The present invention relates to a mechanical device, particularly suitable
for the movement of a chair.
Mechanical devices of a known type are currently in use which are
commonly known as rocker plates and comprise a first plate that is
associable under the lower surface of the chair.
Said first plate has two first shoulders that protrude laterally and
downward, so as to form an interspace for accommodating a second plate
that is smaller and approximately U-shaped, so as to form two second
shoulders.
In particular, the second plate is pivoted to the first plate by way of a
pivot that is arranged transversely approximately at the centerline of the first
and second shoulders, which act as means for limiting the stroke of the
mutual oscillation between the first and second plates.
Oscillation compensating means are associated with the second plate in a
forward position and comprise a pair of shells between which a spring is
accommodated; said spring can be preloaded during a backward oscillation
of the chair.
The compensation means further comprise a tension element, arranged
coaxially to the spring, for connection to the first plate.
In particular, the traction element has a head that can be arranged in
abutment against the upper surface of the first plate and with which a stem is
associated; said stem passes through suitable first holes formed in the first
and second plates, so as to associate with a nut that is accommodated in a
knob arranged on the outside of the lower half-shell.
The stem and the nut are threaded, so that a rotation of the knob produces
a translational motion of the nut along the stem of the tension element and
therefore a compression of the spring between the two shells.
To the rear of the compensating means, a third plate is further associated
with the second plate; the third plate is also approximately U-shaped and is
provided with two third shoulders for contact against the lower surface of the
second plate.
The second and third plates respectively have a second hole and a third
hole, formed along the same axis, which constitute a seat for accommodating
the upper end of a central column for supporting the chair.
The central column of the mechanical device of a known type
accommodates a gas-filled cylinder, whose stroke is controlled by activating
an upper button.
Such button can be activated selectively by the user by way of the
rotation that can be imparted to a rod that is pivoted transversely and
approximately horizontally to the mechanical device.
In particular, the rod is arranged so as to pass through two fourth holes,
which are formed transversely in the second shoulders and through a slot and
a fifth hole, both provided in the first shoulders.
In this manner, an axial movement of the rod entails the disengagement
or, alternately, the engagement of its free end in the fifth hole, allowing or
not the free oscillation of the first plate and of the chair with respect to the
second plate and the central column.
The main drawback of this mechanical device of a known type is that the
first shoulders, which are designed to protect against accidental insertion of
fingers in the mechanism, often do not offer complete safety for the user
during the oscillation of the chair.
Another disadvantage is that in order to provide mechanical devices of
the known type it is necessary, so as to ensure good mechanical strength, to
use plates of particularly high thickness, for example 3 millimeters or more.
This entails a considerable use of material, usually steel, with consequent
considerable expenses and a high overall weight of the invention.
Another drawback of known types is that the mechanical device is
particularly complicated to manufacture, since it usually requires welding
between said second and third plates.
Another important drawback is that the tension element must be inserted
in the first holes manually, before assembling the compensating means: this
entails a further cost increase and considerably greater constructive
complexity.
The aim of the present invention is to solve the above-mentioned
problems, eliminating the drawbacks of the cited known art, by providing a
mechanical device that allows to rock the chair in maximum safety, avoiding
the danger of injury to fingers due to accidental jamming in the mechanism
of said device.
Within this aim, an object of the invention is to provide a device that
allows to reduce manufacturing costs, preferably by way of a reduction of
the number of components and of the amount of material employed, and by
way of an improvement of the efficiency of the manufacturing process.
In particular, an object of the present invention is to be very strong and at
the same time light, mainly due to an overall weight reduction and to the use
of reduced thicknesses of material.
Another important object is to provide a device that allows rapid and
effective assembly of the compensation means, which can optionally be
performed after the assembly of the device.
Another object is to facilitate and simplify the activation of the device on
the part of the user by way of an optimum placement of the actuation rod.
Another object is to provide a device that is structurally simple and can
be manufactured with machines of a known type.
