Abstract:
An aeroplane tire that operates at an inflation pressure in excess of 12 bar includes a crown, two sidewalls, two beads, a carcass ply reinforcement anchored in the two beads and including at least one ply of textile reinforcements, a crown reinforcement, and an electronic component. The crown reinforcement includes, radially from inside outward, a working block that includes plies of textile reinforcement, and a protective block that includes reinforcements directed substantially circumferentially. The electronic component has elongate overall shape and includes a passive radio frequency identification device transponder equipped with two antennas forming a dipole. The electronic component is positioned in the tire under the crown, radially on an inside portion in relation to the carcass ply reinforcement, and directed in a substantially axial direction.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/307,613 filed on Feb. 24, 2010, the entire disclosure of which is incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a tire comprising an electronic component. 
         [0003]    It applies in particular, although not exclusively, to a tire intended to support heavy loads and inflated to a very high pressure in excess of 12 bar, such as an aeroplane tire, for example. 
       RELATED ART 
       [0004]    A tire that meets the above criteria usually comprises a carcass ply reinforcement equipped with textile threads, unlike a tire for a heavy goods vehicle, which generally comprises carcass ply threads made of a metallic material. 
         [0005]    The axial, radial, and circumferential directions of a tire will be defined herein in relation to an axis of revolution of this tire. 
         [0006]    EP 0 389 406 discloses a tire comprising an electronic component. In that document, the electronic component comprises a passive radio frequency identification device transponder equipped with two antennas forming a dipole. This type of transponder is generally known by the English-language acronym RFID. Such a component can store data, for example, relating to the manufacture of the tire. 
         [0007]    The tire described in EP 0 389 406, notably illustrated in  FIG. 2  of that document, comprises an annular bead wire, of revolution about an axis that coincides substantially with the axis of revolution of the tire and a carcass ply reinforcement of generally toroidal shape, coaxial with the bead wire, comprising a part folded around the bead wire. 
         [0008]    The transponder is positioned in the tire&#39;s mass so that within the tire it creates an interface with materials, namely the interface defined by the junction between at least a first mass of rubber and a second mass formed by the transponder. 
         [0009]    In EP 0 389 406, part of the transponder, particularly one of the antennas, extends in the volume contained between the folded-back part of the carcass ply reinforcement and a part of this carcass reinforcement that axially faces the folded-back part. 
       SUMMARY OF THE INVENTION 
       [0010]    Now, it has been found that, in the case of an aeroplane tire, the positioning of the transponder as proposed in EP 0 389 406 is not optimized because of the particularly high loadings to which this tire is subjected in service, which may cause the transponder, and notably its antennas, to break. 
         [0011]    According to an aspect of the invention, an electronic component, such as a transponder, is positioned within a tire&#39;s mass so as to optimize the endurance of the transponder and the transmission of the data stored in the transponder. The positioning of the electronic component in the tire is done without altering the key steps of the manufacture of the tire or the architecture thereof. 
         [0012]    To this end, an embodiment of the invention is an aeroplane tire having the ability to operate at an inflation pressure in excess of 12 bar, comprising a crown, two sidewalls and two beads, a carcass ply reinforcement anchored in the two beads and including at least one ply of textile reinforcements, a crown reinforcement with, radially from inside outward, a working block comprising at least one ply of textile reinforcement and a protective block comprising reinforcements directed substantially circumferentially, and an electronic component of elongate overall shape, comprising a passive radio frequency identification device transponder equipped with two antennas forming a dipole wherein the reinforcements of the protective block are metal reinforcements laid in a wavy configuration and wherein the electronic component is positioned in the tire&#39;s structure under the crown, radially on an inside portion in relation to the carcass ply reinforcement, and directed in a substantially axial direction. 
         [0013]    By being positioned axially on an inside portion in relation to the carcass ply reinforcement, the component is closer to the surface of the tire in contact with internal air than is the carcass ply reinforcement. 
