Abstract:
A wheel cover having collars ( 1 ) with elastic tabs ( 3 ) for mounting and fixing the collars on the heads of nuts or bolts ( 2 ) used to fix the wheel to a vehicle. The tabs ( 3 ) have protrusions ( 4 ) with a double ramp ( 5  and  5 ′), that are used to mount and dismount the collars ( 1 ) to the nuts or bolts ( 2 ). The collars ( 3 ) are retained by locking the protrusions ( 4 ) onto an annular projection ( 14 ) of the head of the nut or bolt. Independent caps ( 10 ) are locked by the protrusions to the collars ( 1 ) whereby the caps ( 10 ) protect and conceal the screws or heads of the bolts ( 2 ) and remain locked while being able to turn freely.

Description:
RELATED APPLICATIONS 
   The present application is a Continuation of co-pending PCT Application No. PCT/ES2005/000055, filed on Feb. 8, 2005 which in turn, claims priority from Spanish Application Serial No. P200400386, filed on Feb. 18, 2004. Applicants claim the benefits of 35 U.S.C. §120 as to the PCT application and priority under 35 U.S.C. §119 as to said Spanish application, and the entire disclosures of both applications are incorporated herein by reference in their entireties. 

   BACKGROUND OF THE INVENTION 
   One of the methods of fixing a wheel cover to the wheel of a vehicle consists of using sleeves which are embedded in respective collars provided in the wheel cover. The collars are, in turn, coupled in the recesses or cavities of the wheel where the bolts are positioned for fixing that wheel to the hub. Such sleeves usually have tabs ending in a harpoon-shape for their retention on the bolts or on projections provided in the cavities for housing the bolts. Moreover, those sleeves are provided with appropriate means, such as external projections, for retention of the wheel cover, specifically an edge which the collars of said wheel cover have for that purpose. 
   A retention device is described and claimed in U.S. Pat. No. 4,998,780, where the fixing of the wheel cover to the wheel of a vehicle is done by means of a kind of cap which is introduced via the collar of the wheel cover and is retained by being screwed to a tubular piece forming part of the wheel of the vehicle. This means that a fixing nut or screw for the tire is required that is threaded, and the screw, which is fixed by being screwed to the wheel itself, axially passes through the tubular piece. 
   The cap itself has an upper polygonal section, and also an intermediate cylindrical section in which have been provided for screwing of the cap on the piece arranged axially to the screw and forming part of the wheel. 
   Also, the lower part of said body, in the form of a cap, presents a series of tabs with a protrusion at the end projecting outwards which acts as a stop against the collar of the wheel cover through which passes the fixing screw, and in which is located the retention cap of the actual wheel cover. 
   The device of U.S. Pat. No. 4,998,780, includes the feature of having an unthreaded edge, as a consequence of which the tabs provided at the protrusioned end are free at their ends between the protrusion and the threaded zone of the cap, which permits the latter to be unscrewed with respect to the wheel in order to carry out the removal of the wheel cover. The unscrewing of the screw is carried out simultaneously with the unscrewing of the device or cap, since they are coupled in such a way that the polygonal head of the screw and the polygonal upper section of the device, or of the cap, which is the same thing, remain locked together in the direction of rotation. 
   Mention can likewise be made of Spanish invention patent P-200300899 referring to a wheel cover for the wheels of a vehicle, in which the wheel cover presents collars with elastic tabs which permit retention on the associated screws screwed to the wheel hub for the fixing of the wheel. Also, introduced into the collars of the wheel cover and coupled there are some sleeves which act as means of centering and of covering of the grooves established between the elastic tabs of the collars of the wheel cover. 
