Note: Descriptions are shown in the official language in which they were submitted.
CA 02539854 2006-03-16
CgAIR CONTROL DEVICE
FIELD OF THE INVENTION
The present invention relates to an adjustment mechanism
for a chair allowing relative displacement of two chair parts.
In an exemplary embodiment, the invention provides a seat tilt
and locking device.
BACFtGROUN D
It is typical in office chairs for the seat to tilt
rearwardly as an occugant leans back in the seat. To
~ accommodate this motion, known chair control devices allow a
seat portion of a chair to tilt in relation to its wheeled
support. These chair control devices are provided with an
adjustable spring to counteract the rearward force exerted on
the chair by the user, which force will ordinarily cause the
chair to return to an upright position when unoccupied. This
adjustable spring may be pretensioned by a user to a greater or
lesser degree to cause the spring to exert a greater or lesser
reaction farce to the rearward force supplied by the user.
Sophisticated chair control devices are known which, in
addition to having an adjustable spring, incorporate a clutch
assembly which allows a user to lock the chair in any reclined
or uprigrt position throughout its range of motion. Simpler
devices are also known which have a tilt sock mechanism which
~:erely prevents the chazr from righting itself when in a
reclined position and/or locks the chair in an upright position.
The ~rere sophisticated chair control devices which
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incorporate the clutch assembly feature are far more expensive
and complicated to manufacture than the simpler tilt lock
mechanisms. This is due to certain design considerations,
because of which it has been necessary in the past to use an
expensive tilt assembly and torsion spring in devices featuring
both an adjustable pretensioned sgring for counteracting the
tilt force exerted by a user and a clutch assembly for locking
in a tilt position.
SUMMARY OF THE TNVENTTON
Tn an exemplary embodiment, an adjustment mechanism for a
chair comprises a base, an adjustable member tiltably mounted on
the base and moveable between a first position and a second
position, a compression spring bearing on the adjustable member
which urges the adjustable member toward the first position when
compressed and a clutch attached to the base and the adjustable
member capable of engaging to hold the adjustable member in a
fixed position relative to the base between or including the
first position and the second position.
In another embodiment, an adjustment mechanism for a chair
comprises a base, an adjustable member tiltably mounted on the
base and moveable between a first position and a second
position, an elastic element bearing on the adjustable member
which urges the adjustable member toward the first position when
deformed, and a clutch comprising a clutch lever mounted on the
base and a clutch assembly attached to the adjustable member.
she clutch assembly connects the clutch lever and the adjustable
member, and the clutch is capable of engaging to hold the
adjustable member in a fixed position relative to the base
between or including the first position and the second position.
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In yet another embodiment, an adjustment mechanism for a
chair comprises a base comprising a first central plate and a
first pair of sidewalk extending substantially perpendicularly
downward from the first central plate, the first pair of
sidewalls being substantially parallel to one another, an
adjustable member tiltably mounted on the base below the first
central plate moveable between a first position and a second
Position, an elastic element provided below the adjustable
member and the first central plate of the base which bears on
the adjustable member and urges the adjustable member toward the
first position when deformed, and a clutch attached to the base
and the adjustable member capable of engaging to hold the
adjustable member in a fixed position relative to the base
between or including the first position and the second position.
In yet another embodiment, an adjustment mechanism for a
chair comprises a base comprising a first central plate and a
first pair of sidewalls extending substantially perpendicularly
2~ downward from the first central plate, the first pair of
sidewalls being substantially parallel to one another, an
adjustable member moveable between a first position and a second
position which is tiltably mounted on the base, and which
comprises a second central plate, a column mount and a second
pair of sidewalls extending substantially perpendicularly
downward from the second central plate to the column mount, the
second pair of sidewalk being substantially parallel to one
another, an elastic element bearing ors the adjustably member
which urges the adjustable member toward the first position when
3'~ deformed, and a clutch attached to the base and the adjustable
member capable of engaging to hold the adjustable member in a
fixed position relative to the base between or including the
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first position and the second position.
