Chair with flexible lumbar support

Abstract

A chair having a tubular frame, a seat base fixed to the frame. The seat base and the frame forming the seat. A single-piece tubular arch forming the seat back and connected to two of the legs of the frame. An elastic dorsolumbar support having two ends, one of which is free and the other is fixed to the seat.

1 . A chair comprising:
 a tubular frame comprising at least three frame legs;   a seat base fixed to said frame, said seat base and said tubular frame forming a seat;   a tubular arch forming the seat back and connected to two frame legs of the tubular frame;   an elastic dorsolumbar support comprising two ends, one of which is free and the other is connected to the seat;   wherein the frame and the tubular arch are composed of a composite material with fiber reinforcement, comprising a natural fiber.   
     
     
         2 . The chair according to  claim 1 , wherein the tubular arch is a single piece. 
     
     
         3 . The chair according to  claim 1 , wherein a connection of the elastic dorsolumbar support to the seat is a disassemblable connection. 
     
     
         4 . The chair according to  claim 3 , wherein a tubular cross-section of the tubular arch varies between its connections to the two frame legs. 
     
     
         5 . The chair according to  claim 3 , wherein a tubular cross-section of the frame legs varies between their ends configured to be in contact with a floor and their connections to the seat base. 
     
     
         6 . The chair according to  claim 1 , wherein the seat base is composed of a plastic material. 
     
     
         7 . The chair according to  claim 1 , wherein the seat base is composed of a metallic material 
     
     
         8 . The chair according to  claim 1 , wherein the seat base comprises a connecting ring with a frame and a seat cushion, the frame and the seat cushion being assembled with said connecting ring. 
     
     
         9 . The chair according to  claim 1 , the elastic dorsolumbar support is composed of a plastic material. 
     
     
         10 . The chair according to  claim 1 , in which the elastic dorsolumbar support is composed of a composite material with fibrous reinforcement. 
     
     
         11 . A pre-constituted assembly or kit, comprising a chair according to  claim 3  and a plurality of the elastic dorsolumbar supports. 
     
     
         12 . A pre-constituted assembly or kit, comprising a chair according to  claim 8  and a plurality of the seat cushions. 
     
     
         13 . The chair according to  claim 1 , wherein the composite material with the fiber reinforcement comprises a plant fiber.