mechanism comprising a first section, a second section and a third section sequentially and pivotably connected to one another, wherein the first section is fixed to a side of the seat portion, the second section is fixed to a side of the backrest portion, and a protruding portion is provided at a position where the first section is connected with the second section; 
   each armrest frame formed with a slideway for receiving the protruding portion and guiding the protruding portion to slide therein, and an end of the third section opposite to the second section is pivotally connected to the armrest frame; and   the first section and the second section configured to be lockable relative to each other so that the main body frame can be positioned in a sofa configuration, and to allow the protruding portion to slide along the slideway in a locked state to drive movement of the main body frame.   
     
     
         2 . The sofa bed according to  claim 1  wherein the first section includes a first section rod portion and a first section sleeve portion for receiving the first section rod portion, and the first section sleeve portion opens towards the seat portion so that the first section sleeve portion and the seat portion together enclose the first section rod portion; and
 the second section includes a second section rod portion and a second section sleeve portion for receiving the second section rod portion, and the second section sleeve portion opens towards the backrest portion so that the second section sleeve portion and the backrest portion together enclose the second section rod portion. 
 
     
     
         3 . The sofa bed according to  claim 1  wherein the first section is a one-piece member, and the second section is a one-piece member. 
     
     
         4 . The sofa bed according to  claim 3  wherein each of the first section and the second section is an elongated member having an L-shaped cross section, wherein a plurality of reinforcing portions are disposed at a corner portion of the L-shaped first section and the second section. 
     
     
         5 . The sofa bed according to  claim 1  wherein the main body frame is configured such that the seat portion is operable to pivot towards the backrest portion when the first section and the second sections are in a locked state, thereby releasing the locking between the first section and the second section. 
     
     
         6 . The sofa bed according to  claim 5  wherein a ratchet is disposed on one of the first section and the second section, and a pawl is disposed on the other one of the first section and the second section, wherein the ratchet and the pawl are engageable with each other so that the first section is locked at a predetermined angle relative to the second section. 
     
     
         7 . The sofa bed according to  claim 6  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 into the recessed portion when the first section and the second section are arranged at the predetermined angle, thereby locking the first section with the second section. 
     
     
         8 . The sofa bed according to  claim 1  wherein both the seat portion and the backrest portion are formed into a rectangular structure. 
     
     
         9 . The sofa bed according to  claim 1  wherein one end of the slideway is positioned higher than the other end of the slideway, and the one end is open toward an upper edge of the armrest frame to receive the protruding portion.