Abstract:
An obturator for an opening of predetermined outline produced in a metal sheet comprising a cap, at least one stiff wall projecting transversely of said cap and at least one snap-fastening blade having a resting position in the absence of urging in which it extends in a direction parallel to said cap, said snap-fastening blade being moveable parallel to said cap against elastic return forces returning it towards said resting position, said snap-fastening blade having an insertion cant adapted to bear on the surface of said metal sheet delimiting said opening when the obturator is pushed therein, said insertion cant sloping relative to a direction transverse to said cap such that said snap-fastening blade is driven to displace to pass through said opening and that slope progressively increasing between said attachment end and said free end.

Description:
RELATED APPLICATIONS 
     The present application is national phase of International Application Number PCT/IB2009/051595 filed Apr. 16, 2009, and claims priority from, French Application Number 0852958 filed Apr. 30, 2008. 
     The invention relates to an obturator for an opening produced in a metal sheet, in particular in an automobile body metal sheet. 
     BACKGROUND 
     There is known already from French patent application 2 682 072 an obturator of this kind that includes a cap provided with a peripheral rim that comes to face the metal sheet at the border of the opening when the obturator is placed in it. A wall whose external surface has a shape corresponding to that of the opening is connected transversely to the peripheral rim. A number of lugs project from this wall, extending it. At the end of each lug a snap-fastening blade extends between an attachment end where it is connected to the lugs and a free end, parallel to the peripheral rim. Each snap-fastening blade has on the outside an insertion cant that is sloped as far as a step. 
     French patent application 2 707 233 also describes an obturator having the above features which further includes a fin disposed on the step of each snap-fastening blade and the exterior surface of which forms a gripping counter-cant. 
     The openings for which these obturators are provided are generally produced in the metal sheet by punching, and often have a rough peripheral border. It therefore often happens that the portions of this border in contact with the insertion cants dig into the blades instead of sliding over them and causing them to bend. 
     SUMMARY 
     The invention aims to improve the fitting of such an obturator into the opening. 
     To this end it proposes an obturator for an opening of predetermined outline produced in a metal sheet, comprising:
         a generally planar cap having a peripheral rim adapted to face said metal sheet around the border of the opening when the obturator is put in place therein;   at least one stiff wall transversely projecting from said cap; and   at least one snap-fastening blade having a resting position in the absence of urging in which it extends in a direction parallel to said cap, between an attachment end in which it is connected to said wall and a free end, said snap-fastening blade being moveable parallel to said cap against elastic return forces returning it towards said resting position, said snap-fastening blade having an insertion cant adapted to bear on the surface of said metal sheet delimiting said opening when the obturator is pushed therein, said insertion cant sloping relative to a direction transverse to said cap such that said snap-fastening blade is driven to displace to pass through said opening;       

     characterized in that the slope of said insertion cant relative to said transverse direction progressively increases between said attachment end and said free end. 
     The progressive increase in the slope of the insertion cant between the attachment end of the snap-fastening blade and its free end, by applying minimal force to the cap, produces the required displacement of the blade during the insertion phase. 
     Furthermore, this progressive increase reduces the risks of embedding of the border of the opening in the blade at the level of the cant, such variation enabling, compared to the cant of the prior art obturator where the slope is marked and constant, limiting the area of steep slope in proximity to the free end of the blade and enlarging the area in which the cant bears on the surface delimiting the opening. 
     According to features preferred for the performance that they achieve, said slope varies in predetermined manner in relation to said predetermined outline in order for each region in which said insertion cant is adapted to bear on said surface delimiting said opening when the obturator is pushed therein, to comprise a major part of the region of said cant which is then facing said surface delimiting said opening. 
