SPIRAL JAW LOCKING MECHANISM FOR ADJUSTMENT SYSTEM IN CHAIRS

MECANISME DE VERROUILLAGE DE MACHOIRES EN FORME DE SPIRALE POUR SYSTEME DE REGLAGE DE CHAISE

English Abstract

A locking chair adjustment mechanism for adjusting a position of a chair component. The mechanism comprises a central shaft, a spiral jaw clutch comprising two interconnecting spiral jaw interfaces and a slotted element wherein the slot is sized to slideably receive the central shaft for displacement of the slotted element when the mechanism is in an unlocked position. A locking pad locks the mechanism against the slotted element. A rotatable adjustment handle allows the mechanism to toggle from a locked position, to an unlocked position, by displacement of the spring mechanism caused by the rotation of the spiral jaw interface fixedly mounted on the adjustment handle, therefore releasing pressure on the locking pad. A spring mechanism is activated when the claimed mechanism goes from a locked position to an unlocked position, pulling the claimed mechanism back to a locked position. The claimed mechanism provides a low cost solution offering better locking capabilities than traditional braking mechanisms.

French Abstract

Un mécanisme de réglage de chaise verrouillable pour régler une position dun élément de chaise. Le mécanisme comprend un arbre central, un accouplement à crabots hélicoïdaux comprenant deux interfaces de crabots hélicoïdaux et un élément fendu, la fente étant dimensionnée pour recevoir larbre central pour le déplacement de lélément fendu lorsque le mécanisme est en position déverrouillée. Un tampon de verrouillage verrouille le mécanisme contre lélément fendu. Une poignée de réglage rotative permet au mécanisme de passer dune position verrouillée à une position déverrouillée, par déplacement du mécanisme à ressort provoqué par la rotation de linterface de crabots hélicoïdaux montée de manière fixe sur la poignée de réglage, ce qui permet de libérer la pression. Un mécanisme à ressort est activé lorsque le mécanisme revendiqué passe dune position de verrouillage à une position de déverrouillage, tirant le mécanisme revendiqué vers larrière à une position déverrouillée. Le mécanisme revendiqué fournit une solution peu coûteuse offrant de meilleures capacités de verrouillage que les mécanismes de freinage classiques.

Claims

7
CLAIMS:
1. A locking chair adjustment mechanism for adjusting a position of a chair
component, said mechanism comprising:
- a central shaft;
- a spiral jaw clutch comprising two interconnecting spiral jaw interfaces
wherein a first one of said spiral jaw interfaces is fixedly mounted on a
rotatable adjustment handle;
- a slotted element wherein a slot is formed in the slotted element, the
slot
being sized to slideably receive said central shaft therein for displacement
of
said slotted element when the mechanism is in an unlocked position;
- a locking pad for locking the mechanism against said slotted element;
- a spring mechanism attached to said locking pad;
- a rotatable adjustment handle to toggle the adjustment mechanism from a
locked position to an unlocked position by rotating said first one of said
spiral
jaw interfaces in order to produce a displacement of said spring mechanism to
release pressure on said locking pad,
wherein the chair component is mounted on said slotted element and the
position of
the component is adjusted through displacement of the central shaft within the
slot
formed in the slotted element, and wherein said spring mechanism urges said
adjustment mechanism towards the locked position when said adjustment
mechanism is in the unlocked position.
2. The chair adjustment mechanism according to claim 1, wherein a position
of
said central shaft is maintained by a fixed structure of the chair, said
structure being
traversed by said central shaft.
3. The chair adjustment mechanism according to claim 2, wherein a portion
of
said central shaft is covered with a sheath traversing said fixed structure.

8
4. The chair adjustment mechanism according to any one of claims 2 or 3,
further comprising a washer positioned between said fixed structure of the
chair and
said slotted element, said washer being coaxially mounted onto said central
shaft.
5. The chair adjustment mechanism according to any one of claims 1 to 4,
wherein the chair component is a chair seat bottom.

