Abstract:
The invention relates to a device for fastening an electronic monitoring module onto a tire comprising a patch ( 12 ) of rubber mix, an upper surface of which bears at least one rigid insert ( 18, 19 ) having a threaded recess ( 181, 191 ) intended to cooperate with a screw ( 14, 15 ) and a lug ( 131, 132 ) on a casing ( 13 ) bearing the electronic monitoring module.

Description:
This application is a continuation of PCT/EP02/03840 filed Oct. 17, 2002 
    
    
     BACKGROUND AND SUMMARY 
     The invention relates to tires fitted with removable electronic monitoring modules and a device for fastening such modules onto the tires, which modules are generally encapsulated in rigid casings. 
     It has nowadays become very important to be able to monitor the operating conditions of tires, such as load, internal pressure and internal temperature, in order in particular to reduce the cost of the tires and to maximize the efficiency of a vehicle. Of course, such monitoring is particularly advantageous on tires for heavy vehicles or earthmover tires, which are expensive and some of which can be recapped. 
     The currently existing electronic monitoring modules, which may have their own power supply or may require an external power-supply source, are capable of storing information for future evaluation and/or of transmitting data on demand. It should be noted that typical modules are described in particular in U.S. Pat. Nos. 4,862,486, 5,218,861; and 5,573,610. It is important to be able to access the module during the life of the tire, to see the module or even in order to repair or modify it. 
     Nowadays, it is preferred, to the extent that the progress achieved permits, to position these modules inside the tire rather than on the outside, where they are exposed to environmental attack such as climatic conditions, incidents on the road or even vandalism. 
     In order to make it possible to make this means of fastening removable and also for the fastening to be able to take place during after-sales service, certain solutions have been proposed which use repair patches in which a casing bearing the module is removably inserted. 
     European Patent Publication EP-0 936 089 shows such solutions in which modules comprising both circuits and recharging batteries are inserted into rubber patches comparable to those used for effecting repairs. These devices have a circular housing enabling the module to be put in place, the patches being fixed beneath the crown of the tire by a self-vulcanizing system. Different systems for fastening the module in the housing are presented, such as a module with a locking ring or with a thread for screwing it in. 
     Although such solutions may be of interest, they nevertheless have numerous drawbacks, because the position of the patch beneath the crown is liable in certain cases to generate magnetic perturbations on the module which are linked to the presence, in particular, of metal plies in the crown. It may therefore be useful to be able to place such a device elsewhere in the tire, for example at the tire bead zone. However, the presence of batteries in the module makes the latter heavier and bulkier, which adversely affects the positioning of the latter in the tire bead zone. 
     This zone is in fact subjected deformations which risk adversely affecting the high strength of the interface between the patch and the tire. This phenomenon is furthermore accentuated by the large size of the surface of the patch bearing the module, which will produce a large working surface on the tire. It will furthermore be noted that the embodiment shown in the EP document does not make it possible to use a more conventional repair system with a bonding rubber with heat-gluing which improves this strength of the interface. 
     The subject of the invention is tires and removable fastening devices for electronic monitoring modules which may include batteries, which overcomes all the above disadvantages. 
     According to the invention, the device for fastening an electronic monitoring module onto a tire comprises a patch of rubber mix, the surface of which is intended to be in contact with the air bears at least one rigid treaded insert intended to cooperate with a screw and a lug borne by a casing bearing the electronic monitoring module. 
     The invention also relates to a tire thus equipped. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other advantages and characteristics of the invention will become apparent on reading description of an exemplary embodiment of a tire according to the invention with reference to the drawings, in which: 
     FIG. 1 is a section view of a tire onto which an electronic monitoring module according to the invention is fastened on the inside, 
     FIG. 2 is a section through the fastening device for the module shown in FIG. 1, 
     FIG. 3 is a section through the patch used in the fastening device shown in FIG. 2, and 
     FIG. 4 is a section through the patch shown in FIG. 3 in a variant embodiment. 
    
