US 3745736 A
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United States Patent [1 1 Fischer et al.
[ COMPOSITE WALL CONSTRUCTION  Assignee: Artur Fischer, Tumlingen, Germany  Filed: Jan. 22, 1971  Appl. No.: 108,984
Related US. Application Data  Continuation-impart of Ser. No. 816,702, April 16,
- 1969, abandoned.
30 Foreign Application Priority Data [451 July 17, 1973 1,593,297 7/1926 Gilmer 52/311 FOREIGN PATENTS OR APPLICATIONS 1,540,479 8/1968 France 52/211 745,788 2/1956 Great Britain 85/DIG. 2
Primary Examiner-John E. Murtagh Attorney'-Michael S. Striker 57] ABSTRACT A supported element overlies a support element. The support element is provided with at least one groove of undercut configuration and the supported element is provided with one or more male coupling projections which are receivable with a snap action in this groove and undergo elastic deflection so as to enter the groove. To reducefriction, facilitate such elastic deflection, and thus facilitate snap-action introduction into the groove, the coupling projections engage the groove only with line contact and the surface of the supported element which faces the support element is provided with a depression or recess overlying the groove when the two elements are connected, with the coupling projection or projections extending from the bottom of this recess outwardly beyond the surface of the supported element.
12 Claims, 4 Drawing Figures COMPOSITE WALL CONSTRUCTION CROSS-REFERENCE TO RELATED APPLICATION This is a continuation-in-part of our earlier application, filed on Apr. 16, 1969 under Ser. No. 816,702 and entitled Composite Wall Construction, now abandoned.
BACKGROUND OF THE INVENTION The present invention relates generally to a composite wall construction, and more particularly to a wall construction utilizing cladding elements. Still more specifically the present invention relates to such a composite wall construction which can be used to particular advantage in toy erecting sets, although it is not to be considered limited to this application.
It is already known to provide support elements, such as walls which may be of unitary construction or which may be composed of a plurality of individual elements, with cladding elements. The reasons for this are manifold and may be governed by a desire or necessity to cover gaps, to generally enhance the aesthetic appearance-as by utilizing cladding elements of particular materials, particular appearance or the likeor for a variety of other reasons. Of course, the cladding elements must be connected with the support element or elements and for this reason various different connecting arrangements have become known. Thus it is for instance known to provide the supporting elements or element, hereafter referred to for the sake of convenience as supporting element, with grooves at their exposed surfaces whereas the cladding elements, hereafter for the sake of convenience identified as supported elements, are provided with projections which are receivable in these grooves. It is known that the grooves may have rectangular or quadratic cross-section and that the projections may be so configurated that they can be pressed into the grooves while undergoing elastic deformation, so as to be frictionally retained in the grooves. On the other hand, it is also known to provide the grooves with an undercut cross-sectional configuration and to complementarily configurate the projections, with the latter being introduced into the grooves lengthwise from an open end of the latter.
For various reasons the configuration of the grooves in such a manner that they are not of undercut crosssection, with the projections being frictionally received in them, has not been found very satisfactory. On the other hand, to use undercut grooves into which undercut projections must be inserted from an open end of the grooves is not always very practical, either, because frequently the open ends of the grooves are not accessible when the supported elements are to be connected to the support elements.
For this reason yet a further solution which has become known is to provide the grooves of undercut cross-sectional configuration, and to so configurate the projections that they can be snapped into the grooves transversely to the elongation of the latter under elastic deformation. This eliminates the need for having access to open ends of the grooves.
However, both in the latter type of construction where the projections are snapped into the grooves transversely of the elongation of the latter, and in the type of construction where they are introduced into the open ends of the grooves, the projections must undergo elastic deformation. ln some cases the deflection or deformation may last only while the projection is introduced into the groove and, once having entered through the narrowest portion of the groove, the projection can return to its original state because it is relieved of the elastic deflection. in other cases the elastic deflection remains as long as the projection remains in the groove. The important point to remember is that elastic deflection will be present, regardless of the other circumstances and the specific type of construction which is involved. That being the case it is evident that the elastic deflection must be facilitated as much as possible. This, however, is difficult because the juxtaposed surfaces of the support element and the supported element abut against one another so that the elastic deflection or deformation of the projections must take place in or substantially in the plane of the abutting surface of the supported element. Evidently, the projections are stiffest and most resistant to such deflection at this point where they project from the abutment surface and they therefore either cannot be sufliciently deflected at all, or their deflection can be accomplished only against very significant resistance. Neither situation is desirable, as will be appreciated.
