Fastening device

A fastener for fastening an attached or trim part to a support part includes a receptacle part having a pocket with a lateral opening and a guide slot, and a connecting part having at least one flange that can be introduced into the pocket through the lateral opening and having a fastening section. The fastening section has an opening to accommodate a retaining stud projecting from the support part. Located in the opening are latching fingers which can hold the retaining stud in place in the opening.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from German Patent Application No. 10 2008 033 307.7, filed on Jul. 16, 2008, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a fastener for fastening an attached part or trim part to a support part, in particular a body part of a motor vehicle, with a receptacle part that has a pocket with a lateral opening and a guide slot, and with a connecting part that has at least one flange that can be introduced into the pocket through the lateral opening.

Fasteners of the specified type are used primarily in automotive manufacture for fastening trim parts and attached parts to the vehicle body or to body parts such as doors and the like. It is often advantageous to provide fastening in the simplest possible manner and without the aid of tools, and there is frequently a need to be able to compensate for dimensional variations of the parts in the vicinity of the fastener.

BACKGROUND OF THE INVENTION

Various fasteners of the specified type are known from EP 0,020,308 A1, EP 1,895,171 A2, U.S. Pat. No. 6,196,607 B1, for example. The prior art fasteners have in common that an element in the shape of a stud is provided as the connecting part and is joined to the support part in a latching manner by insertion through an opening in the support part. It is a disadvantage here that the support part must have openings at the fastening points and that additional means such as a dished washer and possibly additional sealing rings must be provided so that these openings can be tightly sealed during installation of the attached parts or trim parts.

Moreover, a device for fastening a sound-absorbing panel to the body of a motor vehicle is known from WO 02/072390 A1, wherein the body has a stud onto which a one-piece plastic fastener can be placed. The plastic fastener here is located in an opening of the sound-absorbing panel and engages around the sound-absorbing panel on the side facing away from the body by means of an annular flange. Such a design is unsuitable for fastening decorative trim parts.

In addition, a plastic clip for fastening a trim strip to the body of a motor vehicle is known from EP 0,489,505 B1; said clip snaps onto a T-shaped stud welded to the body panel and has lateral latching fingers that engage in opposing grooves on the inside of the trim strip, which is bent into a U shape. Such a clip is also unsuitable for fastening flat trim parts.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a fastener for fastening attached parts or trim parts does not require fastening openings in the parts that are to be joined together. The fastener may be simple to install and may consist of simple parts that can be manufactured inexpensively. It may also provide the capability to compensate for manufacturing-related dimensional variations, but may also be suitable for providing a fixed mounting point. Lastly, it may be possible to separate the parts joined by the fastener without damage.

According to one embodiment of the invention, the fastener is comprised of a receptacle part having a pocket with a lateral opening and a guide slot, and a connecting part having at least one flange that can be introduced into the pocket through the lateral opening and having a fastening section, wherein the fastening section has an opening to accommodate a stud projecting from the support part and has elastic retaining means in the opening by which the stud can be held in place in the opening.

The fastener according to an aspect of the invention may thus be comprised of three parts, namely a receptacle part, a connecting part, and a stud, wherein the connecting part can be connected to both the receptacle part and the stud. The receptacle part is suitable for attachment to an attached part or a trim part, and can also be an integral part of the attached part or trim part. In contrast, the stud is especially suited for attachment to a metallic support part, for example a body part, and can be joined to a support part in a simple manner using a conventional stud welding method without making an opening. The connecting part may be made of plastic, and can be joined to the receptacle part and the stud by a simple insertion process in each case.

According to a further proposal of the invention, the fastening section of the connecting part is designed as a hollow body, wherein one end of the hollow body is attached to the flange, and the other end has an insertion opening for a retaining stud, and wherein the retaining means for holding the retaining stud in place are located on the inside of the hollow body. The wall of the hollow body preferably consists of cylindrical wall sections and of fluted wall sections that are located between the cylindrical wall sections and that have the raised side of their flute profile projecting into the hollow body. This design permits guidance of the fastening section into the guide slot of the receptacle part with the aid of the cylindrical wall sections with simultaneous guidance and centering of the retaining stud in the interior of the hollow body with the aid of the fluted wall sections. To facilitate the insertion and centering of the retaining stud relative to the fastening section even in the presence of lateral offset of the fastening section relative to the retaining stud, provision can additionally be made for the end faces of the fluted wall sections to be beveled in the vicinity of the insertion opening so as to form guide surfaces inclined in the insertion direction.

