US2147972A | 1939-02-21 | |||
CH355581A | 1961-07-15 | |||
US3662694A | 1972-05-16 | |||
US4064815A | 1977-12-27 | |||
GB2322907A | 1998-09-09 |
1. | Folding table having a table surface (1), table supporting frame (2), table legs (3) comprising: a table leg locking mechanism with its operating handle mechanism, the locking mechanism containing locking pins (8) radially fixed in a common base (7), which common base bears an extending member (9), having a hole (10) forming a pivoting joint with actuating rod (11), which resides within the tubular cross member (4), which cross member also contains spring (12) for driving locking pins (8) into their legs erect, or legs folded locked positions, which locking pins (8) are moved by actuating rod (11) in the holes (14) of disc (13) fixed to the tubular cross member (4), and holes (16) in similarly fixed disc (15), and also holes (18) of plate (17) fixed to the table frame (2), and the table legs (3) together with their interconnecting tubular cross member (4) are rotationally connected to table frame (2) via axle (19), which axle is rigidly fixed to table frame (2). |
2. | Folding table according to claim 1 wherein the operating mechanism contains a handle (5), which is joined to actuating rod (11) via crankshaft (20) and crank plate (21), which crankshaft (20) and crank plate (21) is fixed within tubular cross member 4 by bearing (22), and the position of handle (5) with respect to cross member (4) is held by bracket (23) and washer (24). |
3. | Folding table according to claim 1 wherein the table frame (2) bears extending members (6) for providing frametoleg space for finger safety and strength for table leg carrying support in the folded position. |
4. | Folding table according to claim 1 wherein the number of locking mechanism locking pins are 1 to 4. |
5. | Folding table according to claim 1 wherein the number of holes in the locking mechanism plate (17) is 2 to 4. 6. |
6. | Folding table according to claim 1 wherein the locking mechanism is enclosed substantially within the cross member (4) joining the two legs, for both appearance and safety. |
7. | Folding table according to claim 1 wherein the actuating rods (11) are enclosed substantially within the cross member (4) joining the two legs, for both appearance and safety. |
8. | Folding table according to claim 1 wherein the spring (12) is situated substantially within the cross member (4), and the spring may be executed by a compression, tension, or torsional spring. |
9. | Folding table according to claim 1 wherein the spacing between discs (13) and (15) is substantially the same as the thickness of the table legs, and the discs (13) and (15) are positioned such as to give the table legs maximum support for the purpose of preventing deformation of the leg joining tubular cross member. |
Numerous technical solutions are known in the field of folding tables. From patent US 4 064 815 is known a table leg locking mechanism, which locks the table legs in either their supportive or their folded positions. The locking mechanism includes a pivot mount situated within a rectangular housing attached to the underside of the table. This housing contains a pair of sleeves mounted on a tubular cross member, such that one sleeve is welded, or in some other manner securely united to its associated housing, and the other sleeve is rigidly united to the tubular cross member. A spring is connected to the tubular cross member whereby constant pressure is exerted between the two sleeves, one against the other, to insure locking of the table legs into position. The sleeves are interlocked together by virtue of their shape, in which one of the sleeves has wedge-shaped protrusions on its end, conforming to the same wedge shaped notches in the adjoining end of the other sleeve. The shortcoming of this concept is that it is not optimal for locking four table legs, which limits the utility of the table. There are only two locks per table, one at each end of the table. The resulting table construction does not achieve sufficient rigidity or strength, because the locking mechanism is not attached to a table frame supporting the table top, and does not provide a separate lock to the table frame at each of the four leg positions. The aesthetic execution of this solution is not suitable for every occasion due to bulky mechanical housings which are noticeable on the underside of the table. The given solution is not an optimal design for the best universal table utility, in which a leg is near each corner of a rectangular table.
From patent GB 2 322 907 is known a lockable hinge. The locking of this hinge is accomplished by means of locking pins, by which two hinge elements rotating on a common axis are locked together. The relative angle of these two hinge elements is changeable by means of a locking mechanism, whereby the locking pins are retracted to their unlocked position, the two hinge elements are rotated to their selected relative angular position, and locked into this position by means of the locking pins. This solution
is not associated with a folding table. In the event that this solution were to be implemented into a folding table layout similar to that of the present patent, the resulting table construction would lack the rigidity and strength offered through the present patent, due to the absence of a tubular cross member. Lacking such a tubular cross member, each leg would have its own separate locking hinge. To change the table from its folded condition to its erect condition would require four separate operations.
The current state of the art of folding tables is fundamentally limited by the tradeoff achieved between strength and rigidity, and the aesthetic execution of the locking mechanism. In attempts to overcome this limit, excessively expensive tables have been produced. This limits the utility of tables based on the state of the art.
The objective of the present invention is to offer a compact, strong, rigid, safe, economical, and mechanically and aesthetically optimal folding table. A further objective of this invention is to present a solution for automatically locking the legs into their folded position, and their automatic locking into their erect position.
The objective of the invention is achieved through a construction in which each leg of the table has its own locking mechanism, and the legs of the table are joined rigidly in pairs using a tubular cross member, such that by turning a single control lever two legs are locked into position at a time. Each pair of table legs is rotationally attached to the table frame. At each corner of the table is one locking mechanism, by means of which each pair of legs is rigidly and strongly united to the table frame. The locking pins of the locking mechanism are withdrawn from their locked position into the rotating position using a control handle. Then, at an appropriate initial rotational angle the control handle is released, allowing the table legs to automatically lock when reaching either the folded or the erect positions. When the desired locked position is reached, the control handle returns to its original position, giving the user a positive indication that the table legs are securely locked.
