EP0105957A1

EP0105957A1 - Folding table or like structure

Info

Publication number: EP0105957A1
Application number: EP82109472A
Authority: EP
Inventors: William F. Logan
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-10-13
Filing date: 1982-10-13
Publication date: 1984-04-25

Abstract

A folding table or like structure having a generally planar top (10) supported on the floor by four or more legs (11), a support- structure comprising: two points of articulation (12) below the table top (10) located at some distance inward from the edge of the table, two splayed legs (11) in V-formation extending from each point of articulation (12) to a point on the floor, a cable network interconnecting the lower ends (13) of said legs and extending from proximate each corner of the table top (10) to the lower end (13) of the leg (11) located therebelow the arragement being such that in the assembled state all cables (12, 15, 16) are in tension and the legs (11) are in compression.

Description

This invention relates to a folding table or similar collapsible structures having a generally flat top, rectangular in outline and four collapsible legs which can be readily folded against the underside of the table.
According to the invention there is provided a folding table or like structure having a generally planar table top supported on the floor by multiple legs and a cable network, wherein the legs are articulated below the table top at spaced points located inwardly from the edge of the table, said legs comprising two splayed legs in V-formation extending each from each point of articulation to points on the floor and said cable network interconnecting the lower ends of said legs and extending from proximate each corner of the table top to the lower end of a leg located therebelow, the arrangement being such that in the assembled state all cables are in tension and the legs are in compression.
According to a further aspect of the invention there is provided a folding table or like structure including a generally planar solid table top, two pairs of supporting legs depending from the underside of said table top, each pair of legs defining an inverted V with the apices of said pairs articulated to said underside of the table top at locations spaced apart to provide a table which is symmetrical in the erected state, a cable network interconnecting the ends of the legs remote from the articulated apices and connecting said leg ends with said underside of the table top, and separate tensioning means each secured on the underside of the table top and associated one with each articulated apex to place the cable network in tension and the diverging legs in compression when the table is in the erected state.
According to a further aspect of the invention there is provided a folding table comprising: a generally planar loosely supported rigid table top, two points of articulation located below the underside of the table top approximately midway between the plane of the table top and the floor, an upper and a lower pair of splayed legs in V-formation extending from each point of articulation, the ends of the lower legs resting on the floor and the ends of the upper legs supporting the table top, a transverse bar extending between the points of articulation and substantially parallel to the table top, lower cables interconnecting the lower ends of said legs, upright cables extending generally from the upper ends of the upper legs to the lower leg ends of the lower legs, and upper cables interconnecting the upper ends of said legs, and force release means for placing the cables under tension; the arrangement being such that in the assembled state all the cables are in tension and the legs are in compression.
According to a further aspect of the invention there is provided a folding structure-for use as camping table or bed comprising: a generally rectangular top made from flexible material, two points of articulation located below the underside of the top and which, when the folding structure is erected, are disposed approximately midway between the plane of the top and the ground, an upper and a lower pair of splayed legs in V-formation extending from each point of articulation, the ends of the lower legs resting on the ground and the ends of the upper legs engaging the top, a transverse bar extending between the points of articulation and substantially parallel to the top, lower cables interconnecting the lower ends of said legs and upright cables extending from the upper ends of the upper legs to the lower ends of the lower legs, and upper cables interconnecting the upper ends of said legs, and force release means for placing the cables under tension, the arrangement being such that in the assembled state all the cables are in tension and the top is stretched between the upper ends of the upper pair of legs.
In the tensioned condition of one embodiment of the invention, the lower system of cables forms a planar support so that the table structure can be put on soft ground or sand without loss of stability, the weight of the table being carried by the cables. On release of the tension means, the legs can be collapsed against the underside of the table top. The assembly is then reduced to a flat volume.
The elements of the table support structure are arranged in such a way that the top is prevented from twisting, swaying or moving vertically by the triangulations formed between the support struts, the top and the tension members. In order for the top to remain stable over time in spite of small changes in length of the tension members due to creep or temperature changes a spring element must be introduced into the system. In one form of the invention there is a coil spring situated adjacent to the pre-stressing means. The spring may be placed anywhere in the table support structure. In another embodiment, the spring may be the cambered table top itself, or in a still further embodiment the spring may be part of the strut elements.
One particular advantage of this type of table structure is that it may be easily and compactly disassembled for storage or shipment. This is done by releasing a pre-stressing device so that the tension elements become slack and the legs or struts may be displaced from their normal position to one in which they lie flat against the table top. The flexible tension members may also be placed flat against the top for the same reasons.
In order that the present invention may be more clearly understood and readily carried into effect, embodiments thereof will now be described with reference to the accompanying drawings, in which

