U.S. patent application number 17/235005 was filed with the patent office on 2021-10-21 for element and device for seating furniture.
The applicant listed for this patent is BOCK 1 GMBH & CO. KG. Invention is credited to HERMANN BOCK, SEBASTIAN ROTH, BENJAMIN STOOF, GUIDO WACHTER.
Application Number | 20210321774 17/235005 |
Document ID | / |
Family ID | 1000005583954 |
Filed Date | 2021-10-21 |
United States Patent
Application |
20210321774 |
Kind Code |
A1 |
BOCK; HERMANN ; et
al. |
October 21, 2021 |
ELEMENT AND DEVICE FOR SEATING FURNITURE
Abstract
An element of a device, in particular an element of a seating
furniture assembly or of a seating furniture assembly component is
provided. In addition, a device for an item of seating furniture,
in particular a seating furniture assembly, for example a pivot
mechanism, has an element of this type. Furthermore an item of
seating furniture having a device of this type or having an element
of this type is possible. In order to simplify the construction of
items of seating furniture, the use of a deformation element which
is integral, that is to say integrated into the device, which is
deformable, which is composed preferably of a plastics material,
and which serves as an energy storage member, is proposed.
Inventors: |
BOCK; HERMANN; (PYRBAUM,
DE) ; WACHTER; GUIDO; (HEROLDSBERG, DE) ;
STOOF; BENJAMIN; (NUERNBERG, DE) ; ROTH;
SEBASTIAN; (PILSACH, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BOCK 1 GMBH & CO. KG |
Postbauer-Heng |
|
DE |
|
|
Family ID: |
1000005583954 |
Appl. No.: |
17/235005 |
Filed: |
April 20, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A47C 1/03255 20130101;
A47C 1/03261 20130101 |
International
Class: |
A47C 1/032 20060101
A47C001/032 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 20, 2020 |
DE |
102020110707.2 |
Claims
1-13. (canceled)
14. An element of a device, the device being selected from the
group consisting of a seating furniture assembly and a seating
furniture assembly component, the element being an elastically
deformable element being integrated in single-piece form into the
device and serving as an energy storage member.
15. The element according to claim 14, wherein said elastically
deformable element is deformable owing to an exertion of load on
the device, which said exertion of load has an aim of causing a
movement of the device.
16. The element according to claim 14, wherein said elastically
deformable element is composed of a plastic material.
17. The element according to claim 14, wherein said elastically
deformable element is configured so as to deform differently in a
manner dependent on a direction of action of a force acting
thereon, by virtue of said elastically deformable element having a
plurality of members or structure planes which act in parallel and
which have stiffnesses dependent on the direction of the action of
the force.
18. (canceled)
19. A device for an item of seating furniture, the device
comprising: at least one elastically deformable element being
integrated in single-piece form into the device and serving as an
energy storage member.
20. The device according to claim 19, wherein the device is a pivot
mechanism, in which a pivoting of a backrest support rearward
induces a following movement of a seat support.
21. The device according to claim 20, wherein: said pivot mechanism
has a multi-jointed coupling gear; and said at least one
elastically deformable element is formed as an integral constituent
part of said multi-jointed coupling gear.
22. The device according to claim 21, wherein said at least one
elastically deformable element has a plurality of virtual centers
of rotation in order to provide an infinite joint gear for said
pivot mechanism.
23. The device according to claim 20, wherein a pivoting movement
is provided by said pivot mechanism and would not be implementable
without a deformability of said at least one elastically deformable
element.
24. The device according to claim 23, wherein the pivoting movement
is a movement in a case of which the backrest support pivots
through a pivot angle of greater than 5.degree..
25. The device according to claim 20, wherein: said at least one
elastically deformable element is one of a plurality of elastically
deformable elements; and the device having a single-piece seat
support-base support combination, in which a seat support can be
moved relative to a base support by being connected in single-piece
form to the base support via a number of said elastically
deformable elements.
26. The device according to claim 19, wherein said at least one
elastically deformable element is an only energy-storing structural
part of the device.
27. The device according to claim 19, wherein the item of seating
furniture is a seating furniture assembly.
28. The device according to claim 21, wherein said at least one
elastically deformable element is a coupler or a part of said
coupler.
29. An item of seating furniture, comprising: at least one element
of a device and having an elastically deformable element being
integrated in single-piece form into the device and serving as an
energy storage member; or an apparatus for an item of seating
furniture, said apparatus containing said at least one elastically
deformable element being integrated in single-piece form into said
apparatus and serving as an energy storage member.
30. The item of seating furniture according to claim 29, wherein
the item of seating furniture is an office chair.
Description
[0001] The invention relates to an element of a device,
specifically an element of a seating furniture assembly or of a
seating furniture assembly component. The invention relates
moreover to a device for an item of seating furniture, in
particular a seating furniture assembly, for example a pivot
mechanism, having an element of said type. The invention
furthermore relates to an item of seating furniture having a device
of said type or having an element of said type.
[0002] In the case of office chairs, a seat assembly fixedly
connected to a subframe is generally provided. Said seat assembly
in many cases comprises a so-called chair mechanism which allows
pivoting of the backrest. Known mechanisms for office chairs are
inter alia synchronous mechanisms, asynchronous mechanisms and
tipping mechanisms. Depending on which type of mechanism is
installed, the pivoting of the backrest takes place independently
of the seat or with an immovable seat (asynchronous mechanism),
together with the seat as a movement unit (tipping mechanism) or
with a certain relative movement of seat and backrest with respect
to one another (synchronous mechanism).
[0003] In the case of all of these pivot mechanisms, energy stores
are required. The storage members used for this are, in the case of
the pivot mechanisms known from the prior art, designed as separate
structural parts. Use is often made of spring arrangements with one
or more spring elements. Here, said spring elements are always
distinguished by the fact that they are manufactured from a steel
material. In order to provide an ergonomically particularly
advantageous pivoting movement, it is often necessary for a
relatively large number of structural parts to be connected to form
a pivot mechanism.
[0004] It is an object of the present invention to simplify the
construction of items of seating furniture.
[0005] Said object is achieved by means of an element as claimed in
claim 1 and by means of a device as claimed in claim 5 and by means
of an item of seating furniture as claimed in claim 13. By means of
the solution according to the invention, the construction of items
of seating furniture is simplified.
[0006] Advantageous embodiments of the invention are specified in
the subclaims.
[0007] The advantages and configurations discussed below in
conjunction with the element according to the invention also apply
analogously to the device according to the invention and to the
item of seating furniture according to the invention, and vice
versa.
[0008] The element according to the invention of a device is an
element of a seating furniture assembly or an element of a seating
furniture assembly component, in particular an element of a base
support, of a seat support or of a backrest support. The element is
distinguished by the fact that it is formed as a deformable element
which is integral, that is to say integrated as a single piece into
the device, and which serves as an energy storage member. Said
element will hereinafter be referred to as deformation element. The
deformation element allows not only deformability of the device,
for example of a base support, of a seat support or of a backrest
support, wherein said deformability results in a functionality of
the device based solely on said deformability. As an energy storage
member, the deformation element furthermore also provides--out of
the respective structural part itself--an opposing force which is
directed counter to a functional deformation, for example a
deflection.
[0009] The device according to the invention for an item of seating
furniture, in particular for an office chair, is in particular a
seating furniture assembly, for example a pivot mechanism, or a
seating furniture assembly component, for example a base support, a
seat support or a backrest support. The device is distinguished by
the fact that it has at least one deformation element.
[0010] The item of seating furniture according to the invention is
in particular an office chair. The item of seating furniture is
distinguished by the fact that it has at least one deformation
element or at least one device according to the invention.
[0011] The invention proposes the provision of storage members as
integral deformable structural parts (deformation elements) of the
chair mechanism. In other words, instead of spring elements which
have to be separately produced and installed into the mechanism
assembly, it is the intention that at least one of the mechanism
components that is present in any case for providing the
functionality of the pivot mechanism, in particular base support,
seat support and/or backrest support, is utilized as a storage
member. Additionally, in this way, it is possible for real centers
of rotation, in particular those that have hitherto been realized
by rotary joints, to be replaced by virtual centers of rotation. In
this way, the number of structural parts required for the pivot
mechanism and thus the production and assembly costs for chair
mechanisms can be reduced. By means of a reduction of the number of
real centers of rotation, the material loading and the wear in the
case of axles guided in bearings, and thus the risk of failure, are
minimized, and the service life of the chair mechanism is
lengthened. Further advantages arise from new construction and
design approaches that are made possible with the integrated
design. For example, pivot mechanisms can be provided which require
considerably less structural space. In particular, mechanisms of
considerably shallower construction can be realized.
[0012] The storage members are preferably deformable owing to an
exertion of load, which has the aim of causing a movement, on the
device, or in other words, owing to their integral construction,
deform when the device is intentionally acted on with a force or a
moment. The storage member according to the invention is thus
distinguished by the fact that its deformation is directed to an
intentional and thus desired movement of the device into which it
is integrated.
[0013] The storage members are preferably composed of a plastics
material. Since plastics materials have long been used in the
production of seating furniture components, in particular of office
chair components, suitable devices and installations for production
and assembly already exist. Therefore, no changeover is necessary
in this regard. Aside from the use of plastics materials, use may
basically also be made of other materials that allow a provision of
an elastically deformable energy store, for example the use of wood
materials.