This aim and these and other objects that will become better apparent
hereinafter are achieved by a mechanical device, characterized in that it
comprises a single plate that is associable under a chair and with which an
actuation rod can be associated transversely for the combined rotation and
translational motion of an intermediate element that is pivoted inside a box-like
body that is partially accommodated at a first seat formed below said
single plate, said box-like body being associable with a central column and
interacting with oscillation compensation means that interact with said single
plate.
Further characteristics and advantages of the invention will become better
apparent from the following detailed description of a particular but not
exclusive embodiment thereof, illustrated by way of non-limitative example
in the accompanying drawings, wherein:
Figure 1 is an exploded perspective view of the mechanical device
according to the present invention; Figure 2 is a bottom perspective view of the single plate; Figure 3 is a transverse sectional view of the single plate, taken along a
broken line; Figures 4 and 5 are bottom views of the device with the rod in two
different positions; Figures 6 to 8 are various views of the device with the rod arranged in the
position for blocking oscillation; Figures 9 to 11 are various views of the device with the rod arranged in
the free oscillation position; Figures 12 and 13 are partially sectional side views of the device
illustrating two steps of the insertion of the compensation means; Figures 14 and 15 are top views of the device without the single plate and
with the rod arranged in two different positions; Figure 16 is an exploded view of the device provided with additional
means for locking the plate by interference; Figures 17 and 18 are views, similar to Figures 14 and 15, showing said
additional means during activation for locking the plate by interference.
In the embodiments that follow, individual characteristics, given in
relation to specific examples, may actually be interchanged with other
different characteristics that exist in other embodiments.
Moreover, it is noted that anything found to be already known during the
patenting process is understood not to be claimed and to be the subject of a
disclaimer.
With reference to the figures, the reference numeral 1 designates a
mechanical device that is particularly suitable for the movement of a chair.
The mechanical device 1 comprises a single plate 2, which is
approximately rectangular and is associable under the chair, for example by
means of a plurality of screws, not shown, which pass within respective
slots, generally designated by the reference numeral 3 and formed at the
comers of the plate 2.
An approximately oval ridge 4 protrudes downward at the perimeter
region of the single plate 2, and its transverse cross-section is essentially
triangular with rounded corners.
The ridge 4 forms, approximately centrally and below the plate 2, a first
seat 5 for partially accommodating a box-like body 6 that is associable with
a central column 7, shown partially in Figure 1, for supporting the chair.
In particular, the box-like body 6 has a base 8, which is approximately
flat and oval and from which a hollow and substantially cylindrical stem 9
protrudes downward and in an off-center position; such stem can be
accommodated in a complementarily shaped cavity 10, which is formed
axially at the upper end of the central column 7.
A lateral edge, designated by the reference numeral 11, protrudes
vertically and perimetrically to the base 8 of the box-like body 6, and two
mutually facing first holes 12a and 12b are formed transversely to said edge.
The pair of first holes 12a and 12b is preferably formed in the lateral edge
11 along an axis that is approximately perpendicular to the axis of the stem 9
and to the longitudinal central axis of the box-like body 6, so as to allow to
position two respective bushes 13a and 13b for supporting a transverse pivot
14.
Said pivot is arranged approximately at a central axis that lies
transversely to the box-like body 6.
The transverse pivot 14 has free ends, designated by the reference
numerals 14a and 14b, which protrude outside the bushes 13a and 13b and
are accommodated in respective pairs of second holes, generally designated
by the reference numerals 15a and 15b, which are formed in the ridge 4 of
the single plate 2 along the same axis as the pivot 14.
In this manner, the single plate 2 is pivoted to the box-like body 6 about
an axis that passes through the pivot 14.
As shown in Figures 6 and 9, the shape of the upper perimetric edge of
the lateral edges 11 of the box-like body 6 is preferably shaped, when
viewed from the side, slightly like an inverted V with the vertex located
approximately above the pivot 14, so as to form first and second flat portions
11a and 11b for limiting the stroke of the oscillation of the plate 2 with
respect to the box-like body 6.
