Fastening element for attaching to a wall

A fastening element for attaching to a wall. The fastening element having a contact element having an adhesive surface and a filling opening via which a flowable adhesive agent is capable of being brought between the adhesive surface and the wall. Positioning elements by which the contact element is capable of being positioned at the wall are arranged at the adhesive surface. The positioning element has a width which is variable in dependence on a spacing from the outlet opening. The width reduces at least sectionally as the spacing from the outlet opening increases and is minimal at a maximum spacing from the outlet opening. Accordingly, the adhesive surface is capable of flowing around the positioning element on the introduction between the wall and the adhesive surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National stage application of International Application No. PCT/EP2014/054351, filed Mar. 6, 2014, which claims priority to EP Application No. 13160082.7, filed Mar. 20, 2013, the contents of each of which is hereby incorporated herein by reference.

BACKGROUND

Field of Invention

The invention relates to a fastening element for attaching to a wall.

Background Information

A fastening element for attaching to a wall is described in U.S. Pat. No. 4,822,656. The fastening element has a holder element in the form of a pin which has an external thread. An object can be fastened to the fastening element and thus to the wall via the holder element. The fastening element moreover has a contact element having an adhesive surface. An adhesive agent is applied to the adhesive surface prior to the attachment to the wall. An installation frame into which the fastening element is inserted is subsequently positioned at the wall by positioning elements in the form of adhesive strips, with there not yet being any contact between the adhesive agent and the wall. The fastening element is then brought into a press-on position within the installation frame in which contact position the adhesive surface together with the adhesive agent is pressed against the wall. The installation frame is removed and disposed of after the hardening of the adhesive agent.

A fastening element for attaching to a wall is described in WO 01/81774 A1 in which no installation frame is required. It likewise has a holder element for holding an object. It has a contact element having an adhesive surface and a rear side and a filling passage which leads from the rear side of the contact element to an outlet opening in the adhesive surface of the contact element. A flowable adhesive agent can be introduced between the adhesive surface and the wall via the filling passage for attaching the fastening element to the wall. The contact element, and thus the fastening element, is positioned at the wall by a positioning element in the form of a double-sided adhesive tape before the introduction of the adhesive element.

WO 01/81774 A1 does not make any statement on the design or shape of the positioning element. Trials have shown that when commercial adhesive strips in rectangular form (if the thickness of the adhesive strip is neglected) are used, an uneven distribution of the adhesive agent between the adhesive surface and the wall arises. This in turn has the result that the adhesive surface, and thus the fastening element, are not ideally fastened to the wall.

SUMMARY

In the light of this, it is in particular the object of the invention to propose a fastening element which can be attached to a wall without the use of an installation frame and which nevertheless allows a very good adhesion to the wall. In accordance with the invention, this object is satisfied by a fastening element having the features described herein.

The fastening element in accordance with the invention for attaching to a wall has a holder element for holding an object, a contact element having an adhesive surface and a rear side and a filling passage which leads from the rear side of the contact element to an outlet opening in the adhesive surface of the contact element. A flowable adhesive agent can be brought between the adhesive surface and the wall via the filling passage. The fastening element moreover has a positioning element by which the contact element can be positioned at the wall. “Positioning” is to be understood in this connection such that the fastening element is positioned and thus (pre-)fastened to the wall before the final attachment at a desired position.

In accordance with the invention, the positioning element has a width which is variable in dependence on a spacing from the outlet opening. The width of the positioning element results from an extent parallel to the adhesive surface and perpendicular to a direction of flow from the outlet opening through a center of area of the positioning element. The width reduces at least sectionally as the spacing from the outlet opening increases and is minimal at a maximum spacing from the outlet opening. The width at the maximum spacing is in this respect minimal at least with respect to the section with reducing width toward the maximum spacing. It is possible that the positioning element also has a smaller width than at the maximum spacing in another section which is closer to the outlet opening.