     According to other features of the obturator preferred for reasons of simplicity and convenience as much in fabrication as in use:
         said snap-fastening blade is connected to said wall by a deformable elastic hinge formed on molding with said wall and said snap-fastening blade;   said snap-fastening blade is stiffer than said hinge such that it is essentially said hinge which deforms to drive the pivoting of said snap-fastening blade about said hinge when the obturator is pushed into said opening;   said hinge is bowed inwardly of said obturator;   the major part of said insertion cant forms a section of a helicoid;   said snap-fastening blade has a gripping counter-cant adapted to bear on said metal sheet when said blade is returned towards said resting position, said gripping counter-cant being oriented such that said cap is then driven towards said metal sheet;   said gripping counter-cant extends over a distal portion of said snap-fastening blade and has two portions with different slope angles relative to said direction transverse to said cap;   said predetermined outline being circular, said obturator is of circular general shape and comprises three said snap-fastening blades that are similar and that are evenly angularly distributed;   said slope varies in predetermined manner relative to said predetermined circular outline in order for each region in which said insertion cant is adapted to bear on said surface delimiting said opening when the obturator is pushed therein, to form an arc of a circle;   said obturator is adapted to a thickness of said metal sheet of between 0.5 and 5 mm;   said predetermined outline being oblong, said obturator is of oblong general shape and comprises two said planar walls, disposed facing each other, two said snap-fastening blades being connected on respective opposite sides of each planar wall;   said slope varies in predetermined manner relative to said predetermined oblong outline in order for each region in which said insertion cant is adapted to bear on said surface delimiting said opening when the obturator is pushed therein, to form a straight line;   said obturator comprises an annular bead of hot melt adhesive deposited on said peripheral rim, provided to melt when said metal sheet is heated after putting said obturator in place in said opening, in order for the obturator, after cooling, to be bonded to said metal sheet by bonding of said peripheral rim onto said border of the opening; and   said annular bead of hot melt adhesive is deposited on the face of said peripheral rim that is adapted to come to face said metal sheet.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure of the invention will now be continued with the description of two embodiments, given hereinafter by way of nonlimiting illustration with reference to the appended drawings, in which: 
         FIG. 1  is a top view of a metal sheet portion including a circular opening of predetermined diameter; 
         FIG. 2  is a perspective view, enlarged compared to  FIG. 1 , of a first embodiment of an obturator according to the invention, adapted to plug the opening represented in  FIG. 1 ; 
         FIG. 3  is a perspective view of the obturator from  FIG. 2  seen from another angle; 
         FIGS. 4 and 5  are respectively bottom and elevation views of the obturator from  FIG. 2 ; 
         FIGS. 6 ,  7  and  8  are the views in section of the obturator from  FIG. 2  respectively labeled VI-VI, VII-VII and VIII-VIII in  FIG. 4 , represented upside-down to facilitate comprehension; 
         FIG. 9  is a view similar to  FIG. 8  showing the obturator clipped into the opening in the metal sheet portion represented in  FIG. 1 ; 
         FIG. 10  is a top view of a metal sheet portion including an oblong opening of predetermined outline; 
         FIG. 11  is a perspective view, enlarged compared to  FIG. 10 , of a second embodiment of an obturator according to the invention, adapted to plug the opening represented in  FIG. 10 ; 
         FIGS. 12 and 13  are respectively bottom and elevation views of the obturator from  FIG. 11 ; 
         FIGS. 14 and 15  are the views in section of the obturator from  FIG. 11  respectively labeled XIV-XIV and XV-XV in  FIG. 13 ; and 
         FIG. 16  is the view in section of the obturator from  FIG. 11  labeled XVI-XVI in  FIG. 12 , represented upside-down to facilitate comprehension. 
     
    
    
     DETAILED DESCRIPTION 
     The metal sheet  8  illustrated in  FIG. 1  includes a circular opening  9  that can been plugged by a obturator put in place by simply pushing it in. The obturator  1  illustrated in  FIGS. 2 to 9  is adapted to plug such a predetermined opening  9  on offering it up facing the external face  7  of the metal sheet  8 . 
     The obturator  1  which adopts the general circular shape of the opening  9  includes a body  2  molded in one piece onto the periphery of which is deposited an annular bead  3  of hot melt type adhesive. 
     The body  2  includes a cap  4  and three curved stiff walls  10  that project transversely from its inside face. 
     The cap  4  has a circular outline and extends in a plane except in its central zone  4   a  and its peripheral rim  5 . 
     The central zone  4   a  forms a slight recess with a circular outline in order to facilitate the operations of molding the body  2 . 
