The present disclosure generally relates to an article of furniture, and more particularly, to a tiltable stool or chair.
Articles of furniture such as stools or chairs which allow a user to rock forward, backward and sideways are generally known. A tiltable stool is typically configured to be used on a generally horizontal surface such as a floor. The stool comprises a top portion providing a seat and a base portion comprising a bottom surface configured to support the stool on the floor.
An example of a tiltable stool is disclosed in the applicant's U.S. Pat. No. 9,894,998 which is hereby incorporated by reference thereto in its entirety.
A tiltable stool includes a seat, a base, and a body structure extending between the seat and the base. The base includes at least an inner base element and an outer base element. The outer base element extends outwardly around the inner base element. The body structure is firmly connected to a central portion of the inner base element. The outer base element has an annular upper end extending outwardly around the inner base element and a rotationally symmetrical outwardly convex and inwardly concave body extending from the annular upper end to an annular lower end. The outer base element or the inner base element is resiliently deformable, thereby allowing the body structure to pivot in any direction.
The inner base element and the outer base element may be connected to each other with a tongue and groove joint. In particular, the outer base element may have an inwardly facing tongue which engaged an outwardly open groove in the inner base element.
An upper surface of the inner base element and an upper surface of the outer base element may be arranged in a common plane. The upper surface of the inner base element and the upper surface of the outer base element may transition seamlessly into one another.
The inner base element may have an outwardly facing cylindrical support surface which abuts a corresponding inwardly facing cylindrical support surface of the outer base element. The outer base element may have an inwardly facing tongue which engages an outwardly open groove in the inner base element. In this configuration the outwardly facing cylindrical support surface of the inner base element may be arranged above the groove and the inwardly facing cylindrical support surface of the outer base element may be arranged above the tongue.
The inner base element may be made of an inelastic material and the outer base element may be made of a resiliently deformable material. Alternatively, the inner base element may be made of a resiliently deformable material and the outer base element may be made of an inelastic material. In yet another alternative both the inner base element and the outer base element may be made of resiliently deformable material.
An adjustment disk may be arranged at a variable height below the inner base element. A maximum tilt angle of the body structure may then be limited by selecting the variable height of the adjustment disk below the inner base element. The body structure may extend through the inner base element and the adjustment disk may comprise an inner thread which engages a corresponding outer thread arranged at a lower end of the body structure. The adjustment disk may be configured to push against the outer base element when a maximum tilt angle of the body structure has been reached.
The outer base element may have a generally C-shaped cross section. The inner base element may be generally disk-shaped. The inner base element may be made of spring steel and include a plurality of circumferentially distributed slots extending outward away from its central portion.
The seat of the stool may be pivotally mounted to an upper end of the body structure.
In another example, a tiltable stool includes a seat, a resiliently deformable inner base element, and a resiliently deformable outer base element extending outwardly around the inner base element. A body structure extends between the seat and the inner base element. The body structure is firmly connected to a central portion of the inner base element. The inner base element and the outer base element each form a spring damper system, allowing the body structure to pivot in any direction by deforming the inner base element and the outer base element. A damping factor of the outer base element is larger than a damping factor of the inner base element.
In a different configuration, a tiltable stool has a seat, an upper base element, a lower base element, and a body structure extending between the seat and the upper base element. The body structure is firmly connected to a central portion of the upper base element. The lower base element has an annular upper end firmly connected to an annular outer portion of the upper base element. The upper base element is resiliently deformable.
The lower base element may be a rotationally symmetrical outwardly convex and inwardly concave body extending from the annular upper end to an annular lower end.
The lower base element and the upper base element may be connected to each other with a tongue and groove joint. In particular, the lower base element may comprise an upwardly facing tongue which engages a downwardly open groove in the upper base element.
An outer surface of the upper base element and an outer surface of the lower base element may seamlessly transition into one another.
The upper base element may be made of a resiliently deformable material and the lower base element may be made of an inelastic material. Alternatively, both the upper base element and the lower base element may be made of resiliently deformable material.
The upper base element may comprise an annular groove. The annular groove may be deeper than it is wide. The annular groove may have an inner side wall and an outer side wall. The inner side wall and the outer side wall may be arranged at an angle towards one another when the tiltable stool is in an upright position. The annular groove may be arranged concentrically around and proximal to the central portion.
