US3923280A

US3923280A - Adjustable support column for a pivotal chair

Info

Publication number: US3923280A
Application number: US560580A
Authority: US
Inventors: Wayne W Good
Original assignee: Harter Corp
Current assignee: Harter Corp
Priority date: 1975-03-21
Filing date: 1975-03-21
Publication date: 1975-12-02
Anticipated expiration: 1992-12-02
Also published as: CA1007975A

Abstract

An adjustable support column for pivotally mounting the seat section of a chair to the base portion thereof. The nave of the base portion has an upwardly flared bore into which the lower, tapered end portion of a sheath tube is supportingly received. A thrust bearing is mounted inside the lower end portion of the sheath tube and rotatably supports an adjusting screw. The seat section has a conical spindle that is received within a conical socket at the upper end of the spindle tube. A bushing is fixed to the lower end portion of the spindle tube and is threaded onto the adjusting screw. The bearing and bushing are selected such that the bearing offers less resistance to relative rotation between the adjusting screw and the sheath tube than the bushing offers to relative rotation between the adjusting screw and the spindle tube. A knob means is attached to the adjusting screw exteriorily of the support column in order to afford a means by which to overcome the aforesaid resistance to relative rotation offered by the bushing in order to permit selective adjustment in the height of the seat section with respect to the base portion of the seat.

Description

United States Patent Good Dec. 2, 1975 [75] Inventor: Wayne W. Good, Sturgis, Mich.

[73] Assignee: Harter Corporation, Sturgis, Mich.

[221 Filed: Mar. 21, 1975 i [211 App]. No.: 560,580

[52] U.S. Cl. 248/405; 248/415; 297/347 [51] Int. Cl. F16M 13/00 [58] Field of Search 248/405, 406, 161, 415; 297/347, 348; 108/141 [56] References Cited UNITED STATES PATENTS 526,045 9/1894 Morgan 248/415 X 682,844 9/1901 Ellenbecker.. 248/405 1,242,110 10/1917 Koken i 248/405 2,219,814 10/1940 Jones 108/141 3,799,486 3/1974 Mohr et al. 248/406 Primary Examiner-Roy D. Frazier Assistant Examiner-Robert W. Gibson, Jr. Attorney, Agent, or FirmHami1ton, Renner & Kenner [57] ABSTRACT An adjustable support column for pivotally mounting the seat section of a chairto the base portion thereof. The nave of the base portion has an upwardly flared bore into which the lower, tapered end portion of a sheath tube is supportingly received. A thrust bearing is mounted inside the lower end portion of the sheath tube and rotatably supports an adjusting screw. The

-- seat section has a conical spindle that is received within a conical socket at the upper end of the spindle tube. A bushing is fixed to the lower end portion of the spindle tube and is threaded onto the adjusting screw. The bearing and bushing are selected such that the bearing offers less resistance to relative rotation between the adjusting screw and the sheath tube than the bushing offers to relative rotation between the adjusting screw and the spindle tube. A knob means is attached to the adjusting screw exteriorily of the support column in order to afford a means by which to overcome the aforesaid resistance to relative rotation offered by the bushing in order to permit selective adjustment in the height of the seat section with respect to the base portion of the seat.

6 Claims. 4 Drawing Figures US. Patent Dec. 2, 1975 Sheet 1 of2 3,923,280

US. Patent Dc.2,1975 Sheath 2 3,923,280

ADJUSTABLE SUPPORT COLUMN FOR A PIVOTAL CHAIR BACKGROUND OF THE INVENTION The present invention relates generally to an adjustable support column for pivotally mounting the seat section of a chair to a base portion.

Historically, adjustment in the height of a seat has been accomplished by the use of a threaded spindle that becomes progressively exposed as the seat is raised by threading the spindle upwardly out of the bell nut and hub tube.

