The present invention relates to a telescopic stay or brace assembly for supporting two objects which are cap- able of being folded relative to one another, and partic¬ ularly, although not exclusively, for supporting a work surface which can be folded relative to a frame structure.

In the case of foldable work surfaces which are supported in their raised positions by means of some suitable form of brace assembly , it is desirable that the brace can be manipulated easily, both when locking the brace subsequent to raising the work surface and when releasing the brace in order to lower the work surface. The brace must also be capable of locking the raised work surface reliably and to form a firm support for the work surface in the desired working position thereof.

A telescopic brace or stay which fulfills these desiderata to a large extent is known from the British Patent Speci¬ fication No. 1 524 281 and comprises two tubes which can be displaced telescopically in relation to one another anc the mutually opposite ends of which are each pivotally connected to a respective one of said two objects, and further comprises an inner guide tube arranged within the telescopic tubes, a tension spring which extends axially through all tubes, and locking means for releasably locking the telescopic tubes in a given working position relative to one another.

This known brace, however, is encumbered, inter alia, with the following drawbacks. When the telescopic tubes are retracted one within the other, the inner guide tube projects beyond the ends of the telescopic tubes, there- with preventing the brace from being fitted directly to a

complete surface, e.g. a wall. Instead it is necessary to fit the brace to a surface which is laterally offset, so that the inner guide tube can be permitted to project out from the telescopic tube. Alternatively, it may be necessary to form a hole in a rearwardly lying wall in order to accommodate the guide tube.

When braces of this particular kind are intended, inter alia, to support tables or work surfaces in trains, water- craft, caravans and in other cases where relative movement of the aforesaid two objects can occur, it is essential that the brace assembly is capable of preventing the work surface from swinging, or of damping such swinging movement, when the work surface is in its lowered posi- tion. Since, when the known brace assembly is retracted the aforesaid inner guide tube projects from the outer telescopic tube, the tension spring has no damping effect whatsoever on the swinging movement of the downwardly folded work surface.

Our earlier U.S. Patent Application No. 104 022 describes and illustrates a brace assembly of the aforesaid kind which, inter alia, eliminates these drawbacks. A charac¬ teristic feature of this improved brace assembly is that the inner guide tube is fixed axially in relation to one of the telescopically movable tubes and accompanies the movement of this one tube in ^' relation to the other tele¬ scopic tube. A further characteristic feature is that each end of the tension spring is fixed relative to a re- spective telescopic tube and that the length of the spring is such that the spring will constantly exert on the tubes a force which strives to retract the tubes one inside the other.

The inner guide tube of this improved brace assembly

will not protrude from the telescopic tubes, and positive damping of any relative movement between the objects to which the brace is fitted is effected by means of the spring, even when the tubes are retracted and the work surface is folded down.

A common drawback with both of these earlier known brace assemblies however, is that the telescopic tubes can be drawn out completely from one another. In the case of the aforesaid known brace assemblies in which the tubes fit closely one within the other and in which the tension spring extends axially through the tubes, it is difficult, without further complicating the construction and increas¬ ing its costs, to provide a stop which will prevent one tube from being withdrawn completely from the other.

Consequently, the prime object of the present invention is to provide a telescopic brace assembly of the afore¬ mentioned general kind in which, inter alia, the problem of preventing the complete separation of the telescopic tubes is overcome.

This object is achieved in accordance with the present in¬ vention by replacing the tension spring used in the known brace assembly with a compression spring which is so ar¬ ranged that when extending the telescopic tubes, one from the other, the spring is compressed while storing energy therein, the extent to which the telescopic tubes can be extended being determined by the extent to which the spring can be compressed.

According to one preferred embodiment, one end of the com¬ pression spring co-acts with a stop means which is fixed in relation to one of the telescopic tubes and the spring is intended to be compressed against the stop means with

the aid of a pull rod or like device which moves together with the other of said tubes and which is connected to the other end of the spring.

The auxiliary reinforcing or strengthening tube employed in the earlier known brace assemblies can be dispensed with in the inventive brace assembly and the compression spring can therewith be placed internally of the two telescopic tubes, such that the spring is compressed against a stop means located at its free end, with the aid of a pull rod which extends through the spring and one end of which is located in and fixed relative to the outer telescopic tube and the other end of which is connected to the end of the spring distal from the stop means.

If desired, however, the inventive brace assembly may incorporate an auxiliary reinforcing tube which is placed in the outer telescopic tube and fixed in relation thereto and which slides in said inner tele¬ scopic tube when extending and collapsing the brace assembly. In this case the compression spring is mounted in the reinforcing tube so that the spring is compressed against a stop means located at the free end of said tube with the aid of a pull rod which extends through the stop means and one end of which is located in and fixed in relation to the inner telescopic tube and the other end of which is connected to the end of the spring distal from the stop means.

The stop means preferably comprises a first stop plate which is firmly held in one end of an associated tube and the aforesaid other end of the pull rod is connected to a second stop plate which is movable in said tube and which co-acts with the inwardly located end of the spring.

These stop plates and the spring located therebetween will co-act with one another to limit the extent to which the telescopic tubes can be withdrawn from each other.