It is thus achieved that the adhesive agent can flow very easily around the positioning element on the introduction between the wall and the adhesive surface and regions do not result behind the positioning element viewed in the direction of flow into which no or comparatively little adhesive agent arrives. The embodiment of the positioning element in accordance with the invention thus makes it possible that the complete region between the adhesive surface and the wall can be filled uniformly with adhesive agent with the exception of the positioning element and thus an ideal adhesion of the fastening element to the wall is ensured. The quantity of adhesive agent which oozes out unused from the intermediate space between the adhesive surface and the wall is moreover very small due to the easy flowing around of the adhesive agent.

The holder element and the contact element are manufactured from metal or plastic, for example, and are fixedly connected to one another. The connection can be established, for example, by adhesive bonding or by welding, in particular friction welding. It is also possible that the holder element and the contact element are made in one piece. This is in particular advantageous when the elements are composed of plastic. In this case, they can be manufactured using an injection molding process.

A “wall” is to be understood as a surface at which an object, for example a hook, a panel or similar can be fastened. The wall is in particular designed at least regionally as planar. It is, however, possible that the wall is designed as curved. In addition, the wall can also have two or three part surfaces, in particular planar part surfaces, which are arranged at an angle with respect to one another of in particular 90°. The contact element and thus the adhesive surface then in particular have a shape corresponding to the contour of the wall. The adhesive surface can then in particular be made from a first adhesive part surface, a second adhesive part surface and possibly a third adhesive part surface which are arranged at an angle with respect to one another of 90°, for example. The adhesive part surfaces are in particular designed as planar surfaces. Slight differences between the contour of the wall and the shape of the adhesive surface can also be compensated by the adhesive agent. The wall can, for example, be part of a building, of a vehicle or of an aircraft. The wall can in particular be designed as part of an aircraft at which an inner panel is mounted by fastening elements in accordance with the invention.

In the geometrical definition and description of the positioning element, a thickness of the positioning element, that is an extent perpendicular to the adhesive surface, and thus also perpendicular to the wall, is neglected. The positioning element is considered in simplified terms as a two-dimensional surface which is aligned parallel to the wall and to the adhesive surface. The positioning element thus has a center of area which is used for defining the direction of flow. The center of area can as in general be determined by geometrical considerations or by integration. It can also be determined purely mechanically by balancing a homogeneous body with the corresponding shape and constant thickness and density. With axially symmetrical surfaces having at least two axes of symmetry, the center of area lies at the point of intersection of the axes of symmetry.

Reference is also made to the outlet opening in the defining of the direction of flow. In this connection, the outlet opening is only understood as its center, that is its center of area. With a circular outlet opening, this is the center of the cross-sectional surface.

The named rear side of the contact element from which the filling passage leads to the outlet opening is characterized in that it is not part of the adhesive surface and is still accessible after the positioning of the fastening element at the wall. It can, but does not have to be designed as parallel to the adhesive surface.

A two-component adhesive, in particular an epoxy adhesive, can be used as the adhesive agent, for example.

The positioning element in particular adopts a surface portion between 3 and 20%, preferably between 5 and 10%, of the adhesive surface. A very good compromise thus results between the remaining surface which is available for the adhesive agent and thus for the permanent fastening and a holding force of the positioning element after the positioning of the fastening element to the wall and thus on the filling in of the adhesive agent.

In an embodiment of the invention, the positioning element is arranged such that its center of area lies in a range from 20 to 70% of a total flow path of the adhesive agent. The regional indication in this respect is with reference to starting from the outlet opening. A particularly advantageous flowing around of the positioning element and thus a particularly good and uniform of the adhesive agent is thus made possible. A total flow path is to be understood in this respect as the path in the direction of flow from a margin of the outlet opening in the direction of the positioning element up to a margin of the adhesive surface.