The annular groove may have a generally V-shaped cross-sectional profile with a flat bottom.
The annular groove may have an inner side wall and an outer side wall.
Upper portions of the inner side wall and the outer side wall may be arranged at a distance from one another when the tiltable stool is in an upright position. The upper portions of the inner side wall and the outer side wall may touch when the tiltable stool is deflected and reaches a maximum tilt angle.
The tiltable stool may include a tilt angle adjustment ring which is axially displaceable along a longitudinal axis of the body structure. The tilt angle adjustment ring may have a lower portion which engages the annular groove at a selectable depth. A maximum tilt angle of the body structure may be limited by selecting the selectable depth of the lower portion of the tilt angle adjustment ring in the annular groove.
The upper base element of the tiltable stool may include a plurality of concentric and radially spaced annular grooves. The annular grooves have a generally U-shaped cross-sectional profile. The annular grooves may be filled with a compressible compound.
The annular grooves may be wider than they are deep.
The upper base element may be generally disk-shaped.
Referring to
The base 3 may include an inner base element 20 which is connected to an outer base element 10. The body structure 4 is firmly connected to a central portion 29 of the inner base element 20. The central portion 29 may include a receiving opening for a lower portion of the body structure 4. The outer base element 10 is configured to rest on a floor.
The outer base element 10 or the inner base element 20 is resiliently deformable. This allows the body structure 4 to pivot in any direction by deforming the resilient element of the base 3. Throughout this specification and the following claims, the coordinating conjunction “or” is not used to express exclusivity. That is, the outer base element or the inner base element being resiliently deformable means that either the outer base element alone is resiliently deformable, that the inner base element alone is resiliently deformable, or that both the outer base element and the inner base element are resiliently deformable.
When a tilting force is applied to the seat, the seat is moved from a normal position into a dynamic seating position. Typically, the normal position is upright. In the upright position, the vertical axis 5 of the stool 1 is perpendicular to the floor. In response to a tilting force, the resilient element of the base 3 is deformed, and the vertical axis 5 of the stool 1 is tilted by a tilt angle α out of the normal position.
The outer base element 10 surrounds and is firmly connected to the inner base element 20. In particular, an upper annular end of the outer base element is connected to an outer rim of the inner base element. The inner base element 20 may be connected to the outer base element 10 by a tongue and groove joint. As shown in
The inner base element 20 and the outer base element 10 preferably transition seamlessly, i.e. smoothly and without gaps, into one another. An upper surface 26 of the inner base element and an upper surface 16 of the outer base element may be arranged in a common plane. The upper surface 26 of the inner base element and the upper surface 16 of the outer base element thereby transition seamlessly into one another.
The inner base element may have an outwardly facing cylindrical support surface 27 at its outer rim. This outwardly facing cylindrical support surface 27 abuts a corresponding inwardly facing cylindrical support surface 17 of the outer base element. In combination with a tongue and groove joint the outwardly facing cylindrical support surface 27 of the inner base element 20 and the inwardly facing cylindrical support surface 17 of the outer base element 10 are arranged in a plane axially spaced above the tongue 11 and groove 21. The support surfaces 17, 27 are generally vertically oriented.
The inner base element 20 may be generally disc-shaped having a generally vertically oriented, i.e. cylindrical, outer rim. The outer rim may alternatively have a frustoconical shape, in which case the support surfaces between the inner base element and the outer base element may also be frustoconical.
The desired tiltability of the stool can be achieved in that the inner base element is made of an inelastic material and the outer base element is made of a resiliently deformable material. Within the scope of this specification and the following claims, a material will be considered inelastic if a part made thereof, when the same is subjected to typical forces occurring in a stool, do not lead to a noticeable deformation of the part. An inelastic material may also be referred to as rigid. A material will be considered resiliently deformable, or simply resilient, if a part made thereof, when the same is subjected to typical forces occurring in a stool, does elastically deform and resume its original shape when no longer subjected to the typical forces. Within a stool forces up to 2500 N are typical.
The desired tiltability can also be achieved by making the inner base element from a resiliently deformable material and the outer base element from an inelastic material. In yet another variation both the inner base element and the outer base element may be made of resiliently deformable material. In that case, the inner base element and the outer base element are preferably made of different materials, and in particular of materials having different hardness.
