The present invention relates to the stabilisation of objects, such as freestanding furniture and appliances.
Many objects such as items of furniture (ie tables, chairs and benches) and white goods are supported at at least four points of contact with the ground or floor (e.g. using ground engaging means such as legs, feet or wheels). These objects are used in a wide range of situations and in many cases the surface on which the object is stood is uneven or not a perfectly flat plane. To prevent, for example, furniture from rocking on an uneven surface it is common for small tables or stools to use three legs since three points are sufficient to define a linear plane and therefore provide location of the object without rocking. However, there are many reasons why three legs are undesirable on many objects, particularly those having a quadrilateral shape in plan view such as square or rectangular topped tables where four legs are generally preferred, located towards each corner. The use of four or more legs of equal length rigidly attached to and supporting a flat table top restricts the feet of the table to lie in a flat plane, so they are unable to all contact the ground simultaneously when the surface is uneven. This causes the table to be unstable and rock, which is most noticeable in four-legged tables with small table tops.
There are numerous applications requiring a support mechanism that is uncomplicated and robust, but can have four or more legs which adapt to uneven surfaces to provide stability.
In U.S. Pat. No. 3,814,362, a table is shown having four L-shaped legs with the vertical portion of each leg located towards the centre of the table, two adjacent legs are fixed to each other and the table top. The other pair of adjacent legs are fixed to each other and pivotally connected to the lower end of the vertical portion of the fixed pair of legs such that relative rotation about the pivot provides adjustment of the four feet to uneven surfaces. The relative rotation is permitted or locked by additional mechanisms. However, the relative rotation of the pairs of legs can provide a misaligned or unattractive look to the table and user intervention is required to operate the additional locking mechanisms.
French Publication Numbers 2 902 619 and 2 902 620 show mechanisms to permit vertical displacement of the four corner legs of a square or rectangular table. The arrangements disclosed maintain the angle of each leg perpendicular to the table top (which is very good for aesthetics) even when the legs have displaced to contact a very uneven surface. However, the linkages used involve an excessive quantity of individual links and joints making them complex and either heavy or fragile.
Canadian Patent Application Number 2,216,869 shows a flexible base for rolling chairs and workstools. Each castor is mounted at the lower end of a T-shaped arm 14, the arm 14 being able to rotatably fixed to the base about axis 24 (along the top bar of the T). Additional T-shaped bridge elements 26 are utilised which can pivot relative to the base about axis 34 (along the vertical bar of the T), the ends of the top bar engaging the T-shaped arms 14 of adjacent castors. Thus the mechanism permits vertical displacement of adjacent castors in opposing vertical directions to maintain contact with uneven surfaces, thereby preventing rocking and providing stability. However, the arrangement is complex having a large number of parts and a large number of joints.
It is therefore a preferred object of the invention to provide a support mechanism having four or more legs which can adapt to uneven surfaces utilising an uncomplicated mechanism.
It is a preferred object of the invention that the mechanism self adjust to the uneven surface without requiring operator intervention.
It is an optional object of the invention to provide a travel stop to limit excess articulation of the mechanism without requiring operator intervention.
With this in mind, according to one aspect of the present invention, there is provided a support mechanism for an object, the support mechanism including at least two fixed legs, at least two moveable legs and an interconnection means, each leg including a ground engaging means. The at least two moveable legs are moveable relative to the fixed legs and the interconnection means. The at least two fixed legs together include a first and a third leg, the interconnection means being intermediate and rigidly connected to the at least two fixed legs. The at least two moveable legs together include a second and a fourth leg, each moveable leg including a beam portion, one end of the beam portion being connected to the interconnection means by a pivot having a pivot axis. Each moveable leg further includes at least one support member connected to the beam portion and extending from the beam portion, at least one object support portion being provided on each support member, in use the object support portion being in contact with the object and providing a substantially vertical support force to the object. Locating means are attached to the object and located relative to the interconnection means to permit (preferably slidable) relative displacement between the locating means and the interconnection means in a substantially upward direction (relative to the interconnection means) and to prevent relative displacement between the locating means and the interconnection means in a substantially horizontal direction (relative to the interconnection means), such that substantially vertical displacement of the ground engaging means of one of the moveable legs relative to the fixed legs causes substantially vertical displacement of the support member of the associated moveable leg and therefore substantially vertical displacement of the object and the locating means relative the interconnection means and the fixed legs, causing the other of the at least two moveable legs to rotate (about its pivot point), the support mechanism thereby conforming to an uneven surface.
