Patent Publication Number: US-2010122757-A1

Title: Tire and electronic device assembly

Description:
FIELD OF THE INVENTION 
     The invention relates generally to the incorporation of an electronic device in a tire and, more specifically, to a tire having an embedded radio frequency identification tag. 
     BACKGROUND OF THE INVENTION 
     Incorporation of an RFID tag into a tire can occur during tire construction and before vulcanization or in a post-cure procedure. Such tags have utility in transmitting tire-specific identification data to an external reader. UHF (ultra-high frequency) tags are typically small and utilize flexible antennas for the transmission of data. When embedded into a tire, such as during tire construction, the device represents a foreign object that can affect the structural integrity of the tire. UHF RFID tags, therefore, not only do not serve to reinforce the tire structure but may, in fact, act to degrade the tire in the embedded tag region. 
     Many locations within a tire are not suitable for placing an RFID tag because of cyclical flexural bending in service or because the location does not permit suitable radio frequency compatibility for reading applications. Accordingly, there remains a need for a tire having a UHF RFID tag embedded therein in a manner that does not degrade the performance or durability of the tire, is mechanically suitable and durable in service, provides suitable radio frequency reading capability, and is capable of efficient incorporation into the tire manufacturing process. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the invention, a tire and electronic device assembly is provided. The tire is constructed having a pair of beads, at least one ply layer having a plurality of parallel cords extending from one bead to an opposite bead and a ply ending wrapped around the one bead. The tire further includes an outer sidewall, an apex component positioned above the one bead and extending upward to an apex component end, and a chafer component wrapped around the one bead and extending upward to a chafer component end. The assembly includes an electronic device in which a transponder tag is coupled to a dipole antenna formed by first and second elongate antenna segments. 
     Pursuant to a further aspect of the invention, the transponder tag and at least a portion of the dipole antenna is at least partially embedded within a compound having compatible permittivity and conductivity with operation of the dipole antenna. 
     In another aspect, the electronic device is mounted to the tire apex in a position between the tire apex and the tire sidewall at a predetermined distance above an ending of the tire ply and in an orientation placing a longitudinal axis of the dipole antenna perpendicular to the cords of the tire ply. The electronic device may further be positioned between the tire chafer ending and the tire apex ending and above an ending of the tire ply a distance of at least 10 mm. 
     DEFINITIONS 
     “Aspect ratio” of the tire means the ratio of its section height (SH) to its section width (SW) multiplied by 100% for expression as a percentage. 
     “Asymmetric tread” means a tread that has a tread pattern not symmetrical about the center plane or equatorial plane EP of the tire. 
     “Axial” and “axially” means lines or directions that are parallel to the axis of rotation of the tire. 
     “Camber angle” means the angular tilt of the front wheels of a vehicle. Outwards at the top from perpendicular is positive camber; inwards at the top is negative camber. 
     “Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction. 
     “Equatorial Centerplane (CP)” means the plane perpendicular to the tire&#39;s axis of rotation and passing through the center of the tread. 
     “Footprint” means the contact patch or area of contact of the tire tread with a flat surface at zero speed and under normal load and pressure. 
     “Groove” means an elongated void area in a tread that may extend circumferentially or laterally about the tread in a straight, curved, or zigzag manner. Circumferentially and laterally extending grooves sometimes have common portions. The “groove width” is equal to tread surface area occupied by a groove or groove portion, the width of which is in question, divided by the length of such groove or groove portion; thus, the groove width is its average width over its length. Grooves may be of varying depths in a tire. The depth of a groove may vary around the circumference of the tread, or the depth of one groove may be constant but vary from the depth of another groove in the tire. If such narrow or wide grooves are substantially reduced depth as compared to wide circumferential grooves which the interconnect, they are regarded as forming “tie bars” tending to maintain a rib-like character in tread region involved. 
     “Inboard side” means the side of the tire nearest the vehicle when the tire is mounted on a wheel and the wheel is mounted on the vehicle. 
