Patent Publication Number: US-2016230791-A1

Title: Fastener for two fastening states

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of international PCT/EP2014/072093, filed Oct. 15, 2014 which claims priority from German Patent Application No. DE102013111400.8, filed Oct. 16, 2013, the disclosures of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention concerns a fastener for two fastening states having a receptacle part that has a receiving aperture and fastening means for attachment to a first component, having an insertion part with a pin-like plug-in section that can be inserted with an insertion end of the plug-in section foremost into the receiving aperture of the receptacle part and that has, at a fastening end opposite the insertion end, fastening means for attaching a second component, wherein, in a first fastening state, the plug-in section of the insertion part is inserted deep into the receiving aperture and the insertion part is releasably connected to the receptacle part by latching first retaining means, and the first retaining means are designed such that the insertion part can be displaced by a release force into a second fastening state connected to the receptacle part. 
     Fasteners of the specified type are used in the passenger compartment of motor vehicles for attaching trim parts behind which may be located an airbag. The fastening for trim parts of this nature must be designed in such a way that the trim parts can release in the event of activation of the airbag in order to give the airbag space to deploy. Thus, on the one hand, the fastener is required to fasten the trim part to the vehicle such that it is securely seated in a first fastening state. On the other hand, when a predetermined release force acting on the trim part is reached in the event that the airbag is deployed, the fastener must be able to be released from the first fastening state and permit a movement of the trim part distant from the airbag so that the airbag can deploy properly. In this case, it is additionally necessary for the trim part to be secured by the fastener again after it has traversed the distance releasing the airbag so that it cannot fly into the passenger compartment of the vehicle, and passengers cannot be injured. The fastener must therefore permit a second fastening state in which the trim part is fastened in a position on the vehicle that is different from the first fastening state. 
     In a fastener of the abovementioned type known from U.S. Pat. No. 6,431,585 B1, the receptacle part is a cylindrical sleeve that has a flange at one and is fastened in an aperture in a vehicle part by means of locking fingers. It is possible to insert into the sleeve a pin that is provided at a head end with two parallel flanges, between which is attached a trim part. A flange of the pin is connected to the flange of the sleeve by a flexible strap. In the connected first fastening state, a thicker section of the pin is held by a slotted and expandable end of the sleeve. When an airbag deploys, the pin is pulled out of the sleeve, while the strap retains the pin and the trim attached thereto, thereby restricting their movement into the passenger compartment of the vehicle. 
     Another fastener of the specified type is known from U.S. Pat. No. 7,178,205 B2, in which the receptacle part has a metal clip that can be secured in an aperture in a plate. Located in the clip is an insert made of plastic, to which the end of a flexible strap is attached. Attached to the other end of the strap is a U-shaped connector, which can be connected to a component. The connector has a pin with an enlarged end that can be releasably connected in a bore having radially deflectable latching elements, said bore being located in the insert arranged in the clip. In this known fastener as well, when the pin is detached from the clip by deployment of an airbag, the component continues to be held by the clip by means of the strap and connector. 
     Known from EP 2,357,369 A2 is a fastener for securing a component to a body, which has a shaft with a fastening end and a receiving end, wherein a first securing means extends from the insertion end of the shaft, and a second securing means is implemented on the circumference of the shaft and connects the fastening end to the component. Using the second securing means, the component can be releasably secured in an aperture in the body. The first securing means has a barb, on a flexible stalk, that holds the fastener and the component connected thereto securely in the aperture of the body when the fastener has pulled out of the aperture due to the deployment of an airbag and after the second securing means has released. 
     In the prior art fasteners, the travel of a secured trim part is indeed limited in the case of deployment of an airbag, but the movement of the trim part and its ultimate position in the second fastening state are quite uncertain because of the flexible straps or stalks that hold the component at that point. However, installation situations exist in which it is desirable to have greater restriction of movement of a component part or trim part during displacement from the first fastening state to the second and to have more precise positioning of the part in the second fastening state. 
     BRIEF SUMMARY OF THE INVENTION 
     Consequently, the object of the invention is to create a fastener of the aforementioned type that allows controlled movement of the insertion part during displacement from the first fastening state into the second fastening state, and in which the insertion part assumes a defined position in the second fastening state. 