The resilient element of the base 3 may be made of thermoplastic polyurethane (TPU), rubber, thermoplastic polyolefin (TPO), fiberglass enforced polyamide (PA) or fiberglass enforced polyurethane (PU). The selection of material requires a trade-off decision between cost and functionality. Experiments including durability tests have shown, that a thermoplastic polyurethane with 90 A Shore hardness provides the required robustness at an affordable price. An outer base element 10 made of softer TPU with 75 A Shore hardness would require about twice the amount of material as one made of TPU with 90 A Shore hardness.
The inelastic element of the base 3 may be made of metal, e.g. aluminum, or steel, or be made of a hard plastic, e.g. a plastic with greater than 100 A Shore hardness.
Shown in
The shape of the outer base element 10 can be defined by several characteristic metrics as illustrated in
While experiments have been conducted with parts of certain dimensions, the absolute size of those parts may be scaled, leaving characteristic proportions that have been found to be beneficial:
Generally, use of a thicker and software material (e.g. between 75-85 A Shore) for the outer base element should be considered for high-end products where comfort and service life of the product are critical. For lower cost models it is desirable to reduce the mass of the outer base member to ideally less than 1 kg, which can be accomplished by using thinner and harder material (e.g. above 90 A Shore).
The outer base element 10 may have a generally C-shaped cross section. As illustrated in
A differently shaped outer base element is illustrated in
While the outer base element 10 will preferably be formed as one piece, it may also be formed in two pieces as shown in
It may be desirable to limit the tilt of the stool to a maximum tilt angle and to allow a user to adjust this maximum tilt angle. This can be accomplished by providing an adjustment disk 61 as shown in
The adjustment disk 61 is wide, such that an outer rim of the adjustment disk, upon reaching the maximum tilt angle, pushes against an inner surface of the outer base element. The stool 1 can tilt no further than permitted by the height between the outer rim of the adjustment disk 61 and the inner surface of the outer base element underneath.
The position of the adjustment disk 61 within the base may be adjustable. For example, a lower portion of the body structure 4 may extend through the inner base element with a threaded end. The threaded end of the body structure may be connected with a threaded central opening of the adjustment disk 61. By rotating the threaded adjustment disk 61 within the base it can thus move up and down as indicated by a lower position 61′ in dotted line and an upper position of the adjustment disk 61 shown in solid line in
The concept of limiting the maximum tilt angle of the stool by an adjustment disk can also be applied to the configuration with a resilient inner base element 71 and rigid outer base element 72 shown in
In either configuration, the adjustment disk is arranged within the base at a variable height below the inner base element. A maximum tilt angle of the body structure is limited by selecting the variable height of the adjustment disk below the inner base element.
The stool shown in
While a force fit connection between the inner base element and the outer base element is preferred for recyclability, the inner base element may also be welded (e.g. by ultrasonic welding) or glued to the outer base element. The outer base element may also be overmolded onto the inner base element. The inner base element and the outer base element may also be produced by multi-material injection molding.
Since both the inner base element 20 and the outer base element 10 are resiliently deformable, both deform when the stool is tilted. Surprisingly though, the dynamic response of the inner base element 20 and the outer base element 10 to a sudden lateral movement of the seat 2 can be quite different. Both the inner base element 20 and the outer base element 10 can be considered damped spring systems. The damping factor of the outer base element 10 is significantly larger than the damping factor of the inner base element 20. The different damping factors are attributed to the choice of materials (spring steel vs. thermoplastic) and their relative sizes.
The different damping characteristics of the inner base element and the outer base element support a desirable use of the stool: The inner base element allows small, high-frequency movements of a user, which stimulates the user's muscular system. The user may constantly make micro-adjustments to her position on the stool while maintain balance, and thereby exercising her muscles. Intentional larger movements of the stool, i.e. larger pivot angles when reaching for a distant object, are possible and supported by deformation of the outer base element. However, such larger movements are significantly more dampened than small and fast movements. This provides a sense of stability to the user and avoids a risk of accidental fall.
