Field of the Invention

The present invention relates to chair control mechanisms.

More specifically, the invention relates to office or posture chair mechanisms. In particular the invention relates to mechanisms which control the height and tilting movement of office chairs with a single component.

Background of the Invention

Office or posture chairs are known in the art. These chairs oftentimes have mechanisms for altering the seat and backrest height, the angle of the seat and backrest to name a few and promote efficiency in the workplace while also promoting good health. Many of these mechanisms have numerous critical moving parts and therefore have an increased incidence of failure. Moreover, due to their complexity, these mechanisms are often prohibitively expensive for offices with limited budgets or for the individual who works out of the home.

A few representative complex chair control devices are disclosed in U.S. Patent Numbers 4,364,605, 4,328, 943 and 4,555,085. U.S. Patent 4,364,605 discloses a device suitable for use on a posture chair. The device of the *605 patent uses one lever to control three pneumatic cylinders. One cylinder controls backrest tilt, a second cylinder controls seat tilt, and a third cylinder controls seat height. Using three pneumatic cylinders to control three distinct motions increases the cost of such a device.

U.S. Patent 4,328,943 discloses another chair control device which also uses one lever to adjust height and tilt of

the chair seat. However, the '943 device uses an actuator block to actuate the height and tilt adjustment means in conjunction with the lever. Thus, the actuator block is an additional critical moving part adding increased likelihood for failure of the mechanism.

U.S. Patent 4,555,085 also discloses a tilt and height control mechanism for a chair. The *085 patent uses a lever in conjunction with a slide member. As in the ^» 943 device, the •085 lever does not directly actuate the height or tilt control means.

All of the above-described mechanisms are complicated in that they require numerous or expensive moving parts. The more critical moving components which a device utilizes, the higher the incidence of failure of the device and oftentimes the higher the cost of the device. What is needed in this field is a mechanism which has few critical moving parts and is inexpensive to manufacture.

Description of the Drawings Fig. 1 is an isometric view of the chair control mechanism of the present invention with a chair seat and pedestal mounted thereon. Fig. 2 is a side view of the chair control mechanism of the present invention. Fig. 3 is a rear view of the chair control mechanism of the present invention.

Fig. 4 is a cross section of the mechanism of the present invention taken along line 4-4 of Figure 2.

Fig. 5 is a cross section of the mechanism of the present invention taken along line 4-4 of Figure 2 with the lever actuating the valve of the pneumatic cylinder. Fig. 6 is a cross section of the mechanism of the present invention taken along line 4-4 of Figure 2 further illustrating the horizontal motion of the lever necessary to inhibit pivotal movement of the chair seat. Fig. 7 is a cross section of the mechanism of the present invention taken along line 4-4 of Figure 2 further illustrating the rotational movement of the lever.

Fig. 8 is an exploded view of the mechanism of the present invention.

Summary The present invention provides a novel and elegant solution in the form of a height and tilt control chair mechanism. A single component selectively controls both the height and the tilt of the chair seat. Thus, the invention is inexpensive to manufacture and the reduced number of moving critical parts decreases the probability of device failure. More specifically, the present invention includes a base plate which is suitable for the mounting of a chair seat. The base plate has a pair of spaced apart flanges projecting downwardly from the chair seat mounting surface. A bracket adapted to be supported by the pedestal of the chair having two opposite sides and a bottom portion is provided. The sides of the bracket are pivotally mounted to the downwardly projecting flanges of the base plate so that the bottom of the bracket is spaced apart from the bottom surface of the base plate. The pivotal attachment of the base plate with the bracket allows