The stop plates preferably have an axial extension which enables the plates to reinforce the surrounding tube in the region of said plates.

These and other features characteristic of the present invention are set forth in the claims.

The invention will now be described in more detail with reference to the accompanying drawings, in which

Figure 1A is a sectional view of a brace assembly according to the present invention and illustrates the brace in a state of rest;

Figure 1B illustrates the brace assembly of Figure 1 with the brace in an active working position;

Figure 2 illustrates the use of a brace assembly of Figure 1 for supporting the closing flap of a cabinet.

Figure 3 illustrates an alternative embodiment of the inventive brace assembly with the brace shown in an active working position; and

Figure 4 illustrates a further variant of the inventive brace assembly.

In Figure 1A the reference numeral 1 identifies a work surface which is hinged to a stationary or fixed surface 2 by means of a hinge 3. In order to hold the work

surface 1 in a horizontal work position flush with the fixed surface 2 , a brace assembly 4 according to the invention is mounted between the work surface 1 and a supportive frame structure 5, which may consist, for example, of a table frame, a wall or some corresponding structure.

The brace assembly 4 includes an outer telescopic tube 6 and an inner telescopic tube 7, which are arranged to slide telescopically one within the other. The reference numeral 8 identifies a locking arm, one end 9 of which is sleeve-shaped and embraces the inner tube 7, and the other end of which is cupped or half-cylindrical in shape and presents a bevelled end surface which in its rest position abuts the outer surface of the outer tele¬ scopic tube. When occupying its active working position, the bevelled end surface of the locking arm is intended to encage beneath a correspondingly bevelled end surface on the ourer tube 6 for locking co-action therewith, c.f. Figure 1B.

The inner telescopic tube 7 is pivotally connected to the wcrk surface 1 by means of a pivot in the form of a peg 1C which passes diametrically through the tube 7 and the sleeve-like end 9 of the locking arm 8, between two mutually opposing flanges 11 fitted to the work surface 1. The ourer telescopic tube 6 is similarly pivotally mounted by means of a pivot in the form of a peg 12 which extends between two mutually opposing flanges 13 fitted to the frame 5, and passes diametrically through the tube €.

A compression spring 14 is fitted in the inner tube 7 between a fixed plate 15 at the free end of the tube and a movable plate 16 which is displaceable in the direction

of the longitudinal axis of the tube. The movable plate 16 is connected to one end of a pull rod 17, the other end of which is attached to the pivot or hinge pin 12 of the outer tube 6 through the intermediary of a pull ring. The length of the pull rod 17 is adapted so that the spring 14 is slightly compressed between the plates 15 and 16 even when the work surface is lowered, such as to exert a force which strives to hold the telescopic tubes 6 and 7 retracted, one within the other, and therewith dampen any oscillatory movement of the work surface 1.

The manner in which the inventive brace assembly works is best seen from Figure 1B, which shows the work surface 1 raised to a level in which it is flush with the fixed or stationary surface 2. This upward swinging of the work surface has resulted in the inner tube 7 being withdrawn from the outer tube 6, and in the simul¬ taneous displacement of the movable plate in relation to the inner tube 7 through the action of the pull rod 17, which is secured to the outer tube 6 by the locking pin 12, while at the same time compressing the spring 14 between the movable plate 16 and the plate 15 firmly mounted at the end of the tube 7. With the brace assembly in this working mode, the compressed spring 14 will strive to restore the telescopic tubes to their relative starting positions shown in Figure 1A. This return, or retraction, of the tubes, however, is prevented by the locking arm 8, which in the position shown in Figure 1B is in locking engagement (full lines) with the outer telescopic tube 6. The locking arm is biased towards its locking position by means of a bias spring 18 (see Figure 1A) , which acts between the inner telescopic tube 7 and a tubular part of the locking arm.

ϋnintentional release of the locking arm 8 is also pre¬ vented through the engagement of the free, bevelled end of the locking arm with the undersurface of the corre¬ spondingly bevelled edge of the outer tube 6, this locking engagement being maintained in the illustrated position also through the weight of the work surface 1 acting on the arm. The forward end of the locking arm 8 is also bevelled so that its outer surface will coincide essentially with the outer surface of the outer tele- scopic tube 6. This means that engagement of the bevelled end surface of the locking arm 8 with the end surface of the telescopic tube 6 takes place over a relatively large peripheral arcuate surface, thereby avoiding the draw¬ backs associated with punctiform contact between the mutually engaging surfaces and also the subsequent elevated wear thereon which would result from such contact.

In order to enable the locking arm 8 to swing freely to some slight extent, to the position shown in chain lines in Figure IB, the diameter of the sleeve-shaped part 9 of the arm must be greater than that of the telescopic tube 7, so as to provide sufficient space for such move¬ ment to take place.

