US3831328A

US3831328A - Structural unit for frame construction

Info

Publication number: US3831328A
Application number: US00385328A
Authority: US
Inventors: H Mohr; P Weigel; K Metzl
Original assignee: Nixdorf Computer AG
Current assignee: Wincor Nixdorf International GmbH; Nixdorf Computer AG
Priority date: 1972-08-05
Filing date: 1973-08-03
Publication date: 1974-08-27
Anticipated expiration: 1991-08-27
Also published as: JPS4958632A; JPS5218494B2; DE2238707A1

Abstract

A framing system for supporting false ceilings includes a vertically adjustable suspension member carrying a bracket. Means are provided to mount cross members to the bracket by pushing the cross members from below up into coacting locking means formed on the bracket and the cross members and then moving an arm outwardly from the end of the cross member to rest upon a horizontal bearing surface of the bracket to thereby suspend the cross members from the hanger.

Description

United States Patent [191 Mohr et a1.

[11] 3,831,328 Aug. 27, 19 74 STRUCTURAL UNIT FOR FRAME CONSTRUCTION Inventors: Hans Mohr, Paderborn; Peter Weigel, Borchen; Kurt Metzl, Paderborn, all of Germany Nixdorf Computer AG, Paderbom, Germany Filed: Aug. 3, 1973 Appl. No.: 385,328

Assignee:

Foreign Application Priority Data Aug. 5, 1972 Germany 2238707 US. Cl 52/145, 52/28, 52/484, 52/665 Int. Cl E04b 5/52 Field of Search 52/664, 484, 488, 28, 144, 52/145, 665

References Cited UNITED STATES PATENTS Smith.... 52/484 x 3,014,564 12/1961 Thomsen ..52/484X Primary Examiner.lohn E. Murtagh Attorney, Agent, or Firm-Hauke, Gifford, Patalidis & Dumont [57] ABSTRACT A framing system for supporting false ceilings includes a vertically adjustable suspension member carrying a bracket. Means are provided to mount cross members to the bracket by pushing the cross members from below up into coacting locking means formed on the bracket and the cross members and then moving an ann outwardly from the end of the cross member to rest upon a horizontal bearing surface of the bracket to thereby suspend the cross members from the hanger.

15 Claims, 4 Drawing Figures PATENIED AUG 2 7 I974 SHEET 1 BF 3 PATENTED M1827 m4 SHEET 3 [1F 3 m mmJ STRUCTURAL UNIT FOR FRAME CONSTRUCTION BACKGROUND OF THE INVENTION The present invention relates to a structural unit for supporting false ceilings and more particularly to a THE PRIOR ART It is possible, with frame construcitons the type contemplated by the present invention, to build up a gridlike arrangement, suspended beneath a room ceiling on which grid cover elements may be laid so that false ceiling is formed. Likewise it is possible to fasten the cover elements beneath the grid when a smooth false ceiling is desired. These false ceilings are particularly in demand when rooms which have too high ceilings are to be lowered and when in particular installation lines of various kinds are to be run in large buildings and are to be easily accessible but still invisible. Between the false ceiling and the actual ceiling of the room, there is thus created a space for such installation lines. In addition, the acoustical properties of rooms can be improved by means of a false ceiling.

SUMMARY OF THE PRESENT INVENTION An object of the invention consists in creating a structural unit for a frame construction of the type herein considered, comprising individual parts assembled as uniformly and simply as possible to be mounted with a minimum of expenditure of labor, so as to assure an entirely acceptable flat frame construction, making possible the formation of a flat false ceiling.

A structural unit of this type, used to solve this problem is, according to the invention. characterized by a connecting member provided at the two ends of the cross members, the cross members having frontal faces perpendicular to their longitudinal direction. by connecting elements disposed at the points of connection, each with a hanger and a number of connecting flanges, vertical in the suspended state, and corresponding to the number of connecting members to be joined together frame-wise. by edge guides provided on the faces of the connecting members and forming, in each case. a guide for the insertion of the connecting flange against the respective face, and by an arm, provided on each connecting member, which can be moved outwardly beyond the connecting member, which can be moved outwardly beyond the connecting member in the lengthwise direction of the cross member when the respective connecting flange has been pushed into the position of locking with the corresponding connecting element.