Fig. 1 shows a perspective underside view of an assembled table of one embodiment of the invention,
Fig. 2 shows the same table in a perspective end view,
Fig. 3 shows a modified arrangement for the lower cables,
Fig. 4 is a perspective view from underneath showing the manner in which the points of articulation can be moved along the underside of the table,
Fig. 5 shows a detail view to a larger scale of part of Fig. 4 slightly modified,
Fig. 6 is a sectional end view of the tracks along which the points of articulation can be moved, taken along line IV-IV in Fig. 4,
Fig. 7 is a perspective view of a further embodiment of the invention,
Fig. 8 is a similar view of a further embodiment,
Fig. 9 is a perspective view of yet another embodiment,
Fig. 10 shows the folding structure of Fig. 9 collapsed into a bundle;
Fig. 11 shows an enlarged view of one form of a component of the embodiment of Figs. 7, 8 and 9,
Fig. 12 is a perspective view from below of a further embodiment of the invention,
Fig. 13 is a perspective view from above of the embodiment shown in Fig. 12,
Fig. 14 is a perspective view from above of a further embodiment,
Fig. 15 is a perspective view from below of the embodiment shown in Fig. 14,
Fig. 16 is an enlarged view of a detail of the embodiments shown in Figs. 12 to 15,
Fig. 17 is a section taken along line XVII - XVII of Fig. 16,
Fig. 18 is an enlarged view of a further detail of the embodiments shown in Figs. 12 to 15, and
Fig. 19 is a section taken along line XIX - XIX of Fig. 18.

