AN ARRANGEMENT FOR A DESK COMPRISING A DESK-TOP WHICH CAN BE RAISED AND LOWERED

Abstract: A switchboard desk (1) comprises a top (2) which can be raised and lowered and at least two telescopic legs (5) to enable the top to be raised and lowered. In the respective telescopic legs a hydraulic cylinder and its associated piston are arranged. The cylinder is fixed to the desk-top (2) and the piston is fixed to an outer part of the telescopic leg involved, or vice versa. The inner and outer parts (5a, 5b) of the respective telescopic legs involved are made of closed profile with longitudinally extending, mutually co-acting guide surfaces. The respective hydraulic cylinders in the respective telescopic legs extend inside the closed profiles.

Description: Title: An Arrangement for a Desk comprising a Desk-top which can be raised and lowered. Technical Field The present invention relates to an arrangement for a desk which comprises a desk-top which can be raised and lowered, together with telescopic legs to enable the top to be raised and lowered. The desk has at least two telescopic legs and accordingly can also conceivably have three or more legs. The desk is provided with de¬ vices for effecting the raising and lowering of the desk¬ top. These devices can be automatic or manual in con¬ struction; in the case of the manual version the raising and lowering effect can be accomplished by a crank or similar device. State of the Art It is already known per se to propose a desk, for example a switchboard.desk for office use, which com¬ prises an arrangement for raising and lowering the desk¬ top. It is also known to use telescopic legs for such a desk, each provided with a hydraulic cylinder. In this case, the hydraulic cylinders are supplied with power by a hydraulic pump which can be actuated by a motor, for example an electric or hydraulic motor, and/or by manual actuating devices which may then comprise a crank, as mentioned above. Description of the Invention The Technical Problem With desks of this kind it is important to obtain reliable functioning of the raising and lowering of the ' desk-top. The movable parts in the telescopic legs - - should not display any tendency to become jammed to¬ gether (the so-called jammed-drawer effect). It is also important that the raising and lowering can be carried out with a low noise level and reliably from the func- tioning point of view, even when the desk-top is unevenly- loaded, i.e. when objects placed on the desk act asym¬ metrically on the desk-top. From the maintenance and installation point of view the desk should have a con¬ struction which will meet the demands made upon it. The Solution The main object of the present invention is to pro¬ pose an arrangement which solves the problems indicated above in a satisfactory manner. The features which amongst others can be regarded as characteristic of the new arrangement are that in at least two of the respec¬ tive telescopic legs of t e desk a hydraulic cylinder is arranged, together with its associated piston, the respective cylinders being fixed to the desk-top and the pis-cons being fixed to an outer part of the telescopic leg involved, that the inner and outer parts of the tele¬ scopic legs are made of closed profiles with longitudi¬ nally extending, mutually co-acting guide surfaces, and that the respective hydraulic cylinders in the respective telescopic legs involved extend inside the closed pro¬ files. Separate further developments of the principle of the invention deal in more detail with the specific con¬ struction of the parts concerned. Thus, the outer parts of the respective telescopic legs are fixed at the bottom to a first bar which forms a base part and extends in the depth direction of the desk. The bar is fitted with height-adjusting devices which can co-act with a supprt- ing surface on which the desk is set up. In a preferred embodiment the height-adjusting devices and the bar are designed so that the height can be adjusted from the upper side of the bar. The inner parts of the respective telescopic legs involved are fixed to a second bar, similarly extending in the depth direction of the desk and fixed in turn to the lower face of the desk-top. The first and secondbars consist of an open profile, preferably with a substan¬ tially square or rectangular cross-section. The first bar which forms the base part. as its open section direct- ed downards towards the .foundation on which the desk is set up. The open section of the second bar is directed towards the underside of the desk-top. The space which is enclosed by the second bar and the lower surface of the desk-top is used to house the connecting line or con- necting lines, i.e. the•hydraulic pipeline or hydraulic pipelines for the hydraulic cylinder positioned in the leg. Opposite the open part of its profile the second bar is provided with a cut-out for the said connecting pipeline or connecting pipelines. A cover plate is ar- ranged releasably to cover the said cut-out, and this cover plate forms an abutment surface for the hydraulic cylinders so that they do not act directly on the mater¬ ial of the desk-top. A further special feature of the said developments consists in that the pistons in the respective hydraulic cylinders are connected via a distancing device to the first bar fixed to the respective outer part of the tele¬ scopic leg. The respective base parts have one or more height- adjusting devices which are accessible from the upper side of the base part for influencing. Moreover, preferably means for enhancing the slid¬ ing effect are used, these being in the form of a device which is inserted in the upper region of the respective outer leg parts, between the leg parts. The said device has a low coefficient of friction. The device is fixed in one of the leg parts by means of a securing device, for example a screw. Tolerance take-up devices can be used with this screw so that the tolerances