Abstract:
A part retention system for mating parts comprises a pair of flexible guide ribs, integrated into a cap which is to be attached or interlocked. Each of the guide ribs incorporates one or more detents, which force the guide ribs apart as a tab on the mating component moves along the detents. The guide ribs having angled locating portions to direct the guide ribs over the tab to facilitate blind installation.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to systems for interlocking two parts, and more specifically, it relates to a part retention system for easily locating and affixing an end cap to a bracket of a slidably adjustable seat position adjuster. 
     BACKGROUND OF THE INVENTION 
     Retaining systems for interlocking mating parts of an assembly play an important role in the manufacture of many everyday items. Such systems are utilized in a wide variety of applications. Many industries, particularly the automotive industry, employ retaining systems to interlock parts of an assembly, secure ancillary components to a larger assembly, and add decorative or trim pieces to various more functional components. 
     For example, automotive manufacturers often add trim pieces to cover a seat adjuster mounting bracket and bolt. The trim cover enhances the overall appearance of the seat adjuster track, and also covers up any damaging sharp edges or protrusions of the bracket and/or attaching bolt. 
     Many types of retaining systems are known and disclosed in the prior art. For example, Japanese Patent 3-55331 discloses a retaining system including locking detents which are attached to a non-visible side of a cover. This type of arrangement exhibits two inherent drawbacks: a) unsightly sink marks can appear on the visible surface of a molded part due to the abundance of material concentrated in one area, and b) tolerances must be tightly controlled to maintain appearance and proper fit between the parts. 
     A retaining system disclosed in Japanese Patent 4-123739 utilizes detents formed on flexible ribs to lock to both sides of a tab. However, the locking tab has a triangular cross-section with a complex shape and the flexible ribs are connected at their ends. Product of this structure requires a complex manufacturing process. A retaining system which incorporates a dual detent locking device is disclosed in Japanese Patent 63-117619. This system requires a mating part having a cut out or separately inserted portion to interlock with a part incorporating the dual detents. 
     Thus, it would be desirable to provide a retaining system which minimizes the tolerance precision and the amount of material concentrated behind the visible surfaces of molded parts, resulting in cost savings per part. It would also be desirable to provide a retaining system which permits easy installation for areas of low clearance and which is self-locating. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is directed to a part retainer system for attaching an ancillary part to a component or part of an assembly. The part retainer includes a cap having a pair of flexible guide ribs formed on the inner surface of the cap. Detents extend from the guide ribs to engage a tab formed on the component to which the cap is attached. The guide ribs are deformable. At installation, the guide ribs slide along the tab to permit the detents to pass over the tab. Once the tab passes the detents, the ribs flex toward each other, such that the detents lock the tab in place, resulting in the secure attachment or interlocking of the components. 
     The present invention alleviates the concern for critical tolerance control, through application of flexible ribs which, by their nature, do not require the strict tolerances of the prior art in order to achieve the same objective. These ribs extend normally along the non-visible surface of the cap, allowing the detents, and their inherent high mass concentration, to be spaced away from the visible appearance-tuned surface. This arrangement reduces the potential in molded parts for unsightly sink marks. Moreover, the need for tight tolerances in the present invention is reduced because an imprecise fit between the guide ribs and locking tab on the mating part would be accommodated by a greater variable spacing between the flexible ribs. 
     The present invention combines all of the aforementioned advantages while bypassing the difficulties. The present invention incorporates self-locating features, secure retention, and efficient manufacture in a low-cost fashion by integrating the retention system directly into the attached or interlocked parts. The result is a retaining system with reduced costs, both in the manufacture and assembly of the interlocked parts. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The foregoing summary, as well as the following detailed description of preferred embodiments of the invention, will be better understood when read in conjunction with the appended drawings. It should be understood, however, that the invention is not limited to the precise arrangement and instrumentalities shown. In the drawings: 
     FIG. 1 is a perspective view of an automotive seat adjuster bracket end cap mounted in a vehicle in accordance with the invention; 
     FIG. 2 is a perspective view of the backside of the end cap in accordance with the invention; 
     FIG. 3 is an elevational view of the inside of the end cap in accordance with invention; 
     FIG. 4 is an elevational view of the inside of the end cap piece as engaged with the automotive seat adjuster rail in accordance with the invention; 
     FIG. 5 is a partial side view of the inside of the end cap in accordance with the invention; 
     FIG. 6 is a partial perspective view of the end cap with detents engaging the bracket; 
     FIG. 7 is a section view of a bracket supporting a lower rail of a seat adjuster; 
     FIG. 8 is a perspective view of the bracket in accordance with the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A part retaining system  10  for attaching a cap  12  to a structure is shown in FIG.  1 . The preferred embodiment of the retaining system  10  is shown for attaching the cap  12  to a bracket  14  supporting a lower rail  16  of a seat adjuster mechanism of a vehicle (FIGS. 7,  8 ). An upper rail  17  is mounted beneath a seat  18  to selectively slide within the lower rail  16  (FIG.  4 ). 