When the described inventive .brace assembly is brought to its active state, illustrated in Figure 1B, the brace provides an extremely stable support for the work surface 1 , and in relation to the brace or stay assembly described in our aforementioned U.S. Patent Application also affords, inter alia, the advantage that extension of the telescopic tubes, one from the other, is stopped automa¬ tically subsequent to reaching a given extent of extension. This stop facility comes into affect when the spring 14 is fully compressed between the plates or like devices 15 and 16, therewith preventing further mutual displacement of

the tubes in the direction of their longitudinal axes. This will prevent, for example, the work surface from being raised to an excessive extent, in a manner liable to damage the hinge means 3. It must be possible , how- ever, to lift the work surface 1 slightly above its intended level with the frame surface, in order to enable the locking engagement of the locking arm 8 with the telescopic tube 6 to be released by exerting a slight pressure on the tubular part 9 of the locking arm in the direction of arrow A. Subsequent to releasing this locking engagement of the aπr. 8, the aπr. will take the position shown in broken lines in Figure 1E, therewith enabling the work surface 1 to be lowere .

Figure 2 illustrates the use of a brace assembly 4 of Figure 1 for supporting a closing flap 23 hinged to a cabinet 22 by means of a hinge 24. In this application it is very important that the flap cannot be excessively raised so that the telescopic tubes are separated from each ether. The automatic stop facility of the brace 4 of Figure 2 will prevent this.

A further advantage afforded by the described inventive brace assembly in relation to the aforementioned prior art brace or stay assemblies is that the auxiliary reinforcing tube in the outer telescopic tube 6 can be omitted from the inventive brace. When the brace assembly is extended and actively supports the work surface 1 , as illustrated in Figure 1B, the plates 15 and 16, together with the intermediate compressed spring 14, serve to stiffen the telescopic tube 7 and correspond essentially to an auxiliary reinforcing tube at this location of the brace. This will reduce the risk of the brace buckling under loac, without requiring the presence of an addi- tional reinforcinq tube.

Figure 3 illustrates an alternative embodiment of a brace assembly according to the invention, with the brace in an extended, active position. Corresponding components have been identified in Figure 3 with the same reference signs as those used in Figures 1A and IB. The Figure 3 embodiment differs from the Figure 2 embodiment insomuch as the compression spring 14 is placed in the outer telescopic tube 6 instead of in the inner telescopic tube 7. In addition hereto, the Figure 3 embodiment incorporates an auxiliary reinforcing tube 19 which is arranged in and fixed relative to the outer telescopic tube 6, such that the auxiliary tube will accompany the movement of the outer tube 6 while being guided in the inner tube 7. In the case of the Figure 3 embodiment, the stationary or fixed plate 15 is mounted on one end of the auxiliary tube 19, whereas the movable plate 16 is arranged to be moved in the axial direction of the auxiliary tube 19 by means of the pull rod 17, which in this case is attached to the locking pin 10 extending through the inner telescopic tube 7. The brace assembly illustrated in Figure 3 functions in the same manner as the brace assembly illustrated in Figure 1B, although the Figure 3 brace assembly will withstand a higher load due to the inclusion of the auxiliary rein- forcing tube 19. The embodiment illustrated in Figure IB, however, has been found strong enough for the majority of applications.

The aforedescribed embodiments may also be modified in other respects within the scope of the invention. For example, the brace assembly may include a separate stop element, in the form of an abutment surface, for engage¬ ment with the plate 15 such as to stop withdrawal of the telescopic tubes, one from the other, before the spring 14 is fully compressed. Furthermore, the plates 15 and

16 or like devices may be given axial extensions such as to provide the desired stiffening of the tube 7. The plates may also be given a tubular configuration, so that while being compressed the spring 14 will be urged into the plates. The stop position can therewith be located at the position in which the plates 15 and 16 contact one another. The pull rod may, of course, also be replaced with a pull wire or like device.

When required by a particular application, the work surface 1 can be allowed to swing down further than the positions shown in Figures 1A and 1B, or may be stopped before reaching said positions.

It will be understood that the inventive brace assembly can be used to support other types of flaps or pivotable parts, irrespective of their orientation and pivotal directions. Because the two ends of the brace assembly can be mounted with the aid of through-passing locking pins, the brace can be fitted selectively to any desired object. The brace assembly can also be mounted between two pivotable objects. Although the illustrated tele¬ scopic tubes have a circular cross-section, it will be understood that the tubes may have a square cross-section or any other suitable cross-section.

For certain applications it may be desirable to lock together in different relative positions objects which can be swung relative to one another, for example such objects as the hinged tops of writing desks, drawing tables, ventilation flaps, etc. To this end the brace assembly may be modified in the manner illustrated in Figure 4 , in which corresponding components have been identified with the same reference signs as those used in Figures 1-3. The only difference between the modified

brace assembly and the aforedescribed brace assemblies is that the outer telescopic tube 6 of the Figure 4 embodiment is surrounded by two additional, shorter tubes 20 and 21, respectively. The end surface of each tube 6, 20 and 21 forms one engagement shoulder for the locking arm 8. This enables the brace assembly of Figure 4 to be used to lock the work surface 1 in any of three different positions relative to the other object 2, as illustrated schematically in the Figure. In order to change the position of the work surface between the aforesaid different positions, the same manipulations as those described above with reference to Figures 1-3 must be carried out.

Instead of using three different tubes 6, 20 and 21, several engagement shoulders may be provided on the outer surface of the tube 6 in a suitable manner.