Abstract:
A clip for holding first and second parts together snaps into an opening in a first part and includes a central housing for receiving and retaining a male portion on a second part using catches. The clip has a spring structure allowing sideways displacement of the catches so that it occupies either a locked position in which it projects into the central housing to prevent axial movement of the male portion, or a position of release of the male portion in which it is withdrawn from the central housing. The clip also includes a mechanism for causing the catches to move to their locked positions automatically by snapping the clip onto the first part.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a U.S. National Phase Patent Application based on International Application Serial No. PCT/EP2009/003208 filed May 5, 2009, the disclosure of which is hereby explicitly incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a clip for holding a first and a second part together. 
     2. Description of the Related Art 
     These types of mounting clips find numerous applications, in particular in the automotive industry for mounting two pieces of equipment together. In particular, the clip can be used for mounting trim on an element of the vehicle structure. This trim is visible inside the cabin and for esthetic reasons the mounting must be invisible. 
     A mounting clip of the above mentioned type is described in document EP1482184 in which the mounting clip comprises a summit base from which a pair of external lateral legs is extending and between which is placed a pair of internal lateral legs, also connected to the summit base. The flexible external legs comprise elements that snap in the opening of the first piece. Each internal leg, adjacent to an associated external leg, comprises a first portion connected to the summit base and is extended by a second portion which is bent backward towards the inside of the clip in direction of the summit base. Each second portion is composed of an inside directed folding zone and a blade with free lateral displacement. The blades of the two internal legs, directly opposite of each other, delimit between them a central space for axial insertion of a tang carried by the second piece. Each blade with free lateral displacement carries a catch element for the tang, pointing in direction of the central space in order to retain the tang inside the central space. The catch elements are projecting continually inside the central space, regardless of the status of the clip, in other words whether or not the clip is snapped in the first piece and whether or not the tang of the second piece is inserted in the central space. 
     Because of this projecting arrangement of the catch elements, the axial insertion of the tang of the second piece results in external deterioration of the tang, in the form of permanent superficial deformations such as cuts or scores, which are axially generated by the catch elements. The deterioration of the tang results in a less reliable mounting of the second piece, which becomes susceptible of vibrating and therefore a source of noise, even resulting in fortuitous detachment of the second piece. In addition, the force for installing the clip on the tang is high taking into account the interaction between the catch elements and the tang. 
     On the other hand, starting from the normal situation where the second piece is attached to the first piece by means of the clip in snapped position, any axial displacement of the tang (resulting from an axial force applied on the tang) provokes a corresponding axial withdrawal of the clip (thanks to the engagement of the catch elements in the tang) relative to the opening of the first piece. This axial movement of the clip is accompanied by a progressive withdrawal of the catch elements, involving reduced retention relative to the second piece. Therefore, the fastening of the clip to the second piece decreases progressively as soon as the clip starts to withdraw axially, notwithstanding that the clip is still snapped in the first piece. In other words, from the beginning of the axial withdrawal of the clip, the retention quality of the second piece by the clip decreases in inverse proportion to the value of the axial displacement of the clip, with as consequence reduced reliability of the mounting of the second piece, which is susceptible of vibrating and of becoming a source of noise. In case of voluntary disassembly of the mounting between pieces, sliding is even likely to occur between the clip and the mounting tang of the second piece. 
     SUMMARY OF THE INVENTION 
     The present invention provides a mounting clip which is easy to install and improves the mounting together of the parts, the clip having a first part with an opening in which the clip is snapped and the second part has a tang which is inserted in said opening, and the clip comprises: a summit base; a pair of external lateral legs which are elastically returned in lateral direction towards the outside of the clip, after axially inserting said external legs in the opening in order to engage the external legs and to ensure that the clip is snapped in the first piece; a pair of internal lateral legs, each adjacent to an associated external leg and delimiting, in combination with the summit base, a central space in which the tang is axially inserted between the internal legs; and a catch element carried by each internal leg in direction of the central space for retaining the tang in the central space. 
     The mounting clip according to the invention is remarkable in that each internal leg comprises elastic means for the lateral displacement of the corresponding catch element, in order to occupy selectively a locking position projecting inside the central space for axial blocking of the tang, or a release position where the tang is withdrawn from the central space, and in that the clip is provided with means for actuating the displacement of the catch elements towards their locking positions, which is commanded automatically by snapping the clip in the first piece. 
