US 5,031,869 A · Control assembly for chair height adjustment

Abstract

A displacement control assembly includes a rotatable lead screw longitudinally extending within a tubular column supporting the assembly. A nut is threaded to the screw for relative axial displacement of the screw and nut, for example, to adjust the height of a chair seat or similar fixture. A resilient brake structure is carried by either the nut or the screw for resiliently biased, alternative locking and unlocking of the nut and screw in order to selectively prevent relative rotation and relative axial displacement of the screw and nut. The releasable lock allows the screw and nut to co-rotate without relative axial displacement so that the chair seat can be swiveled without altering the desired height. The assembly can be designed with the parameters correlated so that the seat is lowered at uniform speed independent of the weight of the seat occupant.

Claims22

Dependent claims

A control assembly for adjustable displacement of a chair seat or the like, comprising:

a tubular column for supporting the assembly;
a continuously rotatable lead screw longitudinally extending within said column;
a nut threaded to and longitudinally displaceable along said screw;
a tubular post secured to and movable with said nut for carriage and adjustable displacement of said chair seat therewith;
and a resilient brake structure carried on said nut for resiliently biased, alternative engagement with and retraction from said screw, to selectively prevent relative rotation of said screw and nut thereby locking said post and nut on the screw and preventing axial displacement of the post relative to the screw, swivel means for enabling corotation of said locked screw, nut and post, said brake structure comprises at least one brake shoe means for normally biased engagement with said screw, and release means for selectively withdrawing said shoe means from said screw in opposition to said bias, thereby unlocking said nut from the screw to enable relative rotation therebetween and displacement of said post with the nut, said release means including manually operable linkage means extending within said tubular column and downwardly from the upper end of said tubular column for axial movement along said tubular column to permit selective withdrawing of said shoe means.

2 more elements

A control assembly for adjustable displacement of a chair seat or the like on which an applied load is supported, comprising a rotatable lead screw including lead angle and a nut threaded to and vertically displaceable along said screw, a support structure secured to and vertically movable with said nut for carriage of said seat, a thrust bearing means for supporting the rotation of said screw thereon, wherein said lead angle is selected to enable the torque forces along the screw thread to be equal to or greater than the frictional torque forces generated by said thrust, bearing means and thereby cause said nut and support structure to vertically descend along said rotating screw at uniform speed independent of the weight of the chair seat and independent of said applied load.

Dependencies are inferred from the claim text.

Control assembly for chair height adjustment

Life of this patent

Control assembly for chair height adjustment

Life of this patent

Abstract

Claims22