[0014] In a particularly preferred embodiment of the invention, the
element according to the invention is used for allowing a desired
movement of a device in the first place. In other words, said
movement of the device would not be possible in the first place
without said element. A device according to the invention designed
to this effect comprises a number of interacting structural parts,
the interaction of which serves for the execution of a movement
which takes place in a particular manner, that is to say allows an
intentional mobility and thus functionality of the device, and said
device is distinguished by the fact that at least one of said
structural parts is, under load, in particular under the action of
a force or of a moment, at least partially elastically deformable
such that the intended mobility of the device is realized.
[0015] Here, it is preferably solely the deformability of said at
least one deformation element that allows the intended mobility of
the device. In other words, the intended movement of the device is
made possible solely on the basis of the deformability of the
deformation element. Without said deformation element, the device
would not move. In particular, without said deformation element,
the device would have a degree of freedom of f=0. In other words,
without said deformation element, the number of mutually
independent movement possibilities of the device would be equal to
zero.
[0016] Base support, seat support and backrest support are the only
functional components of a pivot mechanism, that is to say the only
components that are involved in the pivot function of the mechanism
such that they move or transmit forces or moments for the execution
of the movement. Preferably, in such an embodiment of the
invention, no additional coupling devices, such as tensile or
supporting couplers, are provided. Also, preferably, no additional
spring arrangement is provided for establishing the pivoting
resistance of the backrest support.
[0017] Since all pivot connections are formed with the aid of
rotary joints, in particular rotary/sliding joints are provided
neither for connecting the backrest support to the seat support nor
for connecting the base support to the seat support, there is no
degree of freedom of the pivot mechanism resulting from the
connecting elements. Any rotary joint, considered on its own, duly
has a rotational degree of freedom. However, the mechanism viewed
as an overall system would lack at least one degree of freedom for
realizing its pivoting function if one were to assume that the main
components of the mechanism that interact for the execution of the
pivoting movement, specifically base support, seat support and
backrest support, are ideally rigid structural parts, such that the
mechanism could not realize any pivoting movement, in particular no
synchronous movement. The number of mutually independent movement
possibilities of the mechanism would be equal to zero. In other
words, the pivot mechanism would have the degree of freedom zero,
that is to say it could assume only exactly one single
position.
[0018] In the case of assemblies with components connected
pivotably to one another, such as pivot mechanisms, it is the case
even if these are fixed, that is to say the joints thereof are
blocked, that undesired movements of individual mechanism
components relative to one another occur. These movements are
caused on the one hand by a material-inherent deformability which
is present in many cases, in particular in the case of plastics,
and on the other hand by the play provided by connecting means, for
example in the case of rotary or rotary/sliding joints, in the case
of axles guided in bearings etc. Such mobility of individual parts
or assemblies is however not sufficient for the execution of a
pivoting movement that is desired in pivot mechanisms in chairs, in
particular office chairs, in particular a pivoting movement in the
case of which the backrest support pivots by a pivot angle of more
than 5.degree..
[0019] Even if structural parts which are not ideally rigid were
involved, but one allowed the individual components a certain basic
elasticity or deformability, such as arises in any case owing to
manufacturing tolerances and with the use of customary plastics
materials, the pivot mechanism could not execute the intended
movement without irreversible damage to the components involved,
because this would be prevented by the limits of the elastic
deformability of said structural parts.
[0020] This absent degree of freedom of the pivot mechanism is
provided according to the invention by the fact that one component
of the pivot mechanism or a part of one component of the pivot
mechanism is elastically deformable.
[0021] Unless stated otherwise, the expression "deformable" is
always used in the sense of "elastically deformable". In other
words, the deformation element changes its shape under the action
of force, and returns to the original shape upon withdrawal of the
acting force.
[0022] The mobility of the chair mechanism according to the
invention is provided solely on the basis of the presence of the
deformable component or of the deformable component part. In other
words, a suitable deformability of the deformation element is
provided such that, owing to this deformability, the intended
movement, specifically the pivoting movement of the mechanism, in
this case the synchronous movement, can be executed in the first
place despite the absent degree of freedom. In other words, the
deformation element allows the pivoting movement of the chair
mechanism in the first place, by virtue of said deformation element
deforming under load.
[0023] The desired pivoting movement that is allowed in the first
place by the mobility of the deformation element is preferably a
pivoting movement in which the backrest support pivots by a pivot
angle of more than 5.degree..
[0024] Here, the deformability is preferably such that it allows a
movement of the structural part which has the deformation element
beyond that material-based and/or structure-based limit point which
limits the movement in the case of the non-deformable structural
parts used in pivot mechanisms known from the prior art, and the
overshooting of which leads to a fracture of the material. At the
same time, the deformability is preferably such that, during the
deformation of the structural part for the execution of the
pivoting movement of the mechanism, no overshooting of the
elasticity limit, let alone an overshooting of the fracture limit,
occurs.
[0025] The deformation element thus provides the degree of freedom
that is absent for the execution of the desired pivoting movement.
For this purpose, said deformation element forms a number of, that
is to say at least one, but preferably multiple, virtual centers of
rotation. In the simplest case, the deformation element forms a
single virtual center of rotation which replaces exactly one real
center of rotation, for example a rotary joint. If the deformation
element extends along at least one dimension, then it forms a
multiplicity of virtual centers of rotation that are arranged in a
row along the structural extent of said deformation element. In
other words, the deformation element then forms a multi-jointed
structural part, which could also be referred to as an infinitely
jointed structural element.
[0026] Through the use of such a deformation element as a component
of a pivot mechanism or as a part of such a component, an infinite
joint gear for a pivot mechanism is provided. In the case of this
gear, owing to the multiplicity of virtual centers of rotation, a
superposition of movements occurs, resulting in a resultant overall
movement of the coherent movable parts of the pivot mechanism about
an instantaneous center of rotation, the position of which varies
on a certain curved path during the course of the movement. In this
way, through suitable provision and use of corresponding
deformation elements, targeted movements of the pivot mechanism can
be caused, specifically in a simple manner in terms of
construction, in particular with few structural parts.
[0027] Multi-jointed coupling gears, such as are known from the
prior art, can be regarded as a kinematic chain. Owing to the
joints of such a coupling gear, said coupling gears have degrees of
freedom of the movement. In a preferred embodiment of the
invention, a multi-jointed coupling gear can be provided which,
theoretically, with the use of ideally rigid materials, no longer
has such a degree of freedom. A movement of the coupling gear is
then, according to the invention, made possible in the first place
through the use of the deformation element which, in the case of
the invention being applied to a pivot mechanism, is formed as an
integral constituent part of the coupling gear, in particular as
one of the couplers of the coupling gear or as a part of one of the
couplers of the coupling gear. The kinematic chain thus formed
comprises not only a number of real centers of rotation (that is to
say one or more real centers of rotation) but also at least one
virtual center of rotation, but preferably multiple virtual centers
of rotation. Here, the deformation element may be formed so as to
be composed of a series of virtual centers of rotation. In other
words, the invention proposes replacing centers of rotation and/or
coupling elements, the latter entirely or in part, with a number
of, that is to say one or more, component-integrated deformation
elements.
[0028] By means of the invention, it is thus possible in a simple
and inexpensive manner to provide structural parts, components and
assemblies of items of seating furniture, in particular of chairs,
and pivot mechanisms of any type, which have a multiplicity of
centers of rotation positioned in an exactly defined manner. Here,
the position of said centers of rotation may be both static, that
is to say invariant, and also variable. In particular, the position
of the centers of rotation may also change during the movement of
the item of seating furniture or the movement of a structural part,
of a component or of an assembly of the item of seating furniture.
In this way, it is possible with few components to produce
mechanical devices with highly complex movement
characteristics.
[0029] The integrated deformation element on which the invention is
based may basically be an element which can deform owing to any
type of load, in particular owing to tension, compression, torsion,
bending or shear. In practice, deformation commonly occurs that
arises from a superposition of different forms of load, wherein
there is however typically a preferred movement direction. In
preferred embodiments of the invention, a pivoting movement of
backrest support and seat support rearward and forward is the
preferred movement direction, whereas the presence of minimal
torsion-based movement components transversely with respect to the
seat longitudinal direction is tolerated.
[0030] Through targeted design of the deformation element, as
discussed in more detail further below in conjunction with the
exemplary embodiments, the nature of the deformation can be
utilized in a defined and targeted manner for providing a desired
movement of a loaded component, in particular of a mechanism
component.
[0031] The deformation element according to the invention may in
particular also be used in chair mechanisms in which, as an
alternative or in addition to a pivoting movement forward and
rearward, a tilting movement of individual or several mechanism
components to the right and to the left occurs. In these cases, a
component of a chair mechanism or a part of such a mechanism
component is movable transversely with respect to the seat
longitudinal direction, that is to say tiltable about a tilt axis
lying in the seat longitudinal direction, relative to another
component of the chair mechanism or relative to a part of another
mechanism component of said type. In cases in which the deformation
element is provided for allowing such tilting or generally for
allowing a movement transversely with respect to the seat
longitudinal direction, the deformation element is designed as an
element which is deformable primarily by torsion.