     The interlocking of the catch elements with the mounting tang occurs when the tang is already axially in place in the central space of the clip. The mounting is not causing any external deterioration and the forces for installing the clip on the tang are low. On the other hand, the locking position remains in effect as long as the clip is snapped in place, in other words as long as the snap action has not ended. The snap action only ends after a predetermined axial travel of the clip relative to the first piece. In this way, the connection between the clip and the second piece is firmly maintained at the start of the axial withdrawal of the clip. As long as the snap action of the clip in the first piece does not end, the locking position is maintained and the retention of the second piece remains complete and reliable and no vibration is possible between the two pieces. Since the locking position is maintained during a predetermined axial travel of the clip, the risk of sliding between the clip and the mounting tang of the second piece is eliminated in case of voluntary disassembly. 
     According to a preferred implementation mode, each internal leg comprises a first portion connected to the summit base and is extended by a second portion which is bent back towards the outside of the clip in direction of the summit base, each backward bent portion comprises an elastically deformable folding zone and a blade with free lateral displacement carrying the corresponding catch element. The folding zone ensures an arrangement in which the blade is partially inserted laterally between the first portion and the adjacent external leg, while laterally maintaining a part of the blade at the level of the snapping hook carried by said external leg. This kind of clip configuration constitutes a simple and reliable implementation mode of the lateral displacement means of the catch elements, and of the actuating means of the displacement towards their locking position. 
     Other technical characteristics can be used in isolation or in combination: each blade consists of a first section connected to the folding zone, pointing in axial direction of the clip, and a second section laterally inclined towards the inside of the clip when moving axially away from the summit base, the part of the blade held laterally at the level of the clipping hook is positioned along the first blade section; the first portion of each internal leg is provided with tang retention claws which are continually projecting inside the central space; the first portion of each internal leg is provided with a clearance opening for the catch element carried by said internal leg; each catch element has two teeth pointing laterally towards the inside of the clip and connected in transversal direction of the clip by a compression edge laterally curved towards the outside of the clip; and each compression edge has an auxiliary tooth pointing laterally towards the inside of the clip. 
     In one form thereof, the present invention provides a clip for holding a first and a second piece together, the first piece has an opening in which the clip is snapped and the second piece has a tang for insertion in the opening, the clip including: a summit base; a pair of external lateral legs returned elastically in lateral direction towards the outside of clip, after axial insertion of the external legs in the opening to engage the external legs and to ensure that the clip is snapped in the first piece; a pair of internal lateral legs, each adjacent to an associated external leg, and delimiting, in combination with the summit base a central space for axial insertion of tang between the internal legs; a catch element carried by each internal leg in direction of the central space for retaining the tang in the central space; and the clip is characterized in that each internal leg includes elastic elements for lateral displacement of the corresponding catch element, in order to occupy selectively a locked position projecting inside the central space for axial blocking of tang, or a tang release position away from the central space, and in that the clip is provided with actuating means for the displacement of the catch elements towards their locking positions, which are automatically commanded by snapping the clip in the first piece. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above mentioned and other features and objects of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is an isometric view of an example of a mounting clip according to the invention; 
         FIGS. 2 and 3  are examples respectively of second and first pieces to be assembled together by means of the clip of  FIG. 2 ; 
         FIG. 4  illustrates the second piece after the first assembly step; and 
         FIGS. 5 and 6  show the clip and the two pieces after the second assembly step. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. Although the exemplifications set out herein illustrate embodiments of the invention, in several forms, the embodiments disclosed below are not intended to be exhaustive or to be construed as limiting the scope of the invention to the precise forms disclosed. 
     DETAILED DESCRIPTION 
     In  FIGS. 1-6 , the illustrated mounting clip  10  has the shape of a saddle with two superimposed U&#39;s that overlap each other. The clip  10  consists of a summit base  11 , starting from which a pair of flexible external lateral legs  12 ,  13  are extending in axial direction D 1  of clip  10 , the legs are offset relative to each other in lateral direction D 2  of clip  10 . A second pair of internal lateral legs  14 ,  15 , offset relative to each other in lateral direction D 2 , is arranged between the external legs  12 ,  13 . The internal legs  14 ,  15  are approximately parallel to each other and are also pointing in axial direction D 1 . Legs  12  to  15  are all arranged in the same plane including the axial and lateral directions D 1 , D 2 . 