The support mechanism provides support and conforms to an uneven surface (to prevent rocking or instability) inherently or automatically, requiring no additional operator intervention. If only four legs are provided, the load on each leg is substantially unaffected by the magnitude of warp of the uneven surface.
The at least one support member may extend laterally from the beam portion.
The interconnection means may include a substantially vertical sleeve and the locating means may include a substantially vertical protrusion or spigot slidably received in the sleeve. Alternatively, the interconnection means may include a substantially vertical protrusion and the locating means may include a substantially vertical sleeve slidably located around the protrusion of the interconnection means.
Each support member may be flexible in a substantially horizontal direction to accommodate relative lateral motion between the object and the beam portion of an associated leg (preferably substantially parallel to a major axis of the beam portion and perpendicular to the pivot axis of the beam portion pivot), and wherein each support member may be substantially rigid in a vertical direction to provide support of the object relative to the beam portion. Alternatively, motion of each object support portion relative to the object may be permitted in a lateral direction perpendicular to the pivot axis of the respective leg and limited in a lateral direction parallel to the pivot axis of the respective leg by a pin and slot mechanism. In this case, the support members may be substantially rigid.
A travel limit may be provided between the object support portion of each support member and the object, the travel limit being defined by at least one end of the slot of the pin and slot mechanism, thereby limiting the rotation of at least one moveable leg and providing a travel limit to the support mechanism. Alternatively or additionally, a travel limit may be provided between the interconnection means and the locating means to provide a physical limit to the relative displacement between the locating means and the interconnection means in a substantially vertical direction, thereby limiting the rotation of each moveable leg and limiting warp travel. For example the protrusion may extend through the end of the sleeve, the protrusion including a step which interferes with the end of the sleeve at the desired travel limit point. Similarly a pin may be provided on either the sleeve part or the protrusion part, the pin sliding in a slot in the other part with the end of the slot being positioned to interfere with the pin at the desired maximum travel position to provide the limit stop.
At least one leg may include a portion which interferes with the object when warp displacement of the mechanism exceeds a predefined magnitude, said interference providing a travel limit, limiting the maximum articulation of the support mechanism. That portion may be the beam portion of the leg, or a protrusion or additional portion provided specifically as a travel limit.
Each leg may include a downwards extending portion, extending downwards to the respective ground engaging means.
Each fixed leg may include a beam portion which can include a first end and a second end, the first end of the first and third legs being fixed to the interconnection means, the first end of the second and fourth legs being connected to the interconnection means by the pivot.
The beam portion of each leg may be substantially horizontal in use.
The second end of the beam portion of each leg may be connected to the ground engaging means and the at least one support member of each moveable leg may be connected to the beam portion of the respective moveable leg between the first and second ends. Alternatively, the second end of the beam portion of each moveable leg may be connected to the at least one support member of the respective moveable leg and the ground engaging means may be connected between the first and second ends of the beam portion of the respective moveable leg. The support members may not extend perpendicular to the beam portions in plan view, but the position of a line through the top support portions parallel to the pivot axis of the respective moveable leg can be considered the effective position of the support member.
The beam portions of the first and third legs may be substantially parallel to each other in use. The second and fourth leg beam portions may be substantially parallel to each other and substantially perpendicular to the first and third leg beam portions in plan view.
The beam portions of the legs may form a cross in plan view. The pivot axes of the second and fourth legs may be parallel to the beam portions of the first and third legs in plan view.
