METHOD AND MEANS TO PROVIDE ELEVATED FLOORS WITH AN IMPROVED ELECTRICAL SCREENING

Abstract: The purpose of the invention is to provide, in double floors including an elevated floor (3) carried on posts (2) above the floor (1) proper, electrical screening between the spaces on either side of the elevated floor (3). The elevated floor (3) comprises square flooring panels (4) resting at their meeting corners on elastic locating plates (7) arranged on the posts (2), the uppersides of the locating plates (7) being divided into quadrants by guide ridges (14). By providing the locating plates with contact lamella (21, 22), extending from the undersides of the locating plates and up into the different quadrants there is provided a metallic connection of the metal cladding (16) on the undersides of the flooring panels so that a continuous screening plane is formed.

Description: Method and means to provide elevated floors wit an improved electrical screening' TECHNICAL FIELD The present invention relates to a method and apparatus in double floors, including an extra or elevated floor carried above the actual floor on a support system of preferably metal posts, for screening the space under the elevated floor from the space above this floor, which is made up from preferably square panels of electrically non-conduc¬ tive material with metal cladding on its underside, the panels resting on the support posts at the meeting corners of the panels, the upper sides of the support posts being covered by locating plates made from an elastic non-conductive or partially conductive material and provided with guide means for locating the posts and flooring panels relative each other. BACKGROUND ART In switchgear stations and central computer stations double floors are often used in the rooms housing the hardware, for the purpose of enab¬ ling laying such as cables to, and between, different machine units. Such a double floor includes an elevated floor put together from stan¬ dard module panels carried by a support system above the actual floor. In a commonly occurring embodiment, the support system comprises metal posts arranged at the meeting corners of the panels. Each post in¬ cludes a foot and an adjustable upstanding member having at its upper end a carrier plate large enough for enabling it to support with a good safety margin the meeting corners from four panels. The panels, which may be lifted individually, are of strong construction and un¬ supported between the posts. The carrier plate of each post is covered by a locating plate of elastic material, usually plastics, and is pro- vided with guide means for locating post and panels relative each other. To this end a flange runs round the locating plate to engage against the carrier plate, and on the upper side of the locating plate the guide means takes the form of ridges dividing this side into quadrants for locating the corners of the flooring panels. The locating plates are made from elastic material, usually plastics, in order to take up and compensate for small dimensional differences and possible deformities in the flooring panels. The locating plates are also sound-dampening, for the cases where in spite of all there is play between some panel corner and the underlying locating plate, re¬ sul ing in that the panel can move when the floor is wal ed on. Since data processing equipment is to a large extent sensitive to electrical disturbance, and such disturbance can be spread from the current supply cables laid under the elevated floor, the flooring panels, which are usually made from an electrically non-conductive building board of some kind, are provided on their undersides with a metal cladding such as aluminium foil. In order to achieve screening action, the cladding of all the flooring panels must be electrically connected to each other and connected to ground or earth. As the panels must be individually liftable, it is not possible to arrange connection means under the panels and to connect the panels to each other and to an earthing point with the aid of cabling. It has been attempted to solve the connection problem by arranging contact points at the posts, where the meeting corners of the panels rest on the previously mentioned locating plates made from elastic material. Since the locating plates in the original embodiment were not electrically conductive, attempts have been made to use metal locating plates to provide good contact between adjacent panels and between these and earthing means. However, when the elastic locating plates were replaced by stiff metal plates there were large problems with adjusting the height of the posts so that all the corners of the flooring panels were in contact with their respective posts. The re- suit was that certain panels were poorly earthed, and earthing could vary if the pane s moved when the floor was loaded. Furthermore, move¬ ment over panels resting on metal locating plates could be acoustical¬ ly disturbing. Elastic locating plates have therefore come into favour once again to a large extent in the construction of elevated floors, but these plates are now made electrically conductive by mixing into the plastics material powder of a conductive material, preferably carbon. With these locating plates manufactured from conductive plastics material there is, however, the problem that the contact resistance between the metal cladding of the panel and the locating plate as well as between the plate and the post is large and varies with the move¬ ment of the panel and the load. Further to this the poor conductive ability of the plastics material varies both with the floor load and the temperature of the plant. DISCLOSURE OF INVENTION The present invention has the object of eliminating the disadvantages mentioned above by teaching a method and apparatus for carrying out the method whereby good metallic contact at the places in question is achieved while retaining the elasticity of the locating plates. This is achieved by the method and apparatus, the characterizing features of which are disclosed in the following claims. DESCRIPTION OF FIGURES The invention will now be described in detail with reference to the accompanying drawing, on which Figure 1 is a perspective view of a portion of an elevated floor,. Figure 2 is a sideview of a known embodiment of a post with a locat¬ ing plate and portions of two flooring panels, Figure 3 illustrates a short-circuiting metal lamella, Figure 4 illustrates a locating plate with contact lamella in accor¬ dance with the invention and Figure 5 is a sideview of the upper portion of a post provided with a locating plate equipped with a contact lamella in accordance with the invention, '1 together with- portions, of flooring panels * DESCRIPTION OF EMBODIMENT The elevated floor 3, partially illustrated in Figure 1, includes square panels 4 of standard size, resting on posts 2. Cables 9 and other un llustrated pipes and conduits may be placed in the space between the elevated floor 3 and the proper, or structural floor 1. The support posts 2, which are placed everywhere where the corners of the flooring panels 4 meet each other, are adjustable in length so that possible irregularities in the structural floor may be compen¬ sated, as will be seen from Figure 2. Adjustability is achieved by the post including two parts, namely a foot 10, to which is attached an upstanding member 11 threaded on the outside and provided with an adjusting nut 19, this nut engaging against a tubular post portion 12 thrust over the upper portion of the upstanding member 11 and provided with a carrier plate 18 at its upper end. On the carrier plate 18 there is placed a circular locating plate 7 which is made from an elastic material, in appropriate cases made conductive by the admix¬ ture of carbon powder or the like. Along its circumference the plate 7 has a dining flange 8, keeping it in place on the carrier plate 18, but simultaneously allowing the plate 7 to be turned when necessary and be displaced to a limited degree relative the carrier plate 18. The disk.7 is furthermore equipped with guide means in the form of ridges 14 dividing its surface into quadrants and fitting into the joints between the flooring panels 4 to retain them in place. This implementation eliminates the requirement with other known support post types of exact placing at the corners of the flooring slabs 4. The individually liftable panels 4 comprise a core, usually of some kind of building board, with an upper wearing surface 17. The under¬ side of the panel is provided with a metal screen 16 in the form of a sheet or foil. The intention is that the screens 16 of the panels are to be connected via the more or less conductive, elastic locating disks 7 to form an entire screening plane, but as indicated in the introduction, these connections will be uncertain and for established contact they will vary with a number of factors including the contact resistance as well as the resistance in the locating disk itself. In accordance with a preferred embodiment of the invention, contact is ensured and the need of conduct!veness in the locating disk is elimi¬ nated by the use of a contact lamella, configurated as illustrated in Figure 3. The lamella 20, which includes a central portion 21 with four flaps 22 projecting from it and at rightangles to each other, is placed concentrically between the carrier plate 18 and locating disk 7. This is illustrated in Figure 4, which illustrates in plan a locating disk 7 from which a portion has been removed so that the placing of the contract lamella 20 relative the carrier plate 18 is visible. Except for the flap 22a situated in the area of the removed portion of the locating disk, the flaps 22 of the lamella 20 are folded back over the top surface of the disk between the guide ridges 14. In figure 5, which is a sideview of the upper part of a support post and a locating disk equipped with a contact lamella, a portion of the disk 7 has also been removed, and the corresponding flap 22a has been bent down. Also illustrated in Figure 5 is an implementation of the screening plane earthing connection, according to which an earthed cable 23 has been clamped to the tubular post portion 12 with the aid of a clip 24. Since the flaps 22 of the contact lamella are yielding and do not prevent the elastic deformation of the locating disk 7 for different loading conditions, the good properties of the elastic locating disk 7 are retained in the proposed method, while at the same time there is ensured the required mutual contact for good screening action between the metal cladding 16 of the flooring panels as well as the contact of these with the support posts 2 functioning as earting points. With¬ in the scope of the inventive concept, the contact lamella 20 may be formed in many different ways or be replaced by several lamella for one and the same locating plate 7.

