Note: Descriptions are shown in the official language in which they were submitted.
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"IMPROVEMENT8 IN OR RELATING TO A CHAIR CONTROL MECHANISM"
THE PRESENT Ihv~ ON 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.
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 arts 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 US-A-4,364,605, US-A-4,328,943 and US-A-
4,555,085. US-A-4,364,605 discloses a device suitable for
use on a posture chair. The device uses one lever to
control three pneumatic cylinders. One cylinder controls
backrest tilt, a second cylinder controls set tilt, and a
third cylinder controls seat height. Using three pneumatic
cylinders to control three distinct motions increases the
cost of such a device.
US-A-4,328,943 discloses another chair control
device which also uses one lever to adjust height and tilt
of the chair seat. The described chair control mechanism
incorporates a base plate mounted on the underside of the
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chair seat, the base plate having a pair of spaced apart
flanges projecting downwardly from the base plate. The
mechanism further incorporates a bracket having two
opposite upstanding side flanges and a bottom portion. The
side flanges of the bracket are pivotally mounted to the
flanges of the base plate to allow the base plate to tilt
relative to the bracket. The bottom of the bracket is
adapted for accepting a pneumatic cylinder which has an
actuator valve extending into the bracket. A lever is
provided which can be manipulated to actuate the valve.
However, the device uses an actuator block to actuate the
height and tilt adjustment means in conjunction with the
lever. Thus, the actuator bloc~ is an additional critical
moving part adding increased likelihood for failure of the
mechanism.
US-A-4,555,085 also discloses a tilt and height
control mechanism for a chair. The described arrangement
uses a lever in conjunction with a slide member. As in the
device of US-A-4,338,943, the 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 utilises, 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.
According to this invention there is provided a
chair control mechanism for controlling the height and tilt
of a chair seat, comprising a base plate suitable for
mounting a chair seat, said base plate having a pair of
spaced apart flanges projecting downwardly from said base
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plate, a bracket having two opposite sides and a bottom
portion, said sides being pivotally mounted to said flanges
of said base plate to allow said base plate to tilt
relative to said bracket, said bottom of said bracket being
adapted for accepting a pneumatic cylinder, which has an
actuator valve extending into said bracket, and a control
lever to actuate the valve, wherein the mechanism further
comprises a pair of aligned orifices, one in each of said
bracket sides for accepting opposite ends of the lever,
said lever having a cam thereon, said cam being located
between the sides of said bracket, the lever being located
such that said lever cam directly contacts and actuates
against said valve, and such that said lever is free to
directly slidably engage one said base plate flange to
prohibit tilting movement of said base plate.
The mechanism may further comprise a spring means
for providing a restoring force against said tilting
movement of the base plate.
The invention also relates to a chair incorporating
a control mechanism as described above, the chair
comprising a seat to which the base plate is mounted and a
pedestal accepting the pneumatic cylinder.
In order that the invention may be more readily
understood, and so that further features thereof may be
appreciated, the invention will now be described, by way of
example, with reference to the accompanying drawings in
which
FIGURE 1 is an isometric view of a chair control
mechanism of the present invention with a chair seat and
pedestal mounted thereon,
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FIGURE 2 is a side view of the chair control
mechanism of Figure 1,
FIGURE 2 is a side view of the chair control
mechanism of Figure 1,
FIGURE 3 is a rear view of the chair control
mechanism of Figures 1 and 2,
FIGURE 4 is a cross-section of the mechanism of
Figures 1 to 3 taken along line 4-4 of Figure 2,
FIGURE S is a cross-section of the mechanism of
Figures 1 to 3 taken along line 4-4 of Figure 2 with the
lever actuating the valve of the pneumatic cylinder,
FIGURE 6 is a cross-section of the mechanism of the
mechanism of Figures 1 to 3 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,
FIGURE 7 is a cross-section of the mechanism of
Figures 1 to 3 taken along line 4-4 of Figure 2 further
illustrating the rotational movement of the lever, and
FIGURE 8 is an exploded view of the mechanism of
Figures 1 to 7.
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
preferred embodiment of the invention is inexpensive to
manufacture and the reduced number of moving critical parts
decreases the probability of device failure. More
specifically, the preferred embodiment of the present
invention includes a base plate which is suitable for the
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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
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the base plate to tiltably ~ove against the restoring foTce of
a spring means mounted between the brac~et 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
loc~ing apparatus for the device. The lever has a cam thereon
which extends inside and between the sides of the brac~et. h -
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 bac~ward 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.
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.
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The chair shown in Fig 1 has a pedestal 52 supporte~d b~
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 ~as 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. r~tc..~s
4,364,605;L4,328,943;~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 bac~ward, and also controls the actuation valve of
15 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
sc~lare. 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
sécuring 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
2S 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.
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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 assem~ling
S 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~ ~e ~wo 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
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provides a resilient force by urging a~ains~ gpring pl~e 8
and provides a force agai~st 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 brac~et
18 increases the tension on the spring 62 impinging upon the
tilting cf 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 t~e 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
prohibitinq the tilting of the chair seat 14. The lever 42 is
harizonta~ly slidable such that the first end 44 of the lever
42 may pr~trude through the second orifice 40 and ac~ua~e
against the base plate flange 16. When the first lever end 44
extends ~rough the bracket 18 to ~ tc the flange 16, the
first leve~ end 44 prohibits pivotal movement of the chair seat
14. Fig;re~ 4, 5, and 7 illustrate the lever end 44 in a
locked po~ition. By pulling the lever handle 50 away from the
mechani~ as shown in Figure 6, the first lever end 44 no
longer c ~c~c~ 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 c~t portion 86 is preferably larger than second cut
portion 88 so that the second end 90 of lever 42 never contacts
flange 1~ even during rocking of the base plate 12 relative to
the brac~t 18. Second cut 88 is smaller than first cut 86 to
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ensure that the first end 44 of lever 42 contacts th~ flan~e 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
lever~ 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 S 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 adjustmen~ 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 '8 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
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align the flattened cam portion 68 of the lever 42 with,,the
first orifice 38. During insertion of the levur c~m 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
lS completely through the brac~et 18.
Ai~/lENv'D SH~T