     The object is attained according to the invention by a fastener with the features specified in claim  1 . Advantageous further developments of the fastener are specified in the dependent claims. 
     According to the invention, the fastener with two operating states comprises a receptacle part that has a receiving aperture and fastening means for fastening to a first component, an insertion part with a pin-like plug-in section that can be inserted with an insertion end of the plug-in section foremost into the receiving aperture of the receptacle part and that has, at a fastening end opposite the insertion end, fastening means for fastening a second component, wherein, in a first fastening state, the plug-in section of the insertion part is inserted deep into the receiving aperture and the insertion part is releasably connected to the receptacle part by latching first retaining means, and the first retaining means are designed such that the insertion part can be displaced by a release force into a second fastening state in which the insertion part with the plug-in section is arranged in the receiving aperture to engage less deeply therewith and is secured in the receiving aperture by second retaining means. 
     The fastener according to the invention has the advantage that the plug-in section of the insertion part remains in the receptacle part during displacement from the first insertion state into the second fastening state so that it can be guided by the receptacle part as it is displaced. In the second fastening state, the displaced plug-in section is retained in the receiving aperture by the second retaining means, and as a result its location can be precisely positioned. Guidance of the insertion part in the receptacle part and its positioning in the second fastening state carry over to the component held by the insertion part, and determine and restrict its movement and displaced position during deployment of an airbag. 
     According to another advantageous embodiment of the invention, the receptacle part and the insertion part can have cooperating brake means that produce a decelerating force that opposes the displacement during displacement of the insertion part from the first fastening state into the second state. This embodiment has the advantage that the energy acting on the insertion part during the explosive deployment of the airbag is at least partially absorbed by the braking means as early as during displacement of the insertion part into the second fastening state, so that the impact forces arising at the second retaining means upon reaching the second fastening state are reduced. The loads on the second retaining means and on the parts supporting them are reduced in this way, and the fastener can be made commensurately smaller and lighter. 
     The braking of the movement of the insertion part during displacement into the second fastening state is especially important when only relatively short distances are available to the fastener for displacement from one fastening state into the other, and relatively high energy must be absorbed. 
     In an advantageous embodiment of the fastener equipped with braking means, according to the invention the plug-in section can have a wedge-shaped braking section that is tapered toward the fastening end, wherein, in the first fastening state, a deformable section of the receptacle part bears against the wedge-shaped braking section, which can be deformed by the wedge-shaped braking section during displacement of the insertion part into the second fastening state. Since an airbag must be replaced after deployment, and this generally also requires the trim part to be removed, it is also possible, in order to achieve a large braking effect, to permit deformation of the deformable section that is extensive enough that the fastener must also be replaced along with the airbag. 
     In order to retain the insertion part in the receiving aperture of the receptacle part, the plug-in section can have resiliently deflectable locking fingers extending toward the fastening end. Depending on the design of the receptacle part, the locking fingers can constitute either the first or the second retaining means. 
     The insertion part can also have, between the plug-in section and the fastening end, a plate-like flange that bears against the receptacle part in the first fastening state and supports the insertion part on the receptacle part in the insertion direction. The flange is suitable for transmitting installation forces to the receptacle part and can serve to fasten the insertion part to the receptacle part and to align the insertion part in a defined angular position with respect to the receptacle part. 
     According to another proposal of the invention, a simple receptacle part that can be manufactured economically and requires little space can take the form of a flat plate with the receiving aperture arranged in its center, wherein the plate has catches that form first retaining means on one insertion side by which means the flange of the insertion part can be secured on the receptacle part in such a manner that it can only be released by a release force dependent on the design of the retaining means. 
     Preferably the receptacle part in this design can be composed of two identical plate parts that have, on their face, connecting means that plug together, by which means they are connected to one another. The identical plate parts of the receptacle part can be manufactured easily and economically from plastic. The plate parts can be connected to one another around the plug-in section of an insertion part, by which means the insertion part can be joined to the receptacle part to form a preassembled and, if appropriate, nondetachable assembly unit. 
     In order to be fastened in the aperture of a component, for example a part of a motor vehicle body, the receptacle part can have, on a supporting side opposite the insertion side, retaining elements adjacent to the edge of its receiving aperture with resiliently deflectable locking fingers that extend behind the aperture edge on the back of the component after insertion of the retaining elements. 