According to a further proposal of the invention, at least one elastic latching finger that extends in the insertion direction from the insertion opening is arranged on the inside of the hollow body to hold the retaining stud in place. The latching finger is advantageously attached at its end adjacent to the insertion opening to a cylindrical wall section of the hollow body by an elastically flexible section. The cylindrical wall section can have a reinforcement that increases the wall thickness in the area of the attachment point to support the bending load.

The flange of the connecting part may have a circular ring whose inside diameter is greater than the outside diameter of the fastening section, and which is connected to the fastening section by radial webs. To enlarge the contact area of the flange, individual intermediate spaces of the webs can be closed by a smooth wall on the side facing the insertion opening.

The receptacle part may comprise a plate with an open guide slot on one plate side, and a U-shaped wall that projects from one side of the plate and surrounds the guide slot at a distance. Attached to the edge of the projecting wall distant from the plate can be a cover plate, which closes off the space enclosed by the projecting wall at a sufficient distance from the plate so that a large enough space remains to receive the flange of the connecting part. The receptacle part can also be an integral part of the attached part or trim part, wherein the cover plate is composed of the trim part. However, the receptacle part can also be produced as a separate part and be attached later to the cover plate on the attached part or trim part by bonding, welding, or a similar method. According to another proposal of the invention, introduction of the connecting part into the pocket of the receptacle part can be facilitated by the means that the guide slot has an entry section that grows larger toward the outside. Moreover, the plate can have, in the edge region adjacent to the entry of the guide slot, a ramp surface that is inclined towards the edge and whose distance from the cover plate increases towards the edge.

In order to secure the connecting part against falling out after placement in the receptacle part, the plate of the receptacle part may be additionally provided with at least one raised bump that is located opposite the cover plate and has a distance therefrom that is slightly smaller than the thickness of the flange of the connecting part. The bump provides a resistance that can be overcome with light force but that is sufficient to keep the connecting part from coming out by itself once placed in the pocket. The introduction of the connecting part can be further eased by additional ramps on the insertion side of the bump.

The fastener1shown inFIGS. 1 and 2includes a receptacle part3fastened to a panel-like trim part2, a connecting part4, and a T-shaped retaining stud5that is attached to a support part6and has a head7at its free end. The trim part2, the receptacle part3, and the connecting part4are made of thermoplastic material. The retaining stud5and the support part6are made of metal and are welded to one another. However, the invention is not limited to the use of the stated materials. The trim part and receptacle part may be made of metal, and the support part and retaining stud may be made of plastic.

The receptacle part3has a flat plate10with a guide slot11, which forms an entry region12that enlarges conically towards the edge of the plate, a narrow point13, and a circular end region14whose diameter is larger than the width of the narrow point13. Extending along the outer edge15of the plate10is a U-shaped wall16, which surrounds the guide slot11at a distance. The wall16is perpendicular to the plate10and has a constant height H. The edge15of the wall16distant from the plate10is permanently attached to the trim part2. Adjacent to the entry region12are parallel sections of the wall16, which, on their outside facing away from the guide slot11, are additionally supported against the trim part2by triangular ribs17. In conjunction with the trim part2, the receptacle part3forms a pocket18with a lateral insertion opening19into which the connecting part4may be placed. In the edge region adjacent to the insertion opening19, the plate10has, on the side facing the trim part2, a ramp surface20that is inclined toward the edge and whose distance from the trim part2increases towards the edge. Insertion of the trim part2is facilitated by this means.

The connecting part4has an annular flange21, which surrounds an end of a fastening section22in the form of a cup-like hollow body and is rigidly connected to the fastening section22by radial webs23. The thickness and diameter of the flange21are dimensioned such that the flange21can be inserted into the pocket18. The hollow body of the fastening section22has an external wall composed of three cylindrical wall sections24and fluted wall sections25located therebetween. The fluted wall sections25extend parallel to the center axis of the cylindrical wall sections24, and the raised side of their flute profile projects into the hollow body. The end of the fastening section22that is distant from the flange21forms an insertion opening26. The ends of the fluted wall sections25are beveled in the vicinity of the insertion opening26such that their end faces form guide surfaces27that are inclined in the insertion direction in order to center an inserted stud.

