Chair with seat of adjustable length

Abstract

A chair ( 10 ) with a seat of adjustable length includes a chair stand ( 1 ), a transmission shaft ( 2 ), a first chair seat ( 3 ) and a second chair seat ( 4 ). The transmission shaft ( 2 ) is mounted onto the chair stand ( 1 ) and rotatable with respect to the chair stand ( 1 ) and has left and right spiral threads ( 21, 22 ) aligned in opposite directions and formed on the exterior of the transmission shaft ( 2 ). The first and second chair seats ( 3, 4 ) are sheathed on the transmission shaft ( 2 ) and screwed and transmitted along the left and right spiral threads ( 21, 22 ) respectively and synchronously drive the first and second chair seats ( 3, 4 ) to approach or separate from one another. The width of the chair seat can be adjusted to attach the chair to a user's buttock closely for sitting posture correction and pelvic correction.

What is claimed is: 
     
         1 . A chair with a seat of adjustable length, comprising:
 a chair stand ( 1 );   a transmission shaft ( 2 ), mounted onto the chair stand ( 1 ), and being rotatable with respect to the chair stand ( 1 ), and having a left spiral thread ( 21 ) and a right spiral thread ( 22 ) in opposite directions formed on the exterior of the transmission shaft ( 2 );   a first chair seat ( 3 ), sheathed on the transmission shaft ( 2 ), and screwed and rotated along the left spiral thread ( 21 ); and   a second chair seat ( 4 ), sheathed on the transmission shaft ( 2 ), and screwed and rotated along the right spiral thread ( 22 );   such that the first chair seat ( 3 ) and the second chair seat ( 4 ) can be driven synchronously to approach or move away from one another.   
     
     
         2 . The chair with a seat of adjustable length according to  claim 1 , further comprising a position limiting mechanism ( 5 ) for limiting the moving range of the first chair seat ( 3 ) and the second chair seat ( 4 ), and the position limiting mechanism ( 5 ) being coupled to the chair stand ( 1 ). 
     
     
         3 . The chair with a seat of adjustable length according to  claim 2 , wherein the position limiting mechanism ( 5 ) includes at least one positioning guide rod ( 51 ) mounted onto the chair stand ( 1 ) and disposed on a side of the transmission shaft ( 2 ), and the first chair seat ( 3 ) and the second chair seat ( 4 ) are sheathed on the positioning guide rod ( 51 ) and slid along the positioning guide rod ( 51 ). 
     
     
         4 . The chair with a seat of adjustable length according to  claim 3 , wherein the first chair seat ( 3 ) includes a first seat body ( 31 ) and a first actuating element ( 32 ) fixed to the bottom of the first seat body ( 31 ), and the first actuating element ( 32 ) has a first screw hole ( 321 ) and at least one first penetrating hole ( 322 ), and the second chair seat ( 4 ) includes a second seat body ( 41 ) and a second actuating element ( 42 ) fixed to the bottom of the second seat body ( 41 ), and the second actuating element ( 42 ) has a second screw hole ( 421 ) and at least one second penetrating hole ( 422 ), the left spiral thread ( 21 ) of the transmission shaft ( 2 ) is screwed with respect to the first screw hole ( 321 ) and the right spiral thread ( 22 ) is screwed with respect to the second screw hole ( 421 ), and the positioning guide rod ( 51 ) is passed and slid into the first penetrating hole ( 322 ) and the second penetrating hole ( 422 ). 
     
     
         5 . The chair with a seat of adjustable length according to  claim 4 , wherein the position limiting mechanism ( 5 ) further includes a mount ( 52 ) mounted onto the chair stand ( 1 ) and having a base and a wall extended from the periphery of the base, and the transmission shaft ( 2 ) and the positioning guide rod ( 51 ) are posited between both sides of the wall, and the transmission shaft ( 2 ) is rotatable with respect to the mount ( 52 ). 
     
     
         6 . The chair with a seat of adjustable length according to  claim 5 , wherein the first seat body ( 31 ) has a first recessed slot ( 311 ), and the second seat body ( 41 ) has a second recessed slot ( 411 ), and the first actuating element ( 32 ) is fixed to the bottom of the first recessed slot ( 311 ), and the second actuating element ( 42 ) is fixed to the bottom of the second recessed slot ( 411 ), and the mount can be hidden into the first recessed slot ( 311 ) and the second recessed slot ( 411 ). 
     
     
         7 . The chair with a seat of adjustable length according to  claim 1 , further comprising an adjusting mechanism ( 6 ) coupled to the transmission shaft ( 2 ) and operated together with the transmission shaft ( 2 ). 
     
     
         8 . The chair with a seat of adjustable length according to  claim 7 , wherein the adjusting mechanism ( 6 ) is a handwheel ( 61 ) integrally formed with the transmission shaft ( 2 ) and exposed from a side of one of the first chair seat ( 3 ) and the second chair seat ( 4 ). 
     
     
         9 . The chair with a seat of adjustable length according to  claim 7 , wherein the adjusting mechanism ( 6 ) is a motor drive assembly ( 62 ) capable of driving the transmission shaft ( 2 ) to rotate. 
     
     
         10 . The chair with a seat of adjustable length according to  claim 9 , further comprising a battery ( 8 ) electrically coupled to the motor drive assembly ( 62 ). 
     
     
         11 . The chair with a seat of adjustable length according to  claim 1 , wherein the first chair seat ( 3 ) includes a first seat body ( 31 ), and the second chair seat ( 4 ) includes a second seat body ( 41 ), and the first seat body ( 31 ) has a first sitting portion ( 312 ), and the second seat body ( 41 ) has a second sitting portion ( 412 ), and a first abutting portion ( 313 ) and a second abutting portion ( 413 ) symmetrical to each other extended from sides of the external periphery of the first sitting portion ( 312 ) and the second sitting portion ( 412 ) respectively. 
     
     
         12 . The chair with a seat of adjustable length according to  claim 11 , wherein the first sitting portion ( 312 ) and the first abutting portion ( 313 ) have an inner side with a first hip-shaped cambered surface ( 314 ), and the second sitting portion ( 412 ) and the second abutting portion ( 413 ) have an inner side with a second hip-shaped cambered surface ( 414 ). 
     
     
         13 . The chair with a seat of adjustable length according to  claim 11 , further comprising two pads ( 71 ), one being fixed onto an internal surface of the first sitting portion ( 312 ) and the first abutting portion ( 313 ), and the other being fixed to an internal surface of the second sitting portion ( 412 ) and the second abutting portion ( 413 ). 
     
     
         14 . The chair with a seat of adjustable length according to  claim 13 , wherein the two pads ( 71 ) have an internal surface with a hip-shaped recessed area. 
     
     
         15 . The chair with a seat of adjustable length according to  claim 1 , further comprising an elevating mechanism ( 72 ) for adjusting an elevation of the chair stand ( 1 ), and the elevating mechanism ( 72 ) being coupled to the chair stand ( 1 ). 
     
     
         16 . The chair with a seat of adjustable length according to  claim 1 , further comprising a backrest coupled to the chair stand ( 1 ) and disposed on a side corresponding to the first chair seat ( 3 ) and the second chair seat ( 4 ). 
     
     
         17 . The chair with a seat of adjustable length according to  claim 1 , further comprising a pair of armrests coupled to the chair stand ( 1 ) and disposed on both sides of the first chair seat ( 3 ) and the second chair seat ( 4 ).