     As shown in FIG. 1, the cap  12  is mounted to the bracket  14  (shown in FIGS. 7 and 8) which is bolted to a transmission tunnel  20 . The retaining system  10 , however, can be used to mount caps in other positions or arrangements, such as to a bracket which is mounted to the floor. As shown in FIG. 8, the bracket  14  is formed of metal and has a tab  54  and a bracket extension portion  56  adapted to engage the cap  12 . The tab  54  extends from an arm  55  extending beneath a transverse portion  57  of the bracket which supports the lower rail  16  of the seat adjustment mechanism. 
     As shown in FIGS. 2-5, the cap  12  is unitarily formed of a suitable moldable material such as thermoplastic. The cap  12  has an end wall  22  and a side wall  24  which are formed in a generally L-shape. The side wall  24  extends parallel with the transmission tunnel  20  beneath the seat  18 . The side wall  24  has an upper wall portion  26  extending downwardly to an intermediate wall  28  which extends horizontally beneath the lower track  16  to a vertically extending lower wall portion  30 . An open channel  32  is formed to extend inwardly from the end wall  22  to freely receive the rail  17 . The channel  32  is formed by a transverse lower wall  34  extending between an inner surface  36  of the side wall  24  and a vertical wall  38 . A flange  40  extends from the side wall  24  towards a flange  41  extending from the vertical wall  38  to extend partially over the rails  16 ,  17  as shown in FIG.  4 . 
     As shown in FIG. 3, a pair of guide ribs is formed on the inner surface of the lower wall portion  30  to guide the cap  12  on the tab  54  during installation. Each guide rib  52  extends from the wall portion  30  to an edge  70 . Each guide rib  42  extends from an outer end  45  extending from a front edge  47  of the cap  12  to an inner end  48  which is spaced apart from the end wall  22 . The spacing of the inner end  48  away from the side wall  22  permits ready deformation of the guide ribs  42  as the tab  54  passes between a pair of detents  50  located adjacent the inner ends  48  of the guide ribs  42 . Each guide rib  42  has a locating portion  44  extending from the outer edge  45  to an intermediate portion  46 . The locating portions  44  converge towards each other from the angle of 25° to 35° to receive and direct the tab  54  of the bracket  14  into the space formed by the intermediate portions  46  of the guide ribs  42 . The intermediate portions  46  converge slightly from the locating portions  44  to the width of the tab  54  at the detents  50 . 
     As shown in FIGS. 3-6, each detent  50  has a ramp  57  which angles outwardly from a front edge  58  towards a rear edge  60 . As shown in FIG. 6, a pair of L-shaped fingers  52  are positioned between the guide ribs  42  and extend outwardly from the inner surface of the end wall  22  and side wall  30 . Each finger  52  has an edge  53  which is spaced from the rear edge  60  of the detent a distance “d” generally equal to a thickness “t” of the tab  54  (FIG.  6 ). The edges  53 ,  60  thus hold the tab  54  securely. 
     As shown in FIG. 2, a secondary positioning mechanism  64  is formed on the inner surface  34  of the intermediate wall portion  28  and inner surface of the upper wall portion  26  of side wall  24 . The secondary positioning mechanism  64  includes a guide wall  66  and four spaced apart support walls  68 . The guide wall  66  extends upwardly from the intermediate wall portion  28  and is angled inwardly from the front edge  47  towards the upper portion  26  of the side wall  24 . The support walls  68  are spaced apart parallel and extend upwardly from the intermediate portion transversely to the longitudinal axis of the guide ribs  42 . The support walls  68  have flat upper surfaces  70  spaced inwardly from arms  72  formed on outer edges  74  of the support walls. The guide wall  66  centers and guides cap  12  over the bracket extension portion  56 . The arms  72  abut the bracket extension  56  to hold the cap  12  in the transverse direction. 
     INSTALLATION 
     The cap  12  is positioned with the front edge  47  adjacent the bracket  14  with the tab  54  between the locator portions  44  of the guide ribs  42  and the bracket extension portion  56  abutting the guide surface  66 . 
     The guide ribs  42  and guide wall  66 , as well as the flanges  40 ,  41  and surfaces of the U-shaped channel guide the cap as it is slid toward the front of the vehicle. The tab  54  engages the ramps of detents  50  and displaces the detents and guide ribs outwardly until the detents  50  snap inwardly after the tab  54  passes the rear edge  60  of the detent to fix the tab  54  in position. The snap permits the installer to know the cap  12  is in position. Because the inner ends  48  of the guide ribs  42  are free and not attached, the ribs  42  deform to permit easy passage of the tab  54  through the detents  50 . At the same time, the secondary positioning mechanism  64  is aligning the cap  12 . After installation, the arms  72  of the support walls  68  hold the cap  12  from transverse dislocation from the bracket  14 . Thus, the cap  12  is easily installed. The guide ribs  42  and guide wall  66  center the cap  12  during installation and together with the snap permit a “blind” assembly which is easily accomplished. 
     The retaining system  10  of the present invention securely retains the cap  12  in position when subjected to external forces, such as cleaning instruments and movement from passenger&#39;s feet. Thus is provided a cap with a retaining system that may be easily installed and inexpensively manufactured. 
     The discussion and examples hereinabove represent a specific embodiment of applications of the present invention. Within the guidelines given herein, one of skill in the art could readily recognize variations of the invention. Therefore, it is to be understood that the foregoing discussion, description and example are illustrative of a particular embodiment of the present invention but are not meant to be limitations upon the practice thereof. It is the following claims, including all equivalents, which define the scope of the invention.