     Two pieces can be fastened together with mounting clip  10 ; these pieces can be, for instance, parts of an automotive vehicle. The pieces are indicated by reference numbers  19 ,  20 . The first piece  19  ( FIG. 3 ), which has the function of supporting the assembly, has an opening  21  in which clip  10  is axially engaged by snapping it in place. The second piece  20  ( FIG. 2 ) is clasped in the mounting clip  10 , prior to the step in which clip  10  is snapped in the first piece  19 . 
     The summit base  11  is in general U shaped, and comprises an intermediate portion  16  included in the lateral direction and in the transversal direction D 3  perpendicular to the other two directions. The lateral sides of the intermediate portion  16  are connected with upright edges  17 ,  18  in axial direction D 1 . 
     The external lateral legs  12 ,  13  are returned elastically in lateral direction D 2  towards the outside of clip  10 , after axial insertion of said external legs  12 ,  13  in opening  21  in order to engage the external legs  12 ,  13  and ensure that clip  10  is snapped in the first part  19 . For this purpose, each external leg  12 ,  13  comprises a hollow shaped clipping hook  22 ,  23 , connected to one of the corresponding upright edges  17 ,  18  by a flexible blade  24 ,  25  laterally inclined towards the inside of clip  10  when moving axially towards the summit base  11 . For each external leg  12 ,  13 , the clipping hook  22 ,  23 , which in its junction makes approximately a right angle with the associated flexible blade  24 ,  25 , constitutes a snap in place element that passes through the hard point on the edges of opening  21  of the first piece  19 . The lateral movement of hooks  22 ,  23  is specifically the result of the elastic deformation of flexible blades  24 ,  25 . 
     For each external leg  12 ,  13 , the junction zone between the upright edge  17 ,  18  of the summit base  11  and the corresponding flexible blade  24 ,  25  comprises two successive folds, offset in axial direction D 1  and with inverse curvature: a first fold is connected to the upright edge  17 ,  18  and pointing towards the inside of the clip  10 , and a second fold is connected to the flexible blade  24 ,  25  and pointing towards the outside of clip  10 . The combined presence of two successive folds has the effect of improving the distribution of mechanical stresses. 
     The internal lateral legs  14 ,  15 , each laterally adjacent to an associated external leg  12 ,  13 , are delimiting in combination with the summit base  11  a central space  26  for axial insertion, between the internal legs  14 ,  15 , of a retaining tang  27  in the form of a rib on the second piece  20 , which is inserted in opening  21 . As described further down, each internal leg  14 ,  15  is carrying a catch element  28 ,  29  pointing laterally towards the inside of clip  10  in the direction of the central space  26  in order to retain tang  27  in the central space  26 . 
     Each internal leg  14 ,  15  comprises a first portion connected to the summit base  11 , respectively referenced by  30 ,  31  for legs  14 ,  15 . Each first portion  30 ,  31  is extended by a second portion  32 ,  33  bent backwards towards the outside of clip  10  in direction of the summit base  11 . Each backward bent portion  32 ,  33  comprises an elastically deformable folding zone  321 ,  331  and a blade  322 ,  332  with free lateral travel carrying the corresponding catch element  28 ,  29 . 
     Each blade  322 ,  332  consists of a first section  322   a ,  332   a  connected to the folding zone  321 ,  331 , pointing approximately in axial direction D 1  of clip  10 , and a second section  322   b ,  332   b  laterally inclined towards the inside of clip  10  when moving axially towards the summit base  11 . 