[0032] By means of the deformation element according to the
invention, seat mechanisms that are intended to provide both a
defined pivoting movement and a defined tilting movement of the
seat support can be produced in a particularly simple manner with a
small number of structural parts by virtue of the fact that
deformation elements are used which are deformable in multiple
directions simultaneously, and which allow both a pivoting and a
tilting movement simultaneously.
[0033] The expression "pivot mechanism" used here also encompasses
chair mechanisms which allow a tilting movement of one or more
mechanism components in addition to a pivoting movement, and also
chair mechanisms which are designed exclusively to allow a tilting
movement. Unless expressly stated otherwise, the expressions
"pivoting direction", "pivoting movement" etc. however relate to
pivoting forward and rearward, that is to say in the seat
longitudinal direction.
[0034] According to the invention, the deformation element
simultaneously serves as an energy storage member which is
integrated in the mechanism component that provides the deformation
element. The deformation element can thus not only define a
resetting force for a pivoted mechanism component but also serves
for establishing a pivoting resistance of a mechanism component.
The storage member undergoes reversible deformation under the
influence of load. The elasticity of the storage member gives rise,
under the action of load, to a resetting moment as a result of
which said storage member returns into its non-deformed initial
shape of its own accord as soon as the forces or moments acting on
it are withdrawn.
[0035] In particularly preferred embodiments of the invention, the
stiffness of the deformation element is dependent on the direction
of action of the force acting on the deformation element. If two
load situations inevitably arise during the use of the chair
mechanism, of which one would result in an undesired movement
whereas the other would result in a desired movement, the
deformation element is preferably designed so as to have a lower
stiffness, that is to say to deform more, in a first load situation
than in the second load situation, in the case of which the
deformation element has a higher stiffness, that is to say deforms
less.
[0036] In other words, the deformation element is designed so as to
deform differently in a manner dependent on the direction of action
of the force acting on it. This is preferably achieved by virtue of
the deformation element having multiple members or structure planes
which act in parallel and which have stiffnesses dependent on the
direction of the action force.
[0037] By means of the different deformation behavior, it is
achieved that, despite the integrated structural form, in the case
of which the energy store is provided by means of the existing
components of the chair mechanism, the seating and pivoting
behavior of the chair that is familiar to the user is
maintained.
[0038] By means of the integration according to the invention of
the energy store into an existing component of the pivot mechanism,
the number of structural parts (individual parts, assemblies) can
be reduced in relation to the pivot mechanisms known from the prior
art. The outlay in terms of parts stocking and assembly is thus
reduced. A particularly preferred embodiment of the pivot mechanism
according to the invention has fewer than 10 mechanism-specific
structural parts, that is to say structural parts which are
structurally or functionally adapted to the specific structural
form of the pivot mechanism. These do not include standardized
parts and standard machine elements such as screws, washers, rings,
toothed gears etc.
[0039] During the production of the mechanism component that has
the deformation element, during the injection molding process,
either only a single plastics material is used or two or more
different plastics are used (multi-component injection molding). A
change in the material composition during the injection molding is
not necessary if the desired deformation characteristics of the
deformation element can be attained exclusively by means of a
construction.
[0040] The material suitable for the production of the deformation
element has, on the one hand, the stiffness necessary to ensure the
required stability and strength of the component. On the other
hand, the material is elastic enough to provide the desired
deformability during the desired movement, in particular the
pivoting movement of a pivot mechanism.
[0041] The deformation behavior of the deformation element can be
varied in the installed state by means of suitable adjustment
mechanisms. These may for example be mechanically acting mechanisms
which entirely or partially restrict or block the deformability of
a part of the deformation element or the deformability of the
deformation element as a whole. For the variation of the
deformation behavior, it is however for example also possible for
the stiffness of the deformation element to be varied in targeted
fashion through temporary variation of a material characteristic of
the deformation element.
[0042] If deformation elements composed of plastic are used, as
proposed by the invention, the opposing force that is to be
overcome during the movement of the pivot mechanism by the user of
the chair is generated by the plastics material.
[0043] Since component-integrated deformation elements composed of
plastics material are used instead of spring elements or energy
stores composed of steel, the weight of the device can be reduced
in relation to conventional constructions. This is advantageous in
particular in the case of items of seating furniture if they are
intended to be positionable in mobile fashion, as is the case with
office chairs. At the same time, the recycling of such assemblies
is simplified, because no material separation has to be
performed.
[0044] The deformation element according to the invention may be
used in a variety of ways. Although the principle on which the
invention is based is discussed below predominantly on the basis of
the example of a pivot mechanism for an item of seating furniture,
in particular an office chair, in the case of which a part of the
base support is deformable in order to provide the degree of
freedom required for the execution of the pivoting movement, the
invention is restricted neither to use in a pivoting mechanism nor
to the deformation element being a part of the base support. The
concept of the invention may also be realizable with the aid of
deformable parts of other structural elements or assemblies of
chair mechanisms. Also, said chair mechanisms may involve
synchronous, asynchronous or tipping mechanisms or other types of
chair mechanisms. Furthermore, the deformation element according to
the invention may also be used in an item of seating furniture
without the deformation element being designed as a part of a pivot
mechanism; in other words, said deformation element may also be
used independently of a chair mechanism. In this respect, all
statements made in conjunction with one of the exemplary
embodiments described below are correspondingly also transferable
to other uses.
[0045] The deformation element according to the invention may in
particular be used as part of a base support, as part of a seat
support or as part of a backrest support.
[0046] The deformation element may however also form the entire
base support, seat support or backrest support. Preferably, in
these cases, a minimum number of rigid or substantially rigid
regions are provided on the deformation element, which regions form
non-deformable connecting regions that are required for the
interaction of said assemblies with other assemblies or
components.
[0047] In particular, the deformation element according to the
invention may form a part of a single-piece base support-seat
support combination, a part of a single-piece base support-backrest
support combination, a part of a single-piece seat support-backrest
support combination or a part of a single-piece seat support-base
support-backrest support combination.
[0048] The deformation element may however also form an entire
single-piece base support-seat support combination, an entire
single-piece base support-backrest support combination, an entire
single-piece seat support-backrest support combination or an entire
single-piece seat support-base support-backrest support
combination. Preferably, in these cases, a minimum number of rigid
or substantially rigid regions are provided on the deformation
element, which regions form non-deformable connecting regions that
are required for the interaction of the respective combination with
other components or structural parts.
[0049] If the invention is used in the case of a chair mechanism,
said mechanism need not imperatively be a mechanism in the case of
which the degree of freedom required for the execution of the
pivoting movement is provided in the first place with the use of
the deformation element. The deformation element according to the
invention may also be used in chair mechanisms of traditional
construction, in which steel springs or other separate spring
elements are used. In other words, it is possible for the use of a
deformation element according to the invention to be combined with
conventional spring arrangements. In such hybrid mechanisms, the
combination of separate and integrated energy stores results in a
wide variety of configuration possibilities that can be utilized
both for providing ergonomically advantageous movement sequences
and for realizing chair mechanisms of particularly small or shallow
construction and for creating particularly elegant mechanisms.
[0050] Several exemplary embodiments of the invention will be
discussed in more detail below on the basis of the drawings, in
which:
[0051] FIG. 1 shows a pivot mechanism according to the prior art
with four centers of rotation,
[0052] FIG. 2 shows a first pivot mechanism with a first embodiment
of the deformation element in a basic position (side view),
[0053] FIG. 3 shows the first pivot mechanism in the basic position
(view from below),
[0054] FIG. 4 shows the first pivot mechanism in a rearwardly
pivoted position (side view),
[0055] FIG. 5 shows the first pivot mechanism in a rearwardly
pivoted position (view from below),
[0056] FIG. 6 shows a second embodiment of a deformation element of
a pivot mechanism in the non-deformed state,
[0057] FIG. 7 shows a third embodiment of a deformation element in
the non-deformed state,
[0058] FIG. 8 shows the deformation element as per FIG. 7 in the
deformed state,
[0059] FIG. 9 shows a fourth embodiment of a deformation element of
a pivot mechanism in the second load situation,
[0060] FIG. 10 shows the deformation element of the pivot mechanism
in the first load situation,
[0061] FIG. 11 shows a second pivot mechanism in the basic position
(side view),
[0062] FIG. 12 shows the second pivot mechanism in the basic
position (view from below),
[0063] FIG. 13 shows a first backrest rod in a side view,
[0064] FIG. 14 shows the backrest rod according to FIG. 23 from the
rear,
[0065] FIG. 15 shows a second backrest rod in a side view,
[0066] FIG. 16 shows a third backrest rod in a side view.
[0067] In all of the figures, the invention is shown not true to
scale and merely schematically and only with its main constituent
parts. Here, identical reference designations correspond to
elements of identical or similar function.
[0068] "At the front" or "front" means here that a structural part
is arranged at the front in a seat longitudinal direction or
relates to a structural part which extends in the direction of the
front seat edge or which points in said direction, whereas "at the
rear" or "rear" means that a component is arranged at the rear in
the seat longitudinal direction or relates to a structural part
which extends in the direction of the backrest or of the backrest
support or of the rear seat edge or which points in said direction.