         [0014]    Directing the electronic component in a substantially axial direction has the advantage of allowing this electronic component to withstand, without damaging the shaping of the tire in its green state during the course of its manufacture, that is to say, the operation in which, having layered the first products, notably an inner liner, the component, the carcass ply reinforcement, and the bead wires on a tire-building drum, in giving this cylindrical green tire a toric shape. Moreover, it has been found that, with the component directed axially, the metal reinforcements of the protective block do not limit the effectiveness of the radio frequency transmission of the data by the component. 
         [0015]    Advantageously, with the tire comprising a mass of rubber forming the inner liner, delimited by an internal surface in contact with air inside the tire, and an outer surface in contact with a mass of adjacent rubber, the electronic component is positioned at an interface between the inner liner and the mass of adjacent rubber. 
         [0016]    This position of the electronic component according to the embodiment allows the electronic component to be fitted easily at the time of assembly of the materials of the tire in the raw state. What is more, that can be done irrespective of the variations in architecture on the outside of the carcass ply reinforcement. 
         [0017]    The electronic component is also particularly well protected against external stresses such as impacts of the tire with an obstacle or pot hole on the runway. 
         [0018]    By being positioned inside the tire&#39;s structure, the component is also protected from any type of contaminant that may be situated inside an internal cavity of the tire (e.g., water, oil, sealants, etc.). 
         [0019]    Finally, this position gives the component substantially better endurance in comparison with any position on the outside of the carcass ply reinforcement. 
         [0020]    Advantageously, the electronic component is positioned under the crown of the tire in the middle along a width of the crown. 
         [0021]    With this arrangement, transmission of data by the electronic component is entirely satisfactory. Positioning it in the middle along the width of the crown has the advantage that the component is “read” from the same distance whether it is on the left side or on the right side of the tire. 
         [0022]    According to another optional feature of the tire according to an embodiment of the invention, the electronic component is enveloped in a mass of coating rubber. 
         [0023]    Advantageously, a relative dielectric constant of the mass of coating rubber is lower than a relative dielectric constant of the inner liner and a relative dielectric constant of the mass of adjacent rubber. 
         [0024]    Thanks to the coating rubber, the transmission of stored data by the electronic component is improved. That is, in general, the higher the dielectric constant of the mass of coating rubber enveloping the electronic component, the greater the attenuation of the electrical signal received and transmitted by the electronic component. As the dielectric constants of the inner liner and the mass of adjacent rubber are generally higher than 10 in the UHF range, the transmission of data is greatly enhanced if the relative dielectric constant of the coating rubber is lower than the relative dielectric constants of the inner liner and the adjacent rubber in the frequency band used. For example, the dielectric constant of the coating rubber is below 4 or even below 3 in the UHF frequency band. 
         [0025]    In an example embodiment of the invention, the mass of coating rubber has a limited length in an axial direction, which length exceeds a length of the electronic component by just a few millimetres at each of its ends. For example, a quantity of a few millimetres is of the order of three to five millimetres. 
         [0026]    The mass of adjacent rubber may include the carcass ply reinforcement. This mass of adjacent rubber may also include a mass of additional rubber positioned between the inner liner and the carcass ply reinforcement of the tire. The presence of such a mass of additional rubber is common place in aeroplane tire designs. 
         [0027]    The inner liner may also, according to an example embodiment, include an assembly of at least two masses of rubber. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The invention will be better understood upon reading the description, which will follow, given solely by way of nonlimiting example(s) and made with reference to the drawings, of which: 
           [0029]      FIG. 1  is a view in radial cross section of part of a tire according to an embodiment of the invention; 
           [0030]      FIG. 2  is a detail of the tire of  FIG. 1 ; 
           [0031]      FIG. 3  is a detail of a tire according to another embodiment of the invention; and 
           [0032]      FIG. 4  is a highly schematic perspective view of the part of the tire from  FIG. 1 , shown with a cutaway portion. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]      FIG. 1  shows mutually orthogonal axes X, Y, Z, which correspond to the customary radial (X), axial (Y) and circumferential (Z) orientations of a tire. 
