Fastening Efement

Cross-Reference To Related Applications

This application claims priority from German Patent Application No. 10 2008 007 135.8, filed on January 31 , 2008, the disclosure of which is incorporated herein by reference. Technical Fieid

The invention relates to a fastening element for fastening a structural part to a bolt, having an accommodating cage which has a cage chamber extending along an axis, an insertion aperture through which the bolt is insertabie into the cage chamber in the direction of the axis, and a locking element for securing the bolt in the accommodating cage. Background Art

Fastening elements of the kind indicated are known in a variety of embodiments, for example from EP 1 ,400,709 B1 , EP 1 ,069,326 B 1 or US 6,240,602 B1 , and are used for fastening structural parts such as cables, pipes or the like to a bolt by simple mounting procedures and without the use of special mounting tools.

The known fastening elements have a rigid accommodating cage with an insertion aperture and a cage chamber for accommodation of the bolt. Located in the accommodating cage is a locking pawl, which is flexibly connected with the inner wall of the cage and upon insertion of the bolt yields etasticaily in the direction of insertion, in order then to lock, in a position inclined to the axis of the bolt, with projections on the outside of the bolt and thereby secure the bolt against withdrawal from the cage. Here, it is regarded as disadvantageous that the accommodating cage must be designed

relatively targe, since in addition to the space for accommodation of the bolt, a space for the pawl must also be provided. The space for the locking pawl must have a certain size in order for the pawl to be able to compensate for variations in dimension and for the mounting forces to remain small. If a releasing bar is formed on the pawl, as shown in EP 1 ,069,326 B1 , this results in a width of the cage chamber that corresponds to nearly double the bolt diameter. Disclosure of Invention

The object of the invention is to procure a fastening element of the kind mentioned at the beginning, which is characterized by a small space requirement in the region of the bolt. A further object of the invention consists in keeping the materia! requirement for production of the fastening element small. The fastening element should in addition be characterized by a favorable ratio of mounting force to holding force and should be simple and inexpensive to produce.

According to the invention, this object is accomplished by a fastening element having the features indicated in Claim 1. Additional advantageous embodiments of the invention are indicated in the subclaims.

According to the invention, a fastening element for fastening to a bolt is provided with an accommodating cage which has a cage chamber extending along an axis, an insertion aperture through which the bolt is insertable into the cage chamber in the direction of the axis, and a locking element for securing the bolt in the accommodating cage, where the accommodating cage has at least one section elastically deformable transverse to the axis and in the direction of insertion of the bolt in such a way that

deformation of the section increases the inside diameter of the cage chamber at least in the direction of engagement of the locking element. fn contrast to the known fastening elements, in the fastening element according to the invention the cage is not rigid, but is elasticaliy deformable in such a way that when a bolt is inserted it expands at least in the direction of engagement of the locking element and hence transverse to the longitudinal axis of the bolt, so that the locking element is able to slide over ribs or the like on the outside of the bolt and, by springing back of the cage into its original position, snap into a depression adjoining a rib or the like. Here, the locking element itself may be rigidly connected with a section of the accommodating cage and therefore be designed compact and sturdy.

The fastening element according to the invention has the advantage that it requires little space, since its cage can be designed lying close to the outer contour of the assigned bolt. A large cage chamber for the accommodation of a movable Socking pawl is unnecessary. The design of a flexible cage also makes for a small material input and contributes to inexpensive production. The deformable design of the cage in addition has the advantage that high holding forces can be achieved with comparatively low deformation forces to be overcome in mounting.

For achieving suitable elastic deformability, the elasticaliy deformable section of the accommodating cage has at least one bar-shaped spring element, the ends of which lie in two different parallel planes intersecting the axis of the cage chamber at an angle of 90°. When forces directed to each other act on the ends of the bar-shaped spring element in the direction of the axis, one end is bent in the direction of the plane in which the other end of the bar-like spring element is situated. This results in stretching

of the deformable section transverse to the axis and hence in increase in the inside diameter of the cage chamber. A bolt can therefore easily penetrate the cage chamber. Forces in the reverse direction cause a reduction in size of the cage chamber and thus increase the force for clamping and securing a bolt inserted into the cage chamber.

The elastically deformable section of the fastening element preferably has at least two parallel bar-shaped spring elements. These spring elements may be designed as fixed bending supports or as rods fastened on the accommodating cage by bending or torsion elements.

An additional advantageous embodiment of the fastening element provides that the accommodating cage has a first wall and a second wail opposite the latter, where the two wails, at their lateral edges extending in the direction of the axis, are connected together by elastically deformabfe sections in such a way that the second wall is movable with respect to the first wall in the direction of insertion and in a direction increasing the distance from the first wall. Here, the locking element according to the invention may be comprised of a rib which is located on one of the walls, in particular the second wall, on which the side turned toward the respective other wall is located. For achieving a higher holding force, locking elements may alternatively be formed on both walls.

It may further be provided that a holding element for holding a structural part, in particular a cable, a cable tree or a pipe, is located on the first wall. In addition, the first wall may have on the end opposite the insertion aperture a detent element limiting the insertion depth of the bolt.