The expressions "at the top" or "top" or "higher" and "at the
bottom" or "bottom" or "lower" relate to the intended state of use
of the office chair or of the office chair mechanism.
[0069] In FIG. 1, in order to illustrate the pivoting principle, a
pivot mechanism generally known from the prior art is shown in
highly simplified form. This is a synchronous mechanism 139, in
which the three main components of the mechanism, specifically base
support 1, seat support 3 and backrest support 4 are coupled to one
another by way of rotary joints, such that a pivoting movement of
the backrest support 4 rearward induces a synchronous following
movement of the seat support 3, whereas the base support 1 remains
positionally fixed and immovable. The backrest support 4, with its
articulation to the base support 1, on the one hand, and to the
rear region of the seat support 3, on the other hand, forms a rear
coupling element 140 which is integrated into the backrest support
4, whereas a separate, front coupling element 141 connects the base
support 1 to the front region of the seat support 3. In this way,
four centers of rotation are created, realized by four rotary
joints, wherein each rotary joint is assigned a transverse axis.
These are the first rotary joint 142 for the connection of the base
support 1 to the rear coupling element 140, the second rotary joint
143 for the connection of the rear coupling element 140 to the seat
support 3, the third rotary joint 144 for the connection of the
base support 1 to the front coupling element 141, and the fourth
rotary joint 145 for the connection of the front coupling element
141 to the seat support 3.
[0070] According to the invention, it is now possible in principle
for all of the real centers of rotation realized by rotary joints
142, 143, 144, 145 to be replaced by virtual centers of rotation
that are provided by one or more deformation elements according to
the invention. In the case of the four-jointed coupler depicted by
way of example in FIG. 1, it is for example possible for the
separate, front coupling element 141 to be omitted and for the
function of one or more coupling joints 142, 143, 144, 145 to be
realized by means of structural parts or mechanism components
equipped according to the invention with deformation elements, such
as for example the base support 1. Correspondingly, the invention
is also applicable to mechanisms of other construction, in
particular to mechanisms with a different number of coupling
joints. Here, the real centers of rotation may be replaced not only
by the virtual centers of rotation according to the invention. With
corresponding design of the mechanism, it is possible, by means of
the enhanced deformability of individual mechanism components, for
the number of required centers of rotation to also be reduced,
whereby a simplified construction of the mechanism is possible. On
the other hand, a considerable increase in the number of centers of
rotation is also possible, specifically in the form of virtual
centers of rotation, with a simultaneous decrease in the complexity
of the mechanism construction.
[0071] Referring to FIGS. 2 to 5, a description will firstly be
given of a synchronous mechanism 10 in the case of which the third
rotary joint 144 is replaced by a deformation element according to
the invention.
[0072] The mechanism 10 has a base support 1 which is placed by
means of a cone receptacle 2 onto the upper end of a chair post 20
(see FIG. 2). Furthermore, the synchronous mechanism 10 comprises a
substantially frame-like seat support 3 and a backrest support 4
which is fork-shaped in plan view, the webs 5 of which are arranged
to both sides of the base support 1.
[0073] The seat support 3 is provided for receiving, or for the
mounting of, a seat surface, which may be padded. The assembly
process is performed with the aid of fastening elements (not
illustrated in any more detail) in the conventional manner.
Attached to the backrest support 4 is a backrest (not illustrated
in any more detail) which, in modern office chairs, is
height-adjustable. The backrest may also be connected in
single-piece form to the backrest support 4.
[0074] The entire synchronous mechanism 10 is of mirror-symmetrical
construction with respect to its central longitudinal plane, as
regards the actual kinematics. In this respect, in the following
description of this and further exemplary embodiments of the
invention, it is always to be assumed that structural elements of
the actual pivot mechanism are present in pairwise form on both
sides.
[0075] FIGS. 2 and 3 show the basic position of the synchronous
mechanism 10, in which the seat support 3 assumes a substantially
horizontal position. FIGS. 4 and 5 show the synchronous mechanism
10 in a position of the backrest support 4 in which it has been
pivoted rearward to a maximum extent.
[0076] The backrest support 4 which is pivotable in a pivoting
direction 7 is, with its web 5 which extends in the direction of
the front region 17 of the mechanism 10, articulatedly connected
directly to the base support 1, with the formation of a first
transverse axis 11, by means of a first rotary joint 21, wherein
said transverse axis defines the main pivot axis 11 of the
synchronous mechanism 10. The main pivot axis 11 lies in this case
behind the cone receptacle 2 as viewed in the seat longitudinal
direction 14.
[0077] In the rear region 16 of the mechanism 10 as viewed in the
seat longitudinal direction 14, the backrest support 4 is, by means
of an upwardly extending driver 6 of the web 5, simultaneously
connected by means of a second rotary joint 22 to the rear region
25 of the seat support 3. Here, the main pivot axis 11 is, as
viewed in the seat longitudinal direction 14, arranged behind the
transverse axis 12 formed by the second rotary joint 22. A pivoting
of the backrest support 4 out of the basic position into a
rearwardly pivoted position is associated with a raising movement
of the rear region 25 of the seat support 3.
[0078] In the front region 17 of the mechanism, the front region 18
of the base support 1 is directly articulatedly connected to the
front region 24 of the seat support 3 by means of a third rotary
joint 23, with the formation of a third transverse axis 13. The
relative movement of seat support 3 and backrest support 4 with
respect to one another is determined substantially by the position
of the three joint axes 11, 12, 13 with respect to one another.
[0079] The backrest support 4 is directly connected to the seat
support 3 only at one point, specifically by means of the
transverse axis 12. Furthermore, the base support 1 is directly
connected to the seat support 3 only at one point, specifically by
means of the transverse axis 13. There is only a single direct
connection of the backrest support 4 to the base support 1,
specifically by means of the main pivot axis 11.
[0080] In the situation described by way of example on the basis of
FIGS. 2 to 5, a part of the base support 1, specifically a
deformation element 8 which is integrated into the base support 1
and which forms a longitudinal section of the base support 1, is
elastically deformable, as discussed in detail further below. The
deformation element 8 extends, so as to follow the extent of the
base support 1, in the seat longitudinal direction 14.
[0081] The deformation element 8 in the form of the deformable part
of the base support 1 serves simultaneously as a storage member
integrated into the base support 1. The deformation element 8 thus
not only defines the resetting force for the backrest support 4 but
thus also serves for establishing the pivoting resistance of the
backrest support 4.
[0082] The storage member 8 simultaneously serves as resetting
element and, for this reason, is formed and arranged so as to be
subjected to an exertion of load during a pivoting of the backrest
support 4. Thus, a pivoting of the backrest support 4 always takes
place counter to the spring force of the storage member 8, and the
storage member 8 serves for resetting the backrest support 4 from a
tilted position into its initial position.
[0083] By means of the described pivot mechanism, it is ensured
that the backrest support 4 with the backrest can be pivoted
rearward and downward in the pivoting direction 7 about the main
pivot axis 11. Here, the backrest support 4 is pivoted through a
pivot angle 9 of greater than 5.degree.. Owing to the articulation
of the seat support 3 on the backrest support 4, the seat support 3
is in this case likewise driven along rearwardly. At the same time,
the pivoting movement of the backrest support 4 induces a raising
movement of the rear region 25 of the seat support 3. At the same
time, the front region 24 of the seat support 3 is raised. The base
support 1 remains static during the pivoting movement of the
backrest support 4.
[0084] The deformation element 8 will be described in more detail
below.
[0085] The resistance of a body to elastic deformation by a force
or a moment, which depending on loading is a bending moment or
torsion moment, is described as stiffness. The stiffness and thus
the deformability of a structural part are dependent not only on
the elastic characteristics of the material, such as the modulus of
elasticity, but also significantly on the geometry of the
structural part. In other words, the deformation characteristics of
the deformation element 8 according to the invention are
substantially dependent on the characteristics of the material used
and on the construction of said deformation element.
[0086] The construction of the deformation element 8 is determined
by the respective part geometry, in particular the cross-sectional
shapes used, specifically the length and cross-sectional profile,
and the material thicknesses.
[0087] In the example illustrated here, not the entire base support
1 is of deformable design. Instead, only a part of the base support
1, specifically the integral deformation element 8, is deformable.
The deformation element 8 forms an integral storage member which is
formed as a single piece with the base support 1 and which serves
as an energy store.
[0088] The base support 1 has a central main body 31, which
comprises inter alia the cone receptacle 2 for the chair post 20
and in which the main pivot axis 11 of the pivot mechanism 10 runs.
Proceeding from this main body 31, a connecting piece 33 of the
base support 1 extends forward as viewed in the seat longitudinal
direction 14, and is connected to the front end of the seat support
3, with the formation of the rotary joint 23. The connecting piece
33 is in this case formed as a single piece with the main body 31.
By contrast to the relatively solid, non-deformable main body 31,
the connecting piece 33 is of deformable design at least in certain
sections. The connecting piece 33 serves as deformation element 8
within the meaning of the invention.