As shown in
An alternative configuration of an adjustment member 142 is shown in
A differently configured stool is shown in
The upper base element 150 is resiliently deformable. The lower base element 160 may be resiliently deformable and may in particular be the annular elastic base disclosed in the applicant's U.S. Pat. No. 9,894,998. The lower base element 160 may however be inelastic and may e.g. include roller wheels 281 attached to a rigid support structure 282 as shown in
When a tilting force is applied to the seat, the seat is moved from a normal position as illustrated in
The annular groove 151 is relatively deep, i.e. a depth of the groove is greater than a width of the groove. As illustrated, the groove is about three times deeper than it is wide.
The annular groove 151 allows use of relatively hard materials having a hardness greater than 90 Shore. Elasticity is primarily achieved through the shape of the groove, not the softness of the material used. Use of a relatively hard material is desirable, especially when using TPU which tends to become harder and brittle over time. This is true especially in areas where the TPU is frequently deformed. The structural elasticity afforded by the annular groove provides a longer life than elasticity obtained from use of softer material.
A tilt angle adjustment ring 170 may be provided. The tilt angle adjustment ring 170 as shown in
A lower portion 173 of the adjustment ring is configured to engage the annular groove 151 at a selectable depth. In a lowermost position of the adjustment ring 170 the lower portion 173 protrudes completely into and fills the space within the groove 151. Thereby, the deformability of the upper base member 150 in the area of the groove 151 is substantially reduced.
By raising the adjustment ring, a maximum tilt angle α of the stool can be controlled. The stool can tilt only until the upper end of the outer wall 152 touches the lower portion 173 of the adjustment ring 170.
The lower base element 160 is arranged entirely below and firmly connected to the upper base element 150. In particular, an upper annular end of the lower base element is connected to an outer end of the upper base element. The upper base element 150 may be connected to the lower base element 160 by a tongue and groove joint. As shown in
The upper base element 150 and the lower base element 160 preferably transition seamlessly, i.e. smoothly and without gaps, into one another.
An alternative configuration of an upper base element 180 is shown in
A total width of upper ends of the inner groove 182 and the outer groove 181 determines a maximum tilt angle α of the body structure 4 relative to the base 3. As shown in
The width of the grooves 181,182 should be selected to meet pinch test standards and is preferably less than 8 mm or wider than 23 mm. The grooves 181, 182 may be filled with a compressible material 185, for example a rubber compound.
Alternatively, the grooves 181, 182 may be covered with an annular cover 251 as shown in
Stiffening ribs 186, 187 may be formed in the upper base element 180 radially outwardly of the grooves 181,182. Thereby, resilient deformation of the upper base element 180 is substantially limited to the area of the grooves 181,182.
Another alternative configuration of an upper base element 210 is shown in
Irrespective of a particular embodiment, the upper base element 150,180,210 is preferably an integrally molded single piece. In combination with a single-piece molded lower base element 160 the base 3 may thus consist essentially of only two parts. This allows for very cost effective manufacturing yet provides a desirable dynamic deformation. The utilization of grooves has proven beneficial to extend the useful life of the base.
In some configurations, it may be desirable not form the upper base element as a single part, but rather as an assembly of several pieces. One example of such a modular design is shown in
Desirable configurations of a tiltable stool include: A tiltable stool, comprising: a seat; an inner base element; a body structure extending between the seat and the inner base element, the body structure being firmly connected to a central portion of the inner base element; and an outer base element, the outer base element having an annular upper end extending outwardly around the inner base element and a rotationally symmetrical outwardly convex and inwardly concave body extending from the annular upper end to an annular lower end, wherein the outer base element or the inner base element is resiliently deformable, thereby allowing the body structure to pivot in any direction.
The tiltable stool as described above, wherein the outer base element and the inner base element are connected to each other with a tongue and groove joint.
The tiltable stool as described above, wherein the outer base element comprises an inwardly facing tongue which engaged an outwardly open groove in the inner base element.
The tiltable stool as described above, wherein an upper surface of the inner base element and an upper surface of the outer base element are arranged in a common plane.
The tiltable stool as described above, wherein an upper surface of the inner base element and an upper surface of the outer base element transition seamlessly into one another.
The tiltable stool as described above, wherein the inner base element comprises an outwardly facing cylindrical support surface which abuts a corresponding inwardly facing cylindrical support surface of the outer base element.