     In another advantageous embodiment of the invention, the receptacle part can have a housing with a chamber into which the plug-in section of the insertion part can be inserted, wherein a resilient retaining element is arranged in the chamber, by which means the plug-in section of the insertion part can be secured in the second fastening state. In this design, the plug-in section can have a shoulder near the insertion end with a locking surface facing the fastening end, with which the plug-in section is supported on the resilient retaining element to keep it from being pulled out of the receptacle part in the second fastening state. 
     In the first fastening state, the plug-in section of the insertion part can extend all the way through the chamber of the receptacle part and be supported on the housing on the side of the housing facing away from the insertion side by means of the resiliently deflectable locking fingers to prevent release. 
     In another embodiment of the invention, the resilient retaining element can be supported on the plug-in section of the insertion part and on the housing in such a manner that when the insertion part is displaced from the first fastening state into the second state, a decelerating force opposing its displacement can be produced at the insertion part. 
     In order to achieve this effect, it is advantageous for the resilient retaining element to have a rigid, wedge-shaped clamping section that extends transversely to the direction of insertion along an edge of the insertion aperture and that has wedge surfaces on the side facing the insertion aperture and a contact surface for the insertion part on the opposite side, wherein the clamping section can be inserted into a gap between the plug-in section of the insertion part and the edge of the insertion aperture, and is designed to cause a clamping of the plug-in section in the insertion aperture opposing the displacement of the plug-in section. As a result of this design, a relatively high clamping force and a commensurately strong braking action can be achieved in a simple way when the insertion part is displaced. 
     Preferably, the resilient retaining element has two wedge-shaped clamping sections in a symmetrical parallel arrangement, which are connected to each other by spring elements at both their ends, wherein an aperture into which the plug-in section of the insertion part can be inserted is formed between the clamping sections and the spring elements. 
     In order to be fastened in the chamber, according to the invention, the resilient retaining element can have resilient arms on opposite sides that each extend outward from the ends of the clamping sections and toward one another, whose adjacent ends engage with retention apertures in opposite walls of the chamber and hold the retaining element in contact with a rearward wall of the chamber in the direction of insertion. As a result of this fastening, the retaining element can deform resiliently in the requisite fashion when the plug-in pin is inserted into the receptacle part. In addition, the resilient arms support the pressing of the clamping sections against the plug-in pin and permit an axial displacement of the retaining element toward the insertion aperture of the housing when the insertion part is moved into the second fastening state. As a result of the engagement of the resilient arms with the retention apertures, the retaining element is releasably fastened in the chamber of the receptacle part. Alternatively, the retaining element can be manufactured as a single piece with the receptacle part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is explained in detail below using exemplary embodiments that are shown in the drawings. They show: 
         FIG. 1  is an exploded view of a first exemplary embodiment of a fastener according to the invention. 
         FIG. 2  is a first perspective view of the receptacle part of the fastener from  FIG. 1 . 
         FIG. 3  is a perspective cross-sectional view of the insertion side of the receptacle part along the section line III-III from  FIG. 2 . 
         FIG. 4  is a perspective view of the fastener from  FIG. 1  in ready-to-assemble position. 
         FIG. 5  is a perspective view of the fastener from  FIG. 1  in the assembled state. 
         FIG. 6  is a perspective view of the fastener from  FIG. 1  with a longitudinal section through the receptacle part along the section line VI-VI of  FIG. 5 . 
         FIG. 7  is a longitudinal section through the fastener from  FIG. 1  in the first fastening state along the section line VII-VII of  FIG. 5 . 
         FIG. 8  is the longitudinal section through the fastener from  FIG. 7  now in the second fastening state. 
         FIG. 9  is an exploded view of a second exemplary embodiment of a fastener according to the invention. 
         FIG. 10  is a perspective view of the insertion part of the fastener from  FIG. 9 . 
         FIG. 11  is a perspective view of a plate part for forming the receptacle part of the fastener from  FIG. 9 . 
         FIG. 12  is a perspective view of the fastener from  FIG. 9  in the assembled state. 
         FIG. 13  is a perspective view of the fastener from  FIG. 9  in the first fastening state. 