Thus. the structural unit of the present invention comprises cross members and connecting elements. The connecting elements each have a hanger, by means of which they can be suspended from the ceiling above the contemplated points of connection in line with the frame pattern. Their distance from one another is such as to make it possible to position the respective cross members between them. This may be readily accomplished in that the cross members can be connected, by a lifting motion from below, with each connecting flange of the cross member being pushed into its assigned edge guide on a connecting member.

Likewise, the coupling elements may also be disposed with reference to one another in such a way that coupling can be effected by lowering the respective cross member into place, which, however, in some cases may make the assembly of the frame construction more difficult.

When the coupling position of the cross members on the corresponding connecting elements has been accomplished, it is merely necessary to move an arm carried by the cross members into a position to secure one side of a frame element. Thus it is apparent that, because of the design of the structural unit as contemplated by the present invention, and in view of the structure of its individual elements, a framework construction can be set up in a very short time, even for very large rooms, in that the individual elements, that is the respective connecting element and its assigned connecting member, are put together by pushing or lifting movement. Good stability is provided by reason of the flex-resistant connection at the edge guides and the number of points of suspension, corresponding to the member of the connecting elements.

Each connecting element has a horizontal bearing surface, formed by connecting flanges to support arms of the attached connecting members. Thus, the connecting element has a support, formed by the bearing surface of the connecting elements. As has already been pointed out, connecting flanges of the connecting elements are oriented vertically and therefore, since the facesof the connecting members are perpendicular to the lengthwise direction of the cross members when these are horizontal, this assures in a very simple manner that when these surfaces are coupled together, namely with the arms resting on the respective bearing surfaces and the connecting elements suspended vertically, the frame construction will be disposed horizontally.

The number of connecting flanges on the connecting element is determined by the particular nature of the framework. For example, if the framework consists of triangular elements. there are three flanges on a connecting element, forming an equilateral triangle, if the frame elements are square or rectangular, there are four connecting flanges to form a quadrilateral bearing surface on the connecting elements.

The cross members may have a U-shaped profile, open on one longitudinal side and with such a construction they are particularly suitable for the accommodation of installation lines. with the open side facing upward within theframe construction to be covered by cover elements after the installation lines have been put in place. The structural .unit may further be so designed that the connecting flanges project out from the bearing surface, away from the hanger, and with each connecting member being provided with an arm along its edge, nearest the open side of the U-shaped profile, and parallel thereto. This makes possible a particularly simple mounting of the cross members on the suspended connecting elements, for it is only necessary then to insert them from below with the edge guides on the connecting flange, so that further'upward motion pushes the connecting flanges into the edge guides. Since each connecting member is formed with an arm along its edge, nearest the open side of the U-shaped profile and parallel thereto, the open side of the cross members faces upward, when the cross member is lifted upward with the bracket top-side. When, with an upward motion and the insertion of the connecting flange into the edge guide. the connecting member lies with its upper edge in the same plane as the bearing surface of the connecting element, the respective arm can simply be pushed out so far that it rests on the bearing surface, thus assuring the support of the cross member on two connecting elements and completing the framework construction for one side of a grid element.

Hangers, adjustable for length, are provided on the connecting elements. When the connecting elements are suspended from a ceiling. minor differences in the height of the room can be compensated for by adjusting the length of the hangers. This assures that all connecting elements are at the same level and that a horizontal false ceiling is formed.

The hanger is preferably a threaded round rod, formed with an eye. which is fastened in a turnable threaded guide, disposed on a bracket which is pivoted at points near the region of the bearing surface and directed toward the center of a central recess in the bearing surface. This makes it possible to install even readymade frame constructions in such a way that a flat false ceiling can be formed. For this, it is merely necessary to turn the respective threaded guide. in order to adjust the height ofthe connecting element. For this purpose, a tool may be passed through the central opening in the bearing surface between the connecting members, in order to turn the thread guide.

When the frame construction has been finished, the space between the connecting members may be closed by using cap-like cover elements, which, preferably, are disposed with their cover faces in the same plane as the lower side of the cross members. For this purpose,

each connecting member is fashioned, near the edge corresponding to the base of the U-shaped profile and on its frontal face, with edge guides and retaining elements for the sidewalls of one of several cap-like cover elements which complement the structural unit, the cover faces of which have a geometrical shape determined substantially by the frame construction.

