Folding Wall Table

The present invention pertains to the field of folding wall tables of the type designed to fold between a storage position in which the table is vertically positioned adjacent the wall, and a usable position in which the table extends horizontally from the wall.

One such prior art type of folding table is shown in U.S. Pat. No. 3,866,547, issued to Guyton. In this patent, the end of the table nearest the wall is connected thereto and supported by hinge arms, while the outer end is supported by auxiliary fold-up legs. During folding to the storage position, the outer end of the table rolls along the floor on rollers which are provided in the table end. A disadvantage of this type of structure is the requirement of the roller wheels along the table end. Roller wheels eventually become covered with grease leaking from around the axle, and dirt or dust picked up from the floor. It is of course not desirable to have grease or dirt near the table work surface, and particularly directly in front of a person who might sit at the end of the table. Another disadvantage of this type of structure is the requirement of a separate latch to hold the table in its vertical storage position. The separate latch adds another part to the cost of the table and adds another step which must be performed in the operation of the table.

Another type of prior art folding table is shown in U.S. Pat. No. 3,730,107 issued to Bergkamp et al. In this patent, the table or ironing board folds to the vertical storage position by means of upper and lower hinge arms and pivots on the table and on the wall or other supporting structure, thus eliminating the need for roller wheels at the end of the table. In the Bergkamp et al. structure, the table is held in its storage position by gravity due to a bend in the lower arm which places the center of gravity of the table in storage position between the back wall and the lower pivot point of the bent arm. Unfortunately, this type of structure results in a total mechanism depth or thickness which is so great as to either require a recess in the wall to which the table is attached, or a separate box or closet-like structure into which the table can be folded. This is often undesirable because of space limitations in the room or structural limitations that prevent a recess being formed in the wall.

To overcome these and other problems, the present invention provides a folding wall table that does not require rollers on the table, does not require a separate latch to hold the table in its storage position, and which folds compactly against the wall without requiring either a storage box protruding into the room or a recess being formed into the wall.

According to the present invention there is provided a folding wall table adapted for attachment to a wall and capable of easy movement between a storage position in which it is vertically disposed adjacent the wall, and a usable position in which the table extends horizontally from the wall. The folding wall table includes a table surface member, upper and lower hinge arm means, and upper and lower wall pivot means for pivotally connecting the upper and lower hinge arm means respectively to a wall, with the pivot axis of the upper hinge arm means being higher than the pivot axis of the lower hinge arm means. Upper and lower table pivot means are provided for pivotally connecting the upper and lower hinge arm means respectively to the underside of the table surface member, with the pivot axis of the upper table pivot means being positioned closer to the wall, when the table is in its usable position, than the pivot axis of the lower table pivot means. The hinge arm means and the pivot means are positioned and sized so as to allow movement of the table surface member between its usable and storage positions. The pivot axis of the lower table pivot means is spaced below a plane passing through the pivot axis of the upper table pivot means and parallel with the table surface, when the table is in its usable position. This offsetting provides an overcenter resistance force to the movement of the table when passing through an intermediate position near the storage position. The overcenter resistance force is provided by the offset table pivot geometry and results in the preferred embodiment in compressional resilience of the lower hinge arms while passing through the overcenter position.

According to another aspect of the invention, the lower hinge arm means may be intentionally made slightly longer than strictly required by geometrical considerations so as to preload the lower hinge arm means in the storage position so as to enhance the overcenter resistance force.

According to another apsect of the invention, the lower wall pivot means can be spaced from the wall to bring the lower hinge arm means nearly vertical in the storage position so as to further enhance the resistance force.

The overcenter resistance force serves to push and hold the table against the wall in its storage position without the need for a separate latching device.

In the preferred embodiment, the outer end of the table away from the wall in its usable position is supported by a pair of legs which can be folded flat against the underside of the table when the table is to be moved to its storage position.

