Swivel chair

Abstract

A swivel chair includes a seat unit and a base unit. The seat unit includes a downwardly extending post. The base unit includes: a base member; a sleeve member that extends upwardly from the base member, that surrounds the post of the seat unit, and that has a top end portion; a bearing that is disposed fixedly in the sleeve member and that is sleeved on the post so as to couple rotatably the post to the sleeve member; a first positioning ring that is fixed in the top end portion of the sleeve member, that surrounds the post, and that forms an annular clearance with the post; and a second positioning ring that is sleeved fixedly on the post, that extends into the first positioning ring, and that is rotatable relative to the first positioning ring.

1 . A swivel chair, comprising:
 a seat unit including a downwardly extending post; and   a base unit including
 a base member, 
 a sleeve member that extends upwardly from said base member, that surrounds said post of said seat unit, and that has a top end portion, 
 a bearing that is disposed fixedly in said sleeve member and that is sleeved on said post so as to couple rotatably said post to said sleeve member, 
 a first positioning ring that is fixed in said top end portion of said sleeve member, that surrounds said post, and that forms an annular clearance with said post, and 
 a second positioning ring that is sleeved fixedly on said post, that extends into said first positioning ring, and that is rotatable relative to said first positioning ring. 
   
   
   
       2 . The swivel chair as claimed in  claim 1 , wherein:
 said first positioning ring includes a lower ring segment that surrounds said post and that forms said annular clearance with said post, and an upper ring segment that extends coaxially and upwardly from said lower ring segment, said upper ring segment having an inner ring surface that defines a ring space gradually diverging in an upward direction, and   said second positioning ring has an outer diameter that is gradually reduced in a downward direction, and is received rotatably in said ring space of said upper ring segment of said first positioning ring.   
   
   
       3 . The swivel chair as claimed in  claim 1 , wherein:
 said post has a bottom end portion, and said seat unit further includes a nut fixed to said bottom end portion of said post, and   said base unit further includes a bolt that passes through said base member and that threadedly engages said nut, thereby retaining rotatably said post on said base member.   
   
   
       4 . The swivel chair as claimed in  claim 1 , wherein said base unit further includes a bolt that passes through said base member and that threadedly engages said post, thereby retaining rotatably said post on said base member.