Referring first to Figs. 1 and 2 of the drawings, the folding table of the invention includes a generally planar table top 10. In its preferred form, the table top is rectangular. The table top may also be oval, or even square or round.
The table top can be made from plywood, laminated wood or plastic, fiberglass, glass or steel or other material which has sufficient strength whilst being capable of holding a pre-camber and will not break when flexed against the pre-camber or bow under tension of the cables.
The top is supported at each end by a pair of splayed legs or struts 11, coming together at the top at a point of articulation 12.
The points of articulation are preferably located inwards from the narrow ends 10a of the table top by a distance which is approximately equal to one sixth of the total length of the table top.
The lower ends 13 of the legs 11 rest on the floor. The four table legs are all identical in structure. They are preferably made of steel tubing about 33 inches in length so that in its assembled state the height of the table will be the usual 29 inches above floor level.
The lower ends 13 of the legs are interconnected by a network of cables in the form of a double Y. The central member 14 of the double Y rests on the floor and extends vertically below the longitudinal axis of the table top. The ends of the central member 14 are each joined at points 14a to shorter end cables 15 which in turn are suitably joined to the lower ends 13 of the table legs. The joints 14a of cables 14 and 15 forming the points of the Y lie vertically below the points of articulation 12. The shorter cables 15 also rest on the floor and are generally in the same plane as the central member 14. This lower plane is parallel to and substantially co-extensive with the plane of the table top.
In the modified arrangement of Fig. 3, the lower network of cables 18 is in the form of a rectangle extending between the lower ends of the table legs.
The assembly is completed by vertical cables 16 extending from each corner 17 of the table top to the lower end 13 of the corresponding table leg 11. The vertical cables 16 may be in one piece with the shorter end cables 15 and run through a suitable opening or ferrule or a grooved passage located at the lower leg ends 13. In this manner, a series of triangles are formed at each corner with the longer sides constituted by legs 11 and vertical cables 16. The shorter sides of each of these triangles is constituted by a line running from the corners 17 of the table top to the points of articulation 12.
The advantage of having the cables interconnecting the lower ends of the legs in the formation of a double Y is that the person or persons sitting at the table have greater freedom to move their legs and the legs of the chair will not interfere with the cables. The form shown in Figs. 1 and 2 is thus more suitable as a dining room table. However, much the same effect is obtained by arranging the lower cables 18 in the form of a rectangle as shown in Fig. 3; this embodiment being more suitable as a coffee table. Fig. 3 also makes it clear how the space between the table top, lower cables 18 and vertical cables 16 defines a rectangular parallelepiped or brick-shaped volume which imparts to the whole structure great strength.
The cables are placed under tension by a pre-stressing device which can be in the form of a turn buckle 25 and spring means 26. This spring compensates for small changes in length of the tension cable due to creep or temperature changes. In the Figs. 1 and 2 embodiments, the spring 26 is situated in the central member 14 adjacent to the turn buckle or other pre-stressing means. However, the springs may be placed anywhere along the tension cables, or several springs may be used where the cable is in several parts.
When the table top is pre-cambered or bowed with the shorter ends 10a pointing upwards in the unstressed state, the tension imparted in this way to the cables may be adequate and the spring elements could be omitted.
When the cables are under tension, the legs 11 are under compression and act as struts. When stressed, the triangles formed at each corner by legs 11 and vertical cables 16 impart to the whole structure a great deal of firmness preventing the`table structure from twisting, swaying or moving vertically.
In the Fig. 1 embodiment, the turn buckle 25 or quick force release device (such as a Pelican hook) can incorporate a quick release for the pre-stressing device. This quick release device may be like the lever action in a ski binding. By releasing the pre-stressing device, the tension elements become slack (as shown in Fig. 4) and the legs may be displaced from their normal position to one in which they lie flat against the underside of the table 10. The table can then be stored away occupying very little space.
In the arrangement shown in Figs. 3 and 4, the upper ends of the table legs come together at pin joints 19 which are located at the outer ends of slats 20, 20a which in turn are joined by hinges 21' to sliding pin joint plate 19. The inner ends of the slats are movably joined together by a hinge 21. The slats move in U-shaped guides 22 fastened to the underside of the table top, see Fig. 6.
It will be seen that by manually pushing the hinge 21 upwardly against the underside of the table top in the direction of arrow 23 (see Figs. 4 and 5), the upper ends of the table legs will be moved away from each other. In this manner, the vertical cables 16 and the lower network of cables 14, 15 or 18 will be placed under tension.
To collapse the table, the procedure is reversed and all that is required to release the tension in the cables is to manually move hinge 21 downwardly. To hold the slats 20, 20a in the upper position, a simple catch or latch (not shown) can be provided on the underside of the table top. Or a preferred way is to use an over-center hinge, so that hinge 21 in the tensioned state lies against the underside of the table top over the horizontal plane of hinges 21', see Fig. 3.