A framework construction using a structural unit according to the present invention has, in every one ofthe above-described embodiments ofthe unit, great advantages over the heretofore known constructions of this kind. The most diversified grid elements may be formed, for example elements may be in the form of equilateral triangles, squares or rectangles. For this only a corresponding design of the connecting element and length dimensions of the cross members is'required. In addition, when the cross members have U- shaped profiles, they themselves may be used for other purposes. Thus. for example, it is possible to install sound-damping or sound-absorbing material in the interior of the cross member, thus reacting very favorably on the acoustical properties of a room, in view of the regular grid construction. Of course, this is true only in those cases where the cover elements are placed over,

rather than under, the frame construction. In such a case, the cross members may be made of perforated material in order to be able to utilize the. acoustical effects of the inner material. Also, it is possible to ventilate the room through the cross members.

Another possible application of the cross members is that, on the outside of the legs of the U-shaped profile, provision may be made for securing luminescent bodies at a point which is the same for several cross members. Here, for example, sockets for luminescent lamps may be provided, the lamps being mounted between individual cross members. Thus, it becomes possible, in a simple manner, to provide very uniform illumination for rooms, without supplementary hanging devices, when rooms are equipped with a false ceiling using the structural unit according to the present invention.

The connecting members may be equipped on the upper side with bearing surfaces which extend into the respective cross members. On these bearing surfaces there may be mounted elements for fastening lighting lines or ventilation lines, so that a completed frame construction, with cross members only partly filled, can readily be used as a bearer of installation lines of the most diversified types. It is possible, because of the uniform distribution of the frame construction, to bring the installation lines to every connecting element, so that, for example, in place of a cap-like cover, a fireextinguishing element, a smoke alarm, a loudspeaker for announcements, an emergency light, a panic direction indicator, an illuminated direction sign or a connection for a light switch, or other elements may be mounted.

DESCRIPTION OF THE DRAWINGS An embodiment of a structural unit according to the invention is described below, in the light of the drawings of a frame construction, upon which the cover elements are to be laid to form a false ceiling, and in which:

FIG. 1 is a perspective view of a part of the frame construction of the present invention;

FIG. 2 is a perspective view of a junction element to which the cross members of the present invention are connected;

FIG. 3 is a cross section through a junction element with two connected cross members taken substantially at line 3-3 of FIG. 4, and

FIG. 4 is a horizontal cross section through a junction element, with four attached cross members, taken substantially at line 4-4 of FIG. 3.

DESCRIPTION OF A PREFERRED EMBODIMENT FIG. 1 shows a frame construction with quadangular frame elements, shown perspectively, constructed with a structural unit according to the present invention. This construction preferably comprises cross members 10, I1, 121 and 13 which are filled with sound-absorbing material 14 and which open upward, since they have a U-shaped profile. The cross members 10, ll, 12 and 13 are suspended from a ceiling at their junction points, by means of hangers 24. It is evident from FIG. 1 that the uniform lay-out of the construction makes possible the suspension of every junction point, so that a uniformly suspended false ceiling is formed when cover elements 22 are placed on the cross members. Between the individual cross members lamps, for example, luminescent lamps l8 and 19, may be provided which are fastened to the sides of certain cross members by means of sockets 20. These lamps may be so disposed that they are secured only to those cross members which run in the same direction, so that the lamps are arranged parallel to the cross members perpendicular thereto. Thus, for example, luminescent lamp 18 is parallel to cross member 12 and perpendicular to cross member 11 to which it is attached.

FIG. 2 shows a junction point of four cross members for the framework shown in FIG. 1, perspectively viewed obliquely from below, the cross members not being shown at their full length. It is evident that, in the region of the junction point, the four cross members 10, ll, 12 and 13 are joined together at right angles to one another and that there is a cover 15 which is applied from below to the connectingelement so that the connecting element is not visible in FIG. 2. Furthermore, one may recognize the lamp sockets on

cross members

10 and 11, used to fasten the luminescent lamps l6, 17, 18 and 19, parallel to

Cross members

12 and 13. These sockets 20 may be provided with rotary sleeves 21, hemi-cylindrical in form, which, after insertion of a lamp, are turned in such a manner that the socket itself 20 cannot be seen from below. Because cross member 12 is shown in section, one may recognize the tiller of soundabsorbing material 14. It is evident from the drawing that the cross members may be made of perforated material, for example, perforated sheet metal and that the plane of their base surfaces coincides with the plane of the surface of the covering element 15. It is apparent that in the cover element 15, the previously mentioned devices for protection or lighting the room, signal devices, etc. may be provided.