     The peripheral rim  5  extends outwards with a slight slope, its inside face  6  being adapted to face the outside face  7  of the metal sheet  8  at the border of the opening  9  that is produced therein when the obturator  1  is put in place in the opening  9  ( FIGS. 1 and 9 ). 
     The bead  3  of hot melt adhesive is situated against the inside face  6  of this peripheral rim  5  whereas the three curved stiff walls  10  disposed in proximity to this same peripheral rim  5  ( FIG. 3 ) are evenly angularly distributed ( FIGS. 3 and 4 ). 
     The outside faces of the three curved walls  10  are centered on the axis  11  of the obturator  1  ( FIG. 5 ), with a radius of curvature substantially equal to that of the opening  9  in order to facilitate fitting this same obturator  1 . 
     On the inside of each curved wall  10 , a reinforcing rib  12  ( FIG. 3 ) extends transversely to this wall  10  from its beveled distal end  13  to the cap  4  of the obturator  1 . 
     A snap-fastening blade  14  is connected to a lateral edge  15  of each curved wall  10  via an elastic deformable articulation hinge  16 , the blade  14  and the hinge  16  being molded in one piece with the curved wall  10  ( FIGS. 2 and 4 ). 
     The blades  14  are similar, evenly angularly distributed and in the absence of urging assume a resting position in which each extends in a direction parallel to the cap  4 , between an attachment end  17  attached to the elastic hinge  16  and a free end  18  ( FIGS. 2 and 4 ). 
     The elastic hinges  16 , which have a double function of articulating the blades  14  to the curved walls  10  and of returning these same blades  14  into the resting position, are bowed inwardly of said obturator  1 . 
     They extend from the distal end  13  over approximately two-thirds of the length of the lateral rim  15  of the curved wall  10  ( FIG. 5 ). Alternatively, the length of the hinges  16  can vary as a function of the required return force. 
     The blades  14  will now be described in more detail. 
     Each of these blades  14  has on its outside face an insertion cant  21  that extends from the curved outside edge  22   a  of the beveled portion  22  of this blade  14  to a flat step  23  ( FIG. 5 ). 
     In its beveled portion  22 , and in the absence of urging, each blade  14  extends in line with the curved wall  10  so that the outside edge  22   a  is centered on the axis  11  and has the same radius of curvature as the outside faces of the three curved walls  10  ( FIG. 4 ). 
     The insertion cant  21  slopes relative to the axial direction  11  of the obturator  1  (or to a transverse direction of the cap  4 ) and this slope increases progressively between its attachment end  17  and its free end  18  (the evolution of the angle of slope being clearly visible in  FIGS. 6 to 8 ). 
     Thus at the attachment end  17  of the blade  14  (in proximity to the hinge  16 ), the insertion cant  21  is virtually parallel to the axial direction  11  of the obturator  1  whereas at the free end  18  of the blade  14  the insertion cant  21  forms an angle close to 45° with the same axial direction  11  of the obturator  1  ( FIG. 8 ). 
     In the embodiment represented in  FIGS. 2 to 9 , the major part (more than three-quarters) of the insertion cant  21  forms a section of a helicoid. 
     All the sections of this helicoidal section in a plane parallel to the cap  4  form a circular arc line of intersection the radius of curvature of which remains constant and substantially equal to that of the circular opening  9 . 
     Each blade  14  also has on its outside face a gripping counter-cant  24  that extends over a distal portion of this blade  14  and that is disposed above the step  23 , the insertion cant  21  and the gripping cant  24  being connected to each other. 
     The gripping counter-cant  24  comprises two portions  24   a  and  24   b , the first portion  24   a , which is the farthest from the cap  4 , forming a slightly less pronounced angle with the axis  11  than the second portion  24   b.    
     To put the obturator  1  in place in the opening  9  produced in the metal sheet  8 , it is offered up with the snap-fastening blades  14  to the front, the insertion cants  21  bearing on the surface of the metal sheet  8  delimiting the opening  9  when the obturator  1  is pushed into it. 
