Seat-height Adjustment Device

Abstract

A seat-height adjustment device for a swivel chair including a clutch and upper and lower telescoping tubes. The tubes receive and cover the threaded spindle, hollow post, and bell nut of the chair. The clutch means is actuated by upward movement of the lower tube to releasably lock the bell nut for axial movement relative to the spindle upon a turning of the seat of the chair.

Description

The present invention relates to swivel chairs and more particularly to a novel and attractive seat-height adjustment device for such chairs.

Conventional seat-height adjustment devices for swivel chairs and the like comprise a threaded spindle extending downwardly from a bottom of the seat and into a hollow post of a base for the chair. An enlarged nut commonly referred to as a bell nut is adapted for hand-turning on the spindle and bears on top of the hollow post to limit travel of the spindle into the post and hence define the height of the seat above the base.

To adjust the height of the seat requires one to reach under the seat and manually turn the bell nut relative to the spindle. This causes the spindle to move axially up or down relative to the bell nut to adjust the seat height to the desired level. Such an operation is very laborious particularly for women. Further, the threaded spindle, bell nut, and hollow post are exposed and subject to the collection of dirt, dust, and lint which further impede the manual adjustment of the seat height using the bell nut.

Exposure of the threaded spindle, bell nut, and post also materially detracts from the appearance of the swivel chair. To correct for this, it has been proposed that the spindle and bell nut be covered by a tubular member. While the addition of the tubular member improves the appearance of the swivel chair, it does not enhance the ease of adjustment of the seat height. In this regard, the tubular member has been fixedly secured to the bell nut. To adjust the seat height with such a combination requires a manual gripping and turning of the tubular member and bell nut. This is no easier than the manual turning of the bell nut by itself and requires that the tubular member be of a sturdy construction to resist deformation during the turning operation.

In view of the foregoing, it is a general object of the present invention to provide an attractive seat-height adjustment device which is easily actuated and which permits rapid adjustment of seat height simply by turning of the seat relative to the chair base.

Another object of the present invention is to provide a seat-height adjustment device of the foregoing character including telescoping upper and lower tubes receiving and covering the threaded spindle, bell nut, and post of the swivel chair to materially improve the over-all appearance of the swivel chair.

A further object of the present invention is to provide a seat-height adjustment device of the foregoing character further including clutch means actuated by the lower tube for releasably locking the lower tube to the bell nut for axial movement relative to the spindle with a turning of the chair seat relative to the base.

Other objects and advantages of the present invention may be more clearly understood by reference to the following detailed description when considered with the drawing which, by way of example only, illustrates one form of seat-height adjustment device embodying the features of the present invention.

In the drawing:

FIG. 1 is a side view of a swivel chair including the seat-height adjustment device of the present invention;

FIG. 2 is a sectional side view taken along the line 2--2 in FIG. 1 and illustrating the internal construction of the seat-height adjustment device;

FIG. 3 is a cross sectional bottom view taken along the line 3--3 in FIG. 2; and

FIG. 4 is a fragmentary view partially in section showing the clutch means engaged to produce an adjustment of the height of the seat upon a turning thereof relative to the base of the swivel chair.

In FIG. 1, the swivel chair is represented generally by the numeral 10 and includes a conventional seat 12 supported above a base 14 by a seat-height adjustment device 16. As illustrated, the base 14 includes four legs 18 extending radially from a hollow tubular post 20 and supported at their outer ends on casters 22.

The post 20 is adapted to slidably receive the lower plastic covered end of an externally threaded spindle 24 of the seat-height adjustment device 16. The spindle is adapted to turn in the post with a turning of the seat 12. In this regard, and as illustrated most clearly in FIG. 2, the tapered upper end 25 of the spindle 24 is fixedly secured to the bottom of the seat 12 by a cup-shaped coupling member 26.

