The invention relates to a support device, which comprises a column in form of a lower telescopic pipe for supporting against a base during use, and an upper telescopic pipe, which is displaceably disposed in the lower telescopic pipe, and at least one spring for application of a spring force on the lower telescopic pipe in same direction as the gravity, and on the upper telescopic pipe in opposite direction of the gravity.

The invention also relates to a use of the support device to a table leg, and a method for adjusting the size of the spring force, which the spring of the support device has. As example of a support device a table leg for a worktable can be mentioned, where one or more operators work with objects, which rest on the table top of the table. As examples can be mentioned workbenches, desks and computer tables. Such tables often have a fixed height, which fits operators of standard height. Other people of larger or less height are thereby forced to work in ergonomically incorrect position, which in the long run can result in that they will suffer from industrial injuries, as e.g. fibrositis and infiltrations.

A similar situation is present when the work requires change of position, for instance from sitting to a more or less standing position . Industrial injury cause large costs to the individual as well as the society as a whole, and there has been great efforts through the years to solve the problem by developing tables which can be adjusted to the height and built of the individual operator and the kind of the respective work. A popular solution is to design a table leg with an upper and lower telescopic pipe, which are telescopically displaceably in relation to each other. The upper telescopic pipe carries the tabletop, while the lower one supports against the base, e.g. the floor in a building. In addition, the solution comprises displacement means to displace the upper telescopic pipe in relation to the lower, to thereby be able to adjust the table to desired height. Some displacement means operates by means of a motor, which, during the height adjustment via a gear, rotates a spindle to screw the upper telescopic pipe of the telescopic leg, and thus the tabletop, up and down in relation to the lower telescopic pipe, and thus the base, e.g. a floor. The height adjustment is performed simply by pressing on a switch and releasing it again when a desired height is reached. The table can remain in the obtained position, which, if desired, can be secured by means of separate locking means for locking the two telescopic pipes of the table leg together.

This known table leg is thereby extremely easy to operate, but is on the other hand complicated and costly to produce. Additionally it requires space, which is not always available in a worktable.

A widespread displacement means consist of a pressure spring i form of a gas or screw spring to carry or lift a more or less loaded tabletop. In this instance the table will not remain standing by itself when desired height is reached. The two parts of the table leg will have to be locked together positively, and this typically takes place by means of an evenly spring loaded dowel passed through one of a series of locking holes, which are formed in one of the respective table legs telescopic pipes. The pressure springs used usually have a linear characteristic, whereby the spring force get to fluctuate with the actual height position of the table. When the dowel is pulled out of the locking hole in order to adjust the height, the pressure spring is suddenly released, whereupon the operator needs to bear down on the table top by using his person to affect the table top with a downwards force corresponding to the difference between the loads on the pressure spring, including the weight of the table top, and the spring force, which as mentioned fluctuate with the height position of the table top.

Height adjustment of a table by means of a pressure spring is therefore a strenuous and not quite safe task.

From US Patent Publication No. 2007/0137535 Al is known a table with a support device, which as in above mentioned case operates with a pressure spring.

The means of the support device to displace the two telescopic pipes in relation to each other comprises in this case a flexible cable, which on one end is attached to the inner side of the upper telescopic pipe, and at the other end to the upper part of the pressure spring, simultaneously as the cable is wound around a screw-shaped pulley, in such a way that the resulting force between the two telescopic pipes is constant, regardless of the actual height of the table top. This property is advantageously utilized in this known table to ease ^' the height adjustment, because the size of the mentioned constant force is chosen so that it corresponds, in the best possible way, to the total load applied to the spring. When the spring initially is released to carry out a height adjustment, it does no longer as previously, result in that uncontrollable forces are set free, because the load and said resulting force are neutralizing each other. The tabletop simple remains standing and permits displacement to a different height without difficulty and risk. It only requires a minimal pressure up or down on the tabletop.

This adjustable support device in form of a leg for a height adjustable table is however complex and expensive to produce. The durability of the support device is also relatively short, due to the complex structure.