In the drawing,

FIG. 1 is a view in perspective of a folding wall table according to the present invention;

FIG. 2 is a longitudinal section through the table of FIG. 1, portions thereof broken away;

FIG. 3 is a view in bottom plan of the table of FIG. 1;

FIG. 4 is a view in perspective of the hinge assembly for the table of FIG. 1;

FIG. 5 is an exploded fragmentary detail of a hinge arm pivot used in the present invention;

FIG. 6 is a fragmentary detail in perspective of the leg locking assembly of the table of FIG. 1;

FIG. 6A is an enlarged fragmentary detail of a portion of FIG. 6;

FIG. 7 is a diagrammatic view in side elevation of the wall table in storage position;

FIG. 8 is a fragmentary side elevation view showing the geometry of the hinge arms according to the present invention; and

FIGS. 9 and 10 are diagrammatic views illustrating the geometry of the hinge assembly according to the present invention.

In FIG. 1, a folding wall table according to the present invention is shown in its unfolded, or usable position. The present invention is equally applicable to folding tables, desks, and any other type of work surface. Accordingly, although the preferred embodiment is described as a table, the term table is used in this patent application in a generic sense to include any type of work surface. In FIG. 1, the table includes a table surface member 10, and a pair of legs 50a and 50b. The table is attached to wall 12 as explained hereinafter, and legs 50a and 50b support the outer end of the table above floor 11.

FIGS. 2 and 3 show the structural details of the preferred embodiment of the present invention. Table surface member 10 is supported and reinforced by a table frame which includes perimeter members 13, 14, 15 and 16, and interior longitudinal frame members 17, 18 and 19. In the preferred embodiment, table surface member 10 and table frame members 13-19 are made of wood, for lightness and strength, although it will be understood that other materials including metal could be used. Table surface member 10 can be made of plywood, hardboard or particle board, with a suitable decorative top surface mounted thereto. Tabletop 10 can be held by screws, nails or glue to the table frame members, and the table frame members are screwed, nailed or glued together.

As best seen in FIG. 2, the table is secured to the wall by means of a linkage including lower hinge arm 20 and upper hinge arm 30. Lower hinge arm 20 pivotally attaches to the wall at a lower wall pivot 21. Similarly, upper hinge arm 30 pivotally connects to the wall at an upper wall pivot 31. Lower hinge arm 20 connects to the table at lower arm table pivot 22, and similarly, upper hinge arm 30 connects to the table at upper arm pivot 32.

In the preferred embodiment, each of the lower hinge arm and the upper hinge arm comprise a pair of arms, as best seen in FIGS. 3 and 4. Wall mounting plate 40 is generally flat and is adapted to be secured to the wall by bolts or any other suitable means (not shown). Wall mounting plate 40 includes a pair of pad eyes 23a and 23b which may be welded thereto to form the lower wall pivots for the lower hinge arms. The lower hinge arm 20 in the preferred embodiment comprises a pair of metal bars or straps 20a and 20b mounted on a common axis at the lower wall pivot 21. Specifically, lower hinge arm 20a is pivotally mounted to pad eye 23a by means of a bolt 24a. In similar manner, lower hinge arm 20b is pivotally mounted to pad eye 23b by a pivot bolt 24b.

Upper hinge arm 30 in the preferred embodiment includes a pair of rectangular tubular arms 30a and 30b. These arms are pivotally connected to wall mounting plate 40 at the upper wall pivot point 31. Specifically, upper hinge arm 30a pivotally connects to wall mounting plate 40 by means of a hinge 33a which includes a hinge pin and hinge plates attached to the wall mounting plate 40 and upper hinge arm 30a. In the same manner, upper hinge arm 30b connects to wall mounting plate 40 by means of hinge 33b.

The other ends of upper hinge arms 30a and 30b are welded to a tubular crossbar 34. Crossbar 34 has end portions 35a and 35b which extend outwardly of upper hinge arms 30a and 30b respectively, and which fit into pivot blocks attached to the table. A notch 27 is provided in table frame member 18 to provide clearance for crossbar 34. As seen in FIG. 3, end 35a of crossbar 34 fits into a pivot block 36a which is secured to frame member 17 by means of bolts and nuts 37. In the same manner, end 35b of crossbar 34 fits into pivot block 36b which is secured to frame member 19 by bolts 37. The configuration of pivot block 36b is shown in greater detail in FIG. 5. The block includes a cylindrical bore 38b which receives end 35b of crossbar 34 and serves as a journal bearing therefor. Pivot block 36b is preferably made of polyproplene, nylon or similar plastic.