The fastening element preferably is comprised of an especially hard elastic thermoplastic synthetic material and is designed so that it can be made in one piece in the injection molding process. Brief Description of the Drawings

The invention is explained in detail below by an exemplary embodiment that is represented in the drawing, wherein

Figure 1 shows a perspective representation of a fastening element according to the invention and

Figure 2, a view of the fastening element of Figure 1 in a mounting position fastened to a bolt. Modes for Carrying out the Invention

The drawing shows a fastening element 1 , which is designed for fastening a cable tree to a bolt. The fastening element 1 has an accommodating cage 2, which is made of a first wall 3, a second wail 4 located parallel to the latter and bar-shaped spring elements 5, 6 connecting the walls 3, 4 together. The spring elements 5, 6 are arranged pairwise and substantially parallel to each other in such a way that the lateral edges of the walls 3, 4 are connected together by a spring element 5 and a spring element 6, respectively. The spring elements 5 are situated at the upper end of the walls 3, 4 and are connected with them resistant to bending. The spring elements 6 connect the lower end of the second wall 4 with approximately the center of the lateral edges of the first wall 3 and are connected with the walls 3, 4 by elasticaily deformable torsion elements in the manner of a joint. The length of the spring elements 6 is greater than the length of the spring elements 5. The spring elements 5, 6 are in each instance

inclined at an angle of about 30° to the substantially pfane walls 3, 4 in such a way that they extend from the wall 3 in the direction of the wall 4 and downward. The walls 3, 4 and the spring elements 5, 6 surround a cage chamber 8, which is open at a lower end 7 of the fastening element 1. At the top the cage chamber 8 is partially closed by a bow-shaped detent element 9, which is fastened on the first wall 3. On the inner sides turned toward each other, locking elements 10, 11 are fastened to the walls 3, 4. The two locking elements 10, 11 have the shape of a straight strip with a sawtooth profile directed upward. The locking element 11 located on the wall 4 has a greater width, so that it projects more deeply from the wall 4 into the cage chamber 8. The underside of the locking element 11 forms a sliding surface 12, extending upward at an angSe of 45° from the wall 4, which upon mounting of the fastening element 1 cooperates with the end of a bolt 20 insertable into the cage chamber 8 and transmits the force required for expansion of the cage chamber to the wall 4.

On its side turned away from the cage chamber 8, there is formed on the first wall 3 a holding element 13 with a concavely curved contact surface 14 and fastening arms 15 extending in opposite directions. The holding element 13 serves especially for fastening of a cable tree, which rests on the contact surface 14, and by means of straps that wrap around the fastening arms 15, is fastenable to the holding element 13. On its underside turned away from the contact surface 14, the holding element 13 has a rib 16, by which the fastening element 1 in the mounting position can be supported on a contact surface. Owing to the support thereby produced at a distance from the accommodating cage, a supporting moment directed counterclockwise in the drawing is produced, by which the fastening element 1 is pressed by the first wail 3 on a bolt 20

situated in the cage chamber 8. The holding element 13 may in addition be designed elastically yielding, in order to brace the fastening element 1 elastically in the mounting position.

Upon mounting, the lower end 7 of the fastening element 1 is first set up on a bolt

20 fastened to a structural part 21 , so that the free end of the bolt 20 engages in the cage chamber 8 and comes to rest on the sliding surface 12 of the locking element 11. Then, a mounting force directed downward against the bolt 20 becomes effective on the first wall 3 projecting upward. The wal! 3 is thereby first pressed downward, while the wall 4, supported on the bolt 20 by the locking element 11 , remains in its position. Owing to displacement of the wall 3 with respect to the wall 4, the spring elements 5, 6 are elastically deformed, and their inclination with respect to the walls 3, 4 is reduced and the distance between the walls 3, 4 becomes greater. With increasing deformation and corresponding increase in the distance, the sliding surface 12 of the locking element 11 slides further and further outward on the bolt end, until it finally is able to jump over a screw thread 22 of the bolt 20 and with jumps over additional threads on the bolt 20 is able to slide along in the direction of the fastening end of the bolt 20. The same takes place mutatis mutandis with the locking element 10 on the wall 3, which jumps over threads simultaneously or alternating with the locking element 11.

The final mounting position is reached when the rib16 rests on the structural part

21 and the locking elements 10, 11 have assumed a locking position between two threads 22 and, due to the spring action of the holding element 13, rest on a thread against the direction of mounting. Here, the spring elements 5, 6 are sprung back far enough into their starting position so that the wall 3 and the locking elements 10, 11 are

pressed without play, in the radial direction also, and rest on the bolt 20 with a certain press-on force. When a force that attempts to remove the holding element 13 from the structural part 21 acts on the holding element 13, the deformable spring elements 5, 6, because of their inclination, reinforce the press-on force with which the locking elements 10, 11 are pressed against the bolt 20 and thereby prevent the fastening element 1 from becoming loose from the bolt 20. The fastening element 1 is therefore characterized by a high holding force. The fastening element 1 can nevertheless be demounted in simple fashion by, for example, using a screwdriver to move the wall 4 in the direction of release, while at the same time keeping the wail 3 in place. In this way, the walls 3, 4 move away from each other, so that the locking elements 10, 11 release the bolt 20 and the fastening element 1 can be removed from the latter.