The object may be a table top. For example, the top support portions may be in contact with a table top, i.e. the object being supported is a table top. The object could alternatively be a piece of furniture or part of a piece of furniture, or any other object including white goods.
One or more forms of the present invention may provide a table including a table top and first, second, third and fourth legs, the first and third legs being fixed to an interconnection means, the second and fourth legs including a beam portion, the beam portions of the second and fourth legs being connected to the interconnection means by a respective pivot having a pivot axis,
each leg including a downwards extending portion, extending downwards to a respective ground engaging means.
the second and fourth legs each including at least one respective support member connected to the respective beam portion and extending at least laterally from the beam portion, at least one top support portion being provided on each support member, the top support portion providing a substantially vertical support force to the table top,
locating means fixed to the table top and slidably located relative to the interconnection means to permit relative displacement between the locating means and the interconnection means in a substantially vertical direction (relative to the interconnection means) and to prevent relative displacement between the locating means and the interconnection means in a substantially horizontal direction (relative to the interconnection means).
Using this arrangement, the legs of the table are thereby able to conform to uneven surfaces and support forces are transferred between the four legs such that the load on each leg is substantially unaffected by the magnitude of warp of the uneven surface.
It will be convenient to further describe the invention by reference to the accompanying drawings which illustrate preferred aspects of the invention. Other embodiments of the invention are possible and consequently particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding summary of the invention.
In the drawings:
Referring initially to
Although the interconnection means does not provide direct vertical support to the table top, it does provide some lateral location. For this purpose, a locating means 14 is provided including a plate 15 fixed to the table top and a vertical spigot 16 received in a vertical hole or sleeve 17 in the interconnection means 8. The spigot 16 of the locating means can slide vertically in the sleeve 17 of the interconnection means, so vertical translation of the locating means (and the table top) relative to the interconnection means (and the fixed legs) is permitted, but lateral translation is prevented. The spigot can be any protrusion fixed to the plate (or at least a rigid part of the locating means) providing the functionality described above, ie it could be a square section rather than a round section, and it could be solid or hollow. The spigot or protrusion could alternatively be provided on the interconnection means and the hole or sleeve could then be provided as part of the locating means.
The table top is supported vertically by support members 19 and 20 extending from the beam portion 4a of moveable leg 4 and by support members 21 and 22 extending from the beam portion 6a of moveable leg 6. One end of each support member 19a, 20a, 21a or 22a is rigidly connected to a beam portion (4a or 6a) and the other end includes a table top support portion 19b, 20b, 21b or 22b which is connected to the underside of the table top 2. These top support portions 19b, 20b, 21b, 22b provide the vertical forces supporting the table top, these forces being transmitted by the rigid support members to the beam portions of the moveable legs 4 and 6. Taking the example of moveable leg 4, the forces from the support members 19 and 20 acting on the beam portion 4a are reacted by a combination of the force at the ground engaging portion of the leg and the force at the pivot of the leg through bolt 12. If the top support portions 19b and 20b lie on a line perpendicular to the mid point of a line between the ground engaging means and the bolt in plan view, the other moveable arm is of the same proportions and the ground engaging means form a square footprint in plan view, then the loads from the table top will be shared equally between all four ground engaging means (if the load on the table top is central) or at least the combined load at the ground engaging means of the two moveable legs will be equal to the combined load at the ground engaging means of the two fixed legs (even if the load on the table top is eccentric). Due to the articulation feature of the mechanism, allowing the legs to conform to a warped ground surface, this load distribution will remain substantially unchanged when the table is placed on an uneven surface.