In this manner, it is possible to define a first position, which is not rotated
(Figures 6 to 8) and in which the plate 2 rests on the first flat stroke limiting
portions 11a, and a second rotated position (Figures 9 to 11), in which the
plate 2 rests on the second flat stroke limiting portions 11b.
A rod, designated by the reference numeral 16, is further associable
transversely with the plate 2 and with the box-like body 6 and comprises
first and second portions 16a and 16b that are approximately straight and lie
on the same axis and are mutually connected by a third portion 16c that is
approximately C-shaped and is accommodated inside the box-like body 6.
The first portion 16a, which is short, and the second portion 16b, which is
longer, can pass through a pair of third holes, respectively designated by the
reference numerals 17a and 17b, which are formed in the box-like body 6
along an axis that is substantially parallel to the axis of the pivot 14 and is
provided in the opposite direction with respect to the stem 9.
Moreover, the second portion 16b protrudes outside the mechanical
device 1 through a first recess or flattened portion 18, which is provided in
the ridge 4 of the plate 2, and is connected, at its outer end, to a fourth
portion 16d, which is oblique and in turn is connected to a knob 19.
As shown in Figures 4 and 5, the rod 16 can perform an axial
translational motion of a preset length between two end positions, one in
which the first portion 16a is almost entirely accommodated in the box-like
body 6 (Figure 4) and another in which the first portion 16a is arranged
within a second recess or flattened portion 20, which is formed in the ridge 4
opposite the first flattened portion 18 and is shallower than said first portion.
In this manner, the position of the rod 16 determines the degrees of
freedom of the single plate 2 with respect to the box-like body 6; when the
first portion 16a is accommodated in the box-like body 6, the plate 2 can
rotate freely counterclockwise, from the first position of Figure 6 to the
second position of Figure 9.
Vice versa, starting from the first position of Figure 6 and arranging the
first portion 16a of the rod 16 within the second flattened portion 20, the
plate 2 is locked by means of the interference of the first portion 16a with
the ridge 4 of the plate 2.
The first portion 16a of the rod 16 and the flattened portion 20 form
means suitable to lock the plate by interference with respect to the box-like
body.
The rod 16 further allows to actuate the axial translational motion and
partial rotation of an intermediate element 21, which is pivoted inside the
box-like body 6.
The intermediate element 21 has, in plan view, an approximately
triangular shape, which forms a base side 21a, which is arranged at the pivot
14 parallel to the axis thereof, and a vertex 21b, which is arranged opposite
the base side 21a and is directed toward the C-shaped third portion 16c of
the rod 16.
In particular, proximate and parallel to the base side 21a there is, in the
intermediate element 21, a fourth through hole 22 for the passage of the
transverse pivot 14, so as to provide the pivoting of the intermediate element
21.
Proximate to the vertex 21b there is a transverse slot 23, which is formed
approximately parallel to the pivot 14, for partially accommodating rotatably
the third portion 16c.
In this manner, a rotation of the rod 16 about the axis of the first and
second portions 16a and 16b produces a rotation of the intermediate element
21 about the pivot 14.
In particular, when the knob 19 is lifted, the third portion 16c and the
vertex 21b are rotated downward, so as to force a contact between a preset
lower protrusion 21c of the intermediate element 21 and a button 24 that
protrudes at the top of a gas-filled cylinder of a known type, designated by
the reference numeral 25, which is accommodated in the central column 7.
The button 24 constitutes the means for activating the gas-filled cylinder
25, accordingly allowing the user to vary the distance of the chair from the
ground.
Oscillation compensation means, designated by the reference numeral 26,
interacting with the single plate 2 for compensating the oscillation thereof,
protrude below the box-like body 6 approximately opposite the stem 9 of the
box-like body 6 with respect to an axis that approximately coincides with the
axis of the pivot 14.
