Wheeled chair with a seat locking unit

Abstract

A wheeled chair includes a wheeled frame having an upright post that defines a vertical axis, a seat mounted rotatably on the upright post so as to be turnable relative to the wheeled frame about the vertical axis, and a seat locking unit including a retaining member secured to the upright post and formed with a plurality of retaining grooves, a mounting seat secured to the seat, and a spring-biased tongue member disposed above the retaining grooves, mounted movably on the mounting seat, and operable so as to be moved between a locking position, in which, the tongue member is moved downwardly to selectively engage one of the retaining grooves so as to prevent turning of the seat relative to the wheeled frame, and an unlocking position, in which, the tongue member is moved upwardly to disengage from the selected one of the retaining grooves so as to permit turning of the seat relative to the wheeled frame.

I claim:  
     
         1 . A wheeled chair comprising: 
 a wheeled frame having an upright post that has a top end and that defines a vertical axis;    a seat disposed over said upright post and having a bottom side, and an inserting protrusion that projects downwardly from said bottom side and that is mounted rotatably on said top end of said upright post so as to permit turning of said seat relative to said wheeled frame about said vertical axis; and    a seat locking unit including a retaining member secured to said top end of said upright post and formed with a plurality of retaining grooves which are angularly spaced apart from each other, a mounting seat secured to said bottom side, and a spring-biased tongue member disposed above said retaining grooves, mounted movably on said mounting seat, and operable so as to be moved between a locking position, in which, said tongue member is moved downwardly by an urging force to selectively engage one of said retaining grooves so as to prevent turning of said seat relative to said wheeled frame about said vertical axis, and an unlocking position, in which, said tongue member is moved upwardly to disengage from the selected one of said retaining grooves so as to permit turning of said seat relative to said wheeled frame about said vertical axis.    
     
     
         2 . The wheeled chair of  claim 1 , wherein said upright post is cylindrical in shape and is formed with a cylindrical top recess, said inserting protrusion being cylindrical in shape and having a frusto conical bottom end received in said top recess.  
     
     
         3 . The wheeled chair of  claim 1 , further comprising an operating member that includes a lever which is mounted turnably on said mounting seat, which extends in a transverse direction relative to said vertical axis to define a horizontal axis, and which has one end projecting laterally from said bottom side of said seat, and the other end disposed adjacent to said tongue member, said operating member further including a pushing arm that is transverse to and that extends from the other end of said lever to engage said tongue member so as to lift said tongue member to move upwardly to disengage from the selected one of said retaining grooves when said lever is turned in a direction about said horizontal axis.  
     
     
         4 . The wheeled chair of  claim 3 , wherein said mounting seat is formed with a tongue receiving space for receiving said tongue member, a lever receiving space for receiving fittingly the other end of said lever, and an arm receiving space which is transverse to and which is in spatial communication with said lever receiving space and said tongue receiving space and which receives said pushing arm, said tongue receiving space having cylindrical upper and lower sections, said upper section having a diameter greater than that of said lower section, said tongue member having upper and lower portions which are respectively received in said upper and lower sections and which cooperately define a neck therebetween, said lower portion of said tongue member extending through said lower section of said tongue receiving space and into the selected one of said retaining grooves when said tongue member is at said locking position, said upper portion of said tongue member being formed with a top groove, said seat locking unit further including a coil spring that has one end received in said top groove, and the other end abutting against said bottom side of said seat So as to urge said tongue member to move downwardly, said pushing arm having a free end that is disposed underneath and that is in contact with said neck so as to lift said tongue member against the urging force of said coil spring when said lever is turned in said direction about said horizontal axis.  
     
     
         5 . The wheeled chair of  claim 4 , wherein said retaining member is includes a circular plate that has an upper face and an arcuate stopper projecting upwardly from said upper face and engageable with said mounting seat so as to limit the extent of turning of said mounting seat relative to said upright post.