     The folding zone  321 ,  331  ensures that blade  322 ,  332  is partially inserted laterally between the first portion  30 ,  31  and the adjacent external leg  12 ,  13 , and at the same time it ensures that part of the blade is positioned laterally at the level of the clipping hook  22 ,  23  carried by the adjacent external leg  12 ,  13 . The part of the blade positioned laterally at the level of the clipping hook, in other words in the same lateral plane as the back of the clipping hook  22 ,  23  carried by the adjacent external leg  12 ,  13 , is positioned along the first blade section  322   a ,  332   a , while the rest of the blade  322 ,  332 , specifically the second section  322   b ,  332   b , is laterally inserted precisely between the first portion  30 ,  31  and the adjacent external leg  12 ,  13 . The catch elements  28 ,  29  are arranged at the free extremities of the second sections  322   b ,  332   b . The portion of blade  322 ,  332  which is on the same level as the back of clipping hook  22 ,  23 , is held in place by a passage made laterally through the thickness of the back of clipping hook  22 ,  23 , avoiding any direct contact between said blade part and the clipping hook  22 ,  23 . 
     The curvature and the elasticity of the folding zones  321 ,  331 , combined with the elastic deformation of blades  322 ,  332 , has for result that each backward bent portion  32 ,  33  constitutes an elastic element for the lateral displacement of the corresponding catch element  28 ,  29 , so that the latter can selectively vary between a locking position ( FIGS. 5 and 6 ) projecting inside the central space  26  to axially block tang  27 , or a release position ( FIG. 4 ) in which tang  27  is retracted from the central space  26 , in other words outside space  26 . The blade parts maintained laterally at the level of the clipping hooks  22 ,  23  form actuating means for the displacement of catch elements  28 ,  29  towards their locking position; these actuating means are automatically commanded by the snapping action of clip  10  in the first piece  19 . In the release position, the catch elements  28 ,  29  are outside space  26  to release tang  27  and to make the latter axially retrievable from space  26 . 
     The associated internal legs  14 ,  15  and external legs  12 ,  13 , in other words directly adjacent legs, are situated at the same level in transversal direction D 3  of clip  10 . To allow each catch element  28 ,  29  to vary between its locking position and its release position, the first portion  30 ,  31  of each internal leg  14 ,  15  is provided with a clearance opening  34 ,  35  for the catch element  28 ,  29  carried by said internal leg  14 ,  15 . 
     The first portion  30 ,  31  of each internal leg  14 ,  15  is provided with retaining claws  36  for tang  27 . The retaining claws  36  are pointing towards the inside of the clip  10 . Since the central space  26  is laterally delimited by the first portions  30 ,  31 , which are directly opposite each other, the retaining claws  36  project continually inside the central space  36 , regardless of the status of clip  10 , in other words whether or not it is clipped in the first piece  19 , and whether or not the tang  27  of the second piece  20  is inserted in the central space  26 . The role of this type of retaining claws  36  is to keep tang  27  in place inside the central space at the moment of its axial insertion, by engaging claws  36  in the external faces of tang  27 . The tang  27  is held in place automatically by claws  36  to ensure the pre-assembly of the second piece  20  with clip  10  (first assembly step:  FIG. 4 ) before the displacement takes place of catch elements  28 ,  29  towards their locking position at the moment clip  10  is snapped on the first piece  19  (second assembly step:  FIGS. 5 and 6 ). 
     As shown on  FIG. 1 , each catch element  28 ,  29  has two primary teeth pointing laterally to the inside of clip  10 , which are offset relative to each other in transversal direction D 3 , and connected in transversal direction D 3  of clip  10  by a compression edge which is laterally curved towards the outside of the clip  10 . In the shown variant, each compression edge comprises an auxiliary tooth pointing laterally towards the inside of clip  10 . The extremity of the auxiliary tooth is offset towards the outside of clip  10  relative to the extremities of the main teeth. 
     The primary teeth and the curved compression edge have distinct functions. The pointed teeth constitute an aggressive zone in which the penetration of catch elements  28 ,  29  in tang  27  is rapidly initiated, while the role of the curved compression edges is to increase progressively the contact surface between the catch elements  28 ,  29  and tang  27 . The deep penetration of the primary teeth increases the mechanical retention of the assembly. The auxiliary tooth is used in case the material of tang  27  is relatively soft, and forms a safety element extenuating the weak mechanical resistance of tang  27 . 
     In a first assembly step ( FIG. 4 ), the tang  27  is axially inserted in central space  26 , between internal legs  14 ,  15 . Thanks to the pre-assembly retention claws  36  provided on the first portions  30 ,  31  of the internal legs  14 ,  15  that penetrate laterally in tang  27  during its axial insertion, clip  10  is automatically connected to the second piece  20 , but the axial retention is not yet maximum. 
