TABLE-LEG FOR A TABLE HAVING A TABLETOP BEING ADJUSTABLE IN HEIGHT, AND SUCH A TABLE

Abstract: The invention relates to a table leg for a table provided with a table top adjustable in height, comprising two mutually telescopically slidable leg parts (15, 16), an upper leg (15) which is provided with means for fastening to the table top (2), a lower leg part (16) which is provided with a spindle nut (13) in which is screwed a screw spindle (60) mounted on the upper leg part (15), and an electric motor (19) incorporated in the table leg for driving the screw spindle (60), wherein said electric motor is connected to the lower free end of said screw spindle (60) and suspended freely thereon in said lower leg part, and that said electric motor and said lower leg part are provided with co-operating res­ training means (17, 18) which prevent said electric motor, movable up and down in the lower leg, from rotating with respect to said lower leg part, and to a table provided with such table leg.

Description: The present invention relates to a table leg for a table provided with a table top adjustable in height, com­ prising two mutually telescopically slidable leg parts, an upper leg part which is provided with means for fastening to the table top, a lower leg part which is provided with a spindle nut in which is screwed a screw spindle mounted on the upper leg part, and an electric motor incorporated in the table leg for driving the screw spindle. A table leg of the kind is known from DE-A-35.43.-­ 696. The battery-driven electric motor is accommodated in the upper leg part and drives the screw spindle at its upper end. This construction has several disadvantages. Firstly, the load of the table is transmitted to the lower leg part via the electric motor and the screw spindle, an arrangement which necessitates an adequate mounting of the motor in the upper leg part. Secondly, through the electric motor being incorporated in the upper part, it becomes impossible to drive screw spindles of other extensible table legs using one and the same electric motor via connection rods mounted in the top of the upper leg part. Finally, the electric motor is only accessible by unscrewing the table leg from the table top. The present invention has for its object to procure a table leg of the kind stated in the preamble which does not have the above-stated disadvantages. This is achieved accor­ ding to the invention in that the electric motor is connected to the lower free end of the screw spindle and suspended freely thereon in the lower leg part, and that the electric motor and the lower leg part are provided with co-operating restraining means which prevent the electric motor, movable up and down in the lower leg part, from rotating with respect to the lower leg part. In this way, the electric motor moves up and down in the lower leg part whilst suspended on the screw spindle, and the load of the table is transmitted to the lower leg part through the screw spindle and spindle nut. Moreover, the electrical connecting leads for the electric motor can easily be brought up from the floor. In preference, the restaining means comprise at least one longitudinal slot arranged in the inner leg part and an electric motor support sliding in this slot. In a simple manner, the maximum and minimum exten­ sions of the table leg may be adjusted by use of a first and a second switching means that switches the electric motor off when the table leg reaches its respective maximum or minimum extension. It is advantageous if the first and second switch­ ing means are arranged respectively on the top and bottom surfaces of the spindle nut. With a single electric motor equipped table leg according to the invention, a number of other telescopically extensible legs can be adjusted in length, if, by preference, the screw spindle in the upper leg part is furthermore coupled with coupling means for coupling to a non-driven screw spindle of another table leg adjustable extension. The invention relates further to a table of adjust­ able height that is provided with at least one table leg according to the invention. The table 1 shown in figure 1 is known from Dutch patent application No. 84.03471, whose contents should be regarded as interpolated here. The table 1 is provided with a work surface 2, constructed of work surface parts 3, 4 and 5, which are carried by table legs 6 and 8 respectively. Table legs 6 and 8 are provided with supporting feet 10 and 11 respectively, while table leg 7 is provided with a distance foot 9. Work surface 2 is adjustable in height, through table legs 6, 7 and 8 comprising an upper leg part 15 and a lower leg part 16 telescopically slidable in respect thereof. The table leg 7 (figure 2) comprises two mutually telescopically slidable leg parts 15 and 16, an upper leg part 15 that is provided with screws 12 for fastening to the table top 2, a lower leg part 16 in which is fastened a spin­ dle nut 13, into which is screwed a screw spindle 60 which is mounted at its top and in bearings 14 and is connected at its bottom free end to, suspended freely thereon in the lower leg part, an electric motor 19, which is slidably guided by sup­ ports 18 comprising restraining means in longitudinal grooves 17 arranged in the inner, lower leg part 16. The electric motor 19 is connected by means of a lead 20 to a foot or hand-operated switch and is provided with a voltage supply through a transformer 21 and a protection circuit 22. On empowerment the electric motor 19 drives screw spindle 60, which drives, via a transmission gear consisting of bevel gear wheels 61 and 62, a connecting shaft 23, which in turn drives, through a similar transmission gear, the screw spind­ les of table legs 6 and 8 in the same direction. The connecting shaft 23 may further be coupled to a crank handle 24 (figure 1) so that hand operation is possible when electric motor 19 has become inoperative or must be disconnected. Usually, the crank handle 24 will no longer be present. In another embodiment of the table leg according to the invention (figure 3), in a conically formed leg support 30 is held a lower leg part 32, in which a ring core trans­ former 31 is arranged. A supply voltage is fed through a connection 33, through which control signals can also be passed to an electric motor 35 from a foot switch (not shown) on the floor or hand switch on the work surface 34. Between electric motor 35, which is suspended freely on the screw spindle 36, and screw spindle 36 is arranged, on account of the high revolution speed of electric motor 35, a gear box 37 for transmitting the correct force-motion ratio from the electric motor 35, which is for instance a 24V DC motor. Further incorporated between the DC motor 35 and transformer 31 and beneath a partition 38 - provided with an opening (not shown) for passage of an electrical supply voltage lead (not shown) to electric motor 35 - are a relay 39, a fuse 40 and a bridge rectifier 41. The electric motor 35 and the gearbox 37 are slidably guided via supports 28 of the electric motor in longitudinal grooves 29 in the lower leg part 32, so that upon the turning of the spindle 36 the upper leg part 42, which is cylindrically and telescopically slidable with res­ pect to lower leg part 32, is raised from stop member 43 upwards. Arranged on the spindle nut 44 at the upper end of spindle 36 are two microswitches 45 and 46, which are con­ nected, as indicated schematically by leads 47 and 48 respec­ tively, to the controller of electric motor 35. In the lowest position of the table leg shown in figure 3 microswitch 45 switches off electric motor 35, whilst in the fully-extended position of the table leg 27 the top surface 48 of the casing 37 will strike against microswitch 46, whereupon electric motor 35 will likewise be switched off. The transmission of the motion of spindle 36 to other table legs takes place through drive belts 50 and 51, which are coupled by means of the respective pulleys 52 and 53 to spindle 36. The table leg 27 is fastened to work top 34 with the aid of a leaf bolt 65. As a result of countersinking into the wood of the work top, a tight-fitting connection with the leaf bolt 65 is obtained. This sturdy connection between table leg 27 and work top 34 is advantageous on account of the forces delivered by the electric motor. The leaf bolt 65 is provided with apertures 66 so that it can be released with a simple spanner. If the leaf bolt 65 takes a symmetrical form, work top 34 can be reversed in simple manner, so that, for example, the table of figure 1 can easily be embodied in a mirror-image form, which may proved useful for deployment in specific areas. The connection with use of a leaf bolt can of course also be applied with advantage in the embodiment shown in figure 2. In the embodiment shown in figure 4, the spindle 60 is also provided at its top with a bevel gear wheel 61, but this bevel gear wheel is engaged only with one gear wheel mounted on a transverse shaft 64. This transverse shaft 64 is provided at both ends with a square coupling piece 25. On each of the coupling pieces 25 a coupling shaft 63, not shown in the drawing, provided with a corresponding opening can be arranged to connect the leg concerned with other legs. This embodiment is distinguished from the embodiment shown in figure 2 in that both connecting shafts 23 have the same direction of rotation, while in the embodiment shown in figure 2 the two coupling shafts 23 have opposite directions of rotation.