In an embodiment of the invention, the positioning element is arranged so that a free flow path of the adhesive which amounts to at least 20% of the total flow path of the adhesive agent results both between the outlet opening in the adhesive surface of the contact element and the positioning element and also between the positioning element and a margin of the adhesive surface of the contact element. This, on the one hand, makes it possible that the adhesive agent can distribute easily after the exiting of the outlet opening and, on the other hand, that the two part flows of the adhesive agent resulting in the flowing around of the positioning element can recombine after the positioning element and so no regions without adhesive agent arise between the adhesive surface and the wall. A particularly good and uniform distribution of the adhesive agent is thus made possible, which results in a particularly stable fixing of the fastening element to the wall.

In an embodiment of the invention, the positioning element has a length which results from an extent in the direction of flow. A ratio of length to maximum width of the positioning element is larger than 1:1. The named ratio is particularly preferably between 2 and 3. A particularly advantageous flowing around of the positioning element is thus made possible.

In an embodiment of the invention, the width of the positioning element first increases starting from a minimal spacing from the outlet opening up to the reaching of a maximum width in order then to reduce again and to be minimal at the maximum spacing from the outlet opening. A particularly advantageous flowing around of the positioning element is thus made possible.

In an embodiment of the invention, the positioning element has at least one axis of symmetry. A longest axis of symmetry includes an angle y of a maximum of 60°, in particular a maximum of 45°, with the direction of flow. Larger angles y would prevent a flowing around of the positioning element.

The positioning element is in particular made as ellipsoid or as diamond-shaped. It can also have a shape which results from two arcs, in particular two arcs of a circle. In this connection, an arc is understood as a line curved in any desired form toward one side. These shapes allow a particularly advantageous flowing around of the positioning element.

In an embodiment of the invention, the positioning element has a thickness between 0.05 and 3.00 mm, in particular between 0.1 and 0.5 mm. A correspondingly thick layer of adhesive agent can thus form between the adhesive surface and the wall, which allows a particularly good fixing of the fastening element to the wall.

In an embodiment of the invention, the positioning element has a pressure sensitive adhesive. A pressure sensitive adhesive is to be understood as an adhesive which remains highly viscous and permanently sticky after application to a carrier material and can then be applied to a substrate by pressure and remains stuck there. The positioning element can, for example, be designed as a double-sided adhesive tape. The positioning element can thus be handled particularly easily. In addition, a starting material with a pressure sensitive adhesive is inexpensive and a wide selection is available on the market. The individual positioning elements can in particular only be covered by a single masking film after the attachment to the adhesive surface. A particularly simple handling is thus possible. In addition, the masking film can have a projecting tab by which the masking film can in particular also be pulled off with gloves.

In an embodiment of the invention, the positioning element is designed as sprayable. The positioning element is then in particular applied to the adhesive surface in that a spray adhesive having a pressure sensitive adhesive is sprayed onto the adhesive surface. To ensure the desired shape of the positioning element, a stencil is in particular used which covers all regions of the adhesive surface except for the region intended for the positioning element. The positioning element can thus be applied very simply and fast and so inexpensively to the adhesive surface. This is in particular advantageous when not only one, but rather a plurality of positioning elements are provided. They can all be applied together in only one workstep. The positioning elements have in particular already been applied to the wall some time before the attachment of the fastening element to the wall and have been covered by a masking film. In this case, in particular only one masking film is used for all positioning elements of an adhesive surface. The fastening element can thus be prepared very fast and simply for the attaching to the wall by pulling off this one masking film.

In an embodiment of the invention, the fastening element has a plurality of positioning elements which are in particular distributed uniformly around the outlet opening. A secure positioning of the fastening element and also a uniform distribution of the adhesive agent is thus made possible.

In an embodiment of the invention, the holder element has a predominantly hollow-cylindrical shape and forms a first part of the filling passage. A particularly simple structure of the fastening element is thus made possible. To hold an object, the holder element in particular has an external thread which can cooperate with a corresponding internal thread of the object. Other holder types are, however, also possible such as a snap-in connection or a click connection.