These disadvantages and shortcomings of the known support devices are remedied according to the invention by in a first aspect according to the invention providing a support device of the kind mentioned in the opening paragraph, which has a simple and inexpensive construction, in a second aspect according to the invention providing a support device of the kind mentioned in the opening paragraph, which has long durability, in a third aspect according to the invention providing a support device of the kind mentioned in the opening paragraph, which comprises two telescopic pipes and a displacement means for, with a constant force, allowing the two telescopic pipes to be displaced in relation to each other, in a fourth aspect according to the invention providing a support device of the kind mentioned in the opening paragraph, which comprises two telescopic pipes and a displacement means for, with a constant force, allowing the two telescopic pipes to be displaced in relation to each other, and means for modifying the constant force to a constant force of a different size, in a fifth aspect according to the invention providing a support device of the kind mentioned in the opening paragraph, which is suitable to serve as a leg for a height adjustable table, in a sixth aspect according to the invention providing a support device of the kind mentioned in the opening paragraph as leg for a table, and whereby the table height can be adjusted easily and comfortably, in a seventh aspect according to the invention providing a support device of the kind mentioned in the opening paragraph as leg for a table, and whereby which the height of the table can be adjusted without risk to the operator.

The novel and distinctive according to the invention consists of that the spring for mutually displacing the two telescopic pipes associated with the column of the support device is a tension spring, whereby the support device achieves a simple construction and at the same time is inexpensive to produce.

The support device can according to the invention, advantageously be utilized as telescopic table leg for a height adjustable table, and when the tension spring has a constant characteristic the table allows to be quickly and conveniently adjusted, without accompanying risk that the operator or others get injured.

The support device can according to the invention additionally have means to change the constant force to a constant force of a different size, whereby the advantage is achieved that the table can be used to accommodate a larger or smaller load, at the same time as the above-mentioned advantages are maintained. The invention is described further below, disclosing further advantageous properties and effects according to the invention, and describing exemplary embodiments with reference to the drawing, wherein

Fig. 1 shows, seen in perspective, a height adjustable table according to the invention in raised position,

Fig. 2 shows the same in lowered position,

Fig. 3 shows a side view of a partially coiled tension spring for the table shown in fig. 1 and fig. 2,

Fig. 4 shows a first embodiment of the raised table shown in fig. 1 with some of the parts removed, Fig. 5 shows the same for the lowered table shown in fig. 2,

Fig. 6 shows a sectional side view of a second embodiment of the raised table shown in fig. 1, Fig. 7 shows the same for the lowered table shown in fig. 2,

Fig. 8 shows a fragment of the table shown in fig. 6 and 7 in a sectional, longitudinal side view, Fig. 9 shows a section taken along the line IX-IX in fig. 8,

Fig. 10 shows a first embodiment of a tool to expand the spring coil shown in the fig. 3, seen in section in contracted condition,

Fig. 11 shows same in stretched condition,

Fig. 12 shows a second embodiment of a tool for expanding spring coil shown in fig. 3, seen in longitudinal section contracted condition, Fig. 13 shows a section taken along after line VIII-VIII in · fig. 12,

Fig. 14 shows a third embodiment of a tool for expanding the spring coil shown in fig. 3, seen in longitudinal section in contracted condition,

Fig.15 show same in stretched condition, Fig.16 shows fragmentary, seen in longitudinal section, how the table shown in fig. 1 and fig. 2 is locked in height position, and

Fig. 17 is a graph, which shows the relation between the spring force and the diameter of the spring coil.

In the following an embodiment of the support device according to the invention is described, which is designed for serving as a telescopic table leg for the table shown in fig. 1 and fig. 2. It is however noted, that the support device can be used for many other purposes, e.g. for a chair.

In fig. 1 and 2 the table is seen in raised and lowered position, respectively. The table comprises a tabletop 2, a telescopic table leg 3 and a foot 4. The table leg consists of an upper telescopic pipe 5, which is displaceable placed in a lower telescopic pipe 6.

Fig. 3 shows a partially coiled up tension spring 7 for use in height adjustment of said table. The function of the tension spring will be explained further later.

The tension spring is a band 8 of elastic material, e.g. spring steel. In unloaded condition the band forms a bend with such a small radius of curvature, that is attempts to recoil itself to a spring coil 9 with windings 10 in a number that depends on the length of the band.

In fig. 3 the free outer end of the band 11 is fastened to a stationary object 12, while the spring coil being affected by a force K, whereby the band is stressed by a tension force of equal size.

The spring is arranged in such a manner that the tension force is constant, independent of how much or how little of the band, which is, uncoiled the spring coil.

Fig. 4 and 5 show the first embodiment of the table shown in fig. 1 and 2. Some of the parts of the table leg have been removed so that it can be seen how the interior of the table leg is designed.

The free outer end 11 of the tension spring 9 is fastened on the inside of the lower telescopic pipe 6. Additionally, a foot is arranged on the inside of the upper telescopic pipe, which in this case is configured with an arched bottom which rests on the top of the spring coil 9.