The tiltable stool as described above, wherein the outer base element comprises an inwardly facing tongue which engaged an outwardly open groove in the inner base element, and wherein the outwardly facing cylindrical support surface of the inner base element is arranged above the groove and the inwardly facing cylindrical support surface of the outer base element is arranged above the tongue.
The tiltable stool as described above, wherein the inner base element is made of an inelastic material and the outer base element is made of a resiliently deformable material.
The tiltable stool as described above, wherein the inner base element is made of a resiliently deformable material and the outer base element is made of an inelastic material.
The tiltable stool as described above, wherein both the inner base element and the outer base element are made of resiliently deformable material.
The tiltable stool as described above, further comprising an adjustment disk which is arranged at a variable height below the inner base element.
The tiltable stool as described above, wherein a maximum tilt angle of the body structure is limited by selecting the variable height of the adjustment disk below the inner base element.
The tiltable stool as described above, wherein the body structure extends through the inner base element and wherein the adjustment disk comprises an inner thread which engages a corresponding outer thread arranged at a lower end of the body structure.
The tiltable stool as described above, the adjustment disk is configured to push against the outer base element when a maximum tilt angle of the body structure has been reached.
The tiltable stool as described above, wherein the outer base element has a generally C-shaped cross section.
The tiltable stool as described above, wherein the inner base element is generally disk-shaped.
The tiltable stool as described above, wherein the inner base element comprises a plurality of circumferentially distributed slots extending outward away from the central portion.
The tiltable stool as described above, wherein the seat is pivotally mounted to an upper end of the body structure.
A tiltable stool, comprising: a seat; a resiliently deformable inner base element; a body structure extending between the seat and the inner base element, the body structure being firmly connected to a central portion of the inner base element; and a resiliently deformable outer base element extending outwardly around the inner base element, wherein the inner base element and the outer base element each form a spring damper system, allowing the body structure to pivot in any direction by deforming the inner base element and the outer base element.
The tiltable stool as described above, wherein a damping factor of the outer base element is larger than a damping factor of the inner base element.
Various configurations of a tiltable stool are possible by combining any two or more of the following features: The structure of the lower base element being a rotationally symmetrical outwardly convex and inwardly concave body extending from the annular upper end to an annular lower end. The lower base element and the upper base element being connected to each other with a tongue and groove joint, in particular the lower base element having an upwardly facing tongue which engages a downwardly open groove in the upper base element. A seamless transition of an outer surface of the upper base element and an outer surface of the lower base element. A material selection of the upper base element being made of a resiliently deformable material and the lower base element being made of an inelastic material, or alternatively both the upper base element and the lower base element being made of resiliently deformable material. The upper base element having an annular groove, in particular an annular groove that is deeper than it is wide. The specific structure of the annular groove having an inner side wall and an outer side wall, the inner side wall and the outer side wall being arranged at an angle towards one another when the tiltable stool is in an upright position. The position of the annular groove being arranged concentrically around and proximal to the central portion. The shape of the annular groove having a generally V-shaped cross-sectional profile with a flat bottom. The limitation of a maximum tilt angle when the upper portions of an inner side wall and outer side wall of an annular groove touch. The use of a tilt angle adjustment ring which is axially displaceable along a longitudinal axis of the body structure in which the tilt angle adjustment ring has a lower portion which engages the annular groove at a selectable depth. A maximum tilt angle of the body structure being limited by selecting the selectable depth of the lower portion of the tilt angle adjustment ring in the annular groove. The upper base element having a plurality of concentric and radially spaced annular grooves, in particular grooves having a generally U-shaped cross-sectional profile. Annular grooves being filled with a compressible compound or covered by a cover. The annular grooves being wider than they are deep. The upper base element being generally disk-shaped.
One skilled in the art will recognize that various additional configurations can be achieved by adding features not specifically listed above but generally described in this specification.
Within this specification the words “example” and “exemplary” are used herein to mean serving as an instance or illustration. Any embodiment or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word example or exemplary is intended to present concepts in a concrete fashion. As used in this application and the following claims the term “or” is an inclusive “or” rather than an exclusive “or”. That is, “or” means “and/or” unless specified otherwise or clear from context. The articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form.
Filing Document | Filing Date | Country | Kind |
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PCT/IB2020/055459 | 6/10/2020 | WO | 00 |
Number | Date | Country | |
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62859314 | Jun 2019 | US |