Abstract:
A fastener ring ( 1   a ) for fastening to a rod ( 201   a ) on a support ( 200   a ), which fastener ring comprises both a body ( 2   a ) through which an axial orifice ( 3 ) passes that serves to receive said rod ( 201   a ), and flexible tabs ( 4, 5, 6 ) extending radially towards the main axis (A) of the axial orifice ( 3 ) and serving to co-operate with the rod ( 201   a ) to hold it stationary axially, the flexible tabs ( 4, 5, 6 ) including a set of star-shaped tabs ( 4 ), each of which comprises a tongue ( 40 ) secured to the body ( 2   a ), and extended by a star-shaped head ( 41 ) made up of a rounded radial tip ( 42 ) and of two radially rounded side cheeks ( 43 ) remote from the body ( 2   a ), the width (L 2 ) of the tongue ( 40 ) being less than the maximum width (L 1 ) of the star-shaped head ( 41 ). An assembly comprising a part for assembly ( 100   a ) that is provided with such a fastener ring ( 1   a ) for fastening to a support provided with at least one rod.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates generally to the field of temporary fastening, and in particular to temporarily fastening a fuel tank to a rod secured to a motor vehicle chassis before the tank is fastened permanently. The invention relates more particularly to a fastener ring for fastening to a rod, which fastener ring comprises both a body through which an axial orifice passes that serves to receive the rod, and flexible tabs extending radially from the body towards the main axis of the axial orifice and serving to co-operate with the rod to hold it stationary axially relative to the fastener ring. The invention also relates to an assembly comprising a part for assembly as assembled to a support that is provided with at least one rod. 
       PRIOR ART 
       [0002]    Numerous fastener rings of this type exist. 
         [0003]    Publication DE 20 2007 013 238 describes a fastener ring that, in one of its versions, has a set of six first flexible tabs provided at an axial end of the body and one or more sets of four second tabs that are axially offset relative to the first tabs. The free ends of the second tabs are C-shaped or V-shaped, with the recesses of these shapes extending radially and with the ends of these shapes forming spikes serving to engage in the threads or notches of a threaded or notched rod so as to hold it stationary axially. When using that fastener ring, the central axis of the rod necessarily coincides with the main axis of the ring. Thus, in order for the fastener ring to be capable of receiving the rod and of locking it, the central axis of the rod needs to be accurately positioned, which is incompatible with the dimensional dispersions related to methods of manufacturing tanks made of plastics materials. 
         [0004]    Publication JP 2005 076 646 describes a fastener ring that is provided with a set of four flexible tabs and that suffers from the same drawbacks as the preceding publication. 
         [0005]    Publication EP 1 472 464 describes a fastener ring that has two flexible tabs, each of which has a plurality of notches extending transversely and perpendicularly to the main axis of the fastener ring and in a radial plane. Thus, that fastener ring can accommodate dispersion of the transverse position of the rod in one direction only. As a result, that fastener ring does not make it possible to provide a fully satisfactory solution to the problem encountered. 
       SUMMARY OF THE INVENTION 
       [0006]    An object of the invention is to remedy those drawbacks by proposing a fastener ring that is easy to manufacture, that accepts dispersions in the positioning of the central axis of the rod to be held relative to the positioning of the main axis of the fastener ring, and that makes it possible to achieve effective temporary fastening of a part for assembly to a support. 
         [0007]    To this end, the invention provides a fastener ring for fastening to a rod on a support, which fastener ring comprises both a body through which an axial orifice passes that serves to receive the rod, and flexible tabs extending radially from the body towards the main axis of the axial orifice and serving to co-operate with the rod to hold it stationary axially relative to the fastener ring, the fastener ring being characterized in that the flexible tabs include a set of star-shaped tabs, each of which comprises a tongue secured to the body, and extended by a star-shaped head made up of a rounded radial tip and of two radially rounded side cheeks remote from the body, the width of the tongue being less than the maximum width of the star-shaped head as measured between the furthest apart edges of its side cheeks. 
         [0008]    The basic idea of the invention is to use a ring in which the shape of its star-shaped fins facilitates contact with the rod and allows the rod to take up an axial position that is offset relative to the main axis of the fastening ring. The fact that the radial cheeks are wider than the tongue creates a space, behind the radial cheeks, that can receive the rod when said rod is offset axially. 