Description

CA 02707328 2016-12-06
1
SPIRAL JAW LOCKING MECHANISM FOR ADJUSTMENT SYSTEM IN CHAIRS
FIELD OF THE INVENTION
The present invention generally relates to a locking adjustment system for
chairs.
More particularly, it relates to a spiral jaw locking mechanism for an
adjustment
system in chairs.
BACKGROUND OF THE INVENTION
Several types of chairs are provided with reclining mechanisms. Certain
reclining
mechanisms in chairs include a base structure that allows the seat to slide
forwards
and backwards and cause inclination of the back part of the seat. Current
locking
mechanisms that are used to stop movement of the base structure and keep the
seat base from sliding typically include nut and bolt type interfaces.
However, this
type of interface does not provide adequate locking capability for positioning
of the
seat. Bolt systems are typically not very performant and sometimes are
subjected to
problems after long periods of use.
Several different prior art mechanisms using spiral jaws as part of an
adjustment
mechanism in chairs, or other apparatuses, are known to the Applicant.
US 6,135,524 (Faller at al.) discloses a frame structure (unrelated to a chair
mechanism) using a spiral jaw clutch type system for the translational
movement of
a rod against a spring in order to adjust the configuration of a mechanism
inside a
structure.
US 2007/0170767 (Oberlaender et al.) teaches an adjustment mechanism for a
surgical armrest using a spiral jaw clutch type system for the adjustment of a
mechanism of the armrest.

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US 5,029,940 (Golynsky et al.) teaches a chair tilt and chair height control
apparatus
where the tilt control mechanism uses a spiral jaw clutch type system to
control the
adjustment of the tilting of a section of the chair.
Other mechanisms known to the Applicant include US 3,936,091 (Rabinowitz);
US 4,540,148 (Jann); US 4,728,072 (Mitchell); US 6,719,372 (Glaspie et al.);
and
US 7,611,201 (Moriyama et al.).
However, none of the prior art documents cited above discloses a spiral jaw
clutch
mechanism for locking and unlocking an adjustment system sliding along a
slotted
element and associated with the positioning of a chair seat.
Consequently, there is presently a need for a chair adjustment mechanism that
uses
a spiral jaw clutch to offer improved locking performance and operate reliably
over a
longer period of time.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a locking chair adjustment
mechanism that addresses at least one of the above-mentioned needs.
According to the present invention, there is provided a locking chair
adjustment
mechanism for adjusting a position of a chair component, said mechanism
comprising:
- a central shaft;
- a spiral jaw clutch comprising two interconnecting spiral jaw interfaces
wherein a first one of said spiral jaw interfaces is fixedly mounted on a
rotatable adjustment handle;

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- a slotted element wherein a slot is formed in the slotted element, the
slot
being sized to slideably receive said central shaft therein for displacement
of
said slotted element when the mechanism is in an unlocked position;
- a locking pad for locking the mechanism against said slotted element;
- a spring mechanism attached to said locking pad;
- a rotatable adjustment handle to toggle the adjustment mechanism from a
locked position to an unlocked position by rotating said first one of said
spiral
jaw interfaces in order to produce a displacement of said spring mechanism to
release pressure on said locking pad,
wherein the chair component is mounted on said slotted element and the
position of
the component is adjusted through displacement of the central shaft within the
slot
formed in the slotted element, and wherein said spring mechanism urges said
adjustment mechanism towards the locked position when said adjustment
mechanism is in the unlocked position.
The use of the spiral jaw clutch and spring mechanism provides a low cost
solution
offering improved locking capabilities than traditional braking mechanism for
certain
applications, while operating reliably over a period of time.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and advantages of the invention will become apparent
upon
reading the detailed description and upon referring to the drawings in which:
Figure 1 is a perspective view of the claimed mechanism in accordance with a
preferred embodiment of the present invention;
Figure 2 is an exploded view of the locking adjustment mechanism shown in
Figure
1;

