Expandable chair assembly

Abstract

A chair assembly has a seat, a backrest and an expandable leg supporting device. The seat has a front end and a rear end. The backrest is connected to the rear end of the seat. The expandable leg supporting device is mounted on the front end of the seat and has a base, at least one extension frame and a frame driving device. The base is mounted securely on the front end of the seat. The least one extension frame is connected to the base. The frame driving device is mounted on the base and is connected to the at least one extension frame to pivot the at least one extension frame relative to the base. Accordingly, the chair assembly can be expanded to support legs of a user in an expanded condition.

1 . A chair assembly comprising:
 a seat having a front end and a rear end;   a backrest connected to the rear end of the seat; and   an expandable leg supporting device mounted on the front end of the seat and comprising
 a base mounted securely on the front end of the seat; 
 at least one extension frame connected to the base; and 
 a frame driving device mounted on the base and connected to the at least one extension frame to pivot the at least one extension frame relative to the base. 
   
     
     
         2 . The chair assembly as claimed in  claim 1 , wherein the frame driving device comprises
 a driving motor;   a worn rod connected to and driven by the driving motor;   a worn gear engaging and driven by the worn rod;   a pinion co-axially mounted on the worn gear;   a driving gear engaging the pinion; and   a pivotal rod co-axially mounted on and protruding from the driving gear and connected securely to the at least one extension frame.   
     
     
         3 . The chair assembly as claimed in  claim 2 , wherein
 the expandable leg supporting device has three extension frames telescopically connected with each other and including an outer extension frame, a middle extension frame and an inner extension frame arranged from outside to inside in sequence;   each extension frame has a volume gradually increasing from the inner extension frame to the outer extension frame; and   the outer extension frame is connected securely with the pivotal rod of the frame driving device.   
     
     
         4 . The chair assembly as claimed in  claim 3 , wherein
 the outer extension frame has a middle extension driving device comprising
 a middle motor mounted securely on the outer extension frame; 
 a middle threaded rod connected to and driven by the middle motor; and 
 a middle nut mounted rotatably around the middle threaded rod and connected securely to the middle extension frame; and 
   the middle extension frame has an inner extension driving device comprising
 an inner motor mounted securely on the middle extension frame; 
 an inner threaded rod connected to and driven by the inner motor; and 
 an inner nut mounted rotatably around the inner threaded rod and connected securely to the inner extension frame. 
   
     
     
         5 . The chair assembly as claimed in  claim 3 , wherein
 the outer extension frame has
 two side panels each having an inner surface facing to each other; and 
 two rails mounted respectively on the inner surfaces of the side panels; 
   the middle extension frame has
 two side panels each having an inner surface facing to each other and an outer surface opposite to each other; 
 two sliders mounted respectively on the outer surfaces of the side panels of the middle extension frame and slidably connected with the rails on the outer extension frame; 
 two rails mounted respectively on the inner surfaces of the side panels of the middle extension frame; and 
   the inner extension frame has
 two side panels each having an outer surface opposite to each other; 
 two sliders mounted respectively on the outer surfaces of the side panels of the inner extension frame and slidably connected with the rails on the middle extension frame. 
   
     
     
         6 . The chair assembly as claimed in  claim 5 , wherein the expandable leg supporting device further has a foot supporting panel pivotally connected to the inner extension frame. 
     
     
         7 . The chair assembly as claimed in  claim 6 , wherein
 the inner extension frame further has a panel driving device mounted on the inner extension frame, connected to the foot supporting panel and having
 a panel driving motor mounted on the inner extension frame; 
 a driving pulley connected to and driven by the panel driving motor; 
 a driven pulley mounted rotatably on the inner extension frame; 
 a belt mounted endlessly around the driving pulley and the driven pulley; and 
 a pivotal axle co-axially formed on and protruding from the driven pulley; and 
   the foot supporting panel has two ends and two pivotal ears formed respectively on the ends of the foot supporting panel, wherein one of the pivotal ears is connected securely with the pivotal axle of the panel driving device and the other pivotal ear is connected pivotally to the inner extension frame with a pivot.   
     
     
         8 . The chair assembly as claimed in  claim 7 , wherein the expandable leg supporting device further has a middle detecting device mounted between the outer extension frame and the middle extension frame and comprising
 a potentiometer mounted on the middle extension frame;   a detecting gear connected to the potentiometer;   a rod mount mounted securely on the middle extension frame;   a rotatable rod mounted rotatably on the rod mount and having two ends respectively protruding out from two sides of the rod mount;   a first end gear and a second end gear mounted respectively on the ends of the rotatable rod, wherein the first end gear engages the detecting gear; and   a rack mounted securely on the outer extension frame and engaging the second end gear.   
     
     
         9 . The chair assembly as claimed in  claim 8 , wherein the expandable leg supporting device further has an inner detecting device mounted between the middle extension frame and the inner extension frame and has a same components as that of the middle detecting device. 
     