         [0009]    The fastener ring of the invention may advantageously have the following features:
       the radial tip is connected to each side cheek via a curved and concave setback; this setback makes it possible to increase the contact surface area between the fastener ring and the rod when the central axis of the rod is offset axially relative to the main axis of the fastener ring;   the radial tip forms a fold relative to the tongue and to the side cheeks so as to have an inclination that is accentuated relative to said main axis; this fold facilitates engagement of the radial tip into the notches or threads of the rod;   the flexible tabs include a set of first additional tabs that are offset angularly from the star-shaped tabs relative to the main axis, and offset axially from the star-shaped tabs along the main axis;   the flexible tabs include a set of second additional tabs that are offset axially from said first additional tabs; the first and second sets of additional tabs make it possible to occupy the axial orifice to the maximum possible extent; thus, regardless of the axial position of the rod, said rod co-operates with one or the other of the flexible tabs, making it possible to guarantee temporary fastening between the rod and the fastener ring;   the flexible tabs of at least one of the sets has a radial length that is different from the radial length of the flexible tabs of another set; thus, the potential contact points at which the fastener ring is in contact with the rod are at variable distances from the main axis of the fastener ring, thereby increasing the number of possible axial positions for the rod;   the flexible tabs of at least one of the sets are mutually coplanar; and   the free ends of the star-shaped tabs are situated in a main contact plane, and the free ends of at least the first additional tabs or of at least the second additional tabs are situated in a contact plane that is distinct from the main contact plane, namely, respectively, a first contact plane or a second contact plane.       
 
         [0017]    The invention also provides an assembly comprising a part for assembly as assembled to a support that is provided with at least one rod, the assembly being characterized in that the part for assembly is secured to at least one fastening ring according to any preceding claim, the fastening ring being engaged over the rod so as to fasten the part for assembly to the support. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The present invention can be better understood and other advantages appear on reading the following detailed description of two embodiments given by way of non-limiting example and with reference to the accompanying drawings, in which: 
           [0019]      FIG. 1  is a perspective view of a first embodiment of a fastener ring of the invention; 
           [0020]      FIG. 2  is a view from above of a detail of a star-shaped tab of the fastener ring of  FIG. 1 ; 
           [0021]      FIG. 3  is a fragmentary side view in section of the fastener ring of  FIG. 1 ; 
           [0022]      FIGS. 4A to 4E  are views from above showing various positions of the rod in the fastener ring of  FIG. 1 ; 
           [0023]      FIG. 5  is a perspective view of a second embodiment of a fastener ring of the invention; 
           [0024]      FIGS. 6 and 7  are views respectively in cutaway perspective and from above of the fastener ring of  FIG. 5 ; and 
           [0025]      FIGS. 8 and 9  are views of assemblies of the invention that are formed respectively with the first and with the second embodiments of the fastener ring, the fastener rings being shown in bold black lines. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0026]    The fastener ring of the invention makes it possible to fasten a part for assembly, e.g. a fuel tank, to a support, e.g. a motor vehicle chassis. In order to facilitate the steps of assembling the tank to the chassis, the tank may be fastened temporarily to the chassis pending final fastening thereto. For this purpose, the chassis is provided with a rod that may be smooth, threaded, or notched, and the tank is provided with the fastener ring described below, which fastener ring is suitable for receiving and locking the rod. 
         [0027]    In a first embodiment shown in  FIGS. 1 to 4E  and  8 , the fastener ring  1   a  of the invention has a substantially cylindrical body  2   a  through which an axial orifice  3  passes that extends along the main axis A. The body  2   a  is formed by a substantially cylindrical bushing  20   a  and by a radial flange  21   a  that is integral with or secured to a first end of the bushing  20   a  and that extends outwards from the axial opening  3 . As described in detail below, the radial flange  21   a  enables the fastener ring  1   a  to be secured, for example to a tank, by any known suitable means. 
         [0028]    The second end of the bushing  20   a  is provided with three star-shaped tabs  4  that are substantially mutually similar, and that extend towards the main axis A. In addition, the star-shaped tabs  4  are inclined towards the inside of the bushing  20   a,  and are angularly distributed around the periphery of the bushing  20   a  about the main axis A. As described in detail in  FIG. 2 , each star-shaped tab  4  is made up of a tongue  40  secured to the bushing  20   a  and extended by a star-shaped head  41 . Each star-shaped head  41  has a rounded radial tip  42  facing towards the main axis A and two rounded side cheeks  43  extending transversely on either side of the tongue  40 . Thus, the maximum width L 1  of the star-shaped head  41  as measured between the furthest apart edges of the side cheeks  43  is greater than the width L 2  of the tongue  40 . 