The preferred implementation of this invention utilizes rectangular tubing for the frame, as well as a fiberboard or plastic table material. Fiberboard or plastic tables require supporting frames, since in time such a table lacking a supporting frame may distort or fail. The mechanism pertaining to this invention is situated inside of the connecting
members joining the leg pairs of the table, whereby the aesthetic objective of this invention is achieved, in addition to providing safety for the user, in that the locking mechanisms and their operating means are in an enclosed structure. A table incorporating the benefits of this invention permits seating at the ends of the table because the table legs are at the corners of the table; and the enclosed construction avoids possible damage to or snagging of clothing, or user's fingers being caught in the mechanism, or being pinched between the legs and the frame when the legs are folded.
Brief description of the drawings Figure 1 illustrates a bottom view of a preferred embodiment of the table with legs folded according to the present invention.
Figure 2 illustrates table leg locking mechanism according to the present invention.
Figure 3 illustrates an end view of the locking mechanism.
Figure 4 illustrates cross section of the actuating mechanism of the locking mechanism according to the present invention.
Figure 5 illustrates fastening of the actuating rods to the control handle.
Figure 6 illustrates section I-I of the actuating mechanism of the locking mechanism according to the present invention.
Identical elements depicted in Figures 1-6 are designated with the same reference numbers.
Detailed description of the preferred embodiment of the invention Figure 1 shows the table undersurface 1, the table supporting frame 2, providing necessary table rigidity and bearing strength, and table legs 3. Two table legs are rigidly connected by tubular cross member 4. Control handle 5 is provided for bringing table legs 3 into their extended working position, or their folded position. Table frame 2 has spacers 6, which
support the table legs, preventing their possible deformation in the folded position in the event of carrying the table by the legs, and providing a measure of safety.
Figure 2 shows a cross section of the table leg locking mechanism's preferred embodiment. The locking mechanism contains pins 8 set in a base 7. Base 7 contains an extending member 9, in which is hole 10 for joining base 7 and actuating rod 11 at a pivoting joint. The locking mechanism and the actuating rod 11 are situated in the tubular cross member 4 to which the legs are attached. Spring 12 situated in the tubular cross member pushes the pins 8 into either their legs extended locked position or the legs folded locked position. Pins 8 are set in base 7 radially. By action of actuating rod 11, these pins are moved in holes 14 through disc 13 attached to cross member 4; and holes 16 in similarly attached disc 15 ; and holes 18 in plate 17 attached to the table frame 2.
The radial positioning of holes 14,16, and 18 in the preferred embodiment of the invention is depicted in Figure 3. Table legs 3 along with cross member 4 are connected to the table frame 2 by axle 19. One end of axle 19 is connected to table frame 2, for example by a weld in the preferred embodiment. Discs 13 and 15 are situated as to prevent possible deformation of cross member 4. Actuating rods 11 are of suitable strength and construction such that in the event that the locking mechanism does not lock automatically (as in the event of corrosion or contamination), the user may apply force.
Figure 4 depicts a cross section of the preferred embodiment of the locking mechanism's actuating mechanism. The actuating mechanism contains handle 5, which is connected to actuating rods 11 through crankshaft 20 and connecting crank plate 21. Crankshaft 20 with connecting crank plate 21 are supported in tubular cross member 4 by bearing 22.
Connection of actuating rods 11 to connecting crank plate 21 is depicted in Figure 5.
Actuating handle 5 is held in position with respect to cross member 4 by means of washer 24 and bracket 23. Turning handle 5 actuates rod 11 so that base 7 pushes or pulls pins 8 attached to base 7 in holes 14,16, and 18 (see Figure 2). The dimensions of connecting crank plate 21, and the attachment point of actuating rod 11 to its connecting crank plate 21 is chosen such that pins 8 move back and forth a distance which is greater than the thickness of plate 17, but smaller than the combined thicknesses of disc 15 and plate 17.
Figure 6 depicts cross section I-I of Figure 4. One end of crankshaft 20 is supported by bearing 22, which in turn is attached at one end to tubular cross member 4. The other end of crankshaft 20 is supported by washer 24 fitted in bracket 23.
The locking mechanism of this invention works as follows. In order to free the table legs 3 from their erect locked position, handle 5 is given an appropriate turn. Thereby, pins 8 move out of holes 18 of plate 17 such that the end surfaces 25 of the pins reside between the parallel outer surfaces of disc 15. As a result, it becomes possible to turn the table legs 3, connected by cross member 4, to either the erect position, or the folded position. After the table legs 3 are turned a suitable distance, the handle 5 is released, and spring 12 pushes pins 8 into their locked position. Handle 5 also returns to its normal starting (locked) position by the action of spring 12. Thereby it is possible to positively discern by the position of handle 5 whether the table legs are locked or unlocked, which is one of the objectives of this patent, with respect to safety and convenience.
The preferred embodiment of this invention uses four locking pins and four holes. It is possible to have the number of the pins and holes other than four, without departing from the scope of the present invention. The pins (and mating holes) may be of conical shape.
Furthermore, spring 12 may be positioned within cross member 4 in other positions than the preferred embodiment. Spring 12 may be embodied in the control mechanism as compression, contraction, or torsion spring.