In response to considerations of: improving the operating efficiency (by shielding the threaded portion of the spindle from deleterious dust and dirt); providing an aesthetically improved appearance (by shielding the threaded spindle from view); and, maintaining cleanliness (by shielding the person using the chair, and his or her clothes, from the lubricant employed on the threaded spindle), various types of cover assemblies and concomitant mechanisms for permitting selective height adjustability have been provided.

One approach has necessitated the incorporation of a special connection between the seat section of the chair and the threaded spindle often by inserting a pivot therebetween in order to permit the seat section to be rotated without effecting an adjustment in the height of the seat.

Another approach has necessitated some physical connection between the cover assembly and the adjusting mechanism hidden thereby. But irrespective of the approach, the structure has generally required the use of an axially slotted adjusting screw and a J-washer to determine rotation between the adjusting screw and various other parts of the height adjusting mechanism, as required selectively to adjust the height of the seat section with respect to the base portion.

Moreover, the more complex the structure of the support column becomes to effect the desired objectives of providing an efficient, aesthetic and clean height adjusting column, the more tedious and expensive it becomes to manufacture and maintain the support column.

SUMMARY OF THE INVENTION It is, therefore, a primary object of the present invention to provide an improved support column for pivotally mounting the seat section of a chair to the base portion.

It is another object of the present invention to provide an improved support column, as above, which employs an adjusting screw that does not need to be longitudinally slotted and which does not employ the customary J-washer.

It is yet another object of the present invention to provide an improved support column, as above, that can be completely assembled and disassembled with facility, thereby allowing the chair to occupy the minimum volume of space for shipment in its knockeddown state and to be assembled at the point of use without the need for tools.

It is a further object of the present invention to provide an improved support column, as above, which can, because of the facility with which it can be assembled and disassembled, be readily converted from a high base to a low base chair, or vice versa.

It is a still further object of the present invention to provide an improved support column, as above, in which the threaded adjusting screw is shielded from view and no lubricant is required on the adjusting screw itself.

It is an even further object of the present invention to provide an improved support column, as above, that is not only uncomplicated but relatively inexpensive to manufacture and maintain.

These and other objects, together with the advantages thereof over existing and prior art forms which will become apparent from the following specification, are accomplished by means hereinafter described and claimed.

In general, a chair embodying the concept of the present invention has a base portion comprising a plurality of legs radiating from the nave thereof. A collet with an upwardly flared bore is secured within the nave of the base portion supportingly to receive the conically tapered, lower end portion of a sheath tube. A thrust bearing is mounted interiorily of the sheath tube at its lower extremity, and the thrust bearing rotatably supports an adjusting screw.

A knob is presented from the end of the adjusting screw which, though axially fixed within the thrust bearing, extends downwardly through the thrust bearing to be accessible at a location immediately beneath the nave. Upwardly with respect to the thrust bearing the adjusting screw is threaded along substantially its entire length.

A tapered spindle is secured to the underside of the seat section and is received within a tapered socket in,

the upper end of the spindle tube. The spindle tube extends concentrically within the sheath tube, and an annular bushing is secured in the lower end portion of the spindle tube. The interior of the bushing is threaded to be received on the threaded portion of the adjusting screw. The bushing is fabricated so that the resistance to relative rotation between the adjusting screw and the spindle tube is greater than the resistance afforded by the thrust bearing against relative rotation of the adjusting screw with respect to the sheath tube. As such, the seat section may freely rotate with respect to the base portion of the chair without effecting any adjustment in the height of the chair. Yet, by rotating the seat section while grasping the knob to preclude rotation of the adjusting screw or by manipulating the knob to rotate the adjusting screw while holding the seat section against rotation, one can effect relative rotation between the adjusting screw and the spindle tube in order to adjust the height of the seat section with respect to the base portion.

