Base for adjustable chairs

Claim 2

A compact base assembly for a vertically adjustable chair, comprising an upper frame member adapted to be connected to the underside of the seat portion of a chair, a lower frame member adapted to be supported upon a floor surface, an expandable and contractable linkage mechanism including two upstanding sets of links positioned laterally apart to define a space therebetween, each of said sets being operatively connected to both said upper and lower frame members for raising and lower said upper member as said linkage mechanism is expanded and contracted, a motor at least partially disposed in said space, and power transfer means operatively interconnecting said motor and said linkage mechanism for selectively expanding and contracting said mechanism as said motor is operated, said power transfer means including a one-way clutch capable of disengaging when an opposing upward force exceeding a predetermined magnitude is exerted upon said upper frame member, thereby permitting manual expansion of said linkage mechanism when said motor is not operating and preventing contraction of said mechanism when said opposing force restrains downward movement of said upper frame member during operation of said motor.

Claim 3

The structure of claim 1 in which said power transfer means includes a screw shaft operatively connected to said motor for rotation thereby, and a movable member threaded upon said shaft and operatively connected to said linkage mechanism for expansion and contraction of said mechanism as said shaft is rotated in opposite directions.

Claim 4

The structure of claim 2 in which said movable member contains a plurality of ball bearings engaging the threads of said shaft for reducing friction to an extent wherein axial force upon said movable member tends to cause rotation of said screw shaft, said power transfer means also including a self-locking gear assembly and a one-way clutch interposed between said gear assembly and said screw shaft to permit independent rotation of said screw shaft in one direction relative to said gear assembly in response to the application of said upward opposing force upon said upper frame member.

Claim 5

The structure of claim 1 in which at least a substantial portion of said power transfer means is disposed within said space.

Claim 6

The structure of claim 4 in which said motor and said power transfer means are substantially confined by said linkage mechanism and said upper and lower frame members when said linkage mechanism is collapsed.

Claim 7

A base for a vertically adjustable chair, comprising an upper frame member, A lower frame assembly adapted to rest upon a floor surface, an expandable and contractable linkage mechanism including two substantially identical upstanding sets of links positioned laterally apart to define a space between said sets, each of said sets being operatively connected to both said upper and lower frame members for raising and lowering said upper member as said mechanism is expanded and contracted, a motor equipped with a gear reduction assembly having an output shaft, said gear reduction assembly being self-locking to prevent rotation of said output shaft when said motor is de-energized, a screw shaft and a movable member threadedly carried thereby, said movable member being adapted for rotating said screw shaft upon the application of axial force thereagainst and being operatively connected to said linkage mechanism for expanding and contracting the same when said screw shaft is rotated in opposite directions, and a one-way clutch interconnecting said screw shaft and said output shaft, said one-way clutch being engaged when force is exerted upon said upper frame member in the direction of gravitational force and automatically disengaging when a force of predetermined magnitude is exerted upon said upper frame member in opposition to gravitational force.

Claim 8

A base for a vertically adjustable chair, comprising an upper frame member, A lower frame assembly adapted to rest upon a floor surface, an expandable and contractable linkage mechanism including two substantially identical upstanding sets of links positioned laterally apart to define a space between said sets, each of said sets being operatively connected to both said upper and lower frame members for raising and lowering said upper member as said mechanism is expanded and contracted, a motor equipped with a gear reduction assembly having an output shaft, said gear reduction assembly being self-locking to prevent rotation of said output shaft when said motor is de-energized, a screw shaft and a movable member threadedly carried thereby, said movable member being adapted for rotating said screw shaft upon the application of axial force thereagainst and being operatively connected to said linkage mechanism for expanding and contracting the same when said screw shaft is rotated in opposite directions, and a one-way clutch interconnecting said screw shaft and said output shaft, said one-way clutch being engaged when force is exerted upon said upper frame member in the direction of gravitational force and automatically disengaging when a force of predetermined magnitude is exerted upon said upper frame member in opposition to gravitational force.

Claim 9

The structure of claim 6 in which said motor, screw shaft, movable member, and one-way clutch are disposed substantially entirely within said space.

Claim 10

The structure of claim 7 in which said motor, screw shaft, movable member, and one-way clutch are substantially enclosed by said linkage mechanism, said upper frame member, and said lower frame assembly, when said linkage mechanism is collapsed.

Claim 11

A vertically adjustable chair having a seat portion and a base disposed therebelow; said base comprising an upper frame member connected to the underside of said seat portion, a lower frame member adapted to be supported upon a floor surface, and an expandable and contractable linkage mechanism including two upstanding sets of links positioned laterally apart to define a space therebetween; each of said sets of links being operatively connected to both said upper and lower frame members for raising and lowering said seat portion as said linkage mechanism is expanded and contracted; a motor at least partially disposed in said space between said sets of links; and power transfer means operatively interconnecting said motor and said linkage mechanism for selectively expanding and contracting said mechanism as said motor is operated; said power transfer means including a one-way clutch capable of disengaging when an opposing upward force exceeding a predetermined magnitude is exerted upon the seat portion of said chair, thereby permitting manual expansion of said linkage mechanism when said motor is not operating and preventing contraction of said mechanism when an opposing force restrains downward movement of said seat portion during operation of said motor.