[0089] The desired movement of the mechanism 10, in particular the
nature of the pivoting movement, is, according to the invention,
definably influenced in that the deformation behavior of the
connecting piece 33 is predefined in targeted fashion. This is
realized preferably by virtue of the connecting piece 33 being
divided in the direction of its longitudinal extent, and thus in
the seat longitudinal direction 14, into sections of different
stiffness. This results in a different bending behavior
(deformation behavior) of the respective sections and thus in a
certain predefinable deformation behavior of the connecting piece
33. There are preferably no abrupt changes in stiffness. Instead,
continuous stiffness profiles are formed.
[0090] The desired deformation behavior that differs in different
sections is realized for example by means of structural measures,
for example different material thicknesses, and/or through the
targeted use of materials with different deformation
characteristics.
[0091] In the exemplary embodiment as per FIGS. 2 to 5, the
deformable section of the connecting piece 33 extends substantially
over the entire length of the connecting piece 33. Here, a central
section 34 has a lower stiffness than the attachment regions 35, 36
which adjoin the two ends of the central section 34 and which, with
their greater stiffness, serve for the attachment of the connecting
piece 33 to the main body 31 of the base support 1 and to the seat
support 3.
[0092] In other words, only the two end regions 35, 36 of the
connecting piece 33 are of substantially rigid form. This relates
on the one hand to the rear end region 35 of the connecting piece
33, which connects the connecting piece 33 in single-piece form to
the main body 31. On the other hand, this relates to the front end
region 36 of the connecting piece 33, by means of which the
connecting piece 33 is connected to the seat support 3, with the
formation of a rotary joint 23. The connecting piece 33 is
advantageously deformable throughout from directly at the front end
region 36 as far as the rear end region 35, wherein the
deformability decreases in the direction of the main body 31.
[0093] Owing to its deformability throughout, the deformable
central section 34 of the connecting piece 33, which forms the
actual deformation element 8, forms a series of virtual centers of
rotation arranged in a row in the direction of the longitudinal
extent of said central section. Despite the fact that there are
theoretically an infinite number of virtual centers of rotation, a
selection of these virtual centers of rotation 28, 29, 30 is shown
in FIGS. 2 and 4.
[0094] The connecting piece 33 is preferably formed such that the
stiffness of the deformable section 34 as a whole continuously
changes. The changing stiffness profile arises here solely from a
change in the material thickness of the deformable section 34.
Proceeding from the rear end region 35, the material thickness of
the central section 34 decreases continuously in the direction of
the front end region 36 until the front end region 36 and thus the
connecting region of base support 1 and seat support 3 is reached.
The front end region 36 itself is not deformable. The deformation
element 8 thus formed has, between its rigid end regions 35, 36, a
soft stiffness characteristic throughout, which runs in the seat
longitudinal direction 14.
[0095] In another exemplary embodiment (not shown), in which a
different movement of the pivot mechanism 10 arises owing to a
different deformation behavior of the connecting piece 33, the
connecting piece 33 has two deformable subsections which are
arranged spaced apart from one another along the direction of
extent of the connecting piece 33, that is to say in the seat
longitudinal direction 14. The two deformable subsections are
separated from one another by a subsection which is not deformable
or is considerably less deformable, and which is therefore more or
less rigid. The front deformable subsection as viewed in the seat
longitudinal direction 14 is connected by means of a front end
region to the seat support 3, whereas the rear deformable
subsection is connected by means of a rear end region to the main
body 31 of the base support 1. The deformation element 8 thus
formed therefore has, between its rigid end regions, a
soft-rigid-soft stiffness characteristic running in the seat
longitudinal direction 14.
[0096] In the exemplary embodiments described above, the
deformation element 8 is designed to be deformable in the seat
longitudinal direction 14 and is deformed owing to the stresses
acting in this direction in the seat longitudinal direction 14. The
virtual axes of rotation formed by the virtual centers of rotation
28, 29, 30 lie transversely with respect to the seat longitudinal
direction 14.
[0097] The design of the connecting piece 33 is preferably selected
such that the characteristics of its deformation are independent of
whether increasing or decreasing loading with a force or with a
moment is occurring. In other words, the deformation resistance of
the connecting piece 33 and thus the pivoting resistance of the
chair mechanism 10 is not dependent on whether the backrest support
4 is being pivoted rearward, and thus the connecting piece 33 as
energy store is being charged, or whether the backrest support 4 is
pivoting back into its initial position in a forward direction. In
both situations, the deformable section 34 of the connecting piece
33 moves on the same path.
[0098] Force is introduced in two different ways into the pivot
mechanism 10 in the region of the connection of seat support 3 and
base support 1, in particular into the rotary joint 23. The
introduction of force takes place on the one hand as a result of a
movement of the seat support 3 effected by a pivoting of the
backrest support 4 in the pivoting direction 7 (first load
situation). The introduction of force then takes place
substantially horizontally. The direction of action of the force in
the first load situation is indicated in FIG. 2 by the arrow 26.
The connecting point of seat support 3 and base support 1 is
subjected to a rearwardly acting tensile load. On the other hand,
the introduction of force takes place, as a result of a user
sitting down on the chair, in particular into the front edge of the
seat, resulting in loading of the front region 24 of the seat
support 3 (second load situation). The introduction of force then
takes place substantially vertically. The direction of action of
the force in the second load situation is indicated in FIG. 2 by
the arrow 27. The connecting point of seat support 3 and base
support 1 is subjected to a downwardly acting compressive load.
[0099] In the simplest case, the deformation element 8 is in the
form of a beam or plate. In the example shown in FIGS. 2 to 5, the
deformation element 8 is designed in the manner of a leaf spring.
It then has a rectangular cross-sectional profile. The deformation
element 8 then behaves in the same way in both load situations.
[0100] The stiffness of the deformation element 8 is however
preferably dependent on the direction of action of the force acting
on the deformation element 8, in particular such that the
deformation element 8 has a relatively low stiffness, that is to
say deforms to a greater degree, in the first load situation than
in the second load situation, in which the deformation element 8
has a relatively high stiffness, that is to say deforms to a lesser
degree.
[0101] It is thereby ensured that, despite the deformability of the
deformation element 8 that is required for the rearward pivoting
movement, the seat front edge does not unexpectedly sink too low
when a user sits down on the chair. In the ideal case, the base
support 1 is completely rigid in the second load situation, whereas
in the first load situation it allows the desired pivoting movement
owing to its deformability. In practice, by means of the designs
described here, it is achieved that no significant sinking of the
front region 24 of the seat support 3 takes place, or such sinking
is reduced to a minimum.
[0102] In order to achieve that the two load situations lead to
different behavior of the deformation element 8, the deformation
element 8 may be constructed such that, in the load situation,
either only compressive loading or only tensile loading occurs.
[0103] This can be attained for example by virtue of the
deformation element 8 being constructed from multiple members, for
example in the form of a combination of multiple elements acting in
parallel, or by virtue of a single-member connecting piece having a
suitable internal construction or a suitable internal structure in
order to be able to react with different deformation behavior to
forces acting from different directions.
[0104] Variants of such designs of the connecting piece will be
discussed in more detail below.
[0105] In one variant, as illustrated in FIG. 6, the deformable
section 34 of the connecting piece 33 is formed from two members
such that, between the main body 31 of the base support 1 and the
front end region 36, which provides the connecting region of base
support 1 and seat support 3, a division of the section 34 into an
upper link member 38 and a lower link member 39 is provided. In
other words, the deformable section 34 between the rear end region
35 and the front end region 36 is formed by two link members 38, 39
which run spaced apart from one another. Here, the two link members
38, 39 behave in the manner of edge axes of a beam in bending in
the context of the science of strength of materials, whereas the
neutral axis, which is illustrated in FIG. 6 by a dashed line 15,
runs in the empty intermediate space 37 between the two link
members 38, 39.
[0106] In the first load situation, the application of a
horizontally rearwardly acting tensile load to the third rotary
joint 23, which serves as the connecting point of seat support 3
and base support 1, leads to compressive loading of the upper link
member 38 and simultaneously to tensile loading of the lower link
member 39. In the second load situation, the application of a
vertically downwardly acting compressive load to the rotary joint
23 leads to tensile loading of the upper link member 38 and
simultaneously to compressive loading of the lower link member 39.
In practice, depending on how a user moves on the chair, it is also
possible in both load situations for deviations in the direction of
the tensile or compressive loads to arise, instead of ideally
horizontally rearwardly or vertically downwardly acting forces.
Then, the horizontally rearwardly acting tensile load in the first
load situation or the vertically downwardly acting compressive load
in the second load situation are supplemented by further load
components, which are however of considerably smaller magnitude
than the forces acting in the main load directions, such that the
fundamental functional principle described here does not
change.
[0107] By means of a different construction of the two link members
38, 39, it is advantageously achieved that the behaviors of the
link members 38, 39 differ from one another.
[0108] In one embodiment, it is the intention that the deformation
behavior of the upper link member 38 under tensile load differs
from the deformation behavior under compressive load such that the
elongation under compression is greater than the elongation under
tension. In other words, it is the intention that the upper link
member 38 be rigid under tension and at the same time soft under
compression. At the same time, it is the intention that the
deformation behavior of the lower link member 39 under tensile
loading does not differ from the deformation behavior under
compressive loading. The lower link member 39 is therefore again
provided with a rectangular cross-sectional profile, and is in
particular formed as a solid plate.