Claims: 1. Table leg for a table provided with a table top adjustable in height, comprising two mutually telescopically slidable leg parts, an upper leg part which is provided with means for fastening to the table top, a lower leg part which is provided with a spindle nut in which is screwed a screw spindle mounted on the upper leg part, and an electric motor incorporated in the table leg for driving the screw spindle, characterized in that said electric motor is connected to the lower free end of said screw spindle and suspended freely thereon in said lower leg part, and that said electric motor and said lower leg part are provided with co-operating res­ training means which prevent said electric motor, movable up and down in the lower leg part, from rotating with respect to said lower leg part. 2. Table leg as claimed in claim 1, characterized in that the restraining means comprise at least one longitudinal groove arranged in the inner leg part and an electric motor support guided in this longitudinal groove. 3. Table leg as claimed in claim 1 or 2, charac­ terized by first and second switching means that switch off the electric motor when the table leg reaches respectively its lowest or highest position. 4. Table leg as claimed in claim 3, characterized in that the first and second switching means are mounted on the upper surface and lower surface respectively of the spindle nut. 5. Table leg as claimed in claims 1-4, characterized in that a power-supply apparatus for the electric motor is accommodated in the bottom of the table leg. 6. Table leg as claimed in claims 1-5, characterized in that the screw spindle in the upper leg part is coupled with coupling means for coupling to a non-driven screw spindle of another table leg of adjustable height. 7. Table of adjustable height provided with at least one table leg as claimed in claims 1-6. 8. Table as claimed in claim 7, characterized in that the height adjustable, electrically driven table leg is coupled via coupling means to at least one non-driven screw spindle of a height adjustable table leg.

Inventors: VAN ENGELAND, WILLI
Applicants: TECHNISCH HANDELS- EN ADVIESBUREAU VAN ENGELAND B.V.
Application year: 1988
Main classification: A47B9
IPC codes: H02K7, A47B9