Claim 12

A vertically adjustable chair having a seat portion and a base disposed therebelow; said base comprising an upper frame member connected to the underside of said seat portion, a lower frame member adapted to be supported upon a floor surface, and an expandable and contractable linkage mechanism including two upstanding sets of links positioned laterally apart to define a space therebetween; each of said sets of links being operatively connected to both said upper and lower frame members for raising and lowering said seat portion as said linkage mechanism is expanded and contracted; a motor at least partially disposed in said space between said sets of links; and power transfer means operatively interconnecting said motor and said linkage mechanism for selectively expanding and contracting said mechanism as said motor is operated; said power transfer means including a one-way clutch capable of disengaging when an opposing upward force exceeding a predetermined magnitude is exerted upon the seat portion of said chair, thereby permitting manual expansion of said linkage mechanism when said motor is not operating and preventing contraction of said mechanism when an opposing force restrains downward movement of said seat portion during operation of said motor.

Claim 13

The structure of claim 9 in which said power transfer means includes a screw shaft operatively connected to said motor for rotation thereby, and a movable member threaded upon said shaft and operatively connected to said linkage mechanism for expansion and contraction of said mechanism as said shaft is rotated in opposite directions.

Claim 14

The structure of claim 10 in which said movable member includes a plurality of bearings engaging the threads of said shaft for reducing friction to an extent wherein axial force upon said movable member tends to rotate said screw shaft, said power transfer means also including a self-locking gear assembly and a one-way clutch interposed between said gear assembly and said screw shaft for permitting independent rotation of said screw shaft in one direction relative to said gear assembly in response to the application of said upward force upon said seat portion.

Claim 15

The structure of claim 9 in which at least a substantial portion of said power transfer means is disposed within said space.

Claim 16

The structure of claim 12 in which said motor and said power transfer means are substantially enclosed by said linkage mechanism and said upper and lower frame members when said linkage mechanism is collapsed.

Claim 17

A vertical adjustable chair having a seat portion and a base; said base including an upper frame member secured to said seat portion, a lower frame assembly adapted to rest upon a floor surface, and an expandable and contractable linkage mechanism including two substantially identical upstanding sets of links positioned laterally apart to define a space between said sets; each of said sets being operatively connected to said upper frame member and said lower frame assembly for raising and lowering said seat portion as said mechanism is expanded and contracted; a motor equipped with a gear reduction assembly having an output shaft; said gear reduction assembly being self-locking to prevent rotation of said output shaft when said motor is de-energized; a screw shaft and a movable member threadedly carried thereby; said movable member being adapted for rotating said screw shaft upon the application of axial force against said movable member and being operatively connected to said linkage mechanism for expanding and contracting the same when said screw shaft is rotated in opposite directions; and a one-way clutch interconnecting said screw shaft and said output shaft; said one-way clutch being engaged when force is exerted upon said seat portion in the direction of gravitational force and automatically disengaging when a force of predetermined magnitude is exerted upon said seat portion in opposition to gravitational force.

Claim 18

A vertical adjustable chair having a seat portion and a base; said base including an upper frame member secured to said seat portion, a lower frame assembly adapted to rest upon a floor surface, and an expandable and contractable linkage mechanism including two substantially identical upstanding sets of links positioned laterally apart to define a space between said sets; each of said sets being operatively connected to said upper frame member and said lower frame assembly for raising and lowering said seat portion as said mechanism is expanded and contracted; a motor equipped with a gear reduction assembly having an output shaft; said gear reduction assembly being self-locking to prevent rotation of said output shaft when said motor is de-energized; a screw shaft and a movable member threadedly carried thereby; said movable member being adapted for rotating said screw shaft upon the application of axial force against said movable member and being operatively connected to said linkage mechanism for expanding and contracting the same when said screw shaft is rotated in opposite directions; and a one-way clutch interconnecting said screw shaft and said output shaft; said one-way clutch being engaged when force is exerted upon said seat portion in the direction of gravitational force and automatically disengaging when a force of predetermined magnitude is exerted upon said seat portion in opposition to gravitational force.

Claim 19

The structure of claim 14 in which said motor, screw shaft, movable member, and one-way clutch are disposed substantially entirely within said space.

Claim 20

The structure of claim 14 in which said motor, screw shaft, movable member, and one-way clutch are substantially enclosed by said linkage mechanism, said upper frame member, and said lower frame assembly when said linkage mechanism is collapsed.