         [0029]    The radial tips  42  are inclined relative to the tongue  40  along a fold line U so as to have an angle of inclination that is greater relative to the main axis A and that facilitates cooperation with the rod (not shown in  FIG. 2 ). The radial tip  42  is also connected to each side cheek  43  by a curved and concave setback  44  that also facilitates cooperation with the rod. As shown in  FIG. 3 , prior to assembly, the radial tips are aligned in a main contact plane P that is perpendicular to the main axis A. 
         [0030]    The second end of the bushing  20   a  is also provided with three first additional tabs  5  that are substantially mutually similar, and that extend towards the main axis A. The free end of each first additional tab  5  is rounded. The first additional tabs  5  are also inclined towards the inside of the bushing  20   a.  They present a radial length that is less than the radial length of the star-shaped tabs  4  between which they are angularly interposed. Thus, as shown in  FIG. 4A , the distance D 1  between the free ends of the first additional tabs  5  and the main axis A is greater than the distance D between the free ends of the star-shaped tabs  4  and the same main axis A. This difference in radial length and the angular offset contribute to the possibility of the rod taking up different axial positions that are described in detail below. Prior to assembly, the free ends of the first additional tabs  5  are aligned in a first contact plane P 1  that is perpendicular to the main axis A and that is distinct from the main contact plane P. 
         [0031]    Between its first and second ends, the bushing  20   a  is also provided with three second additional tabs  6  that are substantially mutually similar, and that extend towards the main axis A. The second additional tabs  6  are also inclined towards the inside of the bushing  20   a  and they are obtained by cutting and folding the wall of the bushing  20   a.  The second additional tabs  6  are of radial length that is slightly less than the star-shaped tabs  4  and that is greater than the length of the first additional tabs  5 . Thus, the distance D 2  between the free ends of the second additional tabs  6  and the main axis A is greater than the distance D between the free ends of the star-shaped tabs  4  and the main axis A, and less than the distance between the free ends of the first additional tabs  5  and the same main axis A. This difference in radial length contributes to the possibility of the rod taking up the different axial positions. The second additional tabs  6  are angularly aligned with the first additional tabs  5 . The free end of each second additional tab  6  is rounded. Prior to assembly, the free ends of the second additional tabs  6  are aligned in a second contact plane P 2  that is perpendicular to the main axis A and that is distinct from the main contact plane P and from the first contact plane P 1  so that the main contact plane P is situated between the first contact plane P 1  and the second contact plane P 2 . 
         [0032]    The layout of the star-shaped tabs  4 , of the first additional tabs  5  and of the second additional tabs  6  may be different. Thus, the second additional tabs  6  may be angularly aligned with the star-shaped tabs  4 . In addition, the number of star-shaped tabs  4 , of first additional tabs  5  and of second additional tabs  6  may be different. Provision may also be made for the second additional tabs  6  to be shorter than the first additional tabs  5 . 
         [0033]    In the second embodiment shown in  FIGS. 5 to 7  and  9 , the fastener ring  1   b  of the invention has a body  2   b  through which an axial orifice  3  passes that extends along the main axis A. The body  2   b  is formed of a folded plate, the first and second branches  20   b,    21   b  of which define a right-angled V-shape. The axial orifice  3  passes through the first branch  20   b,  and the second branch  21   b  makes it possible to secure the fastener ring  1   b,  e.g. to the tank, by any known suitable means. 
         [0034]    The first branch  20   b  is provided with three star-shaped tabs  4  that are substantially similar to the preceding ones, and that extend from the axial orifice  3  towards the main axis A. In addition, the first branch  20   b  is provided with three first additional tabs  5  and with three second additional tabs  6  that are substantially similar to the preceding ones, and that are disposed in similar manner. 
         [0035]      FIGS. 8 and 9  show two assemblies  10   a,    10   b  obtained with respective ones of the first and second embodiments of the fastener ring  1   a,    1   b  of the preceding figures. In the examples, each of the assemblies is made up of a fuel tank  100   a,    100   b  assembled to a chassis  200   a,    200   b  of a motor vehicle. The chassis  200   a,    200   b  is provided with rods  201   a,    201   b,  e.g. of the pin type, that are fastened by welding. Thus, the rods  201   a,    202   b  can be positioned accurately. The rods  201   a,    201   b  are fastened perpendicularly to the surface of the chassis  200   a,    200   b.  The tank  100   a,    100   b  has large dimensions and is a made of a plastics material. Thus, it has large dimensional dispersions. 