Attached to each of the cylindrical wall sections24on the inside of the fastening section22is an elastic latching finger28that extends in the insertion direction and towards the center from the insertion opening26. Near the insertion opening26, an end of the latching finger28is affixed to the associated wall section24by an elastically flexible section29. The wall sections24are provided with a reinforcement that increases the wall thickness in the area of the attachment point of the latching fingers28, which reinforcement forms a raised shoulder on the outside of the wall sections24. The free ends of the latching fingers28are located a distance from the end of the fastening section22that is near the flange, and have support areas30for bracing against the head7of a retaining stud5. Located in the center of the end of the fastening section22that is near the flange is a rigid stop31, which is attached to the wall sections25by webs. The stop31limits the depth to which the retaining stud5can penetrate the fastening section22.

The retaining stud5that can be placed in the fastening section22has a head7of a larger diameter than the stud shank. The head7is delimited at its top by a cap area33of convex curvature and at its underside by a conical contact area34. The cap area33facilitates centering of the head7in the insertion opening26and spreading of the latching fingers28during installation. The conical contact area34on the underside of the head7compensates mounting tolerances in the axial direction, and spreads the latching fingers28apart as the connection is released. The release force needed to release the connection can be defined by the inclination of the contact area34in conjunction with the spring action of the latching fingers28.

In order to fasten the trim part2to the support part6, the connecting part4is first arranged on the trim part2in front of the opening19of the receptacle part3, as shown inFIG. 1, and then pushed in the direction of the arrow into the receptacle part3. As this is taking place, the pocket18accommodates the flange21, and the fastening section22passes through the entry region12and the narrow point13to reach the end region14. The width of the narrow point13may be slightly smaller than the diameter of the fastening section22, so that the connecting part4has to be pushed into the end region14with a certain force. In this way, the narrow point13ensures that the connecting part4, once it has been placed in the receptacle part3, cannot slip out of it—for example, while being transported into the installation position.

As an alternative to the narrow point13, bumps36in the shape of spherical caps may be arranged on the side of the plate10facing the trim part, as shown inFIGS. 4 and 6, which bumps act in combination with the flange21and secure the connecting part4against slipping out of the receptacle part3. In addition, short ramps37may be arranged on the entry side of the bumps36in order to make insertion easier.

Once the connecting part4has been inserted in the receptacle part3, the trim part2is moved, with the connecting part4forward, towards the support part6in such a way that the retaining stud5can enter the insertion opening26. If the retaining stud5is eccentric to the insertion opening26when this is done, then the guide surfaces27of the wall sections25bring about the necessary centering. During centering, the connecting part4can also shift radially in the receptacle part3if the receptacle part3is oversize to compensate for manufacturing tolerances. Pressing the trim part2onto the support part6causes the retaining stud5to be pressed into the fastening section22until it rests against the stop31, as shown inFIG. 2. The head7of the retaining stud5is centered by the fluted wall sections25during this process, and is held in the center position after reaching the endpoint. The latching fingers28are initially spread apart by the head7, and then spring back to the position shown inFIG. 2, in which they brace against the contact area34. In this position, the latching fingers28hold the connecting part4securely on the support part6, so that the trim part2connected to the connecting part4by the receptacle part3is likewise held on the support part6.

Shown inFIGS. 3 and 4is a receptacle part103, connected to a connecting part4, that is intended to compensate dimensional variations. The receptacle part103has an end region114, which has a larger diameter than the fastening section22of the connecting part4. Because of the existing difference in diameters, when the fastening section22is centered in the end region114, a clearance S is present between the two on all sides. In like manner, the radius of the curved section of the projecting wall116is larger by at least the clearance S than half the outside diameter of the flange21of the connecting part4. The connecting part4can therefore compensate dimensional variations of the magnitude of the clearance S on all sides.

InFIGS. 5 and 6, a variant embodiment of the inventive fastener is shown that is intended as a fixed point for precisely positioned alignment of the connected parts. In this embodiment, the receptacle part203has an inside diameter in the end region214that is essentially equal to the outside diameter of the fastening section22. In addition, the radius of the curved section of the projecting wall216is essentially equal to half the outside diameter of the flange21of the connecting part4. As a result, when the connecting part4is placed in the receptacle part203, it occupies a defined, centered position relative to the receptacle part203. Since the connecting part4is also centered with respect to the retaining stud5during installation on a support part6, the combined action of the receptacle part203, connecting part4, and retaining stud5results in accurately positioned establishment of this connection point between the trim part2and the support part6.