This situation corresponds to the one shown in fig. 3 and described above. Accordingly the tension spring in fig. 4 and 5 will affect the lower telescopic pipe with a downward spring force K and the upper telescopic pipe with an upward spring force K. When the weight of the upper telescopic pipe plus the weight of the table top plus the weight of the item or the items, e.g. a computer placed on the table top, equals the spring force K, the table is in un-locked condition in balance, i.e. that the table top remains standing in a given height position, as long as it is not influenced by other forces than the sum of the above mentioned weights. This balance is kept in all height positions since the tension spring 7, as mentioned, is configured with a constant spring force . Therefore no additional forces are needed to move the tabletop from one position to another, in which it then can be locked when the table is to be used. This adjustment takes place simply, easily and conveniently with a light pressure up or down on the tabletop.

Fig. 6 and 7 shows a second embodiment of the table shown in fig. 1 and 2, but in sectional side view. This embodiment corresponds substantially to the embodiment shown in fig. 4 and 5, and for like parts same reference numbers are therefore used.

However, in this case the spring force K acts between the upper and lower telescopic pipe 5 and 6 in a different manner than in fig. 4 and 5, namely with an axle 14, which rotateably is arranged in consoles 15, which are fastened on the underside 16 of the upper telescopic pipe 5.

This construction is best seen in fig. 8, which in larger scale shows the table leg 3, seen from the side in section, and in fig. 9, which shows a section after line IX-IX in fig. 8.

As can be seen, the spring coil is placed on the axle 15, and thus the force K, which acts between the upper and lower telescopic pipe, is in this case transferred via the consoles 14 and the axle 15, while the uncoiled spring band extends upwards between the outside of the upper telescopic pipe and the inside of the lower telescopic pipe with its free outer end fastened to the inside of this pipe.

This second embodiment has the advantage that the spring band doesn't get worn. When the downward load, which applies on the tension spring, corresponds to the spring's spring force, the tabletop is, as mentioned earlier, in balance and can therefore be height adjusted with a minimal use of manual forces. This is due to the spring force K of the tension spring is constant.

The above-mentioned advantages are therefore only fully achieved by one specific load on the tabletop. But this is a very limited restriction, since a table often is being used for various tasks.

Therefore there is a need for the ability to change the constant force of the tension spring to a different constant spring force, so that the above-mentioned advantages can be kept.

Tests have shown that the spring force of the spring coil changes along with changing its diameter. The support device comprises a tool to change the diameter of the coil accordingly, and which functions by being placed in the coil and activated, until the coil has reached that diameter where the spring force has the desired constant size. Fig. 10 and 11 shows a first embodiment of such a tool 17. In fig. 10 the tool is retracted to a relatively small diameter and in fig. 11 stretched to a relatively large diameter.

The tool is mainly shaped like a wheel 17 with an axle 18 and two discs 19, which in use are placed on each their side of the spring coil (not shown) , and which mutually are connected with stake (not shown) . In this case each disc is formed with three through-going openings . A centre area on each of the three shoes 20 is, via each their knee joint 21, connected to the centre 22 of the wheel. A side area on each shoe is additionally connected to a peripheral area on each of the two discs via swivel joint 23.

The wheel is paced in the opening of the spring coil and by turning the wheel and shoes in relation to each other, the knee joints are successively straightened out, during which the discs is controlled by the swivel joints.

By turning the wheel and the shoes the opposite way in relation to each other the knee joints are folded together.

In this way the diameter of the coil can be changed to the diameter by which the spring force has reached the size, which corresponds to the actual load on the tabletop.

Such an adjustment can e.g. be carried out when the two telescopic pipes are completely pulled together, meaning when number of windings in the spring coil is the least possible and changing of its diameter therefore easiest to carry out.

The adjustment is performed by means of a key (not shown) , which is inserted into a slot in the sidewall of the lower telescopic pipe. Fig. 12 and 13 shows a second embodiment of a tool 24 to change the diameter of the spring coil 9.

In this case the tool includes four shoes 25 abutting the inside of the spring coil 9, and each of which are formed with two opposite sloping slide surfaces 26, two nuts 27, which are abutting the slide surfaces on each their side of the centre of the tool, and a screw 28 with right and left thread for screwing the nuts back and forth in opposite directions. The screw is rotateably positioned in two discs 29, which are placed on each their side of the spring coil 9. Fig. 13 is a section of the tool, after line XIII-XIII in fig. 12, where the plates are seen in cross section view at this point. The outer rim of the nuts is shaped with ripples, which fits into the plates, that allows them to stay positioned in approximate angle.