The compensation means 26 comprise a first half-shell and a second half-shell,
designated by the reference numerals 27 and 28, which are mutually
associable so as to form an enclosure that has a substantially ovoid shape.
The first half-shell 27, which is arranged, upon mounting in a lower
position with respect to the second, upper half-shell 28 and has a larger
diameter, is provided with a fifth axial through hole 29, which is connected
to a second seat 30 that is external and wider and is designed to
accommodate a complementarily shaped nut 31 that is threaded internally.
The complementarily threaded end, designated by the reference numeral
32a, of a tension element 32 is associable with the nut 31; said tension
element is partially accommodated in the first half-shell 27 and the second
half-shell 28 and protrudes therefrom through a sixth upper hole 33.
The tension element 32 has a head 32b that is approximately T-shaped
and protrudes above the sixth hole 33; the head 32b can be made to pass,
during assembly, through a first slot 34 that is formed in the base 8 of the
box-like body 6, approximately opposite the position of the stem 9, and is
obtained along the longitudinal central axis of the body 6.
The head 32b can further pass through a second slot 35, which is
approximately similar to the preceding one and is formed, along the same
axis, within the single plate 2.
A third seat 36 for accommodating the head 32b is provided beforehand
on the upper surface of the plate 2, transversely to the second slot 35, in
order to provide a nonrotating bayonet-like coupling of the tension element
32 to the plate 2.
In this manner, the tension element 32 also acts as an element for
interconnecting the compensation means 26 and the plate 2.
The tension element 32, by interacting with the first half-shell 27 and
with the nut 31, also allows to adjust the compression of an elastically
deformable element, such as a helical spring 37, which is conveniently
accommodated between a first annular pad 38a and a second annular pad
38b, which are in turn respectively accommodated in the first and second
half- shells 27 and 28.
A rotation of the first half-shell 27 in fact entails an axial translational
motion of the nut 31 along the complementarily threaded end 32a of the
tension element 32, so as to move the first pad 38a toward the second pad
38b and thus increase or decrease the compression of the spring 37.
During the use of the chair, the activation of the spring 37 is achieved as
a consequence of the oscillation of the plate 2 with respect to the box-like
body 6: in particular, it is preloaded during the backward rotation of the
chair imparted by the user (counterclockwise until the position of Figure 9 is
reached).
Then, once the force that produced the backward oscillation is no longer
applied, the spring 37 imposes a clockwise rotation, actuating the return to
the original position of Figure 6.
A rotation of the first half-shell 27 with respect to the tension element 32
entails a variation of the compression of the spring 37 and therefore a
variation of the behavior of the compensation means 26 in controlling the
oscillation of the plate 2 with respect to the box-like body 6.
The second slot 35 can be obtained advantageously by cutting the plate 2
and subsequently subjecting it to localized deformation, so as to obtain a
bridge 39 that constitutes a stroke limiting element for the tension element
32.
If the first half-shell 27 is compressed toward the second half-shell 28,
contact in fact occurs between the head 32b of the tension element 32 and
the bridge 39, thus avoiding damage of the lower surface, not shown, of the
chair.
The single plate 2 and the box-like body 6 can be obtained by means of a
pressing operation starting from a single metal sheet: the type of process and
most of all the particular chosen configuration, which is extremely compact
and substantially free from weak regions, allow to provide the invention
starting from metal plates of limited thickness, for example on the order of
2-2.5 millimeters, with consequent considerable financial advantages.
Operation is therefore as follows: with reference to the figures, the user
can actuate the rod by imparting a translational motion thereto, so as to
produce the selective and temporary interconnection of the first portion 16a
with the second flattened portion 20, allowing or not the oscillation of the
chair.
Moreover, the user can act on the knob 19 of the rod 16, lifting it and thus
entailing a rotation of said rod.
This produces the activation, by the third portion 16c, of the button 24 of
the gas-filled cylinder 25, with the consequent possibility to adjust the height
of the chair from the ground.