SUMMARY OF THE INVENTION 7 It is the general object of the present invention to overcome this disadvantage.
More particularly it is an object of the present invention to provide a composite wall construction wherein this disadvantage is avoided.
Briefly stated, one feature of our invention resides in the provision of a wall structure, wherein a supported cladding element overlies a support element, and wherein the support element is provided with at least one groove in which male coupling means provided on the supported element are receivable with a snap action in response to undergoing elastic deflection. According to our invention the supported element is provided with deflection-facilitating means for facilitating the elastic deflection of the male coupling means to thereby correspondingly facilitate snap-action introduction of the male coupling means into the groove.
The deflection-facilitating means is, in accordance with the invention, provided in the form of a depression or recess associated with the coupling means, with the latter projecting from the bottom wall of the depression outwardly beyond the abutment surface of the supported element. In this manner the root or base of the male coupling means or male coupling projection is spaced inwardly from the abutment surface of the supported element so that there are located in the plane of the abutment face of the supported element-in which plane the coupling means must primarily undergo the elastic deflection-will be portions which are significantly less resistant to such deflection than the base of the coupling means or projection.
Thus, even if the coupling projections extend only to a small distance beyond the abutment surface of the supported element, it is possible to obtain sufficient elasticity for the coupling projection in the region of the plane of the abutment surface of the supported element to enable snap-action introduction of the coupling projections into grooves even if the same are undercut and, in fact, even if the grooves are undercut very deeply.
Furthermore, we provide for our coupling projection or projections to engage with a corresponding groove or grooves in such a manner that there is only linecontact between them, rather than surface or area contact. This substantially reduces friction during insertion and withdrawal of the projection or projections and thus also furthers the objects and purposes of our present invention.
The construction according to the present invention is advantageous not only from the point of view of erecting a composite wall structure but also from the point of view of manufacturing, at least of manufacturing the supported element. It is evident that if the coupling projections on the supported element are undercut, and if the supported element with its coupling projections is to be made of synthetic plastic material as is frequently the case, the element may be made by resorting to an injection molding technique. Ordinarily this would require the use of complicated molds because of the undercut configuration of the male coupling projections. Without this it would be difficult if not impossible to remove the completed supported element from the mold. However, because of the significantly enhanced ability of the male coupling projections to undergo elastic deflection, as per the present invention, a rather simple mold can be utilized because the element can be removed by merely withdrawing it from the mold with the projection undergoing elastic deflection during such withdrawal.
' Of course the supported element may be manufactured in various different sizes and configurations. It is feasible to construct it as a cladding element for wall constructions of buildings or the like, and it is equally feasible to construct it as a cladding element for wall constructions erected by connecting a plurality of building blocks of an erecting set such as is used by children.