Alternatively, pivot blocks 36 could be moded with a cylindrical projection which would be received inside crossbar 34 to form the pivot bearing.

The axis of crossbar 34 as positioned with respect to the table by pivot blocks 36a and 36b defines the upper hinge arm table pivot 32. The lower hinge arm table pivot 22 is defined by a pivot bolt 25 which pivotally connects lower hinge arms 20a and 20b to table frame member 18. Metallic reinforcing plates 26a and 26b can be secured by bolts and nuts 28 or any other suitable means to the sides of table frame member 18. Reinforcing plates 26a and 26b have slots 29 through which crossbar 34 passes. Slots 29 provide a further bearing surface for the pivotal motion of crossbar 34. More importantly, reinforcing plates 26 provide more rigid control over the critical dimension between the table pivot axes 22 and 32, by virtue of the fact that pivot bolt 25 and crossbar 34 are both positively located with respect to each other by the reforcing plates. This prevents unwanted bowing of crossbar 34 as explained more fully hereinafter.

Folding leg assembly 50 includes a pair of legs 50a and 50b. As seen in FIGS. 3 and 6, the legs may be made of rectangular metallic tubing. Individual legs 50a and 50b are welded to a crossbar 51 which is positioned in notches 52, 53 and 54 provided in table frame members 17, 18 and 19 respectively. End 55a of crossbar 51 extends beyond leg 50a, and similarly end 55b of crossbar 51 extends beyond leg 50b. The crossbar ends are mounted for pivotal movement in pivot blocks 56a and 56b which are mounted respectively to table frame members 13 and 15 by means of screws 57. Bores 58a and 58b are provided respectively in pivot blocks 56a and 56b, to receive the ends of crossbar 51. Bores 58a and 58b have sufficient depth, with respect to the length of crossbar 51, to permit a degree of axial movement of crossbar 51, as well as rotational movement.

As seen more clearly in FIGS. 6 and 6a, a leg position lock 60 is provided. Leg position lock 60 comprises a mounting plate 61 which is attached to table frame member 18 by means of bolts 62. Plate 61 has a clearance aperture therethrough for receiving crossbar 51. Flange 63 is welded to mounting plate 61 around the opening. Flange 63 includes a pair of cam surfaces 64 generally in the configuration of a ramp, and a pair of detent slot portions 65. A pin 66 secured in an opening bored transversely through crossbar 51 and projecting therefrom on either side cooperates with cam surfaces 64 and detent slots 65 to help hold the legs in their extended position.

To fold the legs, the user pushes the leg in a direction indicated by arrow 67. This causes the pin to ramp up the cam surfaces, causing cross bar 51 to move axially against the force of spring 68 which is provided between leg 50b and pivot block 56b.

The legs move through an arc indicated by arrow 69 to a position against the table surface member with leg 50a between table frame members 13 and 17, and leg 50b between frame members 19 and 15. In the preferred embodiment, the table legs are made no thicker than the table frame members so as to provide a compact arrow profile when the legs are folded up.

Legs 50 are held in the folded position by patches 70 and 71 of a synthetic hook and loop type fastening material, attached to the legs and the underside of the table surface member, respectively.

To unfold the legs, the legs are manually pulled away from the fastening material to a vertical position, with spring 68 and leg position lock 60 helping to hold them in the vertical position.

Once the legs have been folded up, the table can be folded against the wall. As seen in FIGS. 1 and 7, the end of table surface member 10 nearest the wall moves upwardly as indicated by arrow 80, while the outer end moves downwardly and inwardly as indicated by arrow 81. In the folded position, table surface member 10 is closely adjacent and parallel to wall 12. The fold-up path followed by the table during the folding and unfolding operation is controlled by the geometry of the hinge assembly including the upper and lower hinge arms and the various pivots.