     Because the blades  14  are stiffer than the hinges  16 , it is essentially the latter that deform during the pushing phase (as a result of the action of the loads exerted by the metal sheet  8 ), to drive the pivoting of the blades  14  on themselves. 
     The presence of these hinges  16  enables the blades  14  to suffer virtually no deformation that could compromise the quality of the contact with the surface of the metal sheet  8 . 
     Each zone in which the insertion cant  21  bears on the metal sheet  8  is an arc of a circle and includes a major part of the zone of the cant  21  then facing the surface delimiting the opening  9 . 
     This configuration of the insertion cants  21  enables very progressive pivoting of the snap-fastening blades  14  parallel to the cap  4 . 
     Thus the obturator  1  necessitates only a minimal force (here of the order of 2 N) to put it in place, and avoids the rim of the opening  9  becoming embedded in the snap-fastening blades  14 . 
     As soon as the insertion cants  21  have passed the inside rim (opposite the face  7 ) of the opening  9 , the blades  14  are returned to their resting positions by the elastic hinges  16 , so that it is now the counter-cants  24  that bear on the metal sheet  8 , the orientation of the counter-cants  24  being such that the return of the blades  14  draws the cap  4  towards the metal sheet  8  and causes the obturator  1  to be pushed more deeply into the opening  9 . 
     The double-slope configuration of the gripping counter-cants  24  is specifically designed so that the obturator  1  can be used with a wide range of metal sheet thicknesses (between 0.5 and 5 mm). 
     With metal sheets whose thickness is less than 2.5 mm, it is the second portion  24   b  that bears on the surface delimiting the opening  9 . 
     With metal sheets of thickness between 2.5 mm and 5 mm, it is the first portion  24   a  forming a smaller slightly smaller angle with the axis  11  that bears on the surface delimiting the opening  9 . 
     The inside face  6  of the peripheral rim  5  thus approaches the metal sheet  8  until the annular bead  3  of hot melt adhesive comes into contact with the metal sheet  8  ( FIG. 9 ). 
     When the metal sheet  8  is heated, after snap-fastening the obturator  1  to it as described hereinabove and illustrated in  FIG. 9 , the bead  3  of adhesive melts and bonds the peripheral rim  5  to the outside face  7  of the metal sheet  8  at the border of the opening  9 , which provides an excellent seal. 
     In variants that are not represented of this embodiment, the number of snap-fastening blades  14  is different from three, for example two or four, the blades preferably being evenly angularly distributed. 
     In another variant that is not represented, the obturator  1  does not include an annular bead of hot melt type adhesive. 
     The metal sheet  38  illustrated in  FIG. 10  has an oblong opening  39  which can be plugged by an obturator put in place by simply pushing it in. The obturator  31  illustrated in  FIGS. 11 to 16  is adapted to plug this kind of predetermined opening  39  on offering it up to the outside face  37  of the metal sheet  38 . 
     The obturator  31 , which adopts the general oblong shape of the opening  39 , is produced of a body  32  that is molded in one piece that includes a cap  34 , two curved stiff walls  40  and two plane stiff walls  40   a  that project transversely from its inside face. 
     The cap  34  has an oblong outline and extends in a plane except in its central zone  34   a  and its peripheral rim  35 . 
     The central zone  34   a  forms a slight recess with a circular outline in order to facilitate the operations of molding the body  32 . 
     The peripheral rim  35  extends outwards and is slightly sloped, its inside face  36  being adapted to face the outside face  37  of the metal sheet  38  at the border of the opening  39  that is produced therein when the obturator  31  is put in place therein ( FIGS. 10 and 11 ). 
     The two curved stiff walls  40  of semicircular section face each other and are disposed at the two ends of the cap  34  in proximity to the peripheral rim  35  ( FIG. 12 ). 
     The two plane stiff walls  40   a  are situated half way between the two curved walls  40  and are also disposed in proximity to the peripheral rim  35  ( FIG. 12 ). 
     The outside faces of the two curved walls  40  and the two plane walls  40   a  have the same oblong outline ( FIG. 12 ) as the opening  39 , centered on the axis  41  of the obturator  31  ( FIGS. 13 to 16 ). 