the base plate to tiltably move against the restoring force of a spring means mounted between the bracket and the base plate. The bottom of the bracket has an opening for accepting a pneumatic cylinder which provides a height adjustment means for the chair. A pair of aligned orifices are placed one in each of the bracket sides for accepting opposite ends of a lever. The additional orifices located on the sides of the bracket are oriented to slidably allow one end of the lever to protrude through the bracket and actuate a base plate flange thus prohibiting tilt of the base plate. The lever thus provides a locking apparatus for the device. The lever has a cam thereon which extends inside and between the sides of the bracket, fi pneumatic cylinder contains an actuator valve which extends into the bracket such that the cam actuates against the valve to allow height adjustment of the pneumatic cylinder. The lever and cam allows actuation of the pneumatic valve in either of three ways. First, rotating the lever forward or second, rotating the lever backward causes depression or actuation of the pneumatic cylinder valve. Third, simply depressing the lever also causes depression of the valve. Thus, a chair control mechanism is disclosed which uses a single lever to selectively actuate both the height and the tilt controls of the chair.

Detailed Description The chair control mechanism generally indicated at 10 in Figure 1 of the accompanying drawings is shown in its intended environment, that is, mounting a chair seat of a posture chair of the type used by secretaries and others on the mechanism.

The chair shown in Fig. 1 has a pedestal 52 supported by casters 54 which support the chair relative to the floor and allow easy rolling movement of the chair along the floor. A chair column 56 is comprised of a tube 58 positioned centrally on the pedestal 52. The tube 58 accepts a gas or pneumatic spring 30 which is adjustable in length and allows adjustment of the seat 14 height. Pneumatic or gas springs or cylinders are commonly known in the art and are disclosed in U.S. Patents 4,364,605, 4,328,943, 4,555,085 which are hereby incorporated by reference. A chair control device 10 which is described more fully below is secured to the upper end of the pneumatic cylinder 30 and is also secured to the underside of a chair seat 14. The device 10 allows the chair seat 14 to tilt forward or backward, and also controls the actuation valve of a pneumatic cylinder.

The chair control mechanism 10 comprises a base plate 12, preferably comprised of sheet steel. The base plate 12 is formed in any shape including but not limited to a rectangle or square. The base plate 12 need not be planar, but planar is shown here for ease of explanation. The base plate 12 includes a pair of spaced apart downwardly projecting flanges 16. About 4 securing bores 74 are provided on the base plate 12 in spaced apart relation to provide passage therethrough of fastening screws 23 which allow securing of the base plate 12 to the chair seat 14.

The chair control device 10 includes a bracket 18 supported by a pneumatic cylinder 30. The bracket 18 which has two opposite sides 20 and 22 and a bottom portion 24 is shown in Figures 3 and 8.

Base plate flanges 16 are provided with a pair of bores 26 disposed opposite and in alignment with one another. Bracket 18 is also provided with bores in the sides 20 and 22 disposed opposite and in alignment with one another. When assembling the chair control device 10 the flange bores 26 and the bracket 18 bores 76 are aligned and a bolt 60 (shown best in Figures 3 through 8) is placed through the aligned bores. The bracket 18 is pivotally mounted to the base plate 12 by bolt 60 allowing the chair seat 14 to tiltably move forward or backward relative to the pneumatic cylinder 30.

The mounting of the bracket 18 to the flanges 16 is done in a manner to allow the bottom portion 24 of the bracket 18 to be in spaced apart relation to the bottom surface of the base plate 12. The bracket 18 is adapted to receive a pneumatic cylinder 30 by placing an opening 28 in the bottom portion 24 of the bracket 18. Bracket 18 may additionally include a downwardly protruding portion 32 containing another opening 34 therein. The opening 34 also accepts the pneumatic cylinder 30. The two spaced apart openings 28 and 34 together cooperate to ensure that the bracket 18 always remains perpendicular and stationary relative to the pneumatic cylinder 30.

A spring 62, shown best in Figures 4 and 8, is terminally mounted to the base plate 12 by a central bolt 78 which extends through the central portion of the spring and is screwably connected to the center of the tension adjuster 66. Spring 62 extends through the bottom portion 24 of bracket 18 through bracket opening 70 and abuts spring plate 80. Spring plate 80 attaches to bracket 18 via tabbed portions 82 which insert into slit openings 84 in the bracket sides 20 and 22. The spring 62

provides a resilient force by urging against spring plate 80 and provides a force against which the base plate 12 tilts. Tension adjuster 66 is preferably cup-shaped, however a wing nut or similar component may serve as the tension adjuster 66 as well. Rotating the tension adjuster 66 toward the bracket 18 increases the tension on the spring 62 impinging upon the tilting of the base plate 12.