         [0034]    As used herein “substantially circumferential direction” refers to a mean direction that deviates from the circumferential direction Z by no more than five degrees. 
         [0035]      FIGS. 1 to 4  depict a tire according to embodiments of the invention, denoted by the overall reference numeral  10 . In these figures, the tire  10  is intended to be mounted on an aeroplane wheel. 
         [0036]    In the conventional way, the tire  10  comprises a crown S extended by two sidewalls F and two beads B. Just one sidewall F and the crown S have been depicted in  FIG. 1 . 
         [0037]    Bead wires  16  are each embedded in one bead B. For example, two bead wires  16  are arranged symmetrically with respect to a radial mid plane M of the tire  10  (see  FIG. 4 ). 
         [0038]    Each bead wire  16  is of revolution about a reference axis. This reference axis, substantially parallel to the Y direction, is substantially coincident with an axis of revolution of the tire  10 . 
         [0039]    The crown S comprises a tread strip  20 , equipped with tread patterns  22 , and a crown reinforcement  24 . This reinforcement  24  comprises a working block  26  and a protective block  28 . The working block  26  comprises several plies of textile reinforcements. The protective block  28  preferably comprises metal reinforcements laid in a wavy configuration in the plane of the crown S in order to obtain the greatest possible effectiveness. Each reinforcement maintains a substantially circumferential mean direction. 
         [0040]    A mass of rubber  36  extends radially from the crown S as far as the bead wire  16  of the bead B, delimiting an exterior surface  37  of the sidewall F and of the bead B. 
         [0041]    The tire  10  also comprises a mass of airtight inner rubber  40 , and a carcass ply reinforcement  42 . The mass of inner rubber or inner liner  40  is delimited by an internal surface  41  in contact with air inside the tire  10 , and an outer surface in contact with a mass of adjacent rubber. Depending on the architecture of the tire, the adjacent rubber may be the carcass ply reinforcement  42  or one or more additional rubbers positioned between the inner liner  40  and the carcass ply reinforcement  42 . In the example of  FIG. 1 , between the carcass ply reinforcement  42  and the airtight inner liner  40  there is a mass of additional rubber  43 . This mass of additional rubber  43  extends from one bead to the other between the carcass ply reinforcement  42  and the airtight inner liner  40 . The carcass ply reinforcement  42  in the example depicted comprises one or more plies of textile reinforcements directed substantially radially. 
         [0042]    The crown S of the tire  10  also comprises an electronic component  54  optionally coated in a mass of rubber  60 . In an embodiment, the electronic component  54  is of elongate overall shape in a substantially axial direction Y (parallel to the axis of rotation). In this embodiment, the component  54  comprises a passive radio frequency identification device (RFID) transponder  56  equipped with two antennas  58  forming a dipole. 
         [0043]    The component  54  is positioned between the inner liner  40  and the carcass ply reinforcement  42 .  FIG. 2 , which shows a detail of  FIG. 1 , illustrates the position of the component  54  in the crown S. Between the inner liner  40  and the carcass ply reinforcement  42  there is the additional rubber  43 . The component  54  is positioned at the interface between the additional rubber  43  and the inner liner  40 . If there is no such additional rubber  43  then the component  54  may be positioned at the interface between the inner liner  40  and the carcass ply reinforcement  42 . It will be recalled that the carcass ply reinforcement  42  includes one or more plies each comprising textile reinforcements of substantially radial direction embedded between two layers of calendering or calendered rubber. There is therefore no direct contact between the component  54  and the reinforcements of the carcass ply reinforcement  42 . 
         [0044]    The component  54  may also be positioned at the interface between the additional rubber  43  and the inner liner  40 , or at the interface between the carcass ply reinforcement  42  and the additional rubber  43 . In an embodiment, the component  54  is positioned in the middle of the crown S, near the mid plane M. 