[0109] The fact that the upper link member 38 reacts differently
under compression and under tension, and does so in the desired
manner, specifically such that excessive elongation under tension
is prevented, is achieved in the illustrated example by means of a
special construction of the upper link member 38, which allows a
limitation of the elongation by means of stops in the case of
tensile loading, whereas stops are not provided for such a
limitation in the case of compressive loading. For this purpose, it
is provided that the upper link member 38, the basic form of which
is likewise a plate, is constructed from hollow cells, such that a
high mechanical stiffness is generated despite the relatively low
weight of the hollow body structure that is formed. The
construction is honeycomb-shaped, that is to say the cells 40 from
which the upper link member 38 is constructed directly adjoin one
another. Here, the cavities 42 of the cells 40 have a square shape
in cross section and are oriented obliquely with respect to the
seat longitudinal direction 14, resulting in the form of rhombuses.
In this way, relatively large, in this case compression-induced
deformations can be realized without this leading to high stresses
in the material. The cell walls 43 run in this case such that they
can deform during the movement sequence, in this case
advantageously transversely with respect to the seat longitudinal
direction 14.
[0110] The rod-shaped stop elements 41 are arranged in each case
pairwise in the cavities 42 of the cells 40, specifically such that
mutually associated stop elements 41 butt with their head ends
against one another under tensile loading of the upper link member
38 and thus prevent further elongation of the upper link member 38.
At the same time, the compressive loading of the lower link member
39 occurs.
[0111] In this way, an undesired deformation of the connecting
piece 33, and thus sinking of the front region 24 of the seat
support 3 in the second load situation are reduced, whereas the
desired pivoting movement in the first load situation is both
allowed and also not impeded. Alternative constructions of the
upper link member 38 are likewise possible.
[0112] The resulting deformation behavior of the connecting piece
33 influences the movement or the movement path of the connecting
point of seat support 3 and base support 1, which is formed by the
rotary joint 23. On the other hand, the magnitude of the opposing
force, and thus the pivoting resistance of the chair mechanism 10
during a pivoting of the backrest support 4 rearward, are thus also
defined.
[0113] In an alternative variant as illustrated in FIGS. 7 and 8,
the connecting piece 33 is again of single-member form. The
deformable section 34 is however constructed from planes 48, 49
lying one above the other which differ from one another in terms of
construction and which, for this reason, likewise have different
deformation behavior. The planes 48, 49 run, like the link members
38, 39 previously, correspondingly to the longitudinal extent of
the connecting piece 33 in the seat longitudinal direction 14.
[0114] There is at least one upper plane 48, which is preferably
the uppermost plane of the deformable section 34, and at least one
lower plane 49, which is preferably the lowermost plane of the
deformable section 34, which planes both behave in the manner of
edge axes of a beam in bending in the context of the science of
strength of materials, whereas the neutral axis 15 runs in an
intermediate plane 47 between said two planes 48, 49.
[0115] The entire plate-like connecting piece 33 is constructed as
a hollow chamber structure. The upper plane 48 corresponds in terms
of its construction to the upper link member 38 of the variant
described above. The intermediate plane 47 and the lower plane 49
are likewise of honeycomb construction with cells which directly
adjoin one another. As in the variant described above, the
thickness of the cell walls is relatively small in relation to the
dimensions of the cavities, such that the desired deformability is
made possible.
[0116] In the first load situation, the application of a
horizontally rearwardly acting tensile load to the connecting point
of seat support 3 and base support 1, formed by the rotary joint
23, leads to compressive loading of the upper plane 48 and
simultaneously to tensile loading of the lower plane 49. In the
second load situation, the application of a vertically downwardly
acting compressive load to the rotary joint 23 leads to tensile
loading of the upper plane 48 and at the same time to compressive
loading of the lower plane 49.
[0117] Again, in the case of tensile loading, the elongation of the
upper plane 48 is limited by stops, whereas no corresponding
limitation is provided for a deformation caused by compressive
loading. The stops provided in the upper plane 48 are formed in the
same way as in the variant illustrated in FIG. 6, that is to say by
means of stop elements 41, 42 which, under tensile loading of the
upper plane 48 in the second load situation, butt against one
another and thus prevent excessive elongation of the upper plane
48.
[0118] The deformation behavior of the upper plane 48 under tensile
load differs from the deformation behavior under compressive load
such that the elongation under compression is greater than the
elongation under tension. In other words, the upper plane 48 is
rigid under tension and soft under compression.
[0119] In FIGS. 6 and 7, the neutral axes 15 are shown symbolically
centrally between the two link members 38, 39 or planes 48, 49; in
fact, the neutral axis 15 runs very much closer to the lower link
member 39 or the lower plane 49.
[0120] The principle of using structurally and/or functionally
separate link members or planes in the construction of the
connecting piece 33 can also be transferred to other embodiments of
the invention. It can advantageously thus be achieved that the
connecting piece 33 has deformation behavior with which it deforms
more intensely in the first load situation than in the second load
situation. The deformable section 34 of the connecting piece 33 is
softer during pivoting of the backrest support 4 rearward than in
the event of loading of the front region 24 of the seat support 3
owing to the seat front edge being sat on. Ideally, the deformable
section 34 of the connecting piece 33 is rigid or substantially
rigid in the event of loading of the front region 24 of the seat
support 3, whereas said deformable section allows a desired
deformation during a pivoting of the backrest support 4
rearward.
[0121] In a further variant as illustrated in FIGS. 9 and 10, the
deformable section 34 of the connecting piece 33 does not extend
all the way to the third rotary joint 23. The front end region 36,
specifically the rigid region of the connecting piece 33 which
provides the space for the rotary joint 23, thus extends in the
direction of the main body 31 to such an extent that the deformable
section 34 of the connecting piece 33, which is again of two-member
form with an upper link member 38 and a lower link member 39,
connects to the front end region 36 such that the two link members
38, 39 meet, forming a virtual center of rotation 51, at a point
which is spaced apart from the position of the transverse axis 13
assigned to the rotary joint 23. The rotary joint 23, more
specifically the transverse axis 13, is in this case arranged
exactly perpendicularly across the virtual center of rotation 51.
The spacing 52 between the virtual center of rotation 51 and the
transverse axis 13 determines a lever of defined length. If the two
link members 38, 39 meet the front end region 36 with a spacing to
one another, this gives rise to a resulting virtual center of
rotation which is arranged exactly vertically below the transverse
axis 13.
[0122] In the first load situation, the force acting on the rotary
joint 23 generates, owing to this lever, a torque which acts both
on the upper link member 38 and on the lower link member 39 and
which subjects both link members 38, 39 to bending load, see FIG.
10. In other words, the two link members 38, 39 are bent. The
connecting piece 33 allows such a deformation.
[0123] In the second load situation, the load direction, that is to
say the line of action 27 of the force acting on the rotary joint
23, runs through the virtual center of rotation 51, see FIG. 9.
Since the lever is therefore not effective, the torque acting on
the connecting piece 33 is equal to zero. The lower link member 39
is then subjected exclusively to compressive loading, whereas the
upper link member 38 is subjected exclusively to tensile loading.
Therefore, in this load situation, virtually no forces arise that
would cause bending of the link members 38, 39. Therefore, no
significant deformation of the connecting piece 33 occurs.
[0124] The link members 38, 39 are for example in the form of rods.
Alternative embodiments, in which the link members 38, 39 are in
the form of beams, plates etc., are likewise possible.
[0125] Aside from the shapes and the profiles of the cross sections
of the link members 38, 39, the selected lengths of the link
members 38, 39, and the positions of the attachment of the link
members 38, 39 to the main body 31 of the base support 1, and the
selection of the angles that the link members 38, 39 assume
relative to the horizontal, play a role in the provision of the
desired link member functionality. In particular, the form of the
movement of the seat support 3 and the magnitude of the resetting
forces can thus be set in targeted fashion.
[0126] A divergence of the position of a real rotary joint 23 and
the position of a virtual center of rotation 51 that arises owing
to the use of a deformation element 8 according to the invention,
for the purposes of generating movement differences that are
dependent on the load situation, can also be transferred to other
embodiments of the invention.
[0127] Before a description is given of a second pivot mechanism
and other exemplary embodiments, further characteristics of the
deformation element 8 will be discussed below, which may be
relevant both in conjunction with the first pivot mechanism and in
conjunction with said other exemplary embodiments and in
conjunction with other exemplary embodiments of the invention that
are not described here.
[0128] The pivot mechanism 10 that is to be provided is subject to
cycling loading and, for this reason, must withstand up to several
hundred thousand load cycles. In order that the fatigue strength is
ensured, the force loss (relaxation) that occurs under deformation
must be limited. This is preferably achieved in that the pivot
mechanism 10 is not subjected to any permanent and high
prestress.
[0129] A certain low prestress is duly already present in the
system owing to the tolerances in the dimensional accuracy of the
structural parts. A low prestress may also be desired and necessary
in order that the backrest stands upright in the first place. In a
preferred embodiment, a pivot mechanism 10 which has a deformation
element 8 according to the invention is however constructed such
that no significant prestress of the deformation element 8 is
required. The prestress of the deformation element 8 is at any rate
so low, in all variants according to the invention, that no
functionality-impairing relaxation of the deformation element 8
occurs.