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Figure 3A is another exploded view of the locking adjustment mechanism shown
in
Figure 1, with figures 3B and 3C highlighting the spiral jaw interface
components of
= the mechanism;
Figure 4A is a bottom perspective view of the locking adjustment mechanism
shown
in Figure 1, in a locked position, with figures 4B and 4C showing top and
bottom
perspective views of the mechanism positioned on a chair; and
Figure 5A is a bottom perspective view of the locking adjustment mechanism
shown
in Figure 1, in an unlocked position, with figures 5B and 5C showing top and
bottom
perspective views of the mechanism positioned on a chair.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE
INVENTION
In the following description, the same numerical references refer to similar
elements.
The embodiments shown in the figures are preferred.
Moreover, although the present invention was primarily designed for use with
adjustment of a seat bottom of a chair, it may be used with other types of
chair
components, as apparent to a person skilled in the art. For this reason,
expressions
such as "chair" or "seat" used herein should not be taken as to limit the
scope of the
present invention and include all other kinds of chair assemblies or items
with which
= 25 the present invention could be used and may be useful.
Moreover, in the context of the present invention, expressions such as
"structure"
and any other equivalent expressions and/or compound words thereof known in
the
art will be used interchangeably.

CA 02707328 2010-06-11
In addition, although the preferred embodiments of the present invention are
illustrated in the accompanying drawings and although the preferred
embodiments of
the adjustment mechanism as shown consist of certain geometrical
configurations as
explained and illustrated herein, not all these components and geometries are
5 essential to the invention and thus should not be taken in their
restrictive sense, i.e.
should not be taken as to limit the scope of the present invention. It is to
be
understood, as also apparent to a person skilled in the art, that other
suitable
components and cooperations thereinbetween, as well as other suitable
geometrical
configurations may be used for the adjustment mechanism and corresponding
parts
= 10 according to the present invention, as briefly explained and
inferred herein, without
departing from the scope of the invention.
Referring to any one of Figures 1 to 5C, a locking chair adjustment mechanism
is
shown, the mechanism comprises a central shaft 11 and a spiral jaw clutch 12
= 15 comprising two interconnecting spiral jaw interfaces 14 and 16.
One of the spiral jaw
interface 16 is fixedly mounted on a rotatable adjustment handle 10. A slotted
element 19 is also provided wherein the slot is sized to slideably receive the
central
shaft 11 for displacement of the slotted element 19 when the mechanism is in
an
unlocked position shown in Figure 5. A locking pad 18 for locking the
mechanism
20 against the slotted element 19 is also provided with a spring mechanism
22 attached
to it. Finally, a rotatable adjustment handle 10 allows the mechanism to
toggle from a
locked position shown in Figure 4, to an unlocked position shown in Figure 5,
by
rotating the spiral jaw interface 16 fixedly mounted on the adjustment handle
10 in
order to produce a displacement of the spring mechanism 22 therefore releasing
25 pressure on the locking pad 18. The chair component 23 is mounted on the
slotted
element 19 and the position of the component 23 is controlled through
corresponding movement along the longitudinal movement of the slot 20. The
spring
mechanism 22 is activated when the claimed mechanism goes from a locked
position shown in Figure 4, to an unlocked position shown in Figure 5, pulling
the
30 claimed mechanism back to a locked position.

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Preferably, as better shown in Figure 2, a position of the central shaft 11 is
maintained by a fixed structure 13 of the chair, the structure 13 being
traversed by
the central shaft 11.
Preferably, as better shown in Figure 2 as well, a portion of the central
shaft 11 is
covered with a sheath 15 traversing the fixed structure 13.
Preferably, as better shown in Figures 2, 4A to 4C and 5A to 5C, a washer 17
is
positioned between the fixed structure 13 of the chair and the slotted element
19, the
washer 17 being coaxially mounted onto the central shaft 11.
Preferably, the chair component is a chair seat bottom whose displacement is
reflected in the inclination of the back part of the seat. However, the
adjustment
mechanism according to the present invention may be used for adjustment of
other
chair components.
Although preferred embodiments of the present invention have been described in
detail herein and illustrated in the accompanying drawings, it is to be
understood that
the invention is not limited to these precise embodiments and that various
changes
and modifications may be effected therein without departing from the scope or
spirit
of the present invention.

Representative Drawing