The bracket sides 20 and 22 contain additional aligned oppositely disposed orifices 38 and 40 for accepting opposite ends of a lever 42. The lever 42 is placed into and slid through the first orifice 38, through the inside of the bracket 18 and is placed into the second orifice 40. The lever 42, in combination with a flange 16, provide a locking apparatus for prohibiting the tilting of the chair seat 14. The lever 42 is horizontally slidable such that the first end 44 of the lever 42 may protrude through the second orifice 40 and actuate against the base plate flange 16. When the first lever end 44 extends through the bracket 18 to actuate the flange 16, the first lever end 44 prohibits pivotal movement of the chair seat 14. Figures 4, 5, and 7 illustrate the lever end 44 in a locked position. By pulling the lever handle 50 away from the mechanism as shown in Figure 6, the first lever end 44 no longer actuates against the seat support flange 16 and the base plate 12 is free to pivot. Flanges 16 preferably include cut-out portions 86 and 88. First cut portion 86 is preferably larger than second cut portion 88 so that the second end 90 of lever 42 never contacts flange 16 even during rocking of the base plate 12 relative to the bracket 18. Second cut 88 is smaller than first cut 86 to

ensure that the first end 44 of lever 42 contacts the flange 16 to prevent rocking of the base plate 12 relative to bracket 18. Lever 42 also contains a cammed portion 68. In the preferred embodiment the lever 42 is flattened, for example by stamping or grinding, to provide the cam 68. The cam 68 is located between the first end 44 and the second end 90 of the levers 42 and is placed within the sides 20 and 22 of the bracket 18. Pneumatic cylinder 30 contains an actuator valve 36 which extends from the top of the cylinder in a manner commonly known in the art. When the valve 36 is depressed, it allows height adjustment of the pneumatic cylinder 30. The cam 68 of the lever 42 is situated so that the cam 68 actuates the valve 36 of the pneumatic cylinder 30.

The valve 36 is actuated by the lever cam 68 in any of three alternate methods. Figures 5 and 7 illustrate these three methods of actuation. First, in Figure 5, the lever 42 is shown depressed which causes the cam portion 68 of the lever to depress the valve 36 of the pneumatic cylinder 30 allowing height adjustment of the pneumatic cylinder 30 and therefore height adjustment of the chair seat 14. Second, Figure 7 illustrates that lever 42 may be rotated forwardly or third, may be rotated rearwardly. Rotating the lever either direction causes the cam 68 to actuate the pneumatic cylinder valve 36 allowing height adjustment of the cylinder. Besides depression of the actuator valve 36, lever cam 68 serves an additional function. First orifice 38 is preferably elongated and is placed in the bracket side 20 in a vertical orientation as shown in Figure 2. In order to place lever 42 through the first orifice 38, one must rotate the lever to

align the flattened cam portion 68 of the lever 42 with the first orifice 38. During insertion of the lever cam 68 the cam 68 is vertical. Once the cam 68 is through the orifice 38 the lever 42 is rotated until the cam 68 is horizontal. Thus, one can no longer slide the lever 42 out of the first orifice without first rotating the lever 42. Cam 68 contributes to prohibit disassembly of the lever 42 from bracket 18.

Likewise, with respect to the second orifice 40, the cam serves a similar purpose to that just described. Second orifice 40 is preferably substantially round in diameter. The size of the second orifice 40 is sufficient to accept the lever end 44 but not large enough to accept the cam 68. Thus, the lever 42 is slidable to engage the flange 16 to impinge tilting of the base plate 12. However, one cannot slide the lever completely through the bracket 18.

One skilled in the art will recognize that details of the previous embodiment may be varied without departing from the spirit and scope of the invention.