         FIG. 14  is a perspective view of the fastener from  FIG. 9  in the second fastening state. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1 through 8  show a fastener  1  that is suitable for fastening a trim part intended to cover an airbag in the passenger compartment of a motor vehicle. The fastener  1  consists of a receptacle part  2  with a receiving aperture  3  and a pin-like insertion part  4 , which can be inserted into the receiving aperture  3  of the receptacle part  2  and affixed therein. The receptacle part  2  is in the form of a cuboid housing  6 , which surrounds a chamber  7 . The chamber  7  serves to accommodate a resilient retaining element  8 . On its front face, the housing  6  has a front wall  10 , in the center of which is located the receiving aperture  3 . The receiving aperture  3  is rectangular, and its edges are parallel to the housing edges. Located opposite the front wall  10  is a rear wall  11 , which has a rectangular aperture  12  at least as large as the receiving aperture  3 , as can be seen in  FIG. 3 . The walls  10 ,  11  are connected to one another by mutually opposite side walls  13 ,  14 . Arranged on the front face of the front wall  10  are two ribs  15 , which are perpendicular to the side walls  13 ,  14 . 
     On its rear, the housing  6  has a rectangular frame  16 , which serves to fasten the housing  6  to a trim part. The frame  16  has two parallel walls  17 ,  18 , which each have grooves  21  formed by parallel ribs  19 ,  20  on their outer side; the grooves serve to accommodate parallel mounting rails of a trim part. Together with a center, open section, the ribs  20  adjacent to the rear wall  11  form a locking finger  23  by which means a mounting rail of the trim part can be secured in the groove  21 . In place of the frame  16  described, other securing means may be attached to the housing  6 , depending on the design of the trim part. The side walls  13 ,  14  of the housing  6  may also be used for attaching securing means, such as a groove located between ribs. 
     The chamber  7  is provided on two opposing sides with apertures that extend across the entire cross-section of the chamber. The resilient retaining element  8  can be inserted into the chamber  7  through each of the two apertures. The symmetrically designed retaining element  8  has two rigid, wedge-shaped clamping sections  26  that are arranged at a distance from one another and that run parallel to the side walls  13 ,  14  in the chamber  7 , as shown in  FIG. 3 . Each clamping section  26  has an inner wedge surface  27  and an outer wedge surface  28  arranged at an angle to one another on the side facing the front wall  10 , and these wedge surfaces diverge from one another in the direction of the rear wall  11  of the housing  6 . On their side facing the rear wall  11 , the clamping sections  26  are provided with a step  29 , as shown in  FIG. 7 , that is adjoined to the inside by an inside contact surface  30  and to the outside by an outside contact surface  31 . The clamping sections  26  brace against the wall  11  with the contact surface  31 . The contact surface  30 , which is parallel to the wall  11 , serves to retain the insertion part  4 . The wedge-shaped clamping sections  26  are shorter in length than the corresponding length of the receiving aperture  3  so that they can enter the receiving aperture  3 . At their ends, each of the clamping sections  26  has flattened end pieces  33 ,  34 , at which they are connected to one another by V-shaped leaf springs  35 ,  36 . The leaf springs  35 ,  36  hold the clamping sections  26  at a distance such that an aperture  38 , which the insertion part  4  can enter, is present between them. 
     Each of the end pieces  33 ,  34  of the clamping sections  26  have an attached pair of resilient arms  40 ,  41 , which extend at an angle to the clamping sections  26  toward the side walls  13 ,  14  and toward one another. The retaining element  8  in the chamber  7  is kept in contact with the rear wall  11  and centered by the resilient arms  40 ,  41 . For this purpose, the resilient arms  40 ,  41  have, at their free ends, retaining fingers  42  that engage with apertures  43  in the center of the side walls  13 ,  14 . The retaining fingers  42  of adjacent ends of the resilient arms  40 ,  41  are arranged one over the other in such a manner that one retaining finger lies on the outside, and as a result guides the ends of both resilient arms  40 ,  41  along the applicable side wall  13 ,  14  when the retaining element  8  is inserted into the chamber  7 . The retaining element  8  is designed such that it can be primary molded as a single piece from thermoplastic material. 