As previously discussed, it is generally known in the prior art to provide a linkage or hinge assembly connected between a wall or support and a table or other generally planar member, for controlling movement of the table between a horizontal position and a vertical position against the wall. The lengths of the upper and lower hinge arms, and the positioning of the pivots along the wall and along the center line of the table or other planar member can be selected to provide the desired motion. Generally there is an infinite set of different possible geometries which will give the desired motion.

However, when the "correct" geometry is achieved according to the prior art, the table will tend to swing freely away from the wall under the influence of gravity, to come to rest at some intermediate position. Thus, it has been necessary in prior art devices to either provide counterbalance or biasing springs, high pivot friction, or latch means to hold the table in its vertical position.

The present invention intentionally modifies the linkage geometry away from the "correct" geometry of the prior art in a particular manner, so as to provide a linkage which will automatically maintain the table in its stored position, without the need for any latch, counterbalancing springs, or the like. The manner in which this feature is obtained is explained as follows.

FIG. 8 shows the basic geometry of the hinge linkage. Reference number 30 indicates the upper hinge arm, and reference number 20 designates the lower hinge arm. The upper arm wall pivot, which is the point about which upper hinge arm 30 may pivot, is indicated by reference number 31. Reference number 21 indicates the lower arm wall pivot. The point, or more properly axis, about which table 10 and upper hinge arm 30 are pivotable with respect to each other is indicated by reference number 32. The corresponding pivotal connection between table 10 and lower hinge arm 20 is indicated by reference number 22. The resulting geometry can be thought of as a four bar linkage, with arm 20, arm 30, the wall or wall plate between pivots 31 and 21, and the table surface member between pivots 32 and 22 making up the four elements.

When the table is in its folded position, arms 20 and 30 and table 10 are approximately aligned in the same plane, but instead of mounting table pivot points 22 and 32 in the same plane parallel to table 10, these pivot points are intentionally offset by an amount indicated by reference number 90 in FIGS. 2 and 8. Upper arm pivot 32 is intentionally placed higher (closer to the table surface) than lower arm table pivot 22.

The arc travel by pivot point 32 is a circle centered at 31, and is indicated by reference number 91. The arc normally traveled by lower arm table pivot 22 is an arc indicated by reference number 92, centered at pivot point 21.

By providing offset 90, and by making corresponding adjustments in the lengths of the hinge arms, it is possible to provide a built-in resistance force to hold the table in its vertical position. The resistive force is supplied by resilient forces in one or more of the hinge arms caused by an overcenter condition when the table is near the storage position.

This is better explained with the help of the diagram of FIG. 9. In FIG. 9, the arms and pivots are numbered as before, with the arms indicated only by a single straight line. Offset 90 is exaggerated for purposes of illustration. In FIG. 9, the table is in its storage position adjacent and parallel to the wall. For the given pivot point placement, it is apparent that something in the linkage will have to undergo deformation in order to unfold the table. In the vertical position shown, pivot 22 is closer to the wall than pivot 32. However, as the table is unfolded to its horizontal position (rotating counterclockwise in FIGS. 8, 9 and 10) pivot 22 must pass outwardly to a position beneath pivot 32, and when further outwardly on arc 92 before pivot 32 has moved very far outwardly and downwardly on arc 91. (Of course the wall prevents pivot 32 from moving outwardly and downwardly ahead of pivot 22, which would otherwise result in bringing the table down "upside down").

However, the initial movement of pivots 22 outwardly to a position approximately beneath pivot 32 will cause binding or deformation of the linkage. Specifically, hinge arm 30 might be stretched, hinge arm 22 might be compressed, or table pivots 32 and 33 might be moved towards each center. In the preferred embodiment, lower hinge arm 20 is designed to compress or shorten its length slightly by bending or bowing away from the plane of the drawing of FIG. 9. This is achieved by making the upper hinge arms 30 relatively stiff and rigid since they are made of metal tubular sections, while lower hinge arms 20 are made of relatively thin bar stock. As a result, lower hinge arms 20, although having adequate strength in a vertical plane, are relatively flexible in a transverse or lateral plane. During the above-noted compression of the lower hinge arms, hinge arms 20a and 20b bow outwardly or inwardly slightly to achieve the resilient compression of lower hinge arm 20. Also in the preferred embodiment, reinforcing plates 26a and 26b prevent pivots 22 and 32 from being moved together by bowing of crossbar 34.