Claims: CLAIMS 1. Method in double floors including an extra or elevated floor (3) carried by a support system of preferably metal posts (2) above the proper floor (1), of electrically screening the space under the ele¬ vated floor (3) from the space above the elevated floor (3), the method relating to an elevated floor (3) made up from preferably square panels (4) of electrically non-conductive material (15) on the underside of which there is arranged metal cladding (16), said panels (4) resting at their meeting corners on the support posts (2) which have circular uppersides covered by rotatably arranged, preferably circular locating plates (7) made from an elastic non-conductive or partially conductive material and provided with guide means (8, 14) for locating the flooring panels (4) and posts (2) relative each other, the uppersides of the locating disks (7) being divided into quadrants preferably by guide ridges (14) for receiving the corners of the flooring panels assigned to the respective quadrants, characterized in that in each quadrant to which a flooring panel (4) is assigned there is arranged at least one metallic contact (22) in the form of a lamella, thin plate or the like, which is in communi¬ cation with at least one contact (22) arranged in another quadrant, and/or underlying metal post (2) or other means functioning as earth¬ ing means. 2. Method as claimed in claim 1, characterized in that under the locating disks (7) and in contact with the carrier plate (18) of the respective post there are placed contact la ellas (20) with flaps, corners or the like (22) extending outside the outer contour of the locating plate (7), said flaps (22) being folded round the edge of the locating plate (7) such that when the corner of a panel (4) is placed on the locating plate (7) there is electrical contact between the metal cladding (16) of the respective panel and the contact lamella (20). 3. Apparatus for carrying out the method according to claim 1, characterized in that it comprises a contact lamella (20) of thin, easily foldable metal sheet, including a preferably quadratic central portion (21) and a flap (22) projecting diagonally outwards from each corner of the central portion (21) and of a length such that the flap (22) may be folded round the edge of the locating plate (7) to form with its end portion a contact pointon the upperside of the locating plate (7) when the central portion (21) has been concentrically placed between the carrier plate (18) and locating plate (7).

Inventors: SJOEBLOM BENGT INGVAR GEORG, SJOEBLOM, BENGT, INGVAR, GEORG
Applicants: BECO PRODUKTUTVECKLING
Application year: 1985
Main classification: E04F15
IPC codes: E04F15