One preferred embodiment of an adjusting support column for a pivotally mounted chair embodying the concept of the present invention is shown by way of example in the accompanying drawings without attempting to show'all of the various forms and modifications in which the invention might be embodied; the invention being measured by the appended claims and not by the details of the specification.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a frontal-side perspective of a chair embodying the concept of the present invention, the seat section and the support column being exploded vertically with respect to the base portion in order to reveal the interrelation of those components prior to field assembly;

FIG. 2 is an enlarged side elevation of a chair embodying the concept of the present invention, the seat section, support column and base portion being disposed in their normal operative position and the base being partially broken away to reveal the disposition of the support column with respect thereto;

FIG. 3 is a further enlarged vertical section taken substantially along line 33 of FIG. 2; and,

FIG. 4 is a horizontal section taken substantially along line 44 of FIG. 3.

DESCRIPTION OF A PREFERRED EMBODIMENT A support column embodying the concept of the present invention is designated generally by the numeral on the appended drawings and provides means for adjusting the height of a seat section 11 with respect to a base portion 12 in a chair 13.

The base portion 12 may comprise a plurality of radially extending legs 14 that are conjoined at the nave 15 to support a collet 16 which extends vertically therethrough and which presents an upwardly flared bore 18. The radially outer extremity of each leg 14 may be provided with casters 19, as shown.

The support column 10 has an outer sheath, or casing, tube the lower end portion of which is tapered, as at 21, to be matingly received within and supported by the flared bore 18 in collet 16. The lower extremity of the sheath tube 20 is directed radially inwardly to present an annular cavity 22 and an annular supporting flange 23, the latter comprising the lower wall of cavity 22. The supporting flange 23 should have substantial strength because it will be required to support the full weight of the seat section 11 and anyone or anything resting thereon.

A thrust bearing is removably insertable within the cavity 22 accurately to position the thrust bearing 25, and the stationary element 24 of the thrust bearing 25 is carried on the supporting flange 23. An adjusting screw 27 is captured within the moving element 26 of the thrust bearing 25 to be rotatable therewith, and in order to assure a fixed vertical disposition of the adjusting-screw 27 with respect to the thrust bearing 25, one may preferably employ a positioning rib 28 that circumscribes the shaft 29 of the adjusting screw 27. Although the cylindrical lower end portion 30 of the shart 29 is preferably press fit through the bore 31 of the moving element 26, the positioning rib 28 maintains the desired relative vertical disposition of the adjusting screw 27 with respect to the thrust bearing 25 such that the cylindrical lower end portion 30 of the shaft 29 extends through the bearing 25 and teriminates below the collet 16 in order to permit a control knob 32 to be secured thereto, as by the set screw 33, and to permit manual access to the knob 32 immediately beneath the nave 15.

That portion of the shaft 29 which extends vertically upwardly of the positioning rib 28 is provided with external threads 34. An annular bushing 35 is provided with internal threads 36 which allow the bushing 35 to be screwed onto and along the threads 34 of shaft 29. The cylindrical outer surface 37 of the bushing 35 is secured within the cylindrical inner wall 38 at the lower end portion 39 of a spindle tube 40.

The upper end portion 41 of the spindle tube presents a flared socket 43 into which the tapered spindle 45 of the seat section 11 is su'pportingly received. As best seen in FIG. 2, the spindle 45 is secured to rotate with the seat section by staking, press-fitting, or otherwise securing the spindle 45 to a chair control 46 presented from the underside of the seat section 11.

A bearing liner 48 has an elongate, annular sleeve portion 49 that embraces the spindle tube 40. A plurality of ribs 50 extend longitudinally along the outer surface 51 of the sleeve portion 49. The ribs 50 project radially outwardly from the sleeve portion 49 to engage the radially inner wall 52 of the sheath tube 20 and thereby maintain the spindle tube 40 concentrically with respect to the sheath tube 20. In order to minimize frictional resistance between the spindle tube 40 and the sleeve portion 49, at least the sleeve portion 49 of the bearing liner 48 is preferably made of a selflubricating plastic such as Zytel.

