Note: Descriptions are shown in the official language in which they were submitted.
CA 02652183 2009-02-02
PIVOT ASSEMBLY
BACKGROUND
[0001] This invention relates to a pivot assembly and to a chair control
incorporating a pivot assembly.
[0002] It is known to slidably mount a slide plate to the seat plate of a
chair
control to allow the user to change the relative position of a chair seat,
which is
attached to the slide plate, to the seat plate. In a known arrangement, a U-
shaped
member is pivotably mounted to either side of the slide plate with the free
ends of
the U-shaped member received in racks which form part of the seat plate. The U-
shaped member is spring biased so that the free ends are urged into the racks,
thereby fixing the relative position of the slide plate and seat plate. If the
U-shaped
member is pivoted by a user against this spring pressure, the free ends leave
the
racks, freeing the slide plate to slide with respect to the seat plate. When a
desired
position is achieved, the U-shaped member may be released whereupon the free
ends of the member will re-enter the racks and lock the slide plate in this
new
relative position with respect to the seat plate.
[0003] The U-shaped member is pivotably mounted to the slide plate by a pair
of
pivots, each of which has an attachment portion which attaches to the U-shaped
member. A pop rivet may be received through a hole in a pivot and through the
slide plate in order to pivotably affix the pivot to the slide plate.
[0004] This invention seeks to provide an improved pivot assembly.
SUMMARY OF INVENTION
[0005] In accordance with this invention, there is provided a pivot assembly
with
a pivot support member having a keyway. The keyway has two oppositely directed
longer keyway wings extending from a middle section and the middle section has
two oppositely directed shorter keyway wings extending in a direction
transverse to
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that of the longer keyway wings. The shorter keyway wings have convexly
radiused ends. The pivot assembly also has a pivot with an attachment portion
and
a key projecting rearwardly from the attachment portion. The key has a
rearward
section with oppositely directed longer key wings which are longer than the
shorter
keyway wings but sufficiently short to allow the longer key wings to pass
through
the keyway. The key also has a middle section between the rearward section and
the attachment portion. The middle section has oppositely directed shorter key
wings with convexly radiused ends. The shorter key wings extend in a direction
aligned with that of the longer key wings. The shorter key wings have a length
substantially matching that of a length of the shorter keyway wings. The
radiused
end of each shorter key wing has a radius substantially matching a radius of a
radiused end of each of the shorter keyway wings such that the shorter key
wings
fit with a close tolerance between ends of the keyway shorter wings.
[0006] Other features and advantages will be apparent from the following
description in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] In the figures which illustrate an example embodiment of the invention,
[0008] FIG. 1 is a perspective view of a chair control,
[0009] FIG. 2 is a partially assembled fragmentary perspective view of the
chair
control of FIG. 1,
[0010] FIG. 2A is a fragmentary side view of a portion of FIG. 2,
[0011] FIG. 2B is a side view of a portion of FIG. 2,
[0012] FIG. 3A is a partially assembled fragmentary perspective view of the
chair control of FIG. 1,
[0013] FIG. 3B is a cross-sectional view along the lines 3B-3B of FIG. 3,
[0014] FIG. 4A is a partially assembled fragmentary perspective view of the
chair control of FIG. 1,
[0015] FIG. 4B is a cross-sectional view along the lines 4B-4B of FIG. 4,
[0016] FIG. 5 is a partially exploded perspective view of the chair control of
FIG.
1,
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[0017] FIGS. 6A to 6E are schematic side views of the chair control of FIG. 1
illustrating its operation.
DETAILED DESCRIPTION
[0018] Referring to FIGS. 1 and 6B, a chair control 10 has a slide plate 12
with
aligned longitudinal slots 14 receiving bolts 16 that are screwed to a seat
plate 20.
This provides a sliding attachment of the slide plate to the seat plate. A
chair seat
18 (FIG. 6A) may be attached to the slide plate. The seat plate 20 may be
pivotably mounted to the main frame 21 of the chair and the main frame 21 may
be
supported on a gas cylinder (not shown) extending from a chair base (not
shown).
A U-shaped member 22 is joined to the sides 24, 26 of the slide plate 12 by
pivots
30. The U-shaped member has arms 68 terminating in inwardly turned free ends
32, each of which extends through a slot 34 in the slide plate and terminates
at a
rack 36 attached to the seat plate. The medial section of the U-shaped member
22
forms a handle 38. A spring 40 coils around each free end 32 and has its ends
supported by catches 42 formed in the slide plate. These springs bias the U-
shaped member so that the free ends 32 are urged into racks 36.
[0019] With reference to FIGS. 2 and 2A, the slide plate 12 has a keyway 50
formed in each of its sides 24, 26. The keyway has two oppositely directed
longer
keyway wings 52a, 52b extending from a middle section formed by two oppositely
directed shorter keyway wings 54a, 54b. As is apparent from the figures, the
shorter keyway wings extend in a direction transverse to that of the longer
keyway
wings. The shorter keyway wings 54a, 54b have radiused ends 56a, 56b.