[0130] This freedom from prestress is preferably realized by virtue
of the fact that the chair mechanism is constructed as a so-called
"self-setting" mechanism, as discussed below.
[0131] The invention can be used in chair mechanisms 10 with
different numbers n of real centers of rotation (n=0, 1, 2, 3, . .
. ).
[0132] The nature of the pivoting movement, in particular the
relative movement of seat support 3 and backrest support 4 with
respect to one another, is significantly determined by the position
of the centers of rotation with respect to one another.
[0133] It has proven particularly advantageous for the invention to
be used in chair mechanisms 10, in particular synchronous
mechanisms, which are designed as "self-setting" mechanisms. These
are distinguished by the fact that the weight of the user sitting
on the chair counteracts the pivoting movement. In other words, the
user of the chair raises themself upward by means of a load on the
backrest, in that, in actuating the chair mechanism 10 by pushing
the backrest backward, said user acts counter to their own weight
resting on the seat. The desired pivoting resistance is thus, as it
were, set automatically owing to the weight of the user.
[0134] Owing to the principle of "self-setting", the weight of the
user generates an adequately high torque on the backrest support 4.
Said torque can be accommodated entirely or partially by the
deformation element 8 that acts as an energy store member.
Therefore, no high prestresses are required.
[0135] Preferably, by means of the selected position of the centers
of rotation or pivot axes 11, 12, 13, a lever geometry required for
a self-setting mechanism 10 is provided, in the case of which, both
in the non-pivoted basic position and preferably also in the
position pivoted rearwardly to a maximum extent, the main pivot
axis 11, which is arranged transversely with respect to the seat
longitudinal direction 14, of the connection of the backrest
support 4 to the base support 1 is, as viewed in the seat
longitudinal direction 14, arranged behind the articulation point
22 of the backrest support 4 to the seat support 3, that is to say
behind the pivot axis 12 that defines the location of the
introduction of force into the seat support 3.
[0136] A pivoting of the backrest support 4 rearward then causes a
raising of the seat support 3 correspondingly to the movement curve
defined by the interaction of backrest support 4, base support 1
and seat support 3. In particular, a pivoting of the backrest
support 3 rearward in the pivoting direction 7 causes a direct
raising movement of the rear region 25 of the seat support 3 and
simultaneously a direct raising movement of the front region 24 of
the seat support 3. By virtue of the fact that the seat support 3
is not only raised in its rear region 25 but a raising of the front
region 24 of the seat support 3 also occurs simultaneously, the
seat support 3 is synchronously driven along rearwardly and
upwardly in a defined relationship with respect to the backrest
support 4. Since, during a pivoting of the backrest into a rear
position, the user sitting on the seat surface performs a movement
that tracks the movement of the backrest, the so-called "shirt
riding-up effect" is prevented in a particularly effective
manner.
[0137] The deformation element 8 according to the invention can
also be used in chair mechanisms that are not designed as
"self-setting" mechanisms, in particular in mechanisms in which the
presence of a non-negligible prestress is required for correct
functioning. These may in particular be "hybrid" chair mechanisms
which, aside from the deformation element 8 according to the
invention, use separate energy store elements such as steel
springs.
[0138] In the case of the use according to the invention of a
deformation element 8 as part of a component or assembly of a chair
mechanism 10, it is preferable for stops to be provided which, as
force-accommodating elements, prevent overloading of the
deformation element 8 both during a pivoting movement of the
backrest support 4 or of the seat support 3 into the front and rear
end positions and in the case of an exertion of load on the seat
support 3 by a user, which leads to a sinking movement of the seat
support 3. In other words, stops for absorbing seat loads, that is
to say for absorbing movements of mechanism components downward,
and stops for limiting the movement of mechanism components forward
and rearward, are preferably provided. The movement of the chair
mechanism as a whole downward is typically limited by a gas spring
which is installed in the chair post 20 and which provides a
suitable stop.
[0139] Preferably, stops are provided which limit a movement of the
pivot mechanism 10 forward and rearward such that the loads caused
by the pivoting movement of the mechanism are not transmitted via
the deformation element 8. Suitable stop surfaces are typically
formed on the base support 1.
[0140] A second pivot mechanism 10 will be described below. This
substantially corresponds in terms of its basic construction to the
first pivot mechanism as shown in FIGS. 2 to 5, but differs in the
embodiment of the connecting piece 33, which is designated below as
fifth embodiment.
[0141] In the embodiment shown in FIGS. 11 and 12, as in the case
of the variant illustrated in FIGS. 7 and 8, the deformable section
34 of the connecting piece 33 is constructed from planes 48, 49
lying one above the other, which planes differ from one another in
terms of construction and, for this reason, exhibit different
deformation behavior.
[0142] The construction of the connecting piece 33 substantially
corresponds to the construction of the connecting piece 33
illustrated in FIG. 7. The upper plane 48 however, by contrast
thereto, has no stop element.
[0143] Whereas the upper plane 48 is formed with a closed top side,
it is a special feature of the fifth embodiment of the connecting
piece 33 that the lower plane 49 is designed such that, in the
plane structure, there are provided a multiplicity of slots 64
which are spaced apart from one another in the seat longitudinal
direction 14 and which run in the transverse direction and the slot
openings of which point downward. The slots 64 are, in other words,
formed in the bottom side 65 of the lower plane 49.
[0144] In the unloaded basic position of the chair mechanism 10, in
which neither the backrest support 4 is pivoted rearward nor the
seat support 3 is subjected to load by a user, the slots 64 are in
their normal state, in which they are open to a minimal extent. The
walls, which define the slots 64, of the lower plane are in other
words spaced apart from one another by a thin air gap in the region
of the slots 64.
[0145] In the first load situation, which causes a tensile loading
of the lower plane 49, the slots 64 open. The connecting piece 33
is softer, that is to say has a lower stiffness, than in the second
load situation.
[0146] In the second load situation, which causes a compressive
loading of the lower plane 49, the slots 64 close. The walls, which
define the slots 64, of the lower plane 49 make contact with one
another. The opposing force that counteracts the compressive load
that acts in the event of load being exerted vertically downward on
the front region 24 of the seat support 3 increases. The connecting
piece 33 becomes harder, that is to say has a higher resistance to
deformation, than in the first load situation.
[0147] As a result of the opening and closing of the slots 64 in
the lower plane 49, in the context of the science of strength of
materials, the position of the neutral axis 15 within the
deformable section 34 is shifted, and thus the spacing of the
neutral axis 15 to the upper edge axis (not illustrated), which
runs close to the top side 66 of the upper plane 48, is varied. In
this way, the flexural stiffness of the connecting piece 33 is
directly influenced. By means of the number, arrangement and design
of the slots 64, in particular the depth thereof, the deformability
of the connecting piece 33 can be predefined.
[0148] As a result, the deformable section 34 of the connecting
piece 33 is rigid in the event of loading of the seat front edge,
that is to say loading of the front region 24 of the seat support
3, whereas said deformable section allows a deformation during a
pivoting of the backrest support 4 rearward.
[0149] As in all of the other embodiments of the invention
described here, the connecting piece 33 is designed such that the
required stiffness is present in order to achieve the desired
pivoting resistance with respect to the pivot mechanism 10 during a
pivoting of the backrest support 4.
[0150] The stiffness of the deformation element 8 corresponds
figuratively to a hardness, attainable by means of a certain spring
rate, of a separate spring element such as is used in conventional
pivot mechanisms instead of the integral deformation element 8
according to the invention.
[0151] As is also the case in the above-described mechanism
variants, it is advantageously the case that a stop (not shown) is
provided between base support 1 and backrest support 4, which stop,
when the chair is sat on, prevents an excessive forward movement of
the backrest support 4 counter to the pivoting direction 7.
[0152] The principle of a movement limitation achievable by means
of slots 64 or other suitable openings is also transferable, if
required, to the upper link member or the upper plane. Likewise,
this principle is combinable with further variants, or can be
transferred to other embodiments of the invention. Accordingly, the
connecting piece 33 may advantageously be equipped with an upper
link member or an upper plane with stop elements 41, 42 and
simultaneously with a lower link member or a lower plane with slots
64.
[0153] The pivot mechanisms 10 described above have three real
centers of rotation that have been defined by rotary joints 21, 22,
23 with transverse axes 11, 12, 13. The invention is however also
applicable to pivot mechanisms with a different number of real
centers of rotation. By way of example, a deformation element 8 is
used within the meaning of the present invention in the case of a
pivot mechanism with only one real rotary joint, the three rotary
joints 143, 144, 145 shown in FIG. 1 being replaced by virtual
centers of rotation.
[0154] The concept of using a suitably designed component, that is
to say a component which is distinguished by suitable material
selection and suitable parts geometry, in order to be able to omit
a separate spring arrangement, a number of spring elements or some
other energy store for the provision of a pivoting movement or the
realization of a movement of a component of an item of seating
furniture, in particular the resetting of a backrest support in the
case of an office chair, can be used not only in pivot mechanisms
10, for example as specified further above. A
structural-part-integrated deformation element 8, which in
particular serves as energy store, may also be used in some other
way in a chair mechanism. On the basis of the example of a backrest
rod 130, the use of such a deformation element 8 which is
integrated into a component is described below.