BRIEF DESCRIPTION OF THE DRAWINGS
is
Fig. 1 shows a conventional tilt mechanism for use with a
chair control device;
Fig. 2 shows another conventional tilt mechanism for use
with a chair control device;
Fig. 3 shows an exemplary embodiment of a tilt mechanism
for use the present chair control device;
Fig. 4 shows perspective view of an exemplary embodiment of
a chair control device wherein the tilt mechanism is concealed
beneath a shroud:
Fig. 5 shows another perspective view of the chair control
device of Fig. 4 wherein the shroud has been removed;
Fig. 6 shows an overhead view of the chair control device
of Fig. 5;
Fig. 7 depicts outlines of an embodiment of the present
tilt mechanism in both the reclined and upright positions;
Fig. 8 shows a side view of an exemplary embodiment of a
tilt mechanism;
Fig. 9 shows an overhead view of the tilt mechanism of Fig.
8;
Fig. 1~A depicts detail Z of Fig. 8;
Fig. IDB shows an end view of the tilt :rechanism of Fig. 8;
Fig. I1 shows an overhead view of an exemplary eynbodiment
of a i~ase of a chair contras device;
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Fig. 12 shows a side view of the base of Fig. 11;
Fig. 13 shows an end view of the base of Fig. 11;
Fig. 14A depicts detail 1 of Fig. 11;
Fig. 19B depicts section B-B of Fig. 11;
Fig. I4C depicts section A-A of Fig. 11:
Fig, 15A shows a top view of one embodiment of a tilt
clutch bracket;
Fig. 15B shows a side view of the tilt clutch bracket of
Fig. 15A; and
Fig. 15C depicts detail 2 of Fig. 12.
Before any embodiment of the invention is explained in
detail, it is to be understood that the invention is not limited
in its application to the details of construction and
arrangements of components set forth in the following
description, or illustrated in the drawings. The invention is
capable of alternative embodiments and of being practiced or
being carried out in various ways. Specifically, numerical
dimensions, where they appear on the following drawings,
represent those of exemplary embodiments only and may be
modified by one skilled in the art as Conditions warrant. Also,
it is to be understood that the terminology used herein is for
the purpose of illustrative description and should not be
regarded as 3imiting.
_5.
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DETAILED DESCRIPTION
Fig. 1 shows a conventional tilt mechanism for use with a
chair control device. This device, known in the art as a "tilt
lock" device, comprises a tilt mechanism 10 pivotably connected
to a base 11. The underside of the mechanism has a column mount
15 on its underside which may be mounted an the column of the
wheeled support of a standard office chair. As the tilt
mechanism 10 rotates relative to the base 11, this causes the
wheeled support of the chair to tilt relative to a seat of the
chair mounted on the top surface of the base lI.
Counteracting the tendency of the tilt mechanism 10 to
rotate relative to the base 11 is the compression spring 13
compressed between the underside of the tilt mechanism 10 and a
knob 12 secured to the base 11 by the retaining bolt 14. The
knob 12 is adjustably mounted on the retaining bolt 14 so that
it may be rotated to add or remove a preloading force to the
compression spring 13. This preloading force causes the tilt
mechanism 10 to rotate more or less stiffly relative to the base
11 when subjected to an outside force. Through this mechanism,
a user of the chair can adjust the recline resistance of her
chair to her personal comfort.
Fig. 2 shows another conventional tilt mechanism far use
with a chair control device. Similarly to the device of Fig. 1,
a tilt mechanism 20 is provided which rotates relative to the
base 21, and the tilt mechanism 20 is provided with a column
mount 25 on its underside. In contrast to the device of Fig. 1,
in place of a compression spring bearing on the outside of the
tilt mechanism 20 a torsion spring 23 is provided ~~ithin the
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tilt mechanism 20, and a knob 22 bears directly on the tilt
mechanism 20. The knob 22 is drawn downwards by a retaining
hook 24 which passes through an opening in the tilt mechanism 20
to engage with a torsion spring 23 within. The opposition end
of the torsion spring 23 bears on the base 21, and is provided
with a stop 28 for this purpose.
In the conventional mechanism shown in Fig. 2, the
compression spring has been replaced by the torsion spring 23 in
part to accommodate the addition of the clutch assembly 26.
This assembly connects the base 21 and the tilt mechanism 20 and
allows the rotation of one to be halted relative to the other at
any position throughout its range. While the clutch assembly
provides a useful functionality to the chair control device of
Fig. 2, it cannot be added to the chair control device shown in
Fig. 1 as is without significantly redesigning the tilt
mechanism 11 requiring at the very least that it be made larger
overall, significantly so in the area of the added clutch
z0 assembly. This larger tilt mechanism 20 cannot easily
accommodate a compression spring without impeding its function.