In an embodiment of the invention, the contact element is designed as a circular disk through whose central axis a second part of the filling passage extends which ends at the outlet opening. This allows a simple and inexpensive structure of the fastening element. In addition, this shape makes it possible that a quantity of adhesive agent which is as small as possible is sufficient to fill up the total region between the adhesive surface and the wall. This is in particular achieved in that the total flow path is the same in all directions. The contact element in particular has a diameter of 2 to 6 cm. Smaller or larger diameters are, however, also possible depending on the application case.

It is also possible that the contact element does not have an exactly circular outer contour, but is rather slightly “flattened” in the regions in which positioning elements are arranged. Since the adhesive agent is slowed down by the positioning element on the introduction between the adhesive surface and the wall, it can thus be achieved that the adhesive agent reaches the margin at the total outer contour without passing over the margin at any point. It can thus be achieved that a minimal quantity of adhesive agent is sufficient to fill up the total region between the adhesive surface and the wall.

Further advantages, features and details of the invention result with reference to the following description of embodiments and with reference to drawings in which elements which are the same or have the same function are provided with identical reference numerals.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In accordance withFIG. 1, a fastening element10positioned at a planar wall11has a holder element12. The holder element12has a predominantly hollow-cylindrical shape and has at its peripheral surface an external thread13which can cooperate with an internal thread of an object, not shown. The object which is not shown can, for example, be designed as a hook which can be screwed onto the holder element12and can thus be held at the wall11via the fastening element10.

The fastening element10is fixedly connected to a contact element14by a weld connection, not shown. The two elements are produced from metal in this embodiment.

The contact element14is designed as a circular disk through whose central axis15a second part16of a filling passage17extends which ends at an outlet opening18. The holder element12is arranged on the contact element14such that it is arranged coaxial to the central axis15of the contact element14. A first part19of the filling passage17extends within the holder element12and ends with a filling opening20.

The contact element14has a planar adhesive surface21which is aligned toward the wall11and includes the outlet opening18of the filling passage17. The holder element12is arranged on the rear side22of the contact element14disposed opposite the adhesive surface21. The fastening element10is positioned at the wall11and thus prefastened by a total of four positioning elements23a,23b,23c,23d, of which only two positioning elements23band23dcan be seen inFIG. 1. The positioning elements23b,23dare designed as double-sided adhesive tapes whose form will be looked at in more detail in the description ofFIG. 2. The positioning elements23a,23b,23c,23dthus contain a pressure-sensitive adhesive and have a thickness of approximately 0.8 mm so that the adhesive surface21of the contact element14and the wall11have a spacing of approximately 0.8 mm.

A flowable adhesive agent, not shown, can be introduced between the adhesive surface21and the wall11for the final attachment of the fastening element10to the wall11. The adhesive agent dries and then hardens and the fastening means or element10is thus fixedly connected to the wall11.

FIG. 2shows the fastening element10in a view from the wall11, that is a plan view of the adhesive surface21of the contact element14designed as cylindrical or disk-shaped with the exception of the second part16of the filling passage17. The representation is in this respect not exactly to scale. The filling passage17is designed as cylindrical and ends with the circular outlet opening18. The outlet opening18is arranged so that its center24lies on the central axis15of the contact element14. The four positioning elements23a,23b,23c,23dare each designed as identical ellipses and are distributed uniformly around the outlet opening18. The ellipsoid positioning elements23a,23b,23c,23deach have a long axis of symmetry and a short axis of symmetry of which only a respective one long axis of symmetry26aand one short axis of symmetry27aof the positioning element23aare provided with reference numerals. The two axes of symmetry each intersect at a center of area25a,25b,25c,25dof the positioning elements23a,23b,23c,23d. A respective direction of flow28a,28b,28c,28dwhich extends, starting from the center24of the outlet opening18, through the centers of area25a,25b,25c,25dof the positioning elements23a,23b,23c,23dthus results for each positioning element23a,23b,23c,23d. The positioning elements23a,23b,23c,23dare aligned so that the respective long axis of symmetry26a, and thus the longest axis of symmetry, is aligned along the direction of flow28a,28b,28c,28d. A respective angle of 90° results between two adjacent directions of flow28a,28b,28c,28ddue to the uniform distribution of the positioning elements23a,23b,23c,23daround the outlet opening18.