FIG. 3 shows a vertical section through a connecting element, to which

cross members

10, 11 and 13 and the member 12 (not visible here) are joined. Essentially this connecting element consists of a supporting member 29, a bracket 23 pivoted thereon, and suspension means fastened to the bracket 23. The suspension means comprises a hanger 24 which is threaded at its lower end 25 and which engages a nut 25, mounted pivotally to the bracket 23 with the cover 15 removed, a tool may be inserted through the connecting element from below and applied to the nut 26, so that by turning the nut the height of the connecting element on the hanger 24 may be varied. The bracket 23 is fastened to the supporting member 29 by means of

rivets

27 and 28, extending through

upturned flanges

294 and 295 of the supporting members. The range of tilt of the bracket 23 on the supporting member 29 afforded by the

rivets

27 and 28 can be relatively limited for here it is merely necessary to adjust any obliquity which might result from minor inaccuracies in the points of suspension of the hangers 24 in the ceiling.

The supporting member 29 further comprises a horizontal bearing surface and

peripheral flanges

290 and 291 and 293 used for attaching the

cross members

10 and 11 to the supporting member.

The

cross members

10, 11 and 13 are provided with connecting

members

30, 31 and 33, which, for example, may be produced from a plastic by an injection molding process. These

members

30, 31 and 33, when

cross members

10, 11 and 13 are mounted, are so disposed that their front faces are opposite the connecting

flanges

290, 291 and 293. It is also evident that they are formed with edge guides 302, 312 and 332, so that the connecting

flanges

290, 291 and 293 are set between these edge guides 302, 312 and 332 and the faces of the connecting

members

30, 31 and 33. On the upper side of the connecting

members

30 and 31, there are arms 32 and 37 which are formed with

guide slots

33, 34 and 38, 39. These arms 32 and 37 may be'displaced on

pins

34, 36 and 40, 41 in such a way that, when cross members l0 and 11 are in the disassembled position, the arms are inwardly of the ends of the cross members, while, in the assembled position of the

cross members

10 and 11, they are positioned outwardly of the ends of the

cross members

10 and 11. Of course, arms of this kind are also provided for cross members 12 (FIG. 4) and 13. The arms 32 and 37, in the assembled position shown in FIG. 3, rest with their outer ends on the horizontal bearing surface of the supporting member 29.

This representations makes evident the simple manner of mounting the cross members at the respective connecting points. The cross members may be lifted up from below in such a manner that a suspended connecting element, with its connecting

flanges

290, 291 and 293 as shown in FIG. 3, enters between the respective edge guides 302, 312 and 332 and the corresponding face of a connecting

member

30, 31 and 33 so that as a result the connecting

flanges

290, 291 and 293 are, to a certain extent, pushed into these

guides

302, 312, and 332. As shown in FIG. 3, the position of the connecting flanges with respect to the frontal faces is shown in section for

cross members

10 and 11, and for cross member 13 in lateral view. Thus the connecting flange 293 bears against the face of the connecting member 33 and is held between that face and its edge guides 332. The arms 32 and 37 are moved outwardly to rest upon the bearing surface of the supporting member 29.

While the cross members l0, ll, 12 and 13 have been shown as being lifted into place with a suitable rearrangement of the connecting

flanges

290, 291 and 293 it would also be possible to lower the cross members into place.

Near their lower edges the faces of the connecting

members

30, 31 and 33 are provided with guide and

detent elements

311, 330 and 331. A covering cap 15 with

sidewalls

151 and 154 and 152 and 153 (FIG. 4) may be inserted into these guide and

detent elements

311, 330 and 331. The edges of the

sidewalls

151, 152, 153 and 154 are fashioned so that their lengths correspond to the detents in the faces of connecting

members

30, 31, 32 and 33, so that the cap 15 which is provided with peripheral beads can be inserted from below into a connecting element and engage it. Preferably the cap 15 is made of plastic material so that, when it is gently compressed, it can be removed by taking its edges out of the corresponding slots and pulled off downward.