     “Lateral” means an axial direction. 
     “Lateral edges” means a line tangent to the axially outermost tread contact patch or footprint as measured under normal load and tire inflation, the lines being parallel to the equatorial centerplane. 
     “Net contact area” means the total area of ground contacting tread elements between the lateral edges around the entire circumference of the tread divided by the gross area of the entire tread between the lateral edges. 
     “Non-directional tread” means a tread that has no preferred direction of forward travel and is not required to be positioned on a vehicle in a specific wheel position or positions to ensure that the tread pattern is aligned with the preferred direction of travel. Conversely, a directional tread pattern has a preferred direction of travel requiring specific wheel positioning. 
     “Outboard side” means the side of the tire farthest away from the vehicle when the tire is mounted on a wheel and the wheel is mounted on the vehicle. 
     “Radial” and “radially” means directions radially toward or away from the axis of rotation of the tire. 
     “Rib” means a circumferentially extending strip of rubber on the tread which is defined by at least one circumferential groove and either a second such groove or a lateral edge, the strip being laterally undivided by full-depth grooves. 
     “Sipe” means small slots molded into the tread elements of the tire that subdivide the tread surface and improve traction, sipes are generally narrow in width and close in the tires footprint as opposed to grooves that remain open in the tire&#39;s footprint. 
     “Slip angle” means the angle of deviation between the plane of rotation and the direction of travel of a tire. 
     “Tread element” or “traction element” means a rib or a block element defined by having a shape adjacent grooves. 
     “Tread Arc Width” means the arc length of the tread as measured between the lateral edges of the tread. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described by way of example and with reference to the accompanying drawings in which: 
         FIG. 1  is a side elevational view of the electronic device; 
         FIG. 2  is a top plan view of the electronic device showing in phantom the coverage area of a compound spray; 
         FIG. 3  is a perspective view of the electronic device; 
         FIG. 4  is a top perspective view of the electronic device; 
         FIG. 5  is a top perspective view of the electronic device shown in the process of receiving a selective compound coating; 
         FIG. 6  is a top perspective view of the coated electronic device shown subsequent to the coating operation of  FIG. 5 ; 
         FIG. 7A  is a sectional perspective view of a partial tire having an electronic device mounted in a sidewall location; 
         FIG. 7B  is a sectional perspective view of a partial tire having an electronic device mounted at an alternative position; 
         FIG. 8  is a cross sectional view of a tire having an electronic device mounted thereto; 
         FIG. 9A  is a section view of the electronic device shown in  FIG. 7A ; and 
         FIG. 9B  is a section view of the electronic device shown in  FIG. 7-B . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With initial reference to the exemplary embodiment shown in FIGS.  1 , 2 ,  3 , and  4 , an electronic device  10  is shown to include a RFID transponder tag  12  having interface contacts  14  mounted to a substrate  16 . The RFID transponder tag  12  is of a type providing for the electronic memory storage of data and the communication of such data to an external reader (not shown). The transponder tag  12  may utilize UHF frequencies in the transmission of the data to the external reader. Coupled to the transponder tag  12  is a dipole antenna formed by two elongate antennas  18 ,  20  connected by suitable means such as welding to the contacts  14 . The antennas  18 ,  20  are preferably but not necessary formed as elongate coils. The term “antenna” as used herein refers to any suitable antenna configuration functional for the intended application including, but not limited to, the dipole antenna formed by the antenna segments  18 ,  20 . 
     The device  10  is intended to be embedded within a tire as will be explained, preferably although not necessarily during tire construction and before vulcanization. Although the size of the device  10  is relatively small and the antenna  18 ,  20  is flexible, the device  10  nonetheless represents a foreign object within a host tire. As with any foreign object, the device  10  therefore does not reinforce the tire structure but rather represents a structural anomaly that may impact the performance of the tire. Conversely, the environment of a tire in use may be harmful or inhospitable to the survival and performance of the device  12 . Thus, for the intended purpose of the invention, maintaining the structural of a host tire and the electronic device in a manner that will allow the transponder/tag to transmit information as necessary is desired. 