Before discussing the adjustable features of the chair 13 it should be appreciated that the tapered coupling arrangement by which the support column 10 is secured to the base portion 12 and the tapered coupling arrangement by which the seat section 11 is mounted on the support column 10 allow the three basic components of the chair to be assembled and disassembled with facility. This feature not only makes it quite easy to repair the chair but also permits the chair to be shipped disassembled and allows extremely rapid assembly without requiring any tools.

In addition, the component parts of the support column 10 may also be readily assembled and disassembled. For example, if one selects a thrust bearing unit 25 having a diameter less than the internal diameter of the sleeve portion 49 presented by the bearing liner 48, the thrust bearing 25, the adjusting screw 27 and the spindle tube 40 may, upon removal of the control knob 32, be extracted as a unit upwardly through the liner 48. This capability not only allows ready replacement of any parts within the support column 10 but also permits any chair to be changed from a low base to a high base, or vice versa, simply by providing substitute sheath tubes 20 and spindle tubes 40 of appropriate length. As should now be appreciated, these components can be interchanged with relative ease.

As depicted in FIG. 3, the bushing 35 appears to have a greater axial extent and might initially appear to be required. Yet this protracted axial extent serves the very crucial functional purpose of providing more resistance to rotation between the bushing 35 and the adjusting screw 27 than exists between the stationary and moving

elements

24 and 26, respectively, of the thrust bearing 25. Thus, irrespective of whether the chair is empty or filled, rotation of the seat section 11 with respect to the base portion 12 effects relative motion between the elements of the thrust bearing 25 rather than between the bushing 35 (non-rotatably secured to the spindle tube 40) and the adjusting screw 27 so long as the control knob 32 is free to rotate. When, however, relative rotation occurs between the control knob 32 and the seat section 11, the bushing 35 will travel along the threads 34 on the shaft 29 of the adjusting screw 27 to raise, or lower, the seat section 11 with respect to the base portion 12 depending on the relative rotational direction between the adjusting screw 27 and the bushing 35.

It should now be apparent that a pivotal chair employing an improved support column embodying the concept of the present invention can be readily assembled and disassembled, is relatively uncomplicated and otherwise accomplishes the objects of the invention.

What is claimed is:

1. An adjustable support column for pivotally mounting the seat section of a chair to a base portion comprising: a sheath tube extending upwardly from the base portion; bearing means carried by said sheath tube; an adjusting screw supported by said bearing means for rotation relative to said sheath tube; knob means to control rotation of said adjusting screw; a spindle tube supporting the seat section extending downwardly therefrom; a bushing fastened to said spindle tube and threaded onto said adjusting screw to rotate with and with respect thereto; and, means to assure that the resistance to relative rotation between said bushing and said adjusting screw exceeds the resistance to relative rotation between said adjusting screw and said sheath tube.

2. An adjustable support column, as set forth in claim 1, in which said spindle tube is insertable axially within said sheath tube and means are provided slidably to support said spindle tube concentrically with respect to said sheath tube.

3. An adjustable support column, as set forth in claim 2, in which the lower end portion of said sheath tube is directed radially inwardly to present an annular cup and supporting flange, said bearing means being removably positioned within said cup and carried on said supporting flange.

4. An adjustable support column, as set forth in claim 3, in which said knob means is demountably secured to said adjusting screw and the diameter of said bearing means is of lesser dimension than the internal diameter of the means slidably to support said spindle tube concentrically with respect to said sheath tube.

5. An adjustable support column, as set forth in claim 1, in which said base portion comprises a plurality of leg members extending radially outwardly from a nave, a conically upwardly flared bore presented from said nave, the lower end portion of said sheath tube being conically tapered to be supportingly received within said flared bore.

6. An adjustable support column, as set forth in claim 1, in which a conically tapered spindle is secured to and extends downwardly from said seat section, a conically flared socket is presented from the upper end portion of said spindle tube, said spindle being supportingly received within said socket.