     The insertion part  4  has an elongated, pin-like plug-in section  45  and a head  47  that bears a rectangular, plate-like flange  46 . Affixed to the side of the flange  46  facing away from the head  47  is a T-shaped fastener  48 . The fastener  48  is suitable for insertion into a fastening aperture with a keyhole-like design in a component of a motor vehicle body. At the opposite end, the plug-in section  45  has an insertion end  49  designed as a truncated pyramid  50  that tapers toward the end. The truncated pyramid  50  has a rectangular base adjacent to the plug-in section  45 , and the freestanding edges of the longer sides of the base form locking surfaces  51  with which the insertion part  4  can be secured in the receptacle part  2 . 
     The plug-in section  45  has a rectangular cross-sectional profile, and has at its short sides adjacent to the short sides of the truncated pyramid  50 , resiliently deflectable locking fingers  53  that extend outward and toward the flange  46 . Each locking finger  53  has at its free end a locking surface  54  and a stop rib  55  that adjoins the inner side of the locking finger  53  at the locking surface  54 . 
     As can be seen in  FIG. 4 , the plug-in section  45  forms, with the wide sides of its cross-section, a wedge-shaped braking section  56  with flat braking surfaces  57  that are angled with respect to the longitudinal axis of the plug-in section  45  such that their distance from the longitudinal axis decreases continuously toward the T-shaped fastener  48 . Thus the braking section  56  forms a wedge between the braking surfaces  57  that is widest at the truncated pyramid  50  and becomes ever narrower toward the head  47 . The braking surfaces  57  terminate at the head  47 , which adjoins the braking surfaces  57  with oppositely inclined outside surfaces  58 , and accordingly has a cross-section that increases toward the flange  46 . 
     A trim part can be fastened to a vehicle body part using the fastener  1  in the following way: The fastening element  48  of the insertion part  4  is inserted into a fastening aperture in the body part in such a manner that the plug-in section  45  projects on the side of the body part intended for the trim part, and the flange  45  rests firmly against the body part. The receptacle part  2  is connected to the trim part by attaching the frame  16  to mounting rails of the trim part. With the receptacle part  2  foremost, the trim part is then placed on the plug-in section  45  of the insertion part  4  and pushed onto the body part until the final position is reached, in which the front wall  10  of the housing  6  rests against the flange  46  of the insertion part  4 . Reaching of the final position is indicated by a sound that the locking fingers  53  produce by striking the stop ribs  55  at the edge of the aperture  12  in the rear wall  11  when snapping into the locked position. 
     The first fastening state of the fastener  1  achieved in the manner described is shown in  FIGS. 5 through 7  without the attached components. The plug-in section  45  here extends through the receiving aperture  3 , the aperture  12  in the rear wall  11 , and the aperture of the frame  16 , and its truncated pyramid  50  projects out of the frame  16 . The flange  46  resting against the front wall  10  is located between the ribs  15 , which secure the receptacle part  2  against rotation relative to the insertion part  4 . The locking fingers  53  brace against the outer side of the rear wall  11  of the housing  6  facing the frame by means of the locking surfaces  54 . The stop ribs  55  project into the aperture  12  and contact the edge of the aperture. The clamping sections  26  of the retaining element  8  located in the chamber  7  bear against the braking surfaces  57  of the plug-in section  45 , with the clamping surfaces  26  being pressed against the braking surfaces  57  with a spring force produced by the leaf springs  35 ,  36  and the resilient arms  40 ,  41 . The wedge surfaces  27  of the clamping surfaces  26  rest on the outside surfaces  58  of the head  47 . 
     As is evident from  FIG. 4 , the clamping surfaces  26  are spaced a distance apart from one another that is significantly shorter than the greatest width of the truncated pyramid  50  measured in the same direction. During the process of insertion, therefore, the clamping sections  26  are pressed apart from one another by the truncated pyramid  50 . This is made possible by the elastic deformability of the leaf springs  35 ,  36  and resilient arms  40 ,  41 . 
     In the first fastening state shown in  FIG. 6 , the angle of incidence and the spring force of the locking fingers  53 , and the inclination of their locking surfaces  54 , are configured such that, at a certain release force that tends to pull the insertion part  4  out of the receptacle part  2 , the locking fingers  53  leave their locked position and enter the aperture  12  in the rear wall  11 . If a fastened trim part is pushed away from the car body part, for example by deployment of an airbag, with a higher force of this nature, then in consequence the first fastening state brought about by the locking fingers  53  is released, and the insertion part  4  is displaced out of the first fastening state into the second fastening state shown in  FIG. 8 . 