     The subject tire and electronic device assembly  10  locates and orients the device  12  into a tire in a manner that does not degrade the performance or durability of the tire; is mechanically suitable for tag durability in service; and provides a suitable radio frequency compatible environment for sundry reading applications. In addition, the assembly  10  may be created seamlessly and at an efficient relatively low cost in the tire manufacturing process. 
     As shown in  FIGS. 1-6 , the electronic device  12  is embedded by an applicator  22  in a suitable compound  24  that has compatible permittivity and conductivity to not interfere with the antenna performance. In addition to the radio frequency compatibility, the compound  24  preferably will have physical properties that are suitable in the environment of surrounding tire components. The compound  24  preferably will provide smooth transition from the rigid electronic device  12  and antenna  18 ,  20  to the neighboring tire components. For example, the material stiffness and hysterisis must not create unwanted stress concentration or heat build up to not impact the tire performance. The encapsulating compound must also have suitable adhesion to surrounding tire components and to the components of the tag assembly  10 . Material  24  meeting the above criteria is commercially available. 
     The material  24  encapsulates selective portions of the electronic device  12  as shown. Preferably, the compound  24  by a rotation of the electronic device  12  in the shown direction  26  will encapsulate the RFID device  12 , contacts  14 , and the substrate  16  as well as at least the portions of antenna coils  18 ,  20  that connect to the contacts  14 . Preferably the remote end segments of the antenna segments  18 ,  20  will remain uncoated; however, the entirety of the segments  18 ,  20  may be coated if desired. 
     Referring to  FIGS. 7A ,  7 B,  8 ,  9 A, and  9 B, the coated electronic device  12  is intended for incorporation into a tire  28  of generally conventional construction. The invention may be employed in tires suitable for any application. The tire  28  includes beads  30  and apexes  32  proximally situated above the beads  30 . The apexes  32  constitute a rubber filler that is placed above the beads in an area within the tire where air could otherwise be trapped in its absence. Each of the apexes  32  terminates at a radially outward apex end  33 . One or more tire plies  34   44 ; an innerliner  36 ; and sidewalls  38  are further added in the tire build. A belt package  40  is located beneath the tread  42  at the crown of the tire. The plies  34 ,  44  constitute layers of rubber-coated cord fabric extending from bead to bead and are turned up around the bead, thereby locking the bead into the assembly or carcass. The parallel cords  46  forming the tire plies may, pursuant to conventional tire construction, be twisted fiber or filament of polyester rayon, nylon, steel, or other material which gives the tire carcass and belts strength. In general, the parallel cords  46  extend from the bead to bead and reinforce the tire. 
     As will be appreciated from conventional tire build techniques, a green tire is constructed component by component. The beads  30  maintain the integrity of the green tire throughout the build process as layer ends are wrapped and turned up around the beads. The ply turnup  48  from the ply  44  wraps under the beads  30  as shown in  FIGS. 7A and 9A . As explained, each apex  32  is positioned above a respective bead  30  and extends to apex end  33 . A chafer component  50  is positioned during the tire build to the outside of the ply turnup and beads  30 . The chafer  50  is formed of reinforcing material around the bead in the rim flange area to prevent chafing of the tire by the rim parts. The chafer extends to a chafer end  52 . A rim cushion  54  is to the outside of the bead region and the outer tire component is a sidewall  38  extending to the tire tread. 