The table top 10 in its untensioned state may have an in-built camber, bow or concavity with the ends of the table top above its center. The camber 1O_X (shown in broken lines in Figs. 1 and 3) can be quite slight and does not amount to more than 1 or 2 inches in a 6 foot table. However, in this manner, on applying tension to the vertical cables 16, the table top will be flexed in the opposite direction so that in the tensioned state, the table top will generally be quite flat in its horizontal plane. The camber will thus compensate for changes in length in the cables due to temperature variations or wear and the spring 26 can be omitted.
Another manner of moving apart the points of articulation is to arrange the pin joints 19 (holding together the upper ends of the splayed legs 11) on female threaded slides which move in U-shaped guides mounted on the underside of the table top. A spindle with opposed threads on its ends engage in these slides. The spindle has a square end adapted to be engaged by a crank (not shown).
In the Fig. 7 modification, the table top 10' sits loosely on the supporting framework formed by the cables and struts. In this system, the supporting frame takes all stresses and strains and the table top 10 may be made from plate glass, marble or other rigid material.
The supporting framework includes two points of articulation 12' located below the underside of the table top approximately midway between the plane of the table top and the floor. The points of articulation are again located inwardly from the shorter end of the table top by a distance which is roughly equal to one sixth (1/6) of the total length of the table.
Two pairs of splayed legs or struts lla-llb, llc-lld in V-formation extend from each point of articulation 12'. Legs lla-llb form the lower pair extending from the point of articulation to the floor.
Struts llc-lld form the upper pair. The ends of the upper struts at either end of the table form - four supporting points 31 for the loose table top 10'. The points of articulation 12' are held together by a horizontal bar 32 located vertically below the longer axis of the table top. The upper legs or struts llc, lld may be shorter than the lower legs or struts lla, llb so that the horizontal bar 32 will occupy a position which is closer to the underside of the table top than the floor. Such slight variations in length of the legs or struts and their angular disposition may be dictated by aesthetic or structural considerations, but will not affect the basic stability and function of the supporting structure.
The upper free ends 31 of legs or struts llc-lld are joined by straight runs of an upper cable 35 which follows a generally rectangular outline.
The lower corners 36 with which the lower legs or struts lla and llb rest on the floor are joined by a network of cables 14', 15' in the form of a double Y which is similar to the tension cables described and shown in Figs. 1 and 2. Alternatively, the lower network of cables could have the rectangular configuration shown in Fig. 3.
The upper ends 31 and lower ends 36 of the legs or struts are joined by vertical cables 16'. The cables pass through holes or ferrules or grooves at the end of the legs. The cables 14', 15', 16' and 35 may be run through ends 31 and 36 along different routes which will readily suggest themselves to the designer.
As in the Fig. 1 embodiment, a quick force release or quick tensioning device 25' is located at a suitable point or points in the cable network, preferably at a point along central cable 14'. The central cable may (but need not) include a spring 26 to take up slack in the cables.
The arrangement shown in Fig. 7 has the disadvantage that if a heavy load is placed in the middle of table top 10', this may flex downwardly and the table is subject to swaying. To overcome this, in the embodiment shown in Fig. 8, an additional pair of struts 38, 39 in V-formation is joined to struts lla-lld.
Struts 38, 39 at their upper or outer ends are joined at points 42 to the corresponding ends of the struts rising upwardly from the other point of articulation. The run of the upper cable 35 along the longer side of the table passes at point 42 through openings in the abutting upper ends of these struts. The assembly is completed by a triangle of cables 43a-43b-43c with the lower apex 44 joined to triangular ground cables 45a, 45b, 45c running through the lower ends of struts lla, llb.
In this fashion, the ends of six cables, 43c, 43b, 45a, 45b, 45a' and 45b' come together at apex point 44 which is preferably located aboutw4" above floor level. It will be seen that if in this embodiment a load is applied to the middle of the table top along the line joints points 42, any tendency to rotate the structure out of true will be resisted by struts 38, 39 and the triangular network of cables linked therewith.
In the Fig. 8 embodiment the horizontal bar may be in two pieces 32a, 32b one sliding telescopically within the other. A spring catch or umbrella snap 46 secures bars 32a, 32b at the desired spacing.
The folding structure shown in Figs. 9 and 10 uses a generally rectangular canvas top 50 which is stretched between the upper ends of struts llc, lld and 38, 39 reaching upwardly from each point of articulation. The term "canvas" top includes any suitable woven or other sheet material or mesh. The "canvas" top thus combines the supporting function of table top 10 and the tensioning action of the upper cables 35 in the Figs. 7 and 8 embodiments. The edge of the canvas 50 under tension will assume the flat catinary shape shown in Fig. 9. A quick force release device 51 is located in one of the lower cables 52 which interconnects the lower ends of lower legs lla, llb. The lower cable 52 may follow the double Y of Fig. 7 or the cables could have the rectangular configuration shown in Fig. 3. The system of struts and cables could also follow the Fig. 8 configuration, where the upper horizontal cables could be replaced by a "canvas" top.
