A FASTENING DEVICE FOR THE RELEASABLE FASTENING OF A FLAT STRUCTURAL MEMBER TO A SUPPORT STRUCTURE

The present invention relates to a fastener to detachably affix a flat component to a support in the manner defined in claim 1.

Many applications require affixing a component, in particular a planar component illustratively made of sheetmetal, to a support. Many plastic fasteners have become known in this respect. Frequently there is the requirement also to detach again the component in simple manner from the fastener. Illustratively this applies to the so-called automobile door sills.

It is already known to mount such a door sill on a support using plastic fasteners, the door sill being held by a head element of the fastener and being affixed to this fastener using a separate locking element. This locking element must be removed to detach the door sill from the fastener. Moreover comparatively high retention force is desired and also simple assembly that should preclude assembly errors.

The objective of the present invention is to create a fastener to detachably affix a flat component to a support, said fastener enabling easy and error-free assembly and furthermore simple dis-assembly. This objective is attained by the features of claim 1.

The affixation sub-assembly of the fastener of the invention comprises an affixation portion and a top portion. The design of the affixation sub-assembly is arbitrary, for instance being a plastic clip that can be locked in an aperture of the support. The top portion comprises first extensions running away from the affixation portion and engaging a hole in the component in a manner that said affixation sub-assembly is held therein irrotationally. The top portion is fitted with two second extensions situated

within the first ones and constituting at the end away from the affixation portion two snap-in segments subtending between them a snap-in slot. A separate locking element comprises a head and a snap-in foot, the latter comprising a longitudinal axis illustratively perpendicular to the said head. This head subtends a lateral size allowing to cover the said hole in the component. The snap-in foot is fitted with two mutually opposite outer first conical faces converging with distance away from the head. For that purpose the first faces are designed to converge toward each other in the direction of the free end of the said snap-in foot whereas the faces near the head merge into a snap-in shoulder. When the snap-in foot enters the snap- in slot, the snap-in shoulders engage from below the snap-in segments and thereby secure the snap-in foot in the top portion of the affixation sub- assembly. The locking element head resting against the opposite side of said component, this component thereby is then affixed to the fastener. The snap-in foot is fitted at two mutually opposite sides with second faces which also converge from the said head toward said free end. Preferably the second conical faces are offset by 90° from the first conical faces. On the other hand the second conical faces run as far as the underside of the head, namely close to this head, but in any event clearly beyond the shoulder faces. Lastly the said head is fitted on the side opposite the snap-in foot with a clearance to allow access to a rotary tool. If using said rotary tool the locking element is rotated for instance by 90° out of the previously assumed locking position, then the second conical faces shall engage the sides of said slot. In this case the snap-in foot is seated like a wedge in the snap-in slot and as a result the locking element shall be automatically expelled from the snap-in slot. Accordingly the locking element may be unlocked merely by being rotated. Thereupon it is easily

removed manually. This design of the invention allows easy assembly and disassembly of said component. The snap-in foot can be seated at high retentive force in the said snap-in slot because this force need not be overcome when the locking element shall be removed, instead only a locking element rotation about its axis being needed.

The locking element head may be relatively flat, for instance being in the form of a slightly bent flange, as a result of which the height of the fastener of the present invention also may be comparatively low.

In one embodiment mode of the present invention, the snap-in foot is fitted at its end away from said head with a stud and the top portion of the affixation sub-assembly is fitted with a recess below and away from the slot, the shoulders of said snap-in foot only engaging underneath the snap-in segments when the stud in turn engages said recess. The snap-in foot can only be locked in the affixation sub-assembly's top portion provided the locking element is centered relative to said recess. Such locking can be detected acoustically by the assembly personnel to prove to them that assembly was successfully completed. In this manner the above embodiment precludes defective assembly.

In another embodiment mode of the present invention, the snap-in slot is widened along some length in its center zone, said length being slightly larger than the maximum width of the snap-in foot in its inserted position. Centered insertion of the snap-in foot already is made easier in this manner.

Various designs are available for the second extensions and the snap-in segments. In one design of the present invention, the extensions are fitted with two mutually parallel webs, the snap-in segments being joined to said webs and running transversely to them. Stop segments of said snap-

in segments run outward beyond said webs and cooperate with upper rest faces of the first extensions in that the stop elements come to rest against the rest faces when the webs and the snap-in segments are temporarily deformed during insertion of the snap-in foot. The tool clearance in the locking element's head may be designed in any appropriate manner. A longitudinal slot for a screwdriver is preferred.

One illustrative embodiment of the present invention is discussed and elucidated below in relation to the appended drawings.