FIG. 3 shows the cap partly broken away, so that the cross member 13 behind it, with its lower part, becomes clear. The upper ends of the legs of the U- shaped profile of cross member 13 may be recognized at the level of the bracket 23. Because of the break in the drawing, a retaining slot 330 in the face of connecting member 33 becomes visible. The

sidewalls

151, 152 and 153 and 154 of the cap 15 also are attached by means of angle clips 301, 311, 321 and 331 to the faces of the connecting

members

30, 31, 32 and 33. Angle clips 311 and 331 may be recognized in FIG. 3.

FIG. 3 illustrates the possibility of mounting

installation elements

42, 43 and 44 on the upper bearing surface of the connecting member 30. Similarly such elements may also be mounted on connecting member 31. Thus it is possible to place installation lines inside the cross members, over the sound-absorbing material 14. These lines may pass through the corresponding connecting element into the region of the cover cap in which case an installation device may be used in place of the cap 15.

The vertical section shown in FIG. 3 is taken along line 33 of FIG. 4, so that it is evident that different planes were used for the sections of connecting

members

30 and 31, in order to better show the nature of the guide and detent elements for the cover cap 15.

FIG. 4 shows a horizontal section through the four

interconnected cross members

10, 11, 12 and 13, according to line 4-4 of FIG. 3. This section passes through the device on a plane which runs directly under the upper bearing surface of the connecting

members

30, 31, 32 and 33 and thus shows the nature of the edge guides 302, 312, 322 and 332. FIG. 4 also makes evident the symmetrical arrangement of the

cross members

10, 11, 12 and 13 with respect to the junction point. Also, this view was selected so as to show the assembled state of the

cross members

10, 11, 12, and 13 while at the same time, for the sake of clarity, the inserted connecting flanges were omitted, thus disclosing the fastening elements for cover 15 in plan view. This cover is inserted from below with its four

sidewalls

151, 152, 153 and 154 into the device formed by the connecting members. The

sidewalls

151, 152, 153 and 154, on the one hand, are mounted with their peripheral beads in the slots described in connection with FIG. 3 and, on the other hand. they are lodged beneath the angle clips 301, 311, 321 and 331.

FIG. 4 illustrates the construction of the connecting

members

30, 31, 32 and 33, inside the respective cross members 10, ll, 12 and 13. The connecting members have, respectively. a mounting

surface

305, 315, 325, 335 on the inner side of the legs of the U-shaped profiles of a cross member l0, l1, l2 and 13. These mounting surfaces extend into

guide members

306, 316, 326 and 336, which converge slightly, pair-wise. thus facilitating the insertion of the respective connecting

member

30, 31, 32, 33 into the cross members 10, l1, l2 and 13. The connecting

members

30, 31, 32, 33 are so fashioned that, when interconnected. they fit together accurately along their edges. For that purpose, they are designed with connecting edges of varying length. Thus, for example, connecting member 30 has connecting

edges

303, 304 which differ in length, and corresponding

edges

313, 314, 323, 324, 333, 334 are provided on the other connecting

members

31, 32 and 33. In this way an assembly is formed, in which the connecting

members

30, 31, 32 and 33 bear against one another without chance of error and form acceptable closed edges with one another.

FIG. 4 also shows the edge guides 302, 312, 322 and 332 which face the respective faces of the connecting

members

30, 31, 32 and 33. The mounting surfaces of the connecting

members

30, 31, 32 and 33 are extended in the direction of the point of connection and on the thus formed connecting

edges

303, 304, 313, 314, 323, 324, 333 and 334 the guide edges 302, 312, 322 and 332 are formed, all of these being made evident for all connecting

members

30, 31, 32, 33.

The two

cross members

10 and 11 preferably have lamp sockets 30 for luminescent tubular lamps l6, 17, 18 and 19, on their outer sides. These sockets 20 may be fastened by means of screws, rivets etc to the outsides of the

cross members

10 and 11. Likewise, sockets for luminescent lamps may be mounted in another plane on

cross members

12 and 13.

It is apparent that a means for providing a grid-like framework for a false ceiling has been described in which the ceiling can be a rectangular, triangular or any other preferred geometric design. All that is necessary to accomplish this is to provide connecting elements having an appropriate number of sides and cross members of an appropriate length.

Although several preferred embodiments of the present invention have been described, it is apparent that other modifications can be made without departing from the scope of the present invention as expressed by the appended claims.