Furthermore, if one were to try to add a compression spring to
the mechanism shown in Fig. 2 by placing it between the knob 22
and the tilt mechanism 20, the knob 22 would extend an
unacceptably far distance below the base 21 and interfere with
other functions of the chair itself. Thus in the known
mechanism of r ig. 2, in place of a compression spring a torsion
spring 23 is used. Although the redesigned tilt mechanism 24
provides tilt functionality to the chair control device and
accommodates tl:e newly added clutch assembly 26, its complexity
makes it difficult to manufacture and thus relatively expensive.
Likewise the torsion spring 23 is also more expensi;,re than more
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common compression springs. As such the chair control device of
Fig. 2, while providing increased functionality over the chair
control device of Fig. 1, does so only at an increased cost in
materials.
Fig. 3 shows an exemplary embodiment of a tilt mechanism
for use the present chair control device. The device has a tilt
mechanism 30 which as in the previous figures rotates relative
to the base 31. However unlike the prior art figures, this
embodiment of a tilt mechanism features a clutch assembly 36
together with a compression spring 33, as well as a relatively
simple design for the tilt mechanism 30 comprising a central
plate 38, a column mount 35 and a pair of sidewalk 37 extending
from the central plate to the column mount . In one embodiment,
the pair of sidewalls 37 are substantially parallel to one
another and substantially perpendicular to the central plate 38.
In another embodiment, the pair of sidewalls reinforce and add
rigidity to the central plate. In yet another embodiment, an
incline 37 may be provided on the central plate 38, on which
incline 37 the compression spring 33 bears.
Because the tilt mechanism 30 is provided with these
sidewalls 37 extending from the central plate 38 away from the
base 31 towards the bottom of the device in contrast to the tilt
mechanisms of the prior art, the surface of the central plate 38
an which a spring bears can be closer to the base 31 than would
otherwise be the case. As such, a compression spring can be
used rather than torsion spring of the prior art. To further
3p accommodate this substitution, the clutch assembly 36 and a
clutch lever (not shown) can be provided as a unit fixably
fiourted cn ~,he base 31 elow tNhich po=nt it pivotabiy engages
the tilt mechanism 30. A knob 32 is also provided secured to
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the base 31 by the retaining bolt 34. The knob 32 is adjustably
mounted on the retaining bolt 34 so that it may be rotated to
add ar remove a preloading force to the compression spring 33.
Fig. 4 shows perspective view of an exemplary embodiment of
a chair control device wherein the tilt mechanism is concealed
beneath a shroud. The device comprises a base 51 and a tilt
mechanism (not shown) which may be pivotably connected thereto
1~ at the primary pivot point 42. A shroud 49 attached to the base
51 at least partially covers the tilt mechanism to reduce the
risk to a user of a user's finger being caught between the tilt
mechanism and the base 51. A knob 52 is provided which may be
adjusted to add or remove a prelaading force to the compression
Spring 59 mounted beneath the knob 52 on the tilt assembly. In
an alternative embodiment, the spring 59 may be any elastic
element. The base 51 is provided with tabs 67 through which the
device may be attached by bolts or another fastener to the
underside of the seat portion of a chair (not shown).
The tilt mechanism supports the column mount 55 which can
be mounted on the column of a standard wheeled support for an
office chair (not shown). This column may include a gas
cylinder having two-chambers separated by a normally closed
valve. A user actuator 62 may be provided tiltably mounted in a
housing above the valve opening member, and which may be
operated to depress the valve opening member in order to open
the cylinder valve to permit height adjustment of the seat.
Further adjustment devices may be provided as part of the
present chair control device including a primary ciu~ch lever 63
attached to the base 51 by a clutch housing 43. The primary
clutch lever 63 is provided to operate a clutch assemb:.y at
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least partially concealed within the shroud 94, which assembly
comprises at least one clutch plate and a clutch pin 41. The
primary clutch lever 63 may be operated to engage or disengage
the clutch assembly to prevent or permit tilt mechanism to move
relative to the base 51. A secondary adjustment assembly 60 may
be provided to support element for a chair backrest, the motion
of which secondary adjustment assembly 60 may halted by the
engagement of a secondary clutch lever 61. A recline locking
lever 65 may be provided mounted on the base 51 having a recline
locking stop 66 thereon which may be slid into a blocking
position to prevent the tilt assembly from being adjusted to the
fully upright position relative to the base 51.