         [0036]    In order to produce one or other of the assemblies  10   a,    10   b,  the procedure is as follows. During a first step, the tank  100   a,    100   b  is equipped with a plurality of a fastener rings  1   a,    1   b  in such a manner that the theoretical positions of the fastener rings  1   a,    1   b  coincide as closely as possible with the positions of the central axes B of the rods  201   a,    201   b  when the tank  100   a,    100   b  is in its predetermined position relative to the chassis  200   a,    200   b.  Due to the dimensional dispersions, the main axes A of the fastener rings  1   a,    1   b  are often offset relative to the theoretical positions and thus relative to the central axes B of the rods  201   a,    201   b.  During a second step, the tank  100   a,    100   b  is placed in its predetermined position by engaging the rods  201   a,    201   b  into the fastener rings  1   a,    1   b.  This engagement is made possible by the specific construction of the fastener rings  1   a,    1   b  that accept axial offsetting of the rods  201   a,    201   b  relative to their respective main axes A. The tank  100   a,    100   b  is thus pre-held on the chassis  200   a,    200   b  and can then be transferred to another workstation at which it is fastened permanently to the chassis  200   a,    200   b,  e.g. by means of screws. 
         [0037]    When the rod  201   a,    201   b  is threaded or notched, co-operation between it and the star-shaped tabs  4 , and between it and the first and second additional tabs  5 ,  6  is reinforced by their ends engaging between the threads or notches of the rod  201   a,    201   b.  The resulting assembly  10   a,    10   b  thus has improved resistance to being torn apart. 
         [0038]    In the example shown in  FIG. 8 , the chassis  200   a  is provided with a threaded rod  201   a.  The fastener ring  1   a  is received in an orifice passing through two creep rings  101   a  disposed on either side of damper rings  102   a  (or vibration-damping mountings) flanking an orifice  103   a  provided in the tank  100   a.  Thus, the radial flange  21   a  bears against one of the creep rings  101   a.  The resulting assembly  10   a  is consolidated by means of a nut  104   a  screwed onto the threaded rod  201   a,  beyond the fastener ring  1   a.    
         [0039]    In the example shown in  FIG. 9 , the chassis  200   b  is also provided with a threaded rod  201   b.  The second branch  21   b  of the fastener ring  1   b  is secured to the tank  100   b,  e.g. by welding. 
         [0040]    The special shape of the star-shaped tabs  4  and the presence and the positions of the first and second additional tabs  5 ,  6  make it possible to guarantee maximum contact between each fastener ring  1   a,    1   b  and the corresponding rod  201   a,    201   b,  when the rod  201   a,    201   b  is in a plurality of axial positions relative to the fastener ring  1   a,    1   b.    
         [0041]    When the dimensional dispersions are minor, then, after assembly, the rod  201   a  is in a central position as shown by  FIG. 4A . In this configuration, the main axis A of the fastener ring  1   a  and the central axis B of the rod  201   a  substantially coincide. When dimensional dispersions are greater, the rod  201   a  can be in any of the positions shown in  FIGS. 4B to 4E  or in any other position in which the main axis A of the fastener ring  1   a  and the central axis B of the rod  201   a  do not coincide. 
         [0042]    In the configuration shown in  FIG. 4B , the rod  201   a  is in contact with one star-shaped tab  4 , and with two second additional tabs  6  that co-operate to hold it. 
         [0043]    In the configuration shown in  FIG. 4C , the rod  201   a  is in contact with one star-shaped tab  4 , and with one second additional tab  6 . 
         [0044]    In the configurations shown in  FIGS. 4D and 4E , the rod  201   a  is in contact with two star-shaped tabs  4 , with one first additional tab  5 , and with one second additional tab  6 . 
         [0045]    The invention makes it possible to achieve the above-mentioned objectives. The fastener ring  1   a,    1   b  of the invention makes it possible to take up large dimensional disparities in the support and/or in the part for fastening. By way of indication, a fastener ring  1   a,    1   b  in which the dimensions of its body  2   a,    2   b  are approximately in the range 25 millimeters (mm) to 30 mm can thus accommodate an offset of 7 mm in the central axis B of a rod  201   a,    201   b  of diameter 8 mm relative to its main axis A. 
         [0046]    Naturally, the present invention is in no way limited to the above description of two of its embodiments, which can undergo modifications without going beyond the ambit of the invention.