Customarily, where the use of undercut grooves is concerned into which the coupling projections are to be introduced, the coupling projections are so configurated that once introduced they will fill or substantially fill the entire cross-sectional area of the groove. However, this is frequently not practical because of improper adherence to manufacturing tolerances or other factors which have as a result that the coupling projections are too large or the grooves too small in crosssectional area so that the coupling projections cannot be introduced at all, or only with difficulties, and cannot be shifted longitudinally of the groove or, if it is possible to do so, can be shifted only with great difficulty. On the other hand, the tolerance variations may go to the other extreme so that the coupling projections will not be received tightly in the grooves and the supported element will not be tightly and immovably secured on the support element. In accordance with the present invention these disadvantages can be overcome by making the coupling projections of two-part construction with the two parts extending transversely away from one another so that, if both parts are associated with a single groove, each part will press against one side of the groove interiorly thereof. Advantageously the narrowest cross-section of the groove, that is where the groove opens to the exposed surface of the support element in which the groove is provided, will be somewhat greater than the corresponding transverse dimension of the coupling projection measured against the two parts thereof at that portion which will be located within the confines of this narrowest part of the groove. This construction is possible for the portions of the coupling projections to elastically adapt themselves to the configurations of the groove, and at the same time permits greater latitude in the manufacturing tolerances while assuring tight connection between the supported element and the support element. The difference in the dimensions of the narrowest portion of the groove versus those of the coupling projection, or rather the part of the coupling projection which is received within the confines of the narrowest portion, assures that the coupling projection can be readily inserted into the groove. Frictional resistance to such insertion, and also to sliding movement lengthwise of the groove, is further decreased by so configurating the portions of the coupling projections which are located within the groove that the parts which abut against the inner side of the groove will only have line-contact therewith, as mentioned before. Thus, the portions which abut the groove where the latter is undercut may have radii of curvature which are smaller than those of the wall bounding the groove. This is one way of providing the desired line contact and reduces frictional resistance.
If the grooves are of substantially circular crosssectional configuration, then the invention provides that the areas of contact at which the coupling projections engage the interior side walls bounding the groove will be in the outer half of the groove, as measured in direction normal to the surface in which the groove is provided. This assures that the supported element is tightly retained in abutment with the supporting sup port element.
The leading edges of the coupling projection, that is leading in the sense of introduction into the grooves, can be rearwardly bevelled for facilitating their snapaction introduction into the grooves. This is particularly advantageous if the coupling projections cannot be introduced through an open end of the groove.
The construction according to the present invention is particularly advantageous for use in conjunction with erecting kits consisting of a plurality of building blocks which are provided undercut grooves and undercut male coupling heads receivable in these grooves so that the building blocks can be connected. The supported element in this instance can serve as a cladding element or it can serve as a base element on which structures may be erected. In such a use the present invention is particularly advantageous because it is especially important for children that the connections may be effected and terminated readily and without the use of great force. Also, once effected it is frequently necessary that the connected elements be shifted relative to one another and this should be accomplished readily so as not to overtax the strength of a child. The present invention is particularly effective in overcoming the socalled stick-slip-efi'ect. This effect results from the different values of inertial friction and sliding friction, it being understood that the child must first overcome the inertial friction which is greater than the friction resulting during the sliding movement. Because the changeover from inertial friction to sliding friction is not immediately noticed by the child the element may be shifted through larger distances than is desired because the larger pressure needed for overcoming the inertial friction is not quickly enough terminated.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a somewhat diagrammatic perspective view of a supported element according to the present invention;
FIG. 2 is a fragmentary sectional elevation illustrating a supported element connected with a support element; a a
FIG. 3 is a view similar'to FIG. 2 but illustrating a further embodiment of the invention; and
FIG. 4 is a view similar to FIG. 2 but illustrating a fur-' ther embodiment in a partially sectioned fragmentary elevation on an enlarged scale.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing firstly now the embodiment illustrated'in- FIGS, 1 and 2 it will be seen that reference numeral 1 identifies a supported plate-shaped element having an abutment face 2 which in accordance with the present invention is provided with at least one depression or recess 3. Located within this depression or recess 3 and projecting from the bottom wall thereof outwardly beyond the abutment face 2 of the element 1, is male coupling means here illustrated in form of two coupling portion of a wall, a building block, a building block which together with others to which it can be con nected will constitute a wall, or the like. In any case the element 5 is provided with a groove 7, here shown to be of undercut configuration in cross-section, and the coupling projections 4 of the element 1 are received in this groove 7. They are received with a snap action and it will be appreciated that, when they are pressed into the groove 7 in direction transversely .to its elongation, they will be inwardly deflected towards one another, thus undergoing elastic deflection or deformation, until they have passed beyond the narrowest point of the groove 7 at which time they can again move outwardly away from one another to or substantially to their original positions as illustrated in FIG. 1. They then abut the wall bounding the inside of the groove 7, as illustrated in FlG. 2. Note should be taken that each projection 4 has a surface portion which faces outwardly and may be considered to be composed of two sections which include with one another an angle which, in FIGS. 1 and 2 as well as in FIG. 3, is a new angle. Similarly, the wall bounding the inside of groove 7 has at each lateral side two surface portions each of which is also composed of two sections which define with one another a different angle. As a result, there is line-contact engagement between the projections 4 and groove 7, as shown.