Fig. 1 is a perspective of an affixation sub-assembly of the fastener of the invention,

Fig. 2 is a topview of a locking element of the fastener of the invention,

Fig. 3 is a perspective view from below of the locking element of Fig. 2, Fig. 4 is a section of an assembled affixation sub-assembly of the invention with a locking element before assembly,

Fig. 5 is a view similar to that of Fig. 4 for a partly assembled locking element,

Fig. 6 is a view similar to that of Figs. 4 and 5 when the locking element has been fully assembled,

Fig. 7 is a topview of the affixation sub-assembly of Fig. 1 following assembly to a flat component, and

Fig. 8 is a view similar to that of Fig. 6 during disassembly of the locking element. An affixation sub-assembly 10 as shown in Fig. 1 comprises an affixation portion 12 and a top portion 14. The top portion comprises a hollow stem 16 of which the lower end is fitted with obliquely rising arms 18.

These arms are fitted at their upper, outer ends with a fluting 20. A conical, radial flange 22 runs at the upper end of the stem 16 and is integral with a sealing annulus 24. The above design allows inserting the affixation portion 12 into an aperture of an omitted support, the sealing annulus 24 in the process coming to rest against an associated surface of said support and the fluted element 20 engaging the aperture rim on the opposite side of the support. Such affixation modes already are known per se and do not affect the description below.

Two mutually parallel and spaced-apart webs 26, 28 run above said flange 22 and are fitted with radial extensions 30, 32 at their outside that run upward to the plate elements 34, 36 which they support. The webs 26, 28 are connected to each other by a first cross-web 38 at the level of the flange 28 and higher up by another cross-web 40 fitted with a central recess 42. Mutually parallel and spaced-apart web segments 48, 50 are present above the cross-web 40 and contain integral snap-in segments 52, 54.

As shown in particular in Fig. 1 , the snap-in segments 52, 54 subtend between themselves a continuous slot 56 comprising at its middle an insertion widening 58. This insertion widening 58 is concentric with the recess 43. Centering segments 60, 62 are constituted above the plate segments

34, 38. The segments 60, 62 engage an aperture 64 of an automobile door sill 66 as shown in Figs. 4 through 7 and 8. Fig. 7 indicates that the said aperture is oval as indicated at 68. As a result the affixation sub-assembly 10 is secured against rotation but can be shifted within limits as indicated by the two double arrows. The automobile door sill 66 therefore rests by its underside on the upper faces of the plate segments 34, 36. In order to firmly mount the affixation subassembly 10 on the door sill 66, the invention

provides a locking element 70 which is discussed in further detail in relation to Figs. 2 and 3.

The locking element 70 comprises a head 72 in the form of an approximately oval and slightly conical flange. At its top side, the head 72 is fitted with an elongated screwdriver slit 74. At its underside said head is fitted with a snap-in foot 74. Said foot is approximately centrally integral with the underside of the head 72. Said foot comprises two conical faces 78 situated at opposite sides and converging toward the free end. The snap-in foot 76 is fitted with a stud-like element at its free end. The mutually opposite first faces 78 merge into snap-in shoulders 82 toward said head 72.

Second conical faces 86 are constituted at the snap-in foot 76 and offset by 90° from said first faces and also converge toward the free end of said foot. However said faces 86 extend as far as the head 72, though above the shoulders 82, 84 and being of lesser width. As already mentioned above, Figs. 4 through 6 show the affixation subassembly 10 inserted into the aperture 64 of the automobile door sill 66. The locking element 70 is shown prior to assembly in Fig. 4. The snap-in foot is situated above the said insertion widening 58. The snap-in foot 76 can be inserted through the head 72 into the widening 58, in the course of which, as shown in Fig. 5, the snap-in segments 52, 54 are displaced from one another and the webs 48, 50 are deformed away from each other. In the process, parts of the snap-in segments 52, 54 projecting beyond the webs 48, 50 come to rest against the top side of the extensions 60, 62. As the snap-in foot is inserted farther, the stud 80 enters the recess 52 and then the shoulders 82, 84 engage from below the snap-in segments 52, 54 on both sides of the insertion widening 58. This procedure entails noise and therefore can be sensed by the assembly personnel. The head 72 rests

against the other side of the door sill 66, and as a result the affixation sub- assembly 10 is securely affixed to said door sill 66. Next this door sill can be affixed by means of the affixation portion 12 in an aperture of an omitted support. The door sill henceforth cannot accidentally be removed from the affixation sub-assembly 10 now firmly in place. The force of retention holding the snap-in foot 76 in the affixation sub-assembly 10 is comparatively high.

To loosen the locking element 70, a screw driver is inserted into the slit 74 and said locking element is rotated by 90° as indicated by the arrow 90. As a result the snap-in segments 52, 54 are moved apart (Fig. 8) and the edges of the insertion widening 58 will engage the oppositely situated conical faces 86 acting as a wedge and thereby automatically force the locking element 70 in the direction of the arrow Z. Accordingly the locking element need not be pulled out. Said 90° rotation suffices for disassembly. Thereupon the locking element 70 can be removed manually. As a result the door sill 66 also may be lifted off the affixation subassembly 10.