Since all the positioning elements23a,23b,23c,23dhave an identical shape and are also aligned identically with respect their respective directions of flow28a,28b,28c,28d, only the positioning element23bwill be looked at in the following, with the statements also applying to the positioning elements23a,23c,23d.

The positioning element23bhas a width which is variable perpendicular to the direction of flow28, and thus parallel to the short axis of symmetry, and which depends on a spacing from the outlet opening18or more exactly on the spacing from the center24of the outlet opening18. Three widths b1, b2, b3are drawn by way of example, with the first width b1lying, viewed from the outlet opening18, before the short axis of symmetry, the second width b2on it and the third width b3behind it. The width first increases constantly as the spacing from the outlet opening18increases and reaches the maximum width b2at the short axis of symmetry. Subsequently, the width continuously reduces and reaches a minimal width of quasi zero at a maximum spacing29. The positioning element23bfurthermore has a length1which results from an extent of the positioning element23bin the direction of flow28b. A ratio of length1to the maximum width b2of the positioning element23bis in this respect approximately 3 and thus larger than 1:1:

The adhesive agent is supplied via the outlet opening18. It then flows radially outwardly up to a margin30of the adhesive surface21. A total flow path31of the adhesive path thus results which starts at a margin32of the outlet opening18and ends at the margin30of the adhesive surface21. Since both the adhesive surface21and the outlet opening18are circular, the total flow path31is of equal length in all directions.

The positioning element23bis arranged such that its center of area25bhas a spacing33from the margin32of the outlet opening18which corresponds to approximately 62% of the total flow path31. In addition, a first flow path34of the adhesive agent results between the margin32of the outlet opening18and the positioning element23bwhich corresponds to approximately 29% of the total flow path31. The first free flow path34simultaneously represents a minimal spacing of the positioning element23bfrom the outlet opening18. In addition, a second free flow path35of the adhesive agent results between the positioning element23band the margin30of the adhesive surface which likewise corresponds to approximately 29% of the total flow path31.

In the second embodiment in accordance withFIG. 3, an adhesive surface121and an outlet opening118are identical to the embodiment in accordance withFIGS. 1 and 2. Four positioning elements123a,123b,123c,123dare arranged uniformly around the outlet opening118. The positioning elements123a,123b,123c,123dare sprayed on in this embodiment and have a thickness of approximately 0.3 mm.

The ellipsoid positioning elements123a,123b,123c,123deach have a long axis of symmetry and a short axis of symmetry of which only a respective one long axis of symmetry126aand one short axis of symmetry127aof the positioning element123aare provided with reference numerals. The two axes of symmetry each intersect at a center of area125a,125b,125c,125dof the positioning elements123a,123d,123c,123d. A respective direction of flow128a,128b,128c,128dthus results for each positioning element123a,121,123c,123d. The positioning elements123a,121,123c,123dare aligned so that the respective long axis of symmetry126a, and thus the longest axis of symmetry, is aligned along the direction of flow128a,128b,128c,128d.

Since all the positioning elements123a,123b,123c,123dhave an identical shape and are also aligned identically with respect their respective directions of flow128a,128b,128c,128d, only the positioning element121will be looked at in the following, with the statements also applying to the positioning elements123a,123c,123d.