One end of the screw is formed as a squares pin 30, which fits with a key (not shown) for being inserted through a slot in the side of the lower telescopic pipe and screw the nuts back and forth in order to increase or reduce the diameter of the spring coil and thereby the constant force of the tension spring.

The shoes rest against four limited areas of the spring coils inner side, whereby the circular shape of the coil is likely to be deformed. This can to some extent be prevented by using eight shoes instead of four.

Same tendency to deform the spring c il is also present, when the first embodiment of the tool is being utilized.

Fig. 14 and 15 shows a third embodiment of a tool 31 to change the diameter of the spring coil 9. The tool with the spring coil is shown placed in fragments of the telescopic table leg 3.

By means of an inflatable bladder 32 the tool tightens in this case uniformly against the entire inner surface, with the advantageous result that the spring coil keeps its circular shape. Instead of a bladder a tube can be used.

A pipe 33 having a side opening 34 extends between two plates 35, located on each their side of the spring coil 9. The pipe extends out through one of the plates to an area, where it is connected airtight to a coupling nipple 36, which also is connected to flexible tube 37. Since the tool is connected airtight to a flexible tube via a coupling nipple, the spring coil with the tool mounted is allowed to rotate freely during operation, just as the flexible tube allows the spring coil to move up and down during operation.

In present example the tube is thought to be connected to a small, for example manual pump, placed at an easy accessible place underneath the tabletop. Because of this the spring force of the spring coil can be adjusted as needed.

Instead of being connected to a tube via a coupling nipple, the bladder can have a valve, e.g. the type of valve used in a car tire .

The pressure in the bladder, and thereby the spring force, can then be regulated in the same way as the pressure in a tire. For the purpose a manually operated pump can be operated or another external air source, which is connected to the valve of the bladder via an opening in a wall of the lower telescopic in a position, where the two telescopic pipes are locked together.

As mentioned earlier the advantage achieved by the tension spring is that the tabletop in itself is in balance. However in practice it has to be locked in the desired work height.

For this purpose is used the locking arrangement according to the invention shown in the fragmentary view of fig. 16 of the telescopic table leg.

The locking mechanism comprises a guideway 38, which is attached to the inside of the upper telescopic pipe 5. In the guideway is placed a pressure spring, which acts between a bottom 40 in the guideway and a breast 41 on a locking pin 42, which is passed through the guideway. The locking pin can be displaced back and forth between a retracted position and an advanced position, where it extends via an opening 43 in the upper telescopic pipe, into on of several locking holes 44, formed in the wall ^: of the lower telescopic pipe or in a profile (not shown) on the inside of this pipe.

The locking pin is additionally connected with a bowden wire 45 via a tension spring 46, operated via a handle (not shown) on for example the underside of the tabletop. The tension force of the tension spring is in relaxed position less than the pressure force of a pressure spring.

If the table top is loaded more than intended, which corresponds to the adjusted spring force obtained by means of the adjustment tool, or alternately is not loaded at all, the locking pin is clamped in the respective locking hole, whereby it is effectively ensured, that the table top stays in the adjusted position.

The locking can be released manually by operating the bowden wire. But when the load on the table is abnormal, the operation of the bowden wire will provide resistance, which makes the user aware of the possibility of normalizing the load, before the lock is released.

Experiment

The diameter of the spring coil of the kind shown in fig. 3 was expanded and the tension force measured at a series of diameters, which the coil was expanded to.

The result is shown in the graph shown on page 10, in which the abscissa discloses the internal diameter of the spring and the ordinate the measured spring force. The results are indicated by crosses in the graph, and as seen, the relation between the spring force and the diameter is linear . At a diameter of 42 mm a spring force of 11.4 N was measured and at a diameter of 114 mm a force of 6.2 N, thus about a halving of the spring force.

The inherent property of the tension spring is utilized by adapting the tension spring according to the invention to tables with loads within a predetermined interval.

A table with a specific computer on the tabletop requires as an example a spring force of 16 kg to be able to counter balance the load on the tabletop.

If the table is used for other tasks, the size of the spring force can easily be change to counter a load of a different size .

This change is according to the invention done by the means for expanding the spring coil, which means that the table can be utilized within for example an interval of between 12-20 kg with same advantage as with the above-mentioned load of 16 kg and with the same tension spring.

The invention is described above and shown on the drawing on the basis that the support device had only one tension spring. Within the scope of the invention the support device can however have several tension springs.