Fig. 5 shows another perspective view of the chair control
device of Fig. 4 wherein the shroud has been removed so that the
tilt mechanism 50 is visible. As previously mentioned, the tilt
mechanism 50 may be pivotably connected to the base 51 at a
primary pivot point 42. Also visible in Fig. 5 is a spring
loaded clutch bracket 64 which the primary clutch lever 63
mounted on the base 51 may be operated to disengage, as well as
a clutch assembly 56. Fig. 6 shows an overhead view of the
chair control device of Fig. 5 having a clutch spring 68 for
spring loading the clutch bracket 64. The tilt mechanism 50 is
shown here having reinforcing ridges &9 thereon to provide
additional stiffness. Fig. 7 depicts an embodiment of the
present chair control device wherein an outline of the base 71
is si~ot~an in relation to outlines of the tilt mechanism in both
t~:e reclined position 70a as ;cell as an upright p006Fsition 70b.
cig. 8 shows a side view of an exemplary embodiment of a
tilt :rechanism 8G provided with a primary pivot point 82 fcr
engaging with a base of a chair control device, column mount
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flanges 85 for engaging with a column mount, a user actuator 84
to permit height adjustment of the seat and an actuator slot 83
therefore, an incline 86 to provided a bearing surface for a
compression spring or other elastic element, and a retaining
bolt passage 87 through which a retaining bolt may pass to
secure a control knob to the base of a chair control device.
Fig. 9 shows an overhead view of the tilt mechanism 80 of
Fig. 8 wherein clutch mounts 88 are visible. In one embodiment,
the clutch mounts 88 comprise raised tabs which pivotably engage
the at least one clutch plate of the clutch assembly of the
chair control device. the column mount flanges 85 are also
shown having at least one rivet hole 89 to which a plate column
mount may be attached to receive the column of a wheeled or
other support of a chair. Reinforcing flanges 92 extending
downward from the second central plate 90 to reinforce the
second central plate 90 are also shown in Figs. 8, 9 and 10B.
Fig. l0A depicts detail 1 of Fig. 8 showing the user
actuator 84 to permit height adjustment of the seat and the
actuator slot 83 therefore. Fig. lOB shows an end view of the
tilt mechanism of Fig. 8 wherein the a tilt mechanism 80
comprises a second central plate 90, a second pair of sidewalls
91, and column mount flanges 85 which may be attached to a
column mount, in which case a passage is provided through the
tilt mechanism 80 defined by the second central plate 90, the
column support and the first pair of sidewalls 91. In an
exemplary embodiment, the second pair of sidewa y s 91 extend
substantially perpendicular from the central plate 90, and are
substantially parallel to one another.
F:~g, 12 shows an overhead view of an exemplary embodiment
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of a base 111 for use with a chair control device comprising
tabs 117 through which the base 121 may be attached by bolts or
other fasteners to the underside of the seat portion of a chair
(not shown), a raised portion 115 and retaining bolt socket 116
for securing an end of a retaining bolt, a protrusion 114, and a
neck 113 which narrows to provide an attachment point for a
secondary adjustment assembly 60. In ane embodiment, base 111
comprises a base end plate 112 though which a recline locking
stop 66 of a recline locking lever 65 passes.
Fig. I2 shows a side view of the base ill of Fig. 11 having
a passage 121 for a clutch bracket 64, a passage 122 for a
clutch pin 41, an actuator slot 118, a passage 123 for a
secondary clutch pin, secondary pivot point 124 for a secondary
adjustment assembly 60, and a primary pivot point 125 for a tilt
mechanism 50. Fig. 13 shows an end view of the base 111 of Fig.
11 wherein the base comprises a central plate 131 and a pair of
. sidewalls 132. In an exemplary embodiment, the pair of
sidewalls 132 extend substantially perpendicularly downward from
the central plate 131 and are substantially parallel to one
another.
Fig. 14A depicts the protrusion 114 highlighted in detail 1
of Fig. 12, Fig. 14B depicts the raised portion 115 highlighted
in section 3-B of Fig. 11, and Fig. I4C depicts the raised
portion 115 and retaining bolt socket 116 highlighted in section
A-A of Fig. I1. Fig. 15A shows a top view of one embodiment of
a tilt crutch bracket 154 having a clutch pin passage 151, Fig.
15B shows a side view of the tilt clutch bracket 154, and Fig.
I5C depicts detail 2 of Fig. 12.
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