     During this displacement, the clamping sections  26  pressed against the braking surfaces  57  with a force are carried along by the movement of the insertion part  4 , during which process they enter the receiving aperture  3  and come into contact with the edge of the receiving aperture  3  by means of the wedge surfaces  28 . In the process, the resilient arms  40 ,  41  and their retaining fingers  42  slide out of the apertures  43 . Since the clamping sections  26  are braced against the edge of the aperture by the wedge surfaces  28 , they can now no longer follow the further movement of the insertion part  4 , so that the plug-in section  45  with the braking surfaces  57  slides along the clamping sections  26 , and due to its wedge shape, forces the clamping sections  26  apart in opposition to the resistance of the front wall  10  enclosing the receiving aperture  3 . As a result, the housing  6  is deformed, and a clamping force that presses the clamping sections  26  against the braking surface  57  comes into being that increases with the progressive movement of the insertion part  4  and produces a continuously increasing braking action. As the braking forces increase, so does the force that loads the clamping sections  26  in the axial direction, with the result that the clamping sections can travel further into the receiving aperture  3 , which likewise contributes to an increase in the clamping forces and hence in the braking action. 
     As a result of the interaction of the above-described means, a considerable portion of the energy displacing the insertion part is converted into deformation work and frictional heat, so that impact forces occurring when the second fastening state shown in  FIG. 8  is reached are substantially reduced. In this fastening state, the insertion part  4  is securely retained in the receptacle part  2  at the locking surfaces  51  by the wedged clamping sections  26 . 
       FIGS. 9 through 14  show another fastener  101  according to the invention for attaching trim parts that cover an airbag in the passenger compartment of a motor vehicle. The fastener  101  consists of three plastic parts, namely a receptacle part  102  composed of two identical parts  103 , and an insertion part  104 . 
     The insertion part  104  has an elongated shaft with a rectangular, plate-like flange  105 , which divides the shaft into a plug-in section  106  that can be inserted into the receptacle part  102  and a fastening section  108  that is provided with a T-shaped head  107  at its free end. The head  107  is intended for fastening to a trim part that has a pocket or a keyhole-like aperture for accommodating the head  107 . The plug-in section  106  has a front insertion section  109  and a rear guide section  110 . The guide section  110  takes the form of a rectangular plate and is reinforced at its edges extending in the longitudinal direction by integrally molded guide strips  111  that are wider than the thickness of the plate, so that a recess is formed on both sides of the plate between the guide strips  111 . At the end distant from the flange  105 , the guide section  110  has a wedge-shaped braking section  112  that joins the ends of the guide strips  111  and that has, on mutually opposite sides, wedge surfaces  113  whose mutual spacing decreases as the distance from the flange  105  decreases. 
     The front insertion section  109  adjoins the braking section  112  with a plate-like connecting piece  115  on the side facing away from the wedge surfaces  113 . The connecting piece  115  has a smaller width than the guide section  110 . Integrally molded on the free end of the connecting piece  115  is a support section  116  that extends past the side surfaces of the connecting piece  115 , where it bears on each side a pair of locking fingers  117  that extend so as to diverge in the direction of the guide section  110 , and are resiliently deflectable toward one another. The locking fingers  117  have at their ends a locking surface  118  and a projection  119  with which they can be braced on the edge of an aperture. 
     The receptacle part  102  is composed of the two identical parts  103 , which can be assembled in a rotationally symmetric arrangement. Each part  103  consists of a rectangular, flat plate  121  that has a pair of catches  123  on the top  122 . The catches  123  are arranged on the short sides of the plate and consist essentially of a rigid arm  124  projecting vertically from the plate and a flexible locking finger  125  extending at an acute angle from the free end of the rigid arm  124  toward the top  122 . The locking fingers  125  are each located on the sides of the catches  123  facing one another, and have locking surfaces at their ends that are slightly inclined toward the top  122 , as can be seen in  FIG. 11 . 
     The end sections of the plate  121  on which the catches  123  are arranged are implemented as flat, rectangular tubes  126 ,  127  that are raised on the underside of the plate where they form flat supporting surfaces  128 . One tube, the tube  126 , is open at both ends. The tube  127  is closed at one end by a fastening tenon  129  that projects laterally from the plate  121  and that can be inserted into the tube  126  of the respective other receptacle part  103  and that has a locking finger  130  that can latch into a locking recess in the tube  126 . The two parts  103  shown in  FIG. 9  can thus be connected to form the receptacle part  102  by inserting their fastening tenons  129  into the tubes  126  of the respective other part  103 , as shown in  FIG. 12 . 