The positioning element123bhas a width which is variable perpendicular to the direction of flow128band thus parallel to the short axis of symmetry and which depends on a spacing from the outlet opening118. The width first increases constantly as the spacing from the outlet opening118increases and reaches a maximum width b12at the short axis of symmetry. Subsequently, the width continuously reduces and reaches a minimal width of quasi 0 at a maximum spacing. The positioning element123bfurthermore has a length11which results from an extent of the positioning element123bin the direction of flow128b. A ratio of length11to the maximum width b12of the positioning element123bis in this respect approximately 3.5 and thus larger than 1:1.

The positioning element123bis arranged such that its center of area125bhas a spacing from a margin132of the outlet opening118which corresponds to approximately 50% of the total flow path. In addition, a first flow path of the adhesive agent results between the margin132of the outlet opening118and the positioning element1233which corresponds to approximately 21% of the total flow path. The first free flow path simultaneously represents a minimal spacing of the positioning element123bfrom the outlet opening118. In addition, a second free flow path of the adhesive agent121results between the positioning element123band a margin130of the adhesive surface121which likewise corresponds to approximately 21% of the total flow path.

In the third embodiment in accordance withFIG. 4, an adhesive surface221and an outlet opening218are identical to the embodiment in accordance withFIGS. 1 and 2. Four positioning elements223a,223b,223c,223dare arranged uniformly around the outlet opening218.

The positioning elements223a,223b,223c,223dhave a shape which results from two arcs of a circle. They each have a long axis of symmetry and a short axis of symmetry of which only a respective one long axis of symmetry226aand one short axis of symmetry227aof the positioning element223aare provided with reference numerals. The two axes of symmetry each intersect at a center of area225a,225b,225c,225dof the positioning elements223a,223b,223c,223d. A respective direction of flow228a,228b,228c,228dthus results for each positioning element223a,223b,223c,223d. The positioning elements223a,223b,223c,223dare aligned so that the respective long axis of symmetry226a, and thus the longest axis of symmetry, is aligned along the direction of flow228a,228b,228c,228d.

Since all the positioning elements223a,223b,223c,223dhave an identical shape and are also aligned identically with respect their respective directions of flow218a,228b,228c,228d, only the positioning element223bwill be looked at in the following, with the statements also applying to the positioning elements223a,223c,223d.

The positioning element223bhas a width which is variable perpendicular to the direction of flow228band thus parallel to the short axis of symmetry and which depends on a spacing from the outlet opening218. The width first increases constantly as the spacing from the outlet opening218increases and reaches a maximum width b22at the short axis of symmetry. Subsequently, the width continuously reduces and reaches a minimal width of quasi 0 at a maximum spacing. The positioning element223bfurthermore has a length12which results from an extent of the positioning element223bin the direction of flow228b. A ratio of length12to the maximum width b22of the positioning element223bis in this respect approximately 2.8 and thus larger than 1:1.

The positioning element223bis arranged such that its center of area225ahas a spacing from a margin232of the outlet opening218which corresponds to approximately 50% of the total flow path. In addition, a first flow path of the adhesive agent results between the margin232of the outlet opening218and the positioning element223bwhich corresponds to approximately 21%% of the total flow path. The first free flow path simultaneously represents a minimal spacing of the positioning element223bfrom the outlet opening218. In addition, a second free flow path of the adhesive agent results between the positioning element223band a margin230of the adhesive surface221which likewise corresponds to approximately 21% of the total flow path.

The third embodiment in accordance withFIG. 5differs from the embodiment in accordance withFIGS. 1 and 2only in that the ellipsoid positioning elements323a,323b,323c,323dare rotated clockwise by a respective angle y of 15° about their respective centers of area323a,323b,323c,323d. A longest axis of symmetry326band the direction of flow318bthus include an angle y of 15°.

The fourth embodiment in accordance withFIG. 6differs from the embodiment in accordance withFIGS. 1 and 2only in that the positioning elements423a,423b,423c,423dare designed as half-ellipses which only start at the short axis of symmetry of the associated complete ellipse.