are kept ad¬ vantageous for the reciprocal movements of the leg parts. Advantages v/ith the means proposed above a well-adapted rais¬ ing and lowering function is obtained for the desk-top. The design is relatively simple while ' at the same time a high degree of reliability is obtained in operating and in construction. In conjunction with the said further developments advantages are also afforded from the installation and maintenance point of view. The hydraulic cylinders are accessible for maintenance, for example for replacing packing rings and so-on. For replacement work of this sort the second bar can be released and the leg bent out from the desk-top. The cover plate is then taken off, so that the hydraulic cylinder is fully accessible. List of Figures A presently proposed arrangement which displays the characteristics which are significant to the invention is described below with reference to the accompanying drawings, on which Figure 1 is a perspective view looking at an angle from below and from the right, showing the construction of the desk, Figure 2 shows the shaping ^ of a profile which is used as an outer part in the respective telescopic legs, Figure 5 is a cross-section through a profile which is used as an inner part in the respective telescopic legs, Figure - is a longitudinal section showing the positioning of the hydraulic cylinder in the telescopic leg fro ed by the inner and outer parts ' , Figure 5 is a horizontal view showing an example of a device for effecting the raising and lowering, Figure 6 is a horizontal view showing a cover plate which is used on a fixing bar for the telescopic legs on the desk top, and Figure 7 is a horizontal view showing a tolerance take-up device designed to be provided on the respective telescopic legs, Figure 8 is a horizontal view showing a bar which can be provided for the desk-top, and Figure 9 is a vertical section showing a height- adjustment device which is accessible from above. Preferred Embodiment In Figure 1 a desk which may consist of a switch¬ board desk is indicated by 1. The desk is made with a desk-top 2 and a framework 3 which comprises a cross- bar to the ends of which two telescopic legs 5 and 5 are connected. The respective telescopic legs comprise ' an outer part 5a and an inner part 5b. The outer part is provided at the bottom with a base part TS which is in the form of an open profile. The base part extends in the depth direction of the desk. The base parts are equipped with feet 5c v/hich can be adjusted in the height direction and v/hich are designed to co-act with a supporting surface on v/hich the desk is set up. The feet 5c may vary in number and may be two, three or more, for example. The said base Darts are nrovided If " with cover elements AT at their respective ends. These cover elements are provided mainly for the sake of the appearance. The desk-top 2 is fixed to the said inner parts 5b via other profiles 3S or bars. The respective inner parts in the respective telescopic legs can be actuated by means of a hydraulic cylinder (not shown in Figure 1) which is provided in each of the respective legs. The hydraulic cylinders can be arranged in a way which is described in more detail below, so that mutual displacement by means of the res¬ pective hydraulic cylinders can be effected by the leg parts 5a and 5b-, thus raising and lowering the desk-top. The hydraulic cylinders in the telescopic legs can be supplied in a way which known per se. In the present case at least one hydraulic pump HP is used (a so-calleddouble pump). This hydraulic pump is disposed in a motor hous¬ ing M on the lower face of the desk-top. The motor housing is disposed right underneath the desk-top, and substantially in the central region thereof. The deskis also provided with a cable duct 6 and connecting devices 7 for connecting an external electrical current, for ex¬ ample for connecting to the conventional mains power supply. In this instance connection is made to a socket by means of a plug ST. In addition to the said pump HP, in the present case the motor housing contains an electric motor S v/hich drives the hydraulic pump 9 • The hydraulic pump is in communication with the hydraulic cylinders in the tele¬ scopic legs via hydraulic oipelines 8 and 9. A otentio- II It meter P and two limit switches A1 and A2 are arranged on the output shaft of the electric motor. On the lower " face of the top 2, towards the rear and right out to the right-hand side, a manipulation box MA is arranged for controlling the effective devices in the motor housing M . At its rear end the manipulation box is provided with manual actuating devices K1, K2 and K3. The manipulation box MA. contains electronic equipment of a kind which known per se and which is designed to con¬ trol the electric motor and thus also the pump HP. In accordance with the control effected by this equipment the pump in turn controls the hydraulic cylinders in the telescopic legs so that the desired raising andlower¬ ing actions of the desk can be effected. The base parts TS on the respective telescopic legs are made from the same profile as the bars BS, but the base parts TS are longer. The bar profile is of the type which has an open, substantially rectangular or square cross-section, the open part of the profile facing down¬ wards in the case of the base parts 5c and upwards in the case of the bars BS. With the arrangement shown the height-adjustment devices 5c are accessible from above with a- screw-driver, hexagonal key or similar device SM which makes the adjustment of the level of the desk con¬ siderably easier. The said manipulation box also con¬ tains indicating devices which are visible from the upper face of the desk, which is not shown in Figure 1. The outer and inner parts of the respective tele¬ scopic legs consist of closed profile as shown in Figures 2 and 3- where Figure 2 shows the profile for the outer part and Figure 3 the profile for