     A stiffening rib  42  extends transversely between the two plane walls  40   a  from their beveled distal ends  43  to the cap  34  of the obturator  31  ( FIGS. 11 and 12 ). 
     Two snap-fastening blades  44  are each connected to a respective lateral rim  45  of each plane wall  40   a  by an elastic deformable articulation hinge  46 , the blades  44  and the hinges  46  being formed on molding with the plane wall  40   a  ( FIGS. 11 and 12 ). 
     The blades  44  are similar and in the absence of urging assume a resting position in which each extends in a longitudinal direction parallel to the cap  34 , between an attachment end  47  attached to the elastic hinge  46  and a free end  48 . 
     The elastic hinges  46 , which have a double function of articulating the blades  44  to the plane walls  40   a  and of returning those same blades  44  to the resting position, are bowed inwardly of the obturator  31 . 
     They extend from the beveled end  43  over about three-quarters of the length of the lateral rim  45  of the plane wall  40   a . Alternatively, the length of the hinges  46  can vary as a function of the return force required. 
     The blades  44  will now be described in more detail. 
     Each of these blades  44  has on its outside face an insertion cant  51  that extends from the straight external edge  52   a  of the beveled portion  52  of this blade  44  as far as a step forming a gripping counter-cant  54  ( FIGS. 11 and 13 ). 
     In its beveled portion  52  and in the absence of urging, each lug  44  extends in line with the plane wall  40   a  with the result that the outside edge  52   a  has the same oblong outline with axis  41  as the outside faces of the two curved walls  40  and the two plane walls  40   a  ( FIG. 12 ). 
     The insertion cant  51  is sloped relative to the axial direction  41  of the obturator  31  (or to a transverse direction of the cap  34 ) and this slope increases progressively between its attachment end  47  and its free end  48  ( FIG. 11 ). 
     Thus at the attachment end  47  of the blade  44  (in proximity to the hinge  46 ), the insertion cant  51  is virtually parallel to the axial direction  41  of the obturator  31  whereas at the free end  48  of the blade  44  the insertion cant  51  forms an angle close to 30° with the same axial direction  41  of the obturator  31  ( FIG. 15 ). 
     In the embodiment represented in  FIGS. 11 to 16 , the major part (more than three-quarters) of the insertion cant  51  forms a section of a helicoid. 
     All sections of this helicoidal section in a plane parallel to the cap  34  form a straight line segment line of intersection. 
     The obturator  31  is put in place in the opening  39  produced in the metal sheet  38  in a similar manner to the obturator  1 , the insertion cants  51  bearing on the surface of the metal sheet  38  delimiting the opening  39  when the obturator  31  is pushed into it. 
     Because the blades  44  are stiffer than the hinges  46 , it is essentially the latter that deform during the pushing phase (by the effect of the loads exerted by the metal sheet  38 ), to drive pivoting of the blades  44  on themselves. 
     The presence of these hinges  46  enables the blades  44  to suffer virtually no deformation that could compromise the quality of the contact with the surface of the metal sheet  38 . 
     Each zone in which the insertion cant  51  bears on the metal sheet  38  is a straight line segment and includes a major portion of the zone of the cant  51  then facing the surface delimiting the opening  39 . 
     This configuration of the insertion cants  51  enables very progressive pivoting of the snap-fastening blades  44  parallel to the cap  34 . 
     As soon as the insertion cants  51  have passed the lower rim of the opening  39 , the blades  44  are returned to their resting positions by the elastic hinges  46 , with the result that it is now the counter-cants  54  that bear on the metal sheet  38 , the orientation of these counter-cants  54  being such that the return of the blades  44  draws the cap  34  toward the metal sheet  38  and causes the obturator  31  to be pushed further into the opening  39 . 
     The inside face  36  of the peripheral rim  35  therefore approaches the metal sheet  38  until its free end  55  ( FIG. 11 ) comes to face the metal sheet  38 . 
     In a variant that is not represented, the obturator  31  includes at its periphery an annular bead of hot melt type adhesive. 
     It will also be noted that the obturator can adopt a shape other than oblong or circular, and more generally it is pointed out that the invention is not limited to the embodiments described.