We claim:

1. A structural unit for a frame construction, mounted suspended in rooms and consisting of horizontal cross members, disposed at angles to one another and brought together at connecting points, used to support a false ceiling, comprising a connecting member provided at the two ends of the cross members, with frontal faces perpendicular to the longitudinal direction of the cross members, connecting elements disposed at the points of connection, each with one hanger and a number of connecting flanges, vertical in the suspended state, corresponding to the number of connecting members to be joined together frame-wise, edge guides provided on the faces of the connecting members and forming guides for the insertion of the connecting flange against the respective face and arms provided on each connecting member, movable outwardly beyond the connecting member in the lengthwise direction of the cross member when the respective connecting flange has been pushed into the position of locking with the corresponding connecting element to thereby mount the cross members to the connecting elements.

2. A structural unit as defined in claim 1, and in which each connecting element has a bearing surface horizontal in the suspended state to support the arms of the attached connecting members and on the periphery of which the connecting flanges are provided.

3. A structural unit as defined in claim 1 and in which the cross members are open along one lengthwise side, with a U-shaped profile.

4. A structural unit as defined in claim 2 and in which the connecting flanges extend from the bearing surface away from the hanger and in which each connecting member is provided with the arm on its edge which is parallel to the open side of the U-profile and nearest thereto.

5. A structural unit as defined in claim 4, and in which the arm is fastened to the connecting member by means of a sliding guide.

6. A structural unit as defined in claim 1 and in which the hanger is adjustable for length.

7. A structural unit as defined in claim 6 and in which the hanger is a threaded round rod provided with a loop, and which is mounted in a rotary threaded guide disposed on a supporting bracket the hanger being pivotal at points near the periphery of the bearing surface and being aligned with the center of a central recess in the bearing surface.

8. A structural unit as defined in claim 3 in which each connecting member. near that edge which is associated with the base of the U-shaped profile, is fashioned with edge guide and detent elements on its frontal surface, cover elements mounted in place by said edge guide and detent elements.

9. A structural unit as defined in claim 8 said cover elements having sidewalls and in which the distance of the edge guide and detent elements from the base of the U-shaped profile corresponds substantially to the height of the respective sidewall of the cover element.

10. A structural unit as defined in claim 9 and in which the respective sidewall of the cover element has an outer bead along its rim and retaining slots of appropriate dimensions are provided in the faces of the connecting members.

11. A structural unit as defined in claim 10 and including angle clips on the faces of the connecting members which form an edge support for the rim of the respective sidewall with the face.

12. A structural unit as defined in claim 1 and in which the cross members are filled with soundabsorbing material and are made of perforated material.

13. A structural unit as defined in claim 3 and in which the connecting members are not as high as the U-shaped profiles and are fashioned with a bearing surface, disposed at right angles to the legs of the U- shaped profile and extending into the respective cross member.

14. A structural unit as defined in claim 3 and in which the connecting members are fashioned with mounting surfaces which bear against the inner side of the leg of the U-shaped profile.

15. A structural unit as defined in claim 3 and in which the cross members are equipped with means of attachment for luminescent bodies at a predetermined point, the same for several cross members on the outside of the legs of the U-shaped profile.

' v UNITED STATES PATENT OFFICE CERTIFICATE CORRECTION Patent No. 3,831,328 Dated August 27, 1974 InVentor(s) Hons Mohr, et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

column 6, line 1, change "34" to --35- line 3, after "arms" insert --32 and 37- line 11, change "representations" to -representation-- Column 7, line 36, delete "members" and insert -elements-- line 62, delete "30" and insert --20-- Signed and sealed this 19th day of November 1974.

' (SEAL) Attest I a McCOY M. GIBSON JR. C.' MARSHALL DANN Attesting Officer Commissioner of Patents FORM po'wso v I u'scoMM-Dc ooa7o-pe9 i ".5. GOVERNMENT PRlNTING OFFICE 9'9 -3-33.

Claims

8. A structural unit as defined in claim 3 in which each connecting member, near that edge which is associated with the base of the U-shaped profile, is fashioned with edge guide and detent elements on its frontal surface, cover elements mounted in place by said edge guide and detent elements.

12. A structural unit as defined in claim 1 and in which the cross members are filled with sound-absorbing material and are made of perforated material.

13. A structural unit as defined in claim 3 and in which the connecting members are not as high as the U-shaped profiles and are fashioned with a bearing surface, disposed at right angles to the legs of the U-shaped profile and extending into the respective cross member.