The overcenter resistance effect is seen further in FIG. 10. From an observation of arcs 91 and 92 it is seen that these arcs are farthest apart close to the wall, and they become increasingly close together as the pivots move away from the wall. In FIG. 10, a point indicated by reference number 32c indicates the position of upper arm table pivot 32 when the table is in the full vertical storage position. The point indicated by reference number 22c is the position of lower arm table pivot 22 with the table in the full vertical storage position. The offset 90 between these points is again exaggerated for purposes of illustration. The distance on table surface member 10 between table pivots 32 and 22 is fixed, and is indicated in FIG. 10 by dimension A.

It will be appreciated that the shortest distance between point 32c and arc 92 falls at a position approximately vertically beneath point 32c, indicated by reference number 95. It will also be appreciated that dimension A is greater than the distance from point 32c to point 95. Since the initial motion upon unfolding the table requires pivot point 22 to move outwardly beyond pivot point 32, it is clear that binding will result. Since the dimension A is assumed not to change significantly, lower arms 20 deflect and shorten, allowing pivot point 22 to move from point 22c along the path indicated by arrow 96, which is displaced from arc 92. This displacement is accommodated by flexing or bowing or lower hinge arms 20a and 20b as previously explained.

The above described situation would exist if a portion of wall 12 near the top of the table in its stored position were cut away. In normal situations, the top of table 10 immediately butts into wall 12 when the table is first moved away from its stored position, thus preventing stationary rotation about point 32c while pivot point 22 is moved past the point of maximum resistance. Instead, pivot point 32 is caused to move a short distance to a point indicated by reference number 32d while pivot 22 is moving from pivot 22c to point 22d. Since the distance between arcs 91 and 92 decreases as pivot 32 is moved to the right, this has the effect of increasing the mismatch in distance between dimension A and the shortest distance to arc 92. In this case, the point 95 would be shifted somewhat to the right. Thus, the effect of the top end of the table butting against the wall is to increase the overcenter resistance effect somewhat. Nylon glides 46a and 46b are preferably provided on the underside of the table, for example on table frame member 41, to provide bearing surfaces for preventing damage to the wall. Additionally, suitable bearing plates or strips (not shown) can be provided on the wall at corresponding points for engagement by the glides.

After moving past the point of maximum deflection, table pivot 22 comes to position 22d while table pivot 32 comes to position 32d. In this position, table pivot 22 is back on arc 92, and from this point on while lowering the table both pivots 22 and 32 can proceed outwardly and downwardly on arcs 92 and 91 respectively, with the angular positioning of the table moving as controlled by the geometry.

It has been found that the overcenter resistance force caused by offset 90 as described above can be enhanced for better results as follows. The length of lower hinge arm 20 can be selected to provide a preload into the hinge assembly. With the table in its vertical position, the length required forlower hinge arm 20 is initially calculated by noting that all four elements of the equivalent four bar linkage are approximately aligned, distregarding for the moment various offsets which actually amount to only a few degrees variation in the orientation of the various links. The length of arm 20 would then be initially calculated as the length of arm 30 plus the distance between pivot points 21 and 31, less the distance between pivot points 22 and 32. However, the length of arm 20 is next selected to be slightly longer than this initial value. This has the effect of placing arm 20 in compression, with bowing of the lower arms 20a and 20b when the table is in its full storage position. This preloads the arms so that when the table is brought away from storage position through the overcenter position, the resistance force with be greater.

Additionally, lower wall pivots 21 can be displaced by an offset 97 to extend farther from the wall than upper wall pivot 31. This has the effect of placing lower hinge arm 20 in a more nearly vertical, or slightly beyond vertical position than would be the case if pivot 20 were placed closer to the wall. Offset 97 causes the compression and bowing in the lower hinge arms 20a and 20b to be increased as the table passes through the overcenter point of maximum resistance, further increasing the resistance force.