The arrangement of the legs or struts is similar to the Fig. 8 embodiment. The horizontal strut is again in two parts 53, 54 telescopically sliding within each other and held together by an umbrella type snap 55.
To collapse the structure, the quick release device 51 and the umbrella snap are disengaged. The legs are folded towards each other. The upper ends of the upper struts need not be disengaged from the canvas which folds up between the legs as shown in Fig. 10. The folded bundle occupies approximately 2% of the space of the structure in its assembled state shown in Fig. 9.
Because of the small storage space required, the folding structure of Figs. 9 and 10 may find use as a camp bed or scaled upwardly could form part of a tent, water catchment or other military or strategic uses might suggest themselves.
In the above description the points of articulation are generally in the nature of hinges or pivotal joints. In a further form of the invention (Fig. 11), these joints could be made from semi-rigid castings (e.g. fiber-reinforced nylon or aluminum castings). These joints would then consist of a central piece 60 with a number of integral stubs 62 on which the struts lla-lld, 53 would be detachably mounted. The term "articulation" as used herein is thus intended to cover fairly rigid joints in addition to movable joints.
In the embodiment shown in Figures 12 and 13 legs 111 depend from the underside of a table top 110. The legs are arranged in pairs at opposite ends of the table and are articulated to the table top at locations (112) on the longitudinal center line of the table and inwardly of the short sides thereof. In the embodiment shown in the drawings each pair of legs is a single member which takes the form of an inverted V with its apex articulated to the underside of the table top and the remote ends forming the feet of the legs. Those feet are interconnected by a network of cables in the form of a double Y in a manner similar to the embodiment shown in Figure 1. To this end a central member 114 of the Y is arranged to rest on the floor and is joined to shorter end cables 115 which pass through the feet of the legs and extend upwardly as vertical cable runs 116 which are anchored to the corners of the table top.
With the table parts erected in the operative position shown in Figures 12 and 13, the feet of the table legs are located below the corners of the table top and the network of cables imparts the desired rigidity and stability to the table.
Figures 18 and 19 show, on an enlarged scale, how the cables 115, 116 pass through the feet of the legs 111. To this end each leg 111 is bent outwardly at the foot portion to lie on or parallel to the floor or other resting surface and then upwardly at the extremity of the foot end. The cable 115 passes through an aperture in the leg portion and then through the terminal portion of the foot and upwardly for anchoring to the corner of the table top.
If desired, glide clamps 100 can be snapped onto the feet portions which extend parallel to the floor or other support surface.
Instead of having tensioning means included in the cable network, the apex of each pair of legs is articulated to the underside of the table top by an individual tensioning means 150.
In this individual tensioning means 150, which is shown in enlarged detail in Figures 16 and 17 of the drawings, a strap 151 is looped around the apex of the pair of legs 111 and the ends of the loop are secured by fastening means such as, for example, a rivet 152. The remainder of the strap has a track 153 extending along the length thereof to engage a rotatable worm 154. The worm 154 meshes with the track 153 and is supported in position by a housing 155 formed at the end of a strip 156 of metallic or other suitably rigid material. The strip 156 lies along the underside of the table top 110 and is secured by one or more screws 157 or other-suitable means.
A key slot 158 is provided in a head portion 159 of the worm 154. It will be appreciated that this tensioning means is effectively a flattened hose clip or jubilee clip and that rotation of the worm 154 will draw the strap 151 longitudinally along the underside of the table top and thereby create the desired tension in the legs and network of cables.
Figures 14 and 15 show a modification of the embodiment shown in Figures 12 and 13. Figures 14 and 15 show a table top 110' which is square rather than of elongated rectangular shape and which has legs 111' articulated (112') to the underside of the table top in the central region thereof. Articulation of the legs lll' to the underside of the table top 110' is through tensioning means 150' of the type described with reference to Figures 12 and 13 and shown in detail in Figures 16 and 17.
A network of cables is again utilized and in this case comprises cables 115a which interconnect the feet of diametrically opposed legs 111¹.
As in the embodiment of Figures 12 and 13, the cables pass through the feet and extend upwardly to anchorages on the table top. However, unlike the embodiment of Figures 12 and 13, the upwardly directed cable portions 116a are not single cables but, instead, twin cable lengths which diverge from the feet of the legs to spaced anchorages 117 which anchorages are, in turn, spaced from the corners of the table top. In this manner, rigidity and stability against rotational deformation of a square table is enhanced by the triangular configuration adopted by the cable lengths extending upwardly from the feet of the legs.
As explained, the desired tension is imparted to the network of cables 115a, 116a by the individual tensioning means 150'. By selectively adjusting means 150, 150' it is possible to ensure that the table top 110, 110' is level even when the feet of the legs rest on an irregular floor surface.
In the majority of the above discussed embodiments, the feet of the table legs are located directly beneath the corners of the table top. This, however, is not always the case and Figures 14 and 15 show an assembly where the feet of the legs are not disposed directly beneath the corners of the table top.