   More specifically, this Spanish invention patent is characterised by the fact of incorporating a piece in the form of a sleeve which fits tightly under pressure into each of the tubular projections or collars of the wheel cover, and is fixed to them by locking of some projections provided in the lateral surface of the additional piece or sleeve, in recesses made in the internal part of the respective tubular projection or collar. This additional piece or sleeve has an edge associated with its external opening which supports and acts as a stop against a stagger made for the purpose in the tubular projection or collar, the additional piece or sleeve also having associated with the edge of its internal opening some elastic tabs, the internal part of which defines some means of adjustment and centering for a projection provided in the associated fixing bolt, said bolt or nut being the one used normally by the vehicle manufacturer. The elastic tabs of the additional piece or sleeve externally define a means of positioning and retention for an elastic metallic compression ring, both for the flexible tabs associated with the tubular projections or collars of the wheel cover and for the actual elastic tabs of the additional piece or sleeve. 
   DESCRIPTION OF THE INVENTION 
   The wheel cover of the invention is of the type that incorporates collars with elastic tabs for its retention on the head of the bolts or nuts for fixing of the wheel of a vehicle, along with a cap associated with each of the collars for concealing and protecting the respective fixing bolt or nut for the wheel, includes the feature that the protrusion of the elastic tabs of the collars of the wheel cover for retention on the heads of the fixing bolts of the wheel has a double ramp, one ramp that permits introduction by pushing of the collars of the wheel cover on the fixing bolts of the wheel and associated locking or retention of the wheel cover, and the other ramp, for permitting removal of the wheel cover by means of pulling on it, by sliding of that second ramp via the annular projection provided on the bolts or nuts in order precisely to establish the retention or locking thereto. 
   In addition to the double ramp mentioned, the protrusions present a third exterior ramp, defining an axial retention stop for an open metallic ring, to maintain tension of the elastic tabs. 
   In this way, the double ramp protrusions permit passage through the annular ring which the heads of fixing bolts or nut for the wheel normally include, and are retained once that projection of the bolt has been passed by the protrusions of the elastic tabs, such that the wheel cover will be retained on the wheel. 
   The elastic tabs with the retention heels are surrounded by the metallic ring which tends to push them towards the interior in order to achieve an efficient locking, but which in turn permit the divergence of those tabs due to elasticity in order to carry out the fitting/removal of the actual wheel cover, other guide tabs are included for the protection and covering cap which will be fitted on each of the collars of the wheel cover provided precisely with the tabs. 
   Provided in association with these guide tabs, in their initial zone, are some windows for locking the cap, the cap having tabs provided with an external protrusion which becomes locked in those windows without any possibility of detachment, thus once the caps have been fitted on the collars of the wheel cover, said caps become locked thereto and it is necessary to remove the assembly of the wheel cover with the caps in order to be able to access the fixing bolts or nuts for the wheels. 
   As is conventional, the rear closing section of the caps has a polygonal shape complementary to the shape of the head of the fixing bolts or nuts for the wheel, though these polygonal shapes of the head of the bolt and end section of the caps do not become coupled when the fitting of the cap is carried out. 
   So, the caps are fitted and retained axially in the collars of the wheel cover, though they are allowed to rotate freely, which will prevent any attempt at unscrewing by means of rotating the caps from being able to cause the undoing of the bolt or nut to which the cap is retained with the ability to rotate freely. In this case, therefore, the upper polygonal end of the cap acts as a means of covering and protection of the fixing bolt for the wheel, but without being coupled to the polygonal head of this bolt. Said caps, in addition to protecting and concealing the nuts or heads of the fixing bolts, also conceal the grooves defined by the elastic tabs. 
   The removal of the wheel cover will be done by means of pulling on it towards the outside, since, by exerting an extraction force on that wheel cover, the protrusions of the elastic securing tabs will, by virtue of the double ramp of those heels, be able to slide and overcome the annular projection of the bolts or nuts, with the caps becoming released with regard to those bolts and it thereby becomes possible to remove the wheel cover jointly with its caps. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order to complement the description that is going to be made forthwith and with the aim of aiding a better understanding of the characteristics of the invention, this specification is accompanied by a set of drawings on the basis of which the innovations and advantages of the wheel cover for the wheels of a vehicle embodied in accordance with the object of the invention will be more easily understood. 
       FIG. 1  shows an exploded view of the cap which has to be detached from the collar of the wheel cover coupled to the said nut or head of the screw. 
       FIG. 2  shows a lower perspective view of the fitting of a cap on the associated collar of the wheel cover. 