     Then, in a second assembly step ( FIGS. 5 and 6 ), the axial insertion in opening  21  of first piece  19  of the external legs  12 ,  13  of clip  10 , accompanied by tang  27  of the second piece  20 , provokes a lateral approach of the external legs  12 ,  13 , more precisely clipping hooks  22 ,  23  move towards each other. This movement of hooks  22 ,  23  occurs by flexion of the flexible blades  24 ,  25 , and continues until the hard point is passed between blades  24 ,  25  and hooks  22 ,  23 . Beyond that, the elastic return of flexible blades  24 ,  25 , combined with the edge inclination of the hooks  22 ,  23  provokes axial sliding of clip  10  along the opening  21  until the clipping hooks  22 ,  23  of external legs  12 ,  13  engage in the edges of opening  21  of the first piece  19 . The dimensions of opening  21  in lateral direction D 2  are slightly smaller than the distance between the clipping hooks  22 ,  23  when the external legs  12 ,  13  are in their natural configuration, in other words free of outside stresses. In this way, when the hooks  22 ,  23  are engaged in the edges of opening  21 , the external legs  12 ,  13  are slightly deformed towards the inside of clip  10 , so that they are naturally returned towards the outside in permanent manner, ensuring that clip  10  snaps in the first piece  19 . 
     In complementary manner, the part of blade  322 ,  332  intended to be arranged laterally at the same level as the back of the clipping hook  22 ,  23  of the adjacent external leg  12 ,  13 , occupies this position specifically when said external leg  12 ,  13  is in its natural configuration. The result is that in snapped position of clip  10 , the parts of blades  322 ,  332  intended to be at the same lateral level as hooks  22 ,  23  are drawn closer together laterally (through deformation of the folding zones  321 ,  331  possibly combined with deformation of the blade  322 ,  332 ) at the same rate as clipping hooks  22 ,  23  are drawn closer together. This rapprochement of the parts of the first section  322   a ,  332   a  of blade  322 ,  332  provokes a rapprochement which is proportionally greater than the rapprochement of catch elements  28 ,  29 . 
     The insertion of catch elements  28 ,  29  in tang  27  takes place when tang  27  is already axially in place in the central space  26 . The assembly causes no deterioration. 
     Since the edges of hooks  22 ,  23  on the side of the junction to the flexible blades  24 ,  25  are inclined, in the assembled state they have the effect of creating permanent axial compression between pieces  19 ,  20 . If a force is applied axially on tang  27  tending to move pieces  19 ,  20  away from each other, the inclined edges of hooks  22 ,  23  provoke an automatic return of pieces  19 ,  20  against each other. During all or part of the axial displacement of the inclined edges of hooks  22 ,  23  along opening  21  before the inverse crossing of the hard point, in function of the length of the first section  322   a ,  332   a  of blade  322 ,  332 , the catch elements  28 , 29  remain in locked position. In this way, contrary to prior art, the mounting of clip  10  to the second piece  20  is firmly maintained at the beginning of the axial withdrawal of clip  10  relative to opening  21  of the first piece  19 . 
     For disassembly, sufficient axial force must be applied on tang  27  to cross the hard point between hooks  22 ,  23  and flexible blades  24 ,  25 . The snapping of clip  10  in the first piece  19  comes to an end at the moment that the hard point is passed, and the catch elements  28 ,  29  return elastically to their positions in which tang  27  is released. 
     As an example, clip  10  is made by cutting and bending sheet metal with relatively small thickness, which underwent suitable heat treatment to give it elastic properties. The second piece  20  and more specifically retaining tang  27  are made of a softer material than the catch elements  28 ,  29  of clip  10  in order to allow the primary and auxiliary teeth of the latter to dig into the material of tang  27 . For instance, the selected material can be an injectable thermoplastic material. 
     The V configuration of the flexible blades  24 ,  25  and of the second sections  322   b ,  332   b  facilitates the installation of the clip in the first piece  19 . On the other hand, in the proximity of the two backward bent portions, the first portions  30 ,  31  are laterally inclined towards the inside of clip  10  when moving closer to the summit base  11  in order to form a V facilitating the insertion of tang  27  in space  26 . 
     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.