the inner part. The outer part is provided with longitudinal guide surfaces S1, S1 *, ~ Λ • ' and the inner part is provided with corres¬ ponding guide surfaces S2, S2», S2 1 '. The guide surfaces are elongated and are designed to counteract any jamming effect and thereby provide for satisfactory smooth and troublefree raising and lowering of the desk-top. The inner and outer parts are made as elongated narrow closed profiles which provide the necessary rigidity while at the same time being relatively lightweight. According to Figure 3- the inner leg part has a closed inner space U1 and the outer leg part shown in Figure 2 has a closed inner space U2. The inner leg part is also providedwith two smaller separate cavities U1 * and U"1'', while corres¬ ponding cavities U2 » and U2*' in the outer part communi¬ cate with the inner space U2. A hydraulic cylinder HY for the respective leg ex¬ tends in the central inner spaces U and r J2, as shown in Figure 4-. In the respective legs there is a certain dis¬ tancing component D . The outer part BY is fixed direct¬ ly to the bar TS which forms the base part. This fixing can be effected in a way which is known per se. The inner leg part BI is fixed in a corresponding way to the bar BS v/hich is fixed to the desk-top 2 in a mannerknownper se by means of screws v/hich are not shown in Figure 4-. The hydraulic pipeline HS is connected via the upper parts of the cylinders and via the said bars 3S. Only some parts of the said hydraulic pipeline are shown, for the sake of clarity. At the upper end of the outer Leg part BY a sealing element TF is arranged so that it slides against the inner leg part 31. There is also a sliding arrangement TIT between the leg parts, where rings can be provided to take up tolerances. " The bar 3S is provided with a cut-out.in the section opposite the open section of the bar profile. -A cover plate T3 is provided on this cut-out and can be screwed, for example with four screv/s SK, Into a part HY'. ' The force of the hydraulic cylinder is thus delivered via the plate TB, which means that the hydraulic C7/linder does not act directly on the material of the desk-top. The hydraulic cylinders arranged inside the respect¬ ive legs are readily accessible from the end. The bar 3S is released from the desk-top and the leg can then be bent out so that access is not obstructed by the desk¬ top. The cover plate TB is unscrewed and removed, after which the hydraulic cylinder is exposed. The distancing component D adapts the length of the telescopic leg to the length of the hydraulic cylinder. At its upper end D' the distancing device is provided with a fixing device SK' by means of which the end HY' * of the piston is fastened to the end part D* * of the distancing device D . At the bottom the distancing device is fixed to the bar TS. This fixing is effected by a fixing device SK' 1 which co-acts with the said bar TS and another end part D 1 ' ' on the distancing device D . The profile shown in Figure 2 has an elongated, narrow, substantially rectangular cross-section. The profile shown in Figure 3 πas a cross-section which is composed of three substantially rectangular parts of which the central part forms a large rectangular part and the two remaining rectangular parts are substantially the same size as each other and are connected to the short ends of the first-mentioned rectangular part. Figure 5 shows the motor housing M withthe elect¬ ric motor Ξ which may consist of a single-phase non- synchronous motor, and the hydraulic pump HP which may consist of a so-called double pump. The output shaft of the electric motor is indicated by Ξ. 1 and the drive shaft of the hydraulic pump is indicated by HP 1 . The potentiometer P is connected to the -said-transmission S 1 , HP' via a helical thread S . ' The potentiometer con- sits of a ' known 0-revolution potentiometer. The con- * necting pipelines 8, 9 for the hydraulic pump are also shown. Figure 6 shows the cover plate T3 mentioned above, in a horizontal view. Figure 7 shows a tolerance take- up device, designated 9. The said devices consist of thin, substantially uniformly thick plate. The device or plate is provided with a cut-out 9a via v/hich the plate can be suspended on a fixing screw for the sliding part Tϋ mentioned above. Figure 8 shows a horizontal view of the bar BS. The cut-out mentioned above is designated HS', and has exact¬ ly the same shape as a keyhole. As mentioned above, the cut-out is covered by the cover plate shown in Figure 6, the position of the cover plate being shown with dashed lines in Figure 8. The said cover plate thus fixes the position of the hydraulic cylinder. The cover plate can be screwed on o ~ τ four of the above-mentioned screws SK. The bar is also provided with a through-bore BS' for screws which hold the bar securely on the desk. The said bores may be four in number. The cut-out HS' has a nar¬ row part HS" which is not covered by the plate when the latter is fitted on the bar. The part HS" of the cut¬ out which is left uncovered is designed to allow the introduction of the hydraulic pipeline or hydraulic pipe¬ lines HS. The basic construction of the height-adjustment de- vice is shown in Figure 9- A component10 is fixed in a cut-out in the bar TS. The component is made with a tapped through-bore 11 which terminates at the upper sur¬ face of the bar TS. A foot 12 is screwed into the said component via a threaded part 3 appertaining to the foot, which is provided at its upper end 13 with a groove (also a cross-groove), a key shank or the like via v/hich a tool SM can be attached to screw the foot in or out relative to the component 13. The component can be. made of a deformable material so that flanges 10a or similar can be obtained for clamping round the material. The invention is not limited to the embodiment il¬ lustrated above by v/ay of example, byt may be modified within the framework * of the following Patent Claims.