       FIG. 3  shows an upper perspective view of a collar of the wheel cover with the cap fitted, showing the polygonal closing end of the cap. 
       FIG. 4  shows a view in cross-section of the coupling between a collar of a wheel cover and the associated nut or head of a fixing screw for the wheel, and 
       FIG. 5  shows a view like that of the previous figure with the cap fitted on the respective collar of the wheel cover. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   During the course of the present description, when reference is made to the fixing bolt of the wheel of a vehicle, it must be understood that the head of that bolt can equally correspond to the nut which has to screw on to the associated stud emerging from the assembly hub of the wheel for the vehicle. 
   So, as can be seen in the figures, the wheel cover of the invention includes, as is conventional, a plurality of collars  1 , corresponding to the number of bolts  2  required for fixing of the wheel to the vehicle. The collars  1  are provided with a series of elastic tabs  3  which can be fixed and pressing towards the outside, in other words, tensioned by means of an open ring  3 ′. These elastic tabs  3  are provided at their ends, and following a double bend, with respective protrusions  4  with a double ramp, that is, a lower ramp  5  and an upper ramp  5 ′, with the function that is going to be explained further below. The elastic tab  3  also includes an external ramp  5 ″ for the retention of the metallic ring  3 ′. 
   Interspersed with the elastic tabs  3 , the collar  1  of the wheel cover also has a series of tabs  9  at the start of which windows  6  have been provided for the locking of the cap  7  which has to be fitted in the collar  1  of the wheel cover, covering and protecting the polygonal head  2 ′ which can correspond to a fixing nut or bolt  2  for the wheel of the vehicle. 
   Windows  6  associated with the tabs  5  present an internal projection  8 , which is straight on its lower face, and which has the task of achieving the locking of the cap  7 , the latter, as its conventional, having a polygonal upper closing section  10 , as is clearly shown in  FIGS. 1 and 3 . 
   That cap  7 , in addition to the polygonal upper closing section  10  and the associated cylindrical section  7  in  FIG. 1 , is also provided with an annular projection  11  and, towards its end or opening, with a plurality of tabs  12  provided with a protrusion  13 , in such a way that the protrusions are positioned in association with the windows  6  of the collar  1  of the wheel cover and the protrusions  13  are locked with the projections  8  of that collar  1  of the wheel cover, thereby establishing a fastening between the cap  7  and the collar  1  of the wheel cover, without any possibility of removal due to the straight locking that is made of the protrusions  13  of the tabs  12  of the cap  7  and the projections  8 . 
   In accordance with the description, the fitting of the wheel cover is done by coupling its collars  1  on the heads or nuts  2 ′ of the fixing bolts  2  of the wheel, in such a way that in this coupling the ramp  5  of the protrusions  4  associated with the elastic tabs  3  of the collars  1  slide on the annular projection  14  which the head of the bolt or, as the case might be, the nut  2 ′ has been provided with for that purpose. The locking function is illustrated in  FIG. 4 , wherein the cap  7  is introduced into the collar  1  until the protrusions  13  of the tabs  12  of said cap  7  become locked in the windows  6 , and specifically on the projections  8  of the collar  1 , with the cap  7  becoming fastened without any possibility of removal by virtue of the straight stagger defined by the locking between the projections  8  and the protrusions  13 , as represented in  FIG. 5 , though the said cap  7  remains fitted with the ability to rotate freely. 
   In this way, in an attempt to rotate the caps  7 , as a consequence of the fact that the polygonal section  10  of the caps  7  does not lock with the polygonal head  2 ′ of the nut or screws  2 , will result in free rotation of the cap  7  will discourage any manipulation in an attempt to remove the wheel cover, since in order to perform that removal it is necessary to pull outwardly on the wheel cover, due to the fact that the ramp  5 ′ of the protrusion  4  permits sliding via the projection  14  associated with the nut or bolt and with it the removal of the wheel cover together with the caps  7 , leaving the head  2 ′ or nut of the bolt  2  free for carrying out the unscrewing in the event that it is wished to remove the wheel.