         [0045]      FIG. 3  shows, in a similar way to  FIG. 2 , a detail of a tire according to another embodiment of the invention, in which the inner liner  40  includes an assembly of two masses of rubber, a first mass of rubber corresponding to the airtight liner  40  and a second mass of additional rubber  44 . The electronic component  54  is therefore positioned at the interface between the first mass of additional rubber  43  and the second mass of additional rubber  44 . 
         [0046]      FIG. 4  is a highly schematic perspective view showing a partial cutaway of the outer face of the tire  10 . 
         [0047]    As shown in  FIG. 4 , the exterior surface of the tire  10  includes the tread strip  20  tire with the tread patterns  22  comprising four circumferential grooves  19 . Under the tread strip  20  is the crown reinforcement protective block  28 . This protective block  28  comprises a ply of metal reinforcements laid in a wavy configuration while maintaining a circumferential mean direction. Under the protective block  28  may be seen the working block  26  made up of small strips of textile reinforcements laid at an angle of the order of ten degrees or so relative to the circumferential direction, alternating from one layer of reinforcements to the next, optionally supplemented by reinforcements directed substantially circumferentially. Between the blocks  28  and  26  of the crown reinforcement  24  on the one hand and between the crown reinforcement  24  and the carcass ply reinforcement  42  there are masses of cushioning rubber. 
         [0048]    Under the working reinforcement block  26  there are multiple reinforcing plies directed axially under the crown S (and radially in the sidewalls F), constituting the carcass ply reinforcement  42 . Under this carcass ply reinforcement  42  is the component  54 , optionally surrounded by a coating rubber  60 , positioned on the inner liner  40 . This schematic figure does not shown any mass of additional rubber  43 . The internal surface of the tire  10  in contact with the air inside the tire  10  is the internal surface of the mass of rubber referred to as the inner liner  40 . The electronic component  54  includes a passive radio frequency identification device (RFID) transponder  56  equipped with the two antennas  58  forming a dipole. The assembly is directed in the axial direction parallel to hoops of the reinforcements of the carcass ply reinforcement  42 . The electronic component  54  is enveloped in a mass of coating rubber  60  comprising two thin layers  55  of a mass of rubber. These two layers  55  extend axially beyond the antennas  58  by a distance ranging between 3 and 5 mm. The two layers  55  are part of the mass of coating rubber  60  of the component  54 . The axial orientation of the antennas  58  of the component  54  means that signal transmission remains excellent even in the presence of the metal reinforcements of the crown reinforcement protective block  28 . This is because these metal reinforcements are directed circumferentially. This axial orientation also gives the component good endurance in the tire  10  during its manufacture and service. 
         [0049]    The dielectric constant of the coating rubber  60  is lower than the dielectric constants of the inner liner  40  and the additional rubber  43 , and of the calendered rubbers of the carcass ply reinforcement  42 . 
         [0050]    The insertion of the electronic component  54  into the tire&#39;s structure at the time of its building is as follows. Having placed the inner liner  40  on a building drum, an assembly comprising the component  54  and the mass of coating rubber  60  is applied at an appropriate location, the additional rubber  43  is then applied followed by the carcass ply reinforcement  42 . Then, the application of all the rubbers and products needed to form the green form of the tire  10  is completed in the usual way. Once this green tire has been vulcanized, a tire cover or a tire ready for use is obtained. 
         [0051]    The interface chosen at which to locate the electronic component  54  may vary according to the manufacturing techniques employed. When a semi-finished assembly that includes the inner liner  40  and of an adjacent rubber is produced, the interface between this inner liner  40  and the adjacent rubber is not available for the placement of the component  54  during manufacture of the tire  10 . The component  54  would therefore be positioned at the interface between the additional rubber  43  and the carcass ply reinforcement  42  of the tire  10  in the example of  FIG. 2 . In the case of  FIG. 3 , the component  54  is placed at the interface between the additional rubber  43  and a second additional rubber  44  adjacent to the inner liner  40 . 
         [0052]    The invention is not restricted to the exemplary embodiments described and depicted and various modifications can be made thereto without departing from its scope as defined by the attached claims.