The operation for activating the gas-filled cylinder is facilitated by the
fact that the knob 19 protrudes in front of the rod 16, and therefore laterally
to the user, and so can be accessed easily.
This is due to the fact that differently from the background art, the third
portion 16c is directed, with respect to the axis that passes through the first
and second portions, away from the fourth portion 16d for connection to the
knob.
It has thus been found that the invention has achieved the intended aim
and objects, a mechanical device having been provided which allows to
adjust the chair easily and in maximum safety.
This is due mainly to the fact that the shape of the invention is such as to
comprise a single plate that accommodates, in each step of the oscillation,
the upper edges of the box-like body.
Moreover, the interspace between the box-like body and the respective
seat is very small and in any case not sufficient to allow the accidental
insertion or jamming of the fingers of the user inside the mechanism.
The invention can be worked by pressing, and in this manner no
operations for mutually welding the components are necessary.
Moreover, the reduction in the number of components and the
simplification of the operations for assembling them, such as for example the
bayonet-like insertion of the T-shaped tension element, entail faster
assembly and an optimization of production steps and of the organization of
inventory reserves.
These technical solutions and others entail a considerable reduction of
manufacturing costs, while keeping at least unchanged the strength of the
mechanical device.
At the same time, the invention has the advantage of having a reduced
weight, mainly due to the use of reduced thicknesses of material and to the
improvement of the efficiency of the components used.
The invention is of course susceptible of numerous modifications and
variations, all of which are within the scope of the appended claims.
The materials used, as well as the dimensions that constitute the
individual components of the invention, may of course be more pertinent
according to specific requirements.
The various means for performing the different functions mentioned and
defined by the claims need not certainly coexist or be present only in the
illustrated embodiment but can be used, per se, in different embodiments of
chair mechanisms other than those illustrated.
Figures 16, 17 and 18 illustrate additional means that are suitable to lock
the plate 2 by interference; said locking means are constituted by a lever or
latch 40, which is substantially L-shaped so as to form a first wing 41 and a
second wing 42, arranged on the same plane and provided, in the connecting
region, with a locking pivot 44 obtained during pressing, which protrudes at
least below the latch 40 for pivoting said lever to the box-like body 6.
The locking pivot 44 is in fact accommodated at a suitable seat 45,
formed on the base 8 of the box-like body 6 in a region that is adjacent to the
third hole 17b, on the opposite side with respect to the first slot 34.
The free end of the first wing 41, which when inactive lies approximately
transversely to the box-like body 6, has a tooth 46 that is directed, in the
condition in which the interference locking means are not activated, along an
axis that is approximately longitudinal to the box-like body.
A protrusion 47 projects at the free end of the second wing 42 along a
plane that is perpendicular to said wing, and can be arranged at a suitable
eighth hole 48 formed at the overlying intermediate element 21.
The tooth 46 instead faces the adjacent lateral edge 11 of the box-like
body 6; at said tooth there is, on said lateral edge, a milling 49 that is
suitable to allow the free sliding therein of the tooth 46 until it protrudes
outside the lateral edge 11.
As shown in Figures 17 and 18, a movement of the rod 16 that places the
first portion 16a of said rod inside the second flattened portion 20 is also
matched by a rotation imparted to the lever 40, by way of the interference of
the protrusion 47 with the eighth hole 48 formed in the intermediate element
21.
In this manner, the tooth 46 protrudes beyond the milling 49 and engages
at a suitable locator formed at the single plate 2, thus further locking its
movement.
The disclosures in Italian Patent Application No. TV2003A000021 from
which this application claims priority are incorporated herein by reference.
Where technical features mentioned in any claim are followed by
reference signs, those reference signs have been included for the sole purpose
of increasing the intelligibility of the claims and accordingly, such reference
signs do not have any limiting effect on the interpretation of each element
identified by way of example by such reference signs.