Pneumatic height-adjustable desk

Abstract

A pneumatic height-adjustable desk may comprise two legs, two pneumatic rods, two pulleys units, a cross beam, a control spindle, a clutch unit and a desk top. By cooperating the pneumatic rods, the pulleys units, the control spindle and the clutch unit, the two sides of the desk top are configured to go up or down synchronously and maintain even in the raising or lowering process. Also, by using the clutch unit to clamp the control spindle, the desk top is configured to firmly maintain flat and stable even the single side of the desk top is pressed by the heavy stuff.

What is claimed is: 
     
         1 . A pneumatic height-adjustable desk comprising:
 two legs respectively having an outer tube, and an inner tube movably received in the outer tube to achieve a telescoping effect, and each of two lower ends of the two inner tubes connected to a foot which is configured to increase a contacting area and allow the pneumatic height-adjustable desk to firmly stand on a floor; each of two upper ends of the outer tubes connected to a supporting base which has an accommodating space, and an interior space of the outer tube communicated with the accommodating space of the supporting base;   two pneumatic rods respectively comprising a cylindrical body, and a pushing rod, which is movably received in the cylindrical body, pushed by air pressure to extend outwardly at standard condition; the pneumatic rod received in the inner tube and the outer tube to allow two respective upper ends of the cylindrical body and the pushing rod to connect with the two supporting bases and to allow two respective lower ends of the cylindrical body and the pushing rod to connect with the two feet;   two pulleys units respectively having a first pulley and a second pulley which are pivotally connected on the upper end and the lower end of the cylindrical body respectively, and each of two round belts disposed on the first pulley and the second pulley as a chain; when the pneumatic rod with the pulleys unit settled inside each of the legs, each of the two first pulleys protruding from the upper end of the outer tube and positioned inside the accommodating space of the supporting base; a locating piece, which is secured on an upper portion of the inner tube, connected to a clamping piece which is configured to clamp the round belt thereby building the connection between the inner tube and the round belt;   a cross beam, which is secured between the two upper ends of the two outer tubes, comprising a housing space, and an elongated opening, which is formed at a top end of the housing space, configured to allow a control spindle with a clutch unit to put into the housing space of the cross beam;   the control spindle having the clutch unit mounted thereon, and an outer periphery of the control spindle having a polygon-shaped section; when the control spindle with the clutch unit put into the housing space of the cross beam, each of two ends of the control spindle engaged with an engaging hole of the first pulley through the polygon-shaped section; the clutch unit configured to clamp or release the control spindle, and the control spindle configured to achieve power transmission to stop or rotate the two first pulleys synchronously; and   a desk top secured on the two supporting bases and the cross beam, and a control unit, which is settled on a lower surface of the desk top, electrically connected to the clutch unit.   
     
     
         2 . The pneumatic height-adjustable desk of  claim 1 , wherein the upper end of the inner tube has a first cover, and at least two first sliding wheels are pivotally connected to the first cover. 
     
     
         3 . The pneumatic height-adjustable desk of  claim 1 , wherein a bottom end of the outer tube comprises a second cover, and at least two second sliding wheels are pivotally connected to the second cover. 
     
     
         4 . The pneumatic height-adjustable desk of  claim 1 , wherein the clutch unit has a fixing base which is secured on the lower surface of the desk top, and a lateral surface of the fixing base comprises a stepped hole which is configured to be penetrated through by the control spindle; wherein the stepped hole is further engaged with a horizontal moving unit, and a spring is borne against an inner edge of the horizontal moving unit and the fixing base respectively on both sides thereof; a plurality of gear slots are formed at an inner periphery of the horizontal moving unit, and by using the spring to push the horizontal moving unit to move away from the fixing base, the gear slots are configured to engage with an gear formed on the control spindle, and with the engagement among the fixing base, the horizontal moving unit, the gear and the control spindle, the control spindle is fixed and immovable; wherein the clutch unit further has an operating arm which is mounted on the fixing base and electrically connected to the control unit, and through pressing a button on the control unit, the operating arm is driven to push the horizontal moving unit toward the fixing base such that the gear is disengaged with the gear slots of the horizontal moving unit thereby allowing the control spindle to spin.