     The electronic device  12 , subsequent to the coating operation shown in  FIGS. 4-6 , is preferably introduced into the tire during the green tire build operation. As shown in  FIGS. 7A and 9A , the device  12  may be located at a sidewall location between the ply  44  and the sidewall  38 . The device  12  is affixed to the ply layer by suitable known techniques such as the use of adhesive. The device  12  is oriented relative to the tire  28  such that the tag antenna  18 ,  20  extends perpendicular to the circumferentially extending ply layers. In particular, for steel reinforced ply tires, the tag antenna  18 ,  20  extends perpendicular to the ply cords. Embedding the device  12  in such an orientation utilizes the perpendicularly extending cords of the ply behind the device  12  to provide structural support and reinforcement. While the antenna  18 ,  20  in the device  12  is flexible, it is nonetheless desirable to limit the degree of flexure in the antenna to maintain the integrity of the antenna segments and their connection to the contacts  14  of the device  12 . Orienting the antenna segments perpendicular to the ply cords thus minimizes flexure in the antenna  18 ,  20  during the life of the tire. 
     While the location of the tag assembly as shown in  FIGS. 7A and 9A  is advantageous in achieving a good reading from the tag by a remote reader, the sidewall of the tire is a high flexure region in a tire. The flexing that occurs in such a location may cause damage to the tag assembly  10  and the presence of the tag assembly  10  in such a location may tend to cause sidewall fatigue, damage, and/or separation. The tag assembly  10  may as a result have its integrity threatened by the harsh mechanical environment in the sidewall region. 
     Accordingly, the location of the electronic device  12  within the tire  28  may be moved to the position of  FIGS. 7B and 9B . In this location, the device  12  is positioned in a region between the tire apex  32  and the sidewall  38 . As with the tag position of  FIGS. 7A and 9A , in the position of  FIGS. 7B and 9B , the antenna is placed perpendicular to the ply cords and the longitudinal axis of the device is above the ply ending  48 . It is preferred that the spacing between the axis of the device and the ply ending  48  be a minimum of 10 mm. It is further preferred although not necessary that the device  12  be located in the region between the chafer ending  52  and the apex ending  33 . The distance “D” in  FIG. 9B  shows the region between the chafer ending and the apex ending. The device  12  is optimally embedded during the tire build operation. It is further preferred although not necessary that the device  12  be attached by suitable means such as adhesive directly to the apex. Affixation of the device  12  to the apex serves to protect the device from geometry changes associated with circumference changes from the building drum during tire build formation. 
     The location of  FIGS. 7B and 9B  is preferred although not necessary because the device  12  in such a location is positioned to provide good transmission to the remote reader while remaining protected from the mechanical service environment of the tire. The location against the apex and between apex and chafer endings will minimize the potential for sidewall fatigue, damage, and/or separation. So positioned, the device is further in a relatively stable and non-flexing region of the tire that will minimize the potential for tag damage or antenna malfunction. 
     From the foregoing, it will be appreciated that the invention satisfies the need for a tire and electronic device assembly that incorporates a device such as a UHF RFID tag into a tire in a manner that does not degrade the performance or durability of the tire, is mechanically suitable and durable in service, provides suitable radio frequency reading capability, and is capable of efficient incorporation into the tire manufacturing process. The tire and electronic device assembly includes a compound  24  having compatible permittivity and conductivity with the operation of a dipole antenna  18 ,  20 . At least a portion of the dipole antenna is embedded within the compound. The device  12  is oriented to place a longitudinal axis of the dipole antenna  18 ,  20  perpendicular to cords  46  of a tire ply  44  in an uncured tire  28 . The device  12  is preferably located between a tire apex  32  and a tire sidewall  38  of the uncured tire, at a predetermined distance “D” above an ending  48  of the tire ply. This preferred position of the device  12  is between a tire chafer ending and a tire apex ending at a distance of at least 10 mm from an edge of the ply turnup ending. It is further preferred that the device  12  be attached to the tire apex  32  to thereby benefit from the geometric stability of that tire region and to take advantage of the reinforcement and support provided by the apex. Partially encapsulated, such as shown in  FIGS. 4-6 , the antenna segments  18 ,  20  have remote end segments that project compound-free. 
     Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.