The travel of the spindle 24 within the post 20 is limited and the height of the seat 12 above the base 14 defined by a bell nut 28. The bell nut 28 is threaded on the spindle 24 and bears on top of the post 20 for manual turning relative to the spindle. In this regard, the seat-height adjustment device 16 includes a plastic sleeve bearing 30 tightly seated in the open top of the post 20 and including an annular flange 32. A plastic annular thrust bearing 34 rides on top of the annular flange 32 to support the bell nut 28 for turning on the post.

The top of the thrust bearing 34 carries a plurality of circumferentially spaced detents 36 for mating with similarly spaced indentations 38 in the bottom of the bell nut. Further, the thrust bearing 34 includes a spline 40 for riding axially in vertical keyway 42 in the spindle 24 (see FIG. 3). Thus arranged, the weight of seat 12 is normally transmitted by the spindle 24 and bell nut 28 to the thrust bearing such that when the detents 36 are mating with the indentations 38, a turning of the spindle with the seat produces a like turning of the bell nut. As this occurs, the thrust bearing 36 rotates on top of the annular flange 32 to maintain the height of the chair above the base at that established by the bell nut.

To provide means for simply and rapidly altering the height of the seat 12 above the base 14, the device 16 includes telescoping upper and lower tubes 44 and 46 and a manually operable clutch 48. The upper tube 44 is supported for turning on and covers the upper portion of the spindle 24. In this regard, the upper tube includes a top 50 for riding on an annular shoulder 52 defined by the spindle 24 and the tapered end 25 with the tapered end extending through a hole 54 in the top 50.

The lower tube 46 is deminsioned to receive the upper tube 44 and includes four open-bottom slots 56. The slots 56 are adapted to slidably receive the legs 18 such that tops 58 of the slots rest on the legs to limit axial movement of the lower tube and define its normal position relative to the base 14. Thus arranged, and as most clearly represented in FIGS. 1 and 2, the telescoping upper and lower members 44 and 46 completely cover the threaded spindle 24, bell nut 28, and post 20 as well as its connection to the legs 18. This not only protects the spindle and bell nut from dust, dirt, and lint, but also provides a smooth and attractive appearance for the seat supporting portion of swivel chair, materially enhancing the over-all chair appearance.

Basically, the clutch 48 includes interlocking means extending downwardly from the bell nut 24 and upwardly from the lower tube 46 for mating and locking upon upward movement of the lower tube relative to the bell nut. With the lower tube 46 locked to the bell nut 28, a turning of the seat 12 overcomes the locking force of the detents 36 in the indentations 38 and produces a rotation of the spindle 24 relative to the bell nut. Such a turning of the spindle 28 produces axial motion thereof relative to the bell nut causing the seat 12 to move up or down relative to the base 14 depending upon the direction of rotation of the seat.

In addition, when the lower tube 46 is raised to engage the clutch 48, the sides of the slots 58 still engage the sides of the legs 18. Thus, height adjustment of the seat may be accomplished either by actuating the clutch and then spinning the seat or by inverting the chair and with the seat on the floor, engaging the clutch and spinning the base. Both methods effect a very rapid adjustment of the seat height and the latter does not require one to reach under the seat and hold the lower tube 46 in a raised position while adjusting the seat height.

The illustrated form of the clutch 48 includes an annular skirt 60 extending downwardly from the lower marginal edge of the bell nut 28. A set screw 62 passes laterally through the skirt 60 and under the annular flange 32 to lock the bell nut and spindle 24 to the post 20. This prevents undesired separation of the seat 12 from the base 14 upon a lifting of the seat to move the chair 10 from one location to another. An access hole 64 is provided in the upper tubular member for tightening and untightening the set screw 62 when the seat is adjusted to its uppermost height.

The clutch 48 also includes a sleeve member 66 secured at its base 68 to an inner wall of the lower tube to extend coaxial therewith and slideably receive the hollow post 20. In this regard, the sleeve member 66 includes a plurality of circumferentially spaced axially elongated and inwardly extending guide portions 70 (see FIG. 3) for slideably engaging the post 20 and centering the lower tube 46 on the post.