The three factors of table pivot position offset 90, lengthening of the lower hinge arm for preloading, and offset 97 for the lower wall pivot combine to provide the overcenter resistance force to hold the table surface member in its vertical position. In the preferred design, the overcenter compression forces are not fully relaxed when the table is up against the wall, so as to maintain a residual force holding the table against the wall. This prevents the table from sagging away from the wall which it might otherwise do due to mechanical play and tolerance in the pivots.

As the table is moved to its usable position, it is stopped in a horizontal position by stop bolts 41a and 41b. These bolts are threaded into tabbs 42a and 42b formed in wall mounting plate 40 (FIG. 4). In the usable position, the underside of table frame member 14 butts against the tops of stop bolts 41a and 41b. These stop bolts can be threaded inwardly or outwardly as required for horizontal orientation of the table.

When raising the table, legs 11 are first folded up as previously explained. The outer edge of the table is then moved downwardly and inwardly, causing the inner edge of the table to move upwardly. Just before reaching the storage position, increasing resistance is encountered while going through the point of maximum deflection of the lower hinge arms. On further movement of the table, the maximum point is passed and the compression force in the lower hinge arms helps to push the table snugly against the wall or its stops. The table will not fall away from this position on its own, since to do so would require an input of force to overcome the overcenter resistance force.

Additional glides or rubber bumpers 47a and 47b may be provided on the underside of the table or the table frame members near the outer end of the table as indicated in FIG. 3. Bumpers 47a and 47b together with glides 46a and 46b provide the contact points when the table is in its vertical storage position against the wall, as seen in FIG. 7. In case the lower portion of the wall below mounting plate 40 is cut back or cut away, a bumper or stop 48 can be provided attached to wall mounting plate 40 as seen in FIG. 4. Bumper 48 is positioned for engagement by the center table frame member 18 when the table is moved to its storage position.

As an example illustrating the practical application of the principles set forth above according to the present invention, the pertinent dimensions will be set forth for one successful embodiment of the invention. In this example, the table surface is 48 inches long, it being understood that the width of the table in a direction parallel to the wall is immaterial. The table surface is approximately 29 inches above the floor when the table is in its usable position. The wall mounting plate 40 is positioned on the wall so that the upper wall pivot axis 31 is approximately 26 and 3/8 inches above the floor. The effective length of the upper pivot arm 30 from pivot center 31 to pivot center 22 is 12 inches. The effective length of lower hinge arm 20 from pivot center 21 to pivot center 22 is 16 and 3/4 inches. The vertical component of the distance between wall pivot center 31 and wall pivot center 21 is 7 and 1/2 inches. The horizontal component of the distance between pivot center 31 and pivot center 21 (offset 97 in FIG. 8) is 5/8 inch. The component of the distance between table pivot center 32 and table pivot center 22 in a direction parallel to the table surface is 2 and 3/4 inches. The component of the distance between the table pivot center 32 and table pivot center 22 in a direction perpendicular to the table surface (offset 90 in FIGS. 2 and 8) is 1/4 inch.

While the above dimensions pertain to a particular preferred embodiment of the invention, it will be appreciated that different sets of dimensions can be selected according to the principles set forth herein. In particular, for longer tables, the dimensions would have to be adjusted accordingly.

It will further be appreciated that although the deformation which results when passing through the overcenter point in the preferred embodiment is accommodated by compression in the lower hinge arm 20, the present invention also contemplates that the deformation could be accommodated by resilient lengthening of upper hinge arm 30, or resilient bowing of crossbar 34 which would have the effect of shortening dimension A between the table pivot centers. Control of resilient deformation of the various members is achieved by selection of the materials and thicknesses. It would also be possible to provide a spring-loaded telescopic arrangement for one or more of the control arms to accommodate the overcenter forces.

It will also be appreciated that although the preferred embodiment of the present invention disclosed herein uses a pair of upper hinge arms spaced on either side of a pair of lower hinge arms, when viewed from the top or bottom, any number of individual arms or spacings can be used without departing from the scope of the present invention. For example, it would be a simple manner to space the lower hinge arms farther apart with the upper hinge arm or arms therebetween.

Thus, the present invention provides an improved folding wall table or other work surface which is easily moved between usable and storage positions, and which folds compactly against a wall for storage without requiring latches or counterbalancing springs to hold it in the storage position.