[0155] Here, all statements with regard to the characteristics of
the material to be used and the material selection, and with regard
to the geometrical design, that have been made above in conjunction
with a deformation element 8 described there and serving as a
component of a pivot mechanism are also transferable to deformation
elements 8 whose deformability is not imperatively related to the
practicability of the pivoting movement of a chair mechanism but
which serve merely as components or component parts which provide a
certain mobility of a mechanism or of a mechanism assembly. In
other words, the deformation element 8 may also be used in such a
way that it is not imperatively required for an implementation of a
movement of the chair mechanism as a whole, but merely allows a
movement of a single part, of a component or of an assembly of a
chair mechanism or of some other part of a chair or of some other
item of seating furniture.
[0156] The deformation element 8 described below has no
relationship to a "zero degrees of freedom" mechanism, that is to
say allows a pivoting movement to be performed not only on the
basis of its deformability. Instead, the deformation element 8 can
also be used in a conventional chair mechanism.
[0157] FIGS. 13 to 16 illustrate a substantially L-shaped backrest
rod 130, which, by way of its short limb 131, which in the
installed state extends more or less horizontally, can be mounted
in a known manner with the aid of suitable connecting elements on a
backrest support 4, whereas, on its long limb 132, which in the
installed state extends more or less vertically and which is
possibly also inclined forward in the seat longitudinal direction
14, there is mounted a height-adjustable backrest of the chair (not
illustrated), for which purpose suitable fastening means for this
are provided.
[0158] Such backrest rods 130 are conventionally of rigid or
substantially rigid design, in particular also because it is the
intention that an action of leaning against the backrest is
intended to induce a pivoting of the backrest support 4 rearward
and thus, in the case of synchronous and tipping mechanisms, a
following movement of the seat support 3.
[0159] According to the invention, provision is now made for a
section of the backrest rod 130, specifically the connecting part
133 between the two limbs 131, 132, to be of deformable design.
[0160] The deformable section 134 of said connecting part 133
substantially corresponds, in the embodiment described here, to the
region of the bend between the linearly running limbs 131, 132 of
the backrest rod 130.
[0161] Through the use of such a backrest rod 130 in a tipping
mechanism, instead of a common pivoting movement of seat and
backrest as a movement unit on one common movement path, as occurs
in the case of classic tipping mechanism, a movement behavior that
resembles the pivoting behavior of a synchronous mechanism is
generated, in the case of which a pivoting movement of the backrest
rearward results in a different following movement of the seat. It
is duly the case that no determined, that is to say definedly
controlled movement of the seat support 3 occurs. However, owing to
the "soft" coupling to the backrest, the seat moves on a different
movement path similar to that of a classic synchronous mechanism
with fixed coupling relationships.
[0162] The stiffness that is required to ensure the usability of
such a structural part of a component of a chair mechanism is
provided substantially by the geometry of the parts used.
Accordingly, to influence the stiffness of the structure of the
central section 134, a structural design can be selected which
substantially corresponds to the structure of the central section
34 as discussed in conjunction with FIG. 11, wherein the stiffness
of the central section 134 can be set by way of the number of
structural planes provided.
[0163] FIGS. 13 to 16 show a deformable section 134 with a
structure of planes as discussed in conjunction with FIGS. 7 and 8
and FIGS. 11 and 12. Here, the top side 66 of the (internally
situated, short) upper plane 48 of the section 134 in FIGS. 13 and
15 is closed, that is to say formed with a continuous surface which
terminates the plane 48 in an upward direction, whereas FIG. 16
shows an embodiment with an upwardly open structured upper plane
48, in the case of which the surface is formed, as in FIGS. 6 and 7
and FIGS. 11 and 12, by obliquely running cell walls, such that the
upper plane 48 and thus the section 134 can deform more easily. In
all three variants, slots 64 are provided in the (externally
situated, long) lower plane 49, which slots serve for increasing
the stiffness of the central section 134, as discussed below.
[0164] Here, the slots 64 may be of relatively short (FIG. 15) or
relatively long (FIG. 16) form, that is to say may extend to a
greater or lesser extent in the direction of the neutral axis. The
slots 64 run in the cell walls 43 that delimit the cavities 44
(FIGS. 15 and 16) or constitute a connection of said cavities 44 to
the externally situated bottom side 65 of the central part 34 (FIG.
13).
[0165] Upon commencement of a pivoting movement of the backrest
support 4 rearward, the slots 64 are open. The further the pivoting
progresses, the greater the extent to which the slots 64 close,
until, when the maximum usable pivot angle is reached, they close
completely, whereby the flexural stiffness of the central part 34
abruptly increases. The slots 64 thus serve as stop elements for
limiting a deformation of the backrest rod 130 during a movement
rearward. The selected honeycomb or cavity structure serves for
stiffening the connecting part 133 during a movement forward. If it
is the intention for an abrupt stiffening to occur in the case of a
particular forward movement of the backrest rod 130, slots 64 may
also be provided on the top side 66.
[0166] From the description of the last exemplary embodiment, it is
clear that the invention is applicable not only to chair mechanisms
and the components or assemblies thereof. The integrated
deformation element 8 according to the invention that has been
described above by way of example in the form of a connecting piece
33 or of a deformable section 34 may also be used in other parts of
a seat assembly, in the backrest, in the armrests, in the seat, in
further attachment parts of the chair or in a subframe, such as a
cruciform base, in order to serve as an energy store.
[0167] The deformation element 8 is preferably the only
energy-storing component of the device 1, 10, 130 according to the
invention. The deformation element 8 may however also be combined
with other energy-storing structural parts, whilst achieving
additional advantages.
[0168] The positions of the rotary points relative to one another
and relative to other structural elements of the mechanism, as
mentioned in conjunction with the above-described exemplary
embodiments of individual pivot mechanisms, are to be understood
merely as examples for specific advantageous variants of the
invention. The invention is also applicable to pivot mechanisms
which have some other arrangement of the rotary points.
[0169] The invention has been described above primarily in
conjunction with bending deformations of the deformation element,
which serve for realizing a pivoting movement. It is however also
possible for deformation elements to be provided which are based on
a bending deformation for realizing a tilting movement or some
other movement. Also, other deformations of deformation elements,
such as for example torsional deformations, are possible for the
purposes of realizing the same or other movements. Likewise
possible are intentionally effected combinations of deformation
types, for example simultaneous bending and torsional deformations,
in particular for the purposes of realizing superposed movements,
in more than one spatial direction, of the devices which have the
deformation elements.
[0170] All of the structural and functional features,
characteristics and advantages discussed in conjunction with the
deformation element with regard to one exemplary embodiment of the
invention are also transferable to the other exemplary
embodiments.
[0171] All of the features presented in the description, in the
following claims and in the drawing may be essential to the
invention both individually and in any desired combination with one
another.
LIST OF REFERENCE DESIGNATIONS
[0172] 1 Base support [0173] 2 Cone receptacle [0174] 3 Seat
support [0175] 4 Backrest support [0176] 5 Web [0177] 6 Driver
[0178] 7 Pivoting direction [0179] 8 Deformation element, storage
member [0180] 9 Pivot angle [0181] 10 Synchronous mechanism [0182]
11 First transverse axis, main pivot axis [0183] 12 Second
transverse axis [0184] 13 Third transverse axis [0185] 14 Seat
longitudinal direction [0186] 15 Neutral axis [0187] 16 Rear region
of the mechanism [0188] 17 Front region of the mechanism [0189] 18
Front region of the base support [0190] 19 Transverse direction
[0191] 20 Chair post [0192] 21 First rotary joint [0193] 22 Second
rotary joint [0194] 23 Third rotary joint [0195] 24 Front region of
the seat support [0196] 25 Rear region of the seat support [0197]
26 Force direction in the first load situation [0198] 27 Force
direction in the second load situation [0199] 28 Virtual center of
rotation [0200] 29 Virtual center of rotation [0201] 30 Virtual
center of rotation [0202] 31 Main body of the base support [0203]
33 Connecting piece [0204] 34 Central section [0205] 35 Rear end
region, attachment region [0206] 36 Front end region, attachment
region [0207] 37 Intermediate space [0208] 38 Upper link member
[0209] 39 Lower link member [0210] 40 Cell [0211] 41 Stop element
[0212] 42 Cavity [0213] 43 Cell wall [0214] 47 Intermediate plane
[0215] 48 Upper plane [0216] 49 Lower plane [0217] 51 Virtual
center of rotation [0218] 52 Spacing, lever length [0219] 53
Receptacle [0220] 54 Longitudinal edge [0221] 55 Limb [0222] 56
Opening [0223] 57 Tip [0224] 58 Upper member [0225] 59 Lower member
[0226] 60 Partial sub-member [0227] 61 Side wall [0228] 64 Slot
[0229] 65 Bottom side [0230] 66 Top side [0231] 87 Backrest [0232]
130 Backrest rod [0233] 131 Short limb [0234] 132 Long limb [0235]
133 Connecting part [0236] 134 Central part, limb section [0237]
139 Synchronous mechanism (prior art) [0238] 140 Rear coupling
element [0239] 141 Front coupling element [0240] 142 First rotary
joint [0241] 143 Second rotary joint [0242] 144 Third rotary joint
[0243] 145 Fourth rotary joint
* * * * *