If for example the ground engaging means 6c of one of the moveable legs were displaced vertically upwards with respect to the fixed legs, then the leg 6 would rotate about the bolt 12 and the support members 21 and 22 would be displaced a proportional distance upwards, causing the table top 2 to be displaced upwards relative to the fixed legs and the interconnection means. The rotation of the leg 6 causes not only a vertical displacement of the support members 21 and 22, but a lateral displacement of the support members relative to the interconnection means. The spigot 16 of the locating means 14 ensures that the table top does not translate horizontally relative the interconnection means, so a slot 21c and 22c is provided in each top support portion to accommodate the lateral displacement of the support members relative the interconnection means (and the table top). The pins 25 and 26 are fixed to the table top through the slots and can be simple screws, the heads of the screws ensuring that when the table is lifted, the mechanism stays attached. Similar pins 23 and 24 are provided in slots 19c and 20c of the support members on the other moveable leg 4. The vertical displacement of the table top relative the fixed legs and interconnection means drives a similar rotation of the other moveable leg 4 so that the ground engaging means 4c moves in the same vertical direction as 6c.
The length of at least one slot can be limited to limit the displacement of one moveable leg relative to the fixed legs in at least one direction to provide a travel limit or stop to limit the articulation or magnitude of warp of the mechanism. If any slot is to be used as a travel limit, then preferably each slot is used to distribute the limit loads through the mechanism, reducing mechanical stresses. An optional travel limit can alternatively or additionally be provided through interference between portions of the legs and the table top. For example, where the beam portions of each leg extend out to downwards leg portions near the corners of the table top, the outer end of each beam portion could be designed to contact the table top at a given magnitude of warp or articulation of the mechanism. The downwards extending portions of the legs could be extended upwards or specific protrusions or portions could be provided to contact the table top as required.
The table top 2 is round instead of square although any shape of table top can be used with the invention. The legs extend downwards from near the centre of the table, the fixed legs 3 and 5 have minimal or no beam portion, being fixed to the interconnection means 8. However the moveable legs 4 and 6 still incorporate a beam portion 4a or 6a to which the support members are mounted.
The ground engaging means (or feet) 3c, 4c, 5c, 6c feet can again be integrally formed into each leg. Alternatively each foot can be separate and fixed to the leg by any known means such as press fit, screw fit, welding, bonding or by a joint such as a ball joint to allow the foot to adjust to motions of the leg and cambers of the floor or other ground surface. Each foot can be flat, rounded or any other profile and be made from any suitable materials (eg soft materials to protect delicate floors).
The support members 19, 20, 21 and 22 are also flexible to remove the need for the pin and slot (or equivalent) type joint between the top support portions (19b, 20b, 21b, 22b) and the table top. The support members need to be stiff in a vertical direction to provide support of the table top, but flexible in a substantially horizontal direction perpendicular to the pivot axis of the leg pivot through bolt 12. To this end the support members shown in
Alternatively, the support members could be stiff as in
The support members can have any shape and do not need to extend perpendicular (in plan view) to the beam portion of the associated leg, nor extend parallel to the pivot axis of the associated leg. For example, the beam portion 6a and the support members 21 and 22 of
The spigot 16 in
While
The ground engaging means (4c, 6c) of the moveable legs do have a lateral component of their displacement relative to the fixed legs so providing a low friction foot material or profiling the ground engaging means to be rounded in line with the leg pivot can aid operation of the mechanism.
The support mechanisms can be limited to the parts between the locating means and the beam portions of the legs. For example this basic support mechanism (say the parts from
The basic mechanism could be supplied with the plate 15 of the locating means increased in size to incorporate the mounting of the top support portions of the support members. Alternatively, the basic mechanism can include a large plate to which the locating means and the top support portions are connected. That plate then provides a platform to which any object can be mounted.
While in the figures the legs are perpendicular to each other in plan view and form a cross in plan view, asymmetric designs are possible. The footprint of the ground engaging means is not limited to being square as shown and the two legs in each pair do not need to be aligned with each other, although any offset of the moveable legs can require a change to the top support portion. Similarly, while the pivot axes of the moveable legs are shown parallel to the major axis of the fixed legs and perpendicular to the major axis of the moveable legs in plan view, although this constraint is not essential, if the pivot axes of each moveable leg is not perpendicular to the major axis of that leg in plan view a change can be required to the top support portion.
Number | Date | Country | Kind |
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2010900830 | Feb 2010 | AU | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/AU2011/000198 | 2/25/2011 | WO | 00 | 10/22/2012 |