Claims: P a t e n t C l a i m s 1. An arrangement for a desk, for example a switch¬ board desk, which comprises a desk-top (2) which can be raised and lowered and at least two telescopic legs (5,δ) to enable the top to be raised and lowered relative to a reference level, characterised in that in each of at least two of the telescopic legs of the desk a hydraulic cylin¬ der (HY) is arranged with its associated piston (HY"), the respective cylinders being fixed to the top and the pistons being fixed to an outer part (5a) of the tele- scopic leg involved, that the respective telescopic legs have inner and outer parts (5a, 5b) which are made of closed profile with longitudinally extending, co-acting guide surfaces (S1, S1 ', S1 " , and S2, S2', S2 « • respect¬ ively), and that the respective hydraulic cylinders ex- tend inside the closed profiles in the respective tele¬ scopic legs involved. 2. An arrangement according to Patent Claim 1, characterised in that the bottom of the outer ' parts of ϋhe telescopic legs is fixed to a bse part (TS) formed b a f rst bar which extends in the depth direction of the desk. 3. An arrangement according to Patent Claim 1, characterised in that the first bar is provided with height-adjusting devices (5c) which can co-act with a supporting surface on which the desk is set up. 4-. An arrangement. according to Patent Claim 3, characterised in that the height-adjusting device and the first bar are designed so that the height can be adjusted from the upper side of the bar. 5.. An arrangement according to any of the preceding Patent Claims, characterised in that the inner part of the respective telescopic legs involved are fixed to a second bar (33), preferably extending in the depth direc¬ tion of the desk, which in- turn can be fixed to the lower face of the top. 6. An arrangement according to Patent Claim 3, 4- or 5, characterised in that the first and the second bars consist of open profile with a preferably substan- tially square or rectangular cross-section. 7. An arrangement according to Patent Claim 5 or 5, characterised in that the connecting pipeline or con¬ necting pipelines for the hydraulic cylinders pass in ihrough the second bar (3S) which is provided with a cut-out (HS', HS") for the said pipeline or pipelines. 8. An arrangement according to Patent Claim 1, characterised in that the said cut-out can be covered over by means of a detachable cover plate (TB). 9. An arrangement according to any of the preceding Patent Claims, characterised in that the pistons of the respective hydraulic cylinders are connected via a dis¬ tancing device (D) to the first bars (TS) fixed or dis¬ posed on the outer parts of the ' relevant telescopic legs. 10. ■• - An arrangement according to any of the preceding Patent Claims, characterised in that in the upper region of the respective outer parts of the relevant telescopic legs devices for enhancing sliding are arranged, together v/ith means for the disposition of devices (9) for taking UP tolerances.

Inventors: JOHANSSON LARS AOKE, LUNDSTROEM KURT ALBERT, SVENSSON AOKE PEDER, WALLIN PER OLOV THOMAS, WARELL BENGT HUGO, JOHANSSON, LARS, AOKE, LUNDSTROEM, KURT, ALBERT, SVENSSON, AOKE, PEDER, WALLIN, PER, OLOV, THOMAS, WARELL, BENGT, HUGO
Applicants: TELEVERKET
Application year: 1985
Main classification: A47B9
IPC codes: A47B9, A47B17