     
         10 . The chair assembly as claimed in  claim 4 , wherein
 the outer extension frame has
 two side panels each having an inner surface facing to each other; and 
 two rails mounted respectively on the inner surfaces of the side panels; 
   the middle extension frame has
 two side panels each having an inner surface facing to each other and an outer surface opposite to each other; 
 two sliders mounted respectively on the outer surfaces of the side panels of the middle extension frame and slidably connected with the rails on the outer extension frame; 
 two rails mounted respectively on the inner surfaces of the side panels of the middle extension frame; and 
   the inner extension frame has
 two side panels each having an outer surface opposite to each other; 
 two sliders mounted respectively on the outer surfaces of the side panels of the inner extension frame and slidably connected with the rails on the middle extension frame. 
   
     
     
         11 . The chair assembly as claimed in  claim 10 , wherein the expandable leg supporting device further has a foot supporting panel pivotally connected to the inner extension frame. 
     
     
         12 . The chair assembly as claimed in  claim 11 , wherein
 the inner extension frame further has a panel driving device mounted on the inner extension frame, connected to the foot supporting panel and having
 a panel driving motor mounted on the inner extension frame; 
 a driving pulley connected to and driven by the panel driving motor; 
 a driven pulley mounted rotatably on the inner extension frame; 
 a belt mounted endlessly around the driving pulley and the driven pulley; and 
 a pivotal axle co-axially formed on and protruding from the driven pulley; and 
   the foot supporting panel has two ends and two pivotal ears formed respectively on the ends of the foot supporting panel, wherein one of the pivotal ears is connected securely with the pivotal axle of the panel driving device and the other pivotal ear is connected pivotally to the inner extension frame with a pivot.   
     
     
         13 . The chair assembly as claimed in  claim 12 , wherein the expandable leg supporting device further has a middle detecting device mounted between the outer extension frame and the middle extension frame and comprising
 a potentiometer mounted on the middle extension frame;   a detecting gear connected to the potentiometer;   a rod mount mounted securely on the middle extension frame;   a rotatable rod mounted rotatably on the rod mount and having two ends respectively protruding out from two sides of the rod mount;   a first end gear and a second end gear mounted respectively on the ends of the rotatable rod, wherein the first end gear engages the detecting gear; and   a rack mounted securely on the outer extension frame and engaging the second end gear.   
     
     
         14 . The chair assembly as claimed in  claim 13 , wherein the expandable leg supporting device further has an inner detecting device mounted between the middle extension frame and the inner extension frame and has a same components as that of the middle detecting device. 
     
     
         15 . The chair assembly as claimed in  claim 3 , wherein the expandable leg supporting device further has a foot supporting panel pivotally connected to the inner extension frame. 
     
     
         16 . The chair assembly as claimed in  claim 15 , wherein
 the inner extension frame further has a panel driving device mounted on the inner extension frame, connected to the foot supporting panel and having
 a panel driving motor mounted on the inner extension frame; 
 a driving pulley connected to and driven by the panel driving motor; 
 a driven pulley mounted rotatably on the inner extension frame; 
 a belt mounted endlessly around the driving pulley and the driven pulley; and 
 a pivotal axle co-axially formed on and protruding from the driven pulley; and 
   the foot supporting panel has two ends and two pivotal ears formed respectively on the ends of the foot supporting panel, wherein one of the pivotal ears is connected securely with the pivotal axle of the panel driving device and the other pivotal ear is connected pivotally to the inner extension frame with a pivot.   
     
     
         17 . The chair assembly as claimed in  claim 16 , wherein the expandable leg supporting device further has a middle detecting device mounted between the outer extension frame and the middle extension frame and comprising
 a potentiometer mounted on the middle extension frame;   a detecting gear connected to the potentiometer;   a rod mount mounted securely on the middle extension frame;   a rotatable rod mounted rotatably on the rod mount and having two ends respectively protruding out from two sides of the rod mount;   a first end gear and a second end gear mounted respectively on the ends of the rotatable rod, wherein the first end gear engages the detecting gear; and   a rack mounted securely on the outer extension frame and engaging the second end gear.   
     
     
         18 . The chair assembly as claimed in  claim 17 , wherein the expandable leg supporting device further has an inner detecting device mounted between the middle extension frame and the inner extension frame and has a same components as that of the middle detecting device. 
     
     
         19 . The chair assembly as claimed in  claim 3 , wherein the expandable leg supporting device further has a middle detecting device mounted between the outer extension frame and the middle extension frame and comprising
 a potentiometer mounted on the middle extension frame;   a detecting gear connected to the potentiometer;   a rod mount mounted securely on the middle extension frame;   a rotatable rod mounted rotatably on the rod mount and having two ends respectively protruding out from two sides of the rod mount;   a first end gear and a second end gear mounted respectively on the ends of the rotatable rod, wherein the first end gear engages the detecting gear; and   a rack mounted securely on the outer extension frame and engaging the second end gear.   
     
     
         20 . The chair assembly as claimed in  claim 3 , wherein the expandable leg supporting device further has an inner detecting device mounted between the middle extension frame and the inner extension frame.