[0020] Referencing FIGS. 2 and 2B, each pivot 30 has an attachment portion 58
with a key 60 projecting rearwardly from the attachment portion. The key has a
rearward section, R, with oppositely directed longer key wings 62a, 62b. The
key
also has a middle section, M, between the rearward section and the attachment
portion. The middle section has a thickness slightly greater than that of the
thickness of the slide plate 12. The middle section has oppositely directed
shorter
key wings 64a, 64b. The shorter key wings 64a, 64b extend in a direction
aligned
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CA 02652183 2009-02-02
with that of the longer key wings 62a, 62b. The longer key wings 62a, 62b are
longer than the shorter keyway wings 54a, 54b and shorter than the longer
keyway
wings 52a, 52b. The shorter key wings 64a, 64b have a length substantially
matching that of a length of the shorter keyway wings 54a, 54b and each
shorter
key wing has a radiused end 66a, 66b with a radius substantially matching a
radius
of the radiused end of each of said shorter keyway wings 54a, 54b.
[0021] The attachment portion 58 of each pivot 30 is C-shaped with the central
axis of the C-shape aligned with the direction of the longer key wings 62a,
62b. An
arm 68 of the U-shaped member 22 may snap into the attachment section.
[0022] With reference to FIGS. 2, the pivot 30 may be oriented so that the
longer
key wings 62a, 62b are aligned with the longer keyway wings 52a, 52b and the
longer key wings 62a, 62b may then be passed through keyway 50 as shown in
FIGS. 3A and 3B until areas of the rearward surface of the attachment portion
58
that extend outside the periphery of the keyway abut the slide plate 12. In
this
position, the longer key wings 62a, 62b are located behind the back face of
the side
of the slide plate. Next, as shown in FIGS. 4A and 4B, the pivot 30 may be
turned
900 so that the longer key wings 62a, 62b are now aligned with the shorter
keyway
wings 54a, 54b. Thus, the side wall of the slide plate is sandwiched between
the
longer key wings 62a, 62b of the pivot and the rear surface of the attachment
portion 58 of the pivot. Consequently, the pivot is locked to the side wall.
Further,
the shorter key wings 64a, 64b are now located in the keyway and are aligned
with
the shorter keyway wings 54a, 54b with the radiused ends 66a, 66b of these
wings
snugly fitted against the radiused ends 56a, 56b of the shorter keyway wings
54a,
54b.
[0023] Pivot 30 may be pivoted through a range of angles (of about +/- 30 )
from
its position as shown in FIG. 4A while an arcuate segment of each of the
shorter
key wings 64a, 64b remains snugly fitted against the radiused ends 56a, 56b of
the
shorter keyway wings 54a, 54b and the slide plate side wall remains sandwiched
between the longer key wings 62a, 62b and the rear surface of the attachment
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portion 58. Thus, within this range of motion, the pivot will remain securely
locked
to the side wall.
[0024] Prior to attaching a pivot 30 to each of side wall 24 and 26 of the
slide
plate, each pivot may be snapped onto an arm 68 of the U-shaped member 22 and
a spring 40 may be run over each arm. As the pivots are pivoted toward the
position indicated by FIG. 4, the free ends 32 of the U-shaped member may be
deflected outwardly to allow the U-shaped member to pivot until these ends 32
pop
into the slots 34 in the side walls of the slide plate. With the ends 32
within slots
34, the range of pivoting motion of the U-shaped member is limited by the
abutment
of the ends 32 with the ends of the slots 34. This range of motion is selected
so
that the pivots remain securely locked to the side wall throughout this range
of
motion. The ends of the springs may then be inserted into catches 42 to bias
the
ends 32 of the U-shaped member into the racks attached to the seat plate 20.
Lastly, as shown in FIG. 5, a cap 70 may be snap fit to each pivot 30.
[0025] The pivot is of one piece construction and manufactured from a hard
plastic.
[0026] Operation of the chair control 10 is illustrated in FIGS. 6A to 6E.
With the
U-shaped member in a slide plate locking position (FIG. 6A) whereat the free
ends
32 of the U-shaped member are received in the racks of the seat plate, a user
may
lift handle 38 (FIG. 6B). This rotates the U-shaped member against the urging
of
the springs 40 so that the ends 32 of the U-shaped member leave the racks and
abut the lower end of the slots 34 (FIG. 6C). The slide plate may then be slid
to
any desired position. Thereafter, the handle 38 may be released so that the U-
shaped member rotates back to its slide plate locking position (FIGS. 6D and
6E).
(In this regard, the nose of each tooth of the racks may be radiused so that
if each
end 32 hits a tooth, the slide plate would move slightly to align each end 32
with a
notch between rack teeth.)
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[0027] The described pivot assembly avoids the need for a separate fastener
(such as a pop rivet) to hold the pivot to the slide plate. This therefore
simplifies
manufacturing.
[0028] Of course the pivot could be constructed of metal rather than plastic.
The
longer wings of the keyway and key of the pivot need not have radiused ends
but
could, if desired, instead have ends which are squared off. The attachment
portion
of the pivot need not be a resilient clip but could instead be any other
suitable
attachment device, such as a two-piece housing which is held together with a
snap
fit or fasteners.
[0029] The described pivot assembly could be used in other pivoting
applications where the range of pivoting is limited. Further, in applications
where
the pivot may be tilted when it is inserted into the keyway, the longer key
wings
could be longer than the longer keyway wings. (The limit to the length of the
longer
keyway wings would be that where, after the upper longer key wing is inserted
through the keyway at a tilt angle and the pivot raised until its middle
section abuts
the end of the upper longer keyway wing, there is just enough space for the
lower
longer key wing to pass through the lower longer keyway wing.)
[0030] Other modifications will be apparent to those skilled in the art and,
therefore, the invention is defined in the claims.
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