Claims

1. A folding table or like structure including a generally planar table top (10,1.10) supported on the floor by multiple legs (11,111) and a cable network (14, 15,16,18,45,52,114,115,116) characterized in that the legs (11,111) are articulated below the table top (10,110) at spaced points located inwardly from the edge of the table, said legs comprising two splayed legs in V-formation extending each from each point of articulation (12,112) to points on the floor and said cable network interconnecting (14,15,18,45,52,114,115) the lower ends of said legs and extending upwardly (16,116) from proximate each corner of the table top to the lower end of a leg located therebelow, the arrangement being such that in the assembled state all cables are in tension and the legs are in compression.

2. A folding table according to claim 1, characterized in that the table top is pre-formed with a slight camber (lOx) so that when under stress the tension forces exerted by the upwardly extending cables (16) will cause the table top (10) to assume an essentially flat configuration.

3. A folding table according to claim 1 or claim 2, characterized in that the points of articulation (12) on the underside of the table top (10) slide in guides (22) on the underside of the table top and are connected by a pair of hinged struts (20,20a) whereby said points of articulation may be pushed away from each other to place the cables under tension.

4. A folding table according to any of claims 1 to 3, characterized in that the cables interconnecting the lower ends of the legs include a release element and spring member (26) to apply tension to the cables and compensate for slight changes in lengths due to temperature differences.

5. A folding table according to claim 1, characterized in that the table top (110,110') is a rectangular solid and the points of articulation (112, 112') are on the underside of the table'top, each of said points of articulation being associated with a separate tensioning means (150,150').

6. A folding table according to claim 5, characterized in that the tensioning means is arranged to displace the apex of the articulated splayed legs to tension the cables and includes a strap (151) secured around the apex of the splayed legs (111) and a drawing mechanism (154) engaging a tail of the strap to pull said apex into the tensioning position.

7. A folding table according to claim 6, characterized in that a track (153) extends longitudinally along the tail and the drawing mechanism incorporates a worm gear (154) engaging said track.

8. A folding table comprising a generally planar loosely supported rigid table top (107), legs (lla,llb, llc,lld) supporting said table top and a cable network (14',15',16'), characterized in that two points of articulation (12') are located below the underside of the table top (10') approximately midway between the plane of the table top and the floor, with a transverse bar (32;32a,32b) extending between the points of articulation and substantially parallel to the table top, in that the legs include an upper (llc,lld) and a lower (lla,llb) pair of splayed legs in V-formation extending from each point of articulation (12'), the ends of the lower legs resting on the floor and the ends of the upper legs supporting the table top, and in that lower cables (14',15') interconnect the lower ends of said legs, upright cables (16') extending generally from the upper ends of the upper legs to the lower leg ends of the lower legs, and upper cables (35) interconnect the upper ends of said legs said cable network incorporating force release (25',26') for placing the cables under tension in such manner that in the assembled state all the cables are in tenison and the legs are in compression.

9. A folding structure for use as camping table or bed comprising a generally rectangular top (50) made from flexible material, legs (lla,llb,llc,lld) supporting said top and a network of cables (14',16), characterized in that two points of articulation are located below the underside of the top and when the folding structure is erected, are disposed approximately midway between the plane of the top and the ground with a transverse bar (53,54) extending between the points of articulation and substantially parallel to the top in that the legs includes an upper (llc,lld) and a lower (lla,llb) pair of splayed legs in V-formation extending from each point of articulation, the ends of the lower legs resting on the ground and the ends of the upper legs engaging the top, and in that lower cables interconnect the lower ends of said legs and upright cables (16) extend from the upper ends of the upper legs to the lower ends of the lower legs, said network incorporating force release means (51) for placing the cables under tension in such manner that in the assembled state the cables are in tension and the top is stretched between the upper ends of the upper pair of legs.