     On the connection side, the part  103  has a recess  132  by means of which one half of the receiving aperture for accommodating the insertion part  104  in the receptacle part  102  is formed. Located at the edge of the recess  132 , on the underside of the plate  121 , is a frame  133  projecting vertically therefrom; arranged in the frame aperture thereof is a resiliently deflectable locking tab  134 . On its side facing the plate  121 , the locking tab  134  has a locking surface  135  and a stop rib  136  adjacent to the locking surface. 
       FIG. 12  shows the fastener  101  in a position prepared for installation. The parts  103  are connected to one another, and form the receptacle part  102 . In the receiving aperture of the receptacle part  102  that is formed by the recesses  132  of the two parts  103 , the insertion part  104  has been inserted until its flange  105  rests against the top  122 . The catches  123 , which pass over the edges of the flange  105  during insertion, rest with their locking fingers  125  on the edges of the flange  105 , and thereby secure the insertion part  104  on the receptacle part  102 . The plug-in section  106  of the insertion part  104  projects out of the receptacle part  102  on the underside. 
     In order to attach a trim part to a support part, the fastener  101  can either be assembled first with a trim part and then with the support part, or can be assembled in the reverse order. The head  107  of the insertion part  104  serves to fasten the trim part. Fastening in the support part is accomplished with the aid of the receptacle part  102 . As is shown in  FIG. 13 , the support part  140 , which takes the form of a thin-walled plate or sheet, is provided with a rectangular aperture  141  into which the fastener  101  is inserted with the plug-in section  106  foremost. After the receptacle part  102  and the insertion part  104  have been connected to one another, the frames  133  on the two parts  103  of the receptacle part  102  are located at the guide section  110  in the recesses between the guide strips  111 , and are likewise inserted all the way through the aperture  141  of the support part  140 . The locking tabs  134  located on the frame  133  are pressed toward the insertion part  104  during the insertion process by the edge of the aperture  141  and spring back to their initial position when the receptacle part  102  rests against the support part  140 . During this process, the stop ribs  136  strike the edge of the aperture  141 , thereby producing a clicking sound that indicates the correct seating of the fastener  101  in the support part  140 . The locking tabs  134  come into engagement with the rear edge of the aperture  141  of the support part  140 , thereby securing the fastener  101  on the support part  140 . 
       FIG. 13  also shows that the side of the frame  133  to which the locking tab  134  is affixed rests on the wedge surface  113  of the braking section  112 . Therefore, the locking tab  134  can also brace against the braking section  112  when it is loaded by a force that tends to pull the fastener  101  out of the aperture  141 . 
     The catches  123  that retain the insertion part  104  on the flange  105  are designed such that they can slide off the flange  105  when a certain release force pulls on the insertion part  104 . Release should be possible so that a trim part attached to the insertion part  104  can be lifted away from the support part  140  by deployment of an airbag. If this case occurs, the insertion part  104  is displaced relative to the receptacle part  102  and support part  140  into the position shown in  FIG. 14 . During displacement, the mutually opposing wedge surfaces  113  of the wedge-shaped braking section  112  are pressed against the sides of the frame  133  that are braced against the support part  140  by the locking tabs  134 . The displacement of the insertion part  104  is braked by the resistance produced hereby, with which the sides of the frame  133  oppose the displacement of the braking section  112 . In this process the braking section  112  presses the frames  133  apart in opposition to their resistance, and its bottom edge arrives in the region of the aperture  141 , with it pressing the free ends of the locking tabs  134  and their stop ribs  136  against the inside edge of the aperture  141 . At the same time, the locking fingers  117  at the free end of the insertion part  104  reach the support part  140  and secure the insertion part  104  in the displaced position on the support part  140 . In this process, the locking fingers  117  engage with the aperture  141  by means of the projections  119 , and are thereby secured in their locking position. The insertion part  104  is now securely fixed to the support part  140  in this displaced position and can thus prevent the trim part attached to it from being hurled away by the airbag. 
     Although exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.