The enhanced elastic deflection of the coupling projections 4 which, in conjunction with the reduced friction resulting from line-contact, makes this ready introduction into the groove 7 possible, is obtained by the provision of the recess or depression 3 in the abutment face 2 of the element 1, as a result of which the base or root of each of the coupling projections 4 is located inwardly spaced from the abutment face 2, as clearly visible in FIG. 2.
The embodiment illustrated in FIG. 3 differs from that of FIG. 2 in that the element which constitutes the support element, is here identified with reference numeral 6 and is provided with two of the undercut grooves 7 which are transversely spaced and extend in parallelism with one another. The supported element is again of plate-shaped configuration and identified with reference numeral 1, its abutment face being identified with reference numeral 2, Unlike the element 1 in FIG. 1, however, the one shown in FIG. 3 is provided with two of the recesses 3 each of which overlies one of the grooves 7 when the elements 1 and 6 are connected as shown in FIG. 3. In the embodiment of FIG. 3, also, each of the recesses 3 is provided with only of the coupling projections 4 and they are inclined towards one another and are also undercut on the sides which face each other. This is clearly shown in FIG. 3 and it will be appreciated that because the coupling projections 4 are inclined in the illustratedmanner, and are undercut on the sides facing one another, they will abut in their respective grooves 7 with line-contact against that side of the interior wall bounding the groove which faces the respective other groove, so that the element 1 is firmly and reliably connected to the element 6, as shown. or course, during introduction into their respective grooves, the coupling projections 4 are elastically deflected in direction away from one another, rather than towards one another as in FIG. 2.
Coming, finally, to the embodiment illustrated in FIG. 4, it will be seen that here the supported element is again identified with reference numeral 1 and has a recess 3 provided in its abutment face 2. The support element is identified with reference numeral 5 and is again provided with an undercut groove 7 similar to the one shown in FIG. 2. The narrowest portions of the groove are identified by the edge faces 8 and 9 bounding the inlet to the groove 7 and the distance between them is greater, as clearly shown in FIG. 4, than the distance measured in the same plane across the two coupling projections 4 which are illustrated.
It is also shown that the coupling projections 4 abut against the interior wall bounding the groove 7 at the locaitons l0 and 11. At these locations the coupling projections 4 are arcuately curved with the respective curvature having a radius of curvature which is smaller than the corresponding radius of curvature of the abutted portions 10 and 11, respectively. Thus, the contact between the coupling projections 4 and the portions 10 and l 1, respectively, is again a line contact and the friction is correspondingly decreased.
In the illustrated embodiment the groove 7 is of substantially circular cross-sectional configuration and its midpoint-that is half the depth as measured from the exposed surface of the support element 5-is identified with reference numeral 12. In accordance with the invention it will be seen that the contact between the coupling projections 4 and the portions 10 and 11, respectively, is located within the outer half of this distance, that is between the location 12 and the exposed surface of the support element 5.
To facilitate introduction of the coupling projections 4 in direction transversely to the elongation of the groove 7 and into the latter, the leading surfaces 13 and 14 of the coupling projections 4 are bevelled so as to taper towards one another and their ends 15 and 16 are spaced from one another by a distance which is smaller than the distance between the surfaces 8 and 9.
It will be appreciated that, whereas in FIG. 4 the coupling projections 4, 4 are located transversely opposite one another, it is also possible to have them offset or staggered with reference to one another longitudinally of the extension of the groove 7. It is equally clear that the two coupling projections may be replaced with four or more, and that if there are four provided they can be so arranged that they define with one another a right angle and constitute a stud composed of four symmetrically arranged portions. Similarly, any desired number of the recesses 3 and the coupling projections may be provided on any one element 1 without departing in any way from the concept of the present invention.
