Rotational armrest apparatus

Abstract

A chair includes a seat and a rotational armrest apparatus mounted on the seat. The armrest apparatus includes a beam attached to the seat and an armrest rotationally mounted on the beam. The beam includes a socket formed thereon. The armrest includes a lower portion inserted rotationally in the socket and an upper portion for supporting an arm. The beam defines apertures through which fasteners can be driven into the seat for mounting the beam on the seat. The socket defines an upper space and a grooved recess communicated with the upper space. The lower portion of the armrest includes a toothed insert inserted in the grooved recess for retaining the armrest in position relative to the beam.

What is claimed is:  
     
         1 . A chair including a seat and a rotational armrest apparatus mounted on the seat.  
     
     
         2 . The chair according to  claim 1 , wherein the armrest apparatus includes a beam attached to the seat and an armrest mounted rotationally on the beam.  
     
     
         3 . The chair according to  claim 2 , wherein the beam includes a socket formed thereon, and the armrest includes an insert rotationally inserted in the socket and an upper portion for supporting an arm.  
     
     
         4 . The chair according to  claim 2 , wherein the beam defines apertures through which fasteners can be driven into the seat for mounting the beam on the seat.  
     
     
         5 . The chair according to  claim 2 , wherein the socket defines an upper space and a grooved recess communicated with the upper space, and the insert of the armrest includes a toothed tip inserted in the grooved recess for retaining the armrest in position relative to the beam.  
     
     
         6 . The chair according to  claim 5  including a threaded bolt, wherein the toothed tip defines a threaded hole receiving a threaded bolt with a head so as to retain the armrest on the beam, and the socket defines a lower space communicated with the grooved recess for receiving the head of the threaded bolt.  
     
     
         7 . The chair according to  claim 6  including a spring put in the lower space, mounted on the threaded bolt and compressed between the wall of the lower space and the head of the threaded bolt for keeping the toothed tip in the grooved recess.  
     
     
         8 . The chair according to  claim 7  including a washer put in the lower space and sandwiched between the spring and the head of the threaded bolt.  
     
     
         9 . The chair according to  claim 8  including the washer is shaped as a cup for receiving the spring.  
     
     
         10 . The chair according to  claim 5  including a lock for locking the toothed tip in the grooved recess.  
     
     
         11 . The chair according to  claim 10 , wherein the lock is in the form of a ring rotationally mounted on the socket between a locking position and a releasing position.  
     
     
         12 . The chair according to  claim 11 , wherein the lock includes at least one detent extending from an internal side, and the socket defines at least one aperture through which the at least one detent enters the upper space, and the insert of the armrest defines at least one annular groove for receiving the at least one detent.  
     
     
         13 . The chair according to  claim 12 , wherein the lock includes two detents, and the socket defines two apertures, and the insert of the armrest defines an annular groove for receiving the detent.  
     
     
         14 . The chair according to  claim 12 , wherein the socket defines, in an external side, a groove including a first end and a second end where the aperture is located and getting deeper from the first end to the second end.  
     
     
         15 . The chair according to  claim 12 , wherein the detent includes an enlarged head.  
     
     
         16 . The chair according to  claim 15 , wherein the socket defines, in an external side, a recess for receiving the head of the detent in the releasing position.  
     
     
         17 . The chair according to  claim 11  wherein the lock includes ribs formed thereon for facilitating rotation thereof.