    
     DETAILED DESCRIPTION 
     In FIG. 1, the tire  1  carries on its inner liner  10  an electronic monitoring module mounted by a fastening device  11 . This fastening device comprises a repair patch  12  fixed to the tire and a casing  13  bearing the electronic module and fastened to the patch  12 . 
     The electronic contents of the casing, which is not the subject of the invention, will not be described here; however, it will be noted that in the example described here it is a module comprising rechargeable batteries, which involves a certain amount of bulk and a certain amount of weight. However, as is stated hereafter, this type of module does not limit the scope of the invention to this sole embodiment. 
     The fastening device and the manufacturing process therefor will be described in detail below, with reference to FIGS. 2,  3  and  4 . 
     The same reference characters will be used for identical elements shown in the variant embodiments of the patch of FIGS. 3 and 4. 
     As shown in FIG. 2, the casing  13  bears two lugs  131  and  132  for fastening to the patch  12  by means of two bolts or screws  14  and  15  for screwing into the patch  12 , and washers  16  and  17  cooperating with said screws in order to hold the casing  13  in position relative to the patch  12 . 
     The patch  12  will be described more precisely with reference to FIG.  3 . The patch  12  has a lower surface for contact with and bonding to a surface of the tire and an upper surface to be exposed to the air cavity of the tire. The patch  12  has two housings  121  and  122  for receiving inserts  18  and  19  of frustoconical shape which each bear at their respective centre a threaded recess  181  and  191  opening on the upper surface XX and which is intended to cooperate with the screws  14  and  15 . 
     The inserts  18 ,  19  are positioned in the patch  12  with the respective lesser surfaces  182 ,  192  upwardly facing. The connection between the patch  12  made of elastomeric mix and the inserts is effected by gluing, but the frustoconical shape of the inserts and the orientation engaging with the patch material makes it possible for the inserts to resist becoming disconnected from the patch under certain stresses. 
     The contour of the patch follows the frustoconical shape of the inserts  18  and  19 , to define two spaced, upwardly facing protuberances shown in FIG. 3, which enables the patch, by means of the specific shape which it adopts, to act with respect to the casing  13  like a shock-mount damping the stresses and deformations to which the tire and hence the patch is subjected. This arrangement makes it possible in particular to position the fastening device  11  in the bead zone of the tire as shown in FIG. 1, but also in any other internal position of the tire. 
     The outer surface  130  of the patch which will be free once the patch is installed in the tire is covered by a butyl rubber coating in order to maintain its sealing with respect in particular to gases and oxidation. The patch  12  may be made in its entirety of butyl rubber or be formed at the heart of the patch by other elastomeric mixes. 
     As can clearly be seen in FIG. 3, the surfaces  182 ,  192  respectively of the bases of lesser diameter of the inserts  18 ,  19  is not in contact with the air, but in contact with the layer of butyl rubber. 
     The nature of this insert is selected to have both good adhesion to the rubber and good rigidity, so these inserts may be, for example, made of nylon, bronze or brass. The choice of metal in the case of a metal insert is in fact limited in order not to generate a magnetic field which might interfere with the module. 
     Provision may be made for the presence in the patch  12  of a reinforcing fabric  20  such as a rayon fabric in order to impart additional rigidity thereto. 
     In FIG. 3, the patch  12  is in contact with a polyester fabric  21  which will be removed when the patch is used, as for more conventional repair patches, with a bonding rubber for fixing to the tire. Provision may also be made for a self-vulcanizing adhesive for the connection with the tire; however, depending on the position selected for the patch relative to the tire, it may be advantageous to maintain the hot system with the bonding rubber which improves the strength of the patch/tire interface. 
     The patch can be made by hot molding on the inserts in a mould in the event that a single rubber mix is selected to produce it. It is also possible to produce a stack of products in the cold state in a mould and then to effect curing. 
     FIG. 4 shows a variant embodiment of the patch  12 ′, which has a single insert  18 ′ bearing the thread  181 ′. This patch with a single insert may suffice in particular if a module without batteries, and therefore of lesser bulk and lesser weight, is intended. The screw for fastening the casing to the patch may in such a case be directly integral with the casing.