While this has not been particularly shown in the drawing, it is emphasized that any of the supported elements as well as any of the support elements may consist of synthetic plastic material, or of any other material suitable for the purpose. Also it will be clear from the drawing that in all embodiments line contact exists not only when the snap-action connection is in existence, but during the entire insertion and removal of the coupling projections.
It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.
While the invention has been illustrated and described as embodied in a composite wall construction, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:
1. In a wall structure, in combination, a support element having a first surface provided with undercut groove means; a supported cladding element having a second surface overlying said first surface; elastically deflectable male coupling means provided on said second surface and receivable in and withdrawable from said groove means with a snap action; first and second engaging portions on said male coupling means and said groove means, respectively, one of said first and second engaging portions having edges extending longitudinally of said groove means and engaging the other of said first and second engaging portions with only line contact at all times so as to provide minimum friction during insertion and withdrawal of said male coupling means; and deflection-facilitating means on said supported cladding element for facilitating elastic deflection of said male coupling means to thereby correspondingly facilitate snap-action insertion of the same into, and withdrawal thereof from, said undercut groove means.
2. In a wall structure as defined in claim 1, said male coupling means and said groove means each having at least one of said engaging portions; and wherein each of said engaging portions is composed of at least two sections with the sections of one of said engaging portions being inclined to one another at a first angle and the sections of the other of said engaging portions being inclined to one another at a second angle which is different from said first angle.
3. In a wall structure as defined in claim 2, wherein one of said angles approaches zero.
4. In a wall structure as defined in claim 1, wherein said groove means is undercut in direction away from said first surface, and said male coupling means is undercut in direction towards said second surface.
5. In a wall structure as defined in claim 2, wherein said deflection-facilitating means comprises recess means provided in said second surface and being bounded by a bottom wall and transversely spaced side walls, said male coupling means projecting from said bottom wall spaced from said side walls and outwardly beyond said second surface.
6. In a wall structure as defined in claim 5, wherein said male coupling means comprises two elastically deflectable male coupling portions diverging away from one another in direction outwardly from said recess means and each having one of said engaging portions; and wherein said undercut groove means comprises a slot extending inwardly from said first surface and bounded by a pair of transversely spaced lips each having an additional one of said surface portions.
7. In a wall sturcture as defined in claim 6, wherein said groove means is elongated in a predetermined direction, and wherein said male coupling portions and said recess means are also elongated in said predetermined direction.
8. In a wall structure as defined in claim 1, said groove means having a predetermined depth in direction inwardly from said first surface; and wherein said cooperating engaging portions engage one another at locations which are inwardly spaced from said first surface by a distance which corresponds to less than half of said predetermined depth.
9. In a wall structure as defined in claim 1, said male coupling means having free edge portions remote from said second surface and bevelled in directions inclined towards the same so as to facilitate insertion of said male coupling means into said groove means.
10. In a wall structure as defined in claim 1, said groove means comprising a pair of transversely spaced parallel undercut grooves; and wherein said male coupling means comprises a pair of transversely spaced elastically deflectable male coupling portions each receivable with a snap action in one of said grooves.
11. In a wall structure, in combination, a support element having a first surface provided with at least one arcuately undercut groove bounded by an inner peripheral surface having first radii of curvature; a supported cladding element having a second surface overlying said first surface; male coupling means provided on said second surface and receivable in said groove with a snap action, said coupling means including two elastically deflectable parallel male coupling portions diverging away from one another and having abutment sections which abut against said inner peripheral surface bounding said groove and which have second radii of curvature different from said first radii of said inner peripheral surface against which said sections abut; and deflection-facilitating means on said supported element for facilitating elastic deflection of said male coupling portions to thereby correspondingly facilitate their snap-action introduction into said groove.
12. In a wall structure as defined in claim 1 1, wherein said second radii of curvature are smaller than said first radii.
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