In addition to the skirt 60 and sleeve member 66 the clutch includes interlock means on the bottom of the skirt and on the top of the sleeve member. The interlock means is designed to mate upon upward movement of the lower tube 46 relative to the upper tube 44 to lock the bell nut 28 to the lower tube. In this regard, the illustrated form of the interlock means comprises a series of circumferentially spaced lugs 72 extending downwardly from the bottom of the skirt 60 and a plurality of circumferentially spaced lugs 74 extending upwardly from the top of the sleeve member. The lugs 72 and 74 are shaped to mate with each other upon upward movement of the lower tube 46 as illustrated in FIG. 4.

As previously indicated, when the lug members 72 and 74 are engaged as illustrated in FIG. 4, the bell nut 28 is locked to the lower tube 46 and hence to the base member 14. Any turning of the seat 12 will then produce a like turning of the spindle 24 relative to the bell nut and axial movement thereof to adjust the height of the seat relative to the base. As previously stated, this may be accomplished by either holding the lower tube 46 with the clutch engaged and spinning the seat 12 or by inverting the chair 10, lowering the tube 46 to engage the clutch, and spinning the base 14.

In view of the foregoing, it is appreciated that the seat-height adjustment device of the present invention provides attractive cover for the seat-supporting structure of a swivel chair while providing means for simply and rapidly adjusting the height of a seat by a turning of the seat relative to the chair base.

While a particular form of seat-height adjustment device has been described in some detail herein, changes and modifications may be made without departing from the spirit of the invention. Accordingly, it is intended that the present invention be limited only in scope only by the terms of the following claims.

Claims

I claim:

1. A seat-height adjustment device for a swivel chair including a seat, a threaded spindle secured at its upper end to said seat for turning therewith and a base structure including a vertically extending hollow post for receiving a lower end of said spindle to turn therein with said seat, said device comprising:

a nut on said spindle for bearing and turning on a top of said post to limit axial travel of said spindle in said post and hence define the height of said seat above said base;

telescoping upper and lower tubes for receiving and covering said threaded spindle, nut, and post; and

manually operable clutch means for selectively connecting said lower tube to said nut to turn therewith relative to said spindle with a turning of said seat whereby said nut moves axially on said spindle to adjust the height of said seat relative to said base.

2. The seat-height adjustment device of claim 1 wherein said clutch means includes interlocking means extending downwardly from said nut and upwardly from said lower tube for mating upon upward movement of said lower tube relative to said nut to lock said lower tube to said nut.

3. The seat-height adjustment device of claim 2 further including bearing means for said nut on top of said post including a sleeve bearing seated in a top of said post and including an annular flange bearing on top of said post, and an annular thrust bearing riding on top of said annular flange and supporting said nut for turning on said post.

4. The seat-height adjustment device of claim 1 wherein:

said base includes a plurality of legs extending radially from said hollow post at a bottom thereof; and

said lower tube includes a plurality of open bottom slots for receiving said legs around said post such that said lower tube covers the connection of said legs to said post and said lower tube connects to said base to turn therewith relative to said spindle when said clutch means is engaged.

5. The seat-height adjustment device of claim 1 wherein:

said upper tube is supported by said spindle and extends into an open top of said lower tube which is normally supported on said base; and

said clutch means comprises an annular skirt extending downwardly from said nut, a sleeve member secured in and coaxial with said lower tube for slidably receiving said hollow post to center said lower tube thereon, and interlocking means on a bottom of said skirt and a top of said sleeve for mating upon upward movement of said lower tube relative to said upper tube to lock said nut to said lower tube.

6. The seat-height adjustment device of claim 5 wherein:

said sleeve member includes circumferentially spaced axially elongated inwardly extending guide portions for slidably engaging said post; and

said interlock means comprises first lug means extending downward from said skirt and second lug means extending upward from said sleeve for mating with said first lug means upon upward movement of said lower tube relative to said upper tube.