Abstract:
A system and method for post-cure application of electronics to a tire includes: a first stage assembly in which an ends of an annular antenna wire are positioned within conductive grommets in a base member; a second stage in which a plug is affixed to the base member to hold the antenna ends in place during shaping and curing of the antenna wire into a tire; and a third stage in which the plug is replaced by a tag carrier, the carrier including means for establishing and maintaining electrical contact between the antenna ends and the tag.

Description:
FIELD OF THE INVENTION  
       [0001]     The subject invention relates generally to systems and methods for applying electronics to a tire for the purpose of monitoring tire condition parameters and, more specifically, to a system and method for electrically connecting such electronics to a tire-mounted antenna so as to facilitate communication between the electronics and a remote reader/transmitter by means of the antenna.  
       BACKGROUND OF THE INVENTION  
       [0002]     It is common to employ annular apparatus, including an antenna, for electronically transmitting tire or wheel identification or other data at radio frequency. The apparatus includes a radio-frequency tag, or transponder, comprising an integrated circuit chip having data capacity at least sufficient to retain identification information for the tire or wheel. Other data, such as the inflation pressure of the tire or the temperature of the tire or wheel at the transponder location, can be transmitted by the transponder along with the identification data.  
         [0003]     The annular antenna is tire-mounted and transmits, at radio frequencies, data from the transponder to a reader mounted on the wheel assembly. The antenna and transponder may be incorporated into a tire during “pre-cure” manufacture of the tire. The integrity of the connection between the tire and antenna is greatly enhanced by a pre-cure assembly procedure. In practice, however, it is very difficult to do this. Both radial ply and bias ply tires undergo a substantial diametric enlargement during the course of manufacture. Bias ply tires are expanded diametrically when inserted into a curing press, which typically has a bladder that forces the green tire into the toroidal shape of the mold enclosing it. Radial ply tires undergo diametric expansion during the tire building or shaping process and a further diametric expansion during the course of curing. An annular antenna and the electronic tag associated therewith built into the tire in a pre-cure process, therefore, must endure significant strain that can result in component failure. The electronic tag and the connection between the tag and the antenna, in particular, is vulnerable to damage from the forces imposed from pre-cure assembly to tire.  
         [0004]     To avoid damaging the electronic tag or the connection between the tag and the annular antenna during the curing procedure, an alternative known approach is to assemble the tag and antenna into a separate annular apparatus for post-cure attachment to the tire. The annular apparatus may be attached to the tire after the tire is cured by adhesive or other known techniques. While such an approach avoids damaging the tag electronics during tire manufacture, adhesive attachment of the antenna and tag to a tire in a post-cure procedure has certain drawbacks. First, the procedure adds labor, and hence cost, to the manufacturing process. Secondly, the security of the attachment between the annular apparatus and the tire is dependent upon the efficacy of the adhesive system employed. Development of a suitable adhesive that is inexpensive, convenient to use, and durable enough to function throughout the life cycle of a tire has proven problematic.  
         [0005]     Accordingly, there remains a need for a system and method of applying tag electronics to a tire that is convenient, cost effective, and reliable. Such a procedure should further ensure the functional safety of the electronics and result in a positive electrical connection between the antenna and tag electronics. Finally, such a procedure ideally would incorporate the advantages, but avoid the shortcomings, of both the pre-cure and post-cure assembly alternatives discussed above.  
       SUMMARY OF THE INVENTION  
       [0006]     A method for post-cure application of electronics to a tire is disclosed that achieves the objectives of positively securing an antenna apparatus to a tire while protecting the electronics from the damaging forces attendant tire manufacture. The method comprises the steps: forming an antenna wire into a predetermined shape having first and second free ends; interposing a base plate between the free antenna ends, the base member having conductive regions surrounding grommet openings; positioning the free antenna ends into electrical contact with respective base plate conductive portions; affixing a removable plug to the base member to hold the antenna free ends in contact with the base member conductive portions; curing the antenna wire into a tire during a tire manufacturing procedure; removing the plug from the base member in a post-cure operation; affixing a tag carrier to the base member; and establishing electrical contact between the tag carrier and the antenna free ends. Pursuant to one aspect of the invention, the method may include the step of forming the antenna wire into an annular configuration. Pursuant to another aspect, the method may comprise the steps of extending the antenna ends through respective conductive grommets in the base plate, affixing the removable plug to the base plate by means of inserting plug prongs into the base member grommets, and maintaining the antenna ends in place by means of the plug prongs.  
         [0007]     A further aspect of the invention provides that the removable plug and tag carrier interchangeably mate to the base plate. The plug member is incorporated within the antenna assembly during its attachment to a tire during tire manufacture. Thereafter, the plug member is conveniently replaced in a post-cure operation by the tag carrier. The tag carrier electronics are thereby protected from damage during tire manufacture. The tag carrier and plug member are inexpensive to manufacture, readily incorporated into the antenna assembly, and conveniently interchangeable. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     The invention will be described by way of example and with reference to the accompanying drawings in which:  
         [0009]      FIG. 1  is a top plan view of the base plate with antenna ends in contact therewith;  
         [0010]      FIG. 2  is a top plan view of the plug member and antenna assembly prior to attachment to a tire;  
         [0011]      FIG. 3  is a side elevational view of the plug member;  
         [0012]      FIG. 4  is a top plan view of the tag carrier and antenna assembly;  
         [0013]      FIG. 5  is a side elevational view of the tag carrier;  
         [0014]      FIG. 6  is an exploded side elevational view of the tag carrier and antenna assembly;  
         [0015]      FIG. 7  is a longitudinal section view through the tag carrier of  FIG. 5 , taken along the line  5 - 5 ;  
         [0016]      FIG. 8  is a perspective view shown partially in section for illustration of a tire having the annular antenna assembly affixed thereto. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]     Referring initially to  FIG. 8 , a preferred embodiment  10  of the subject invention is shown deployed within a tire  12 . The tire  12  is formed from conventional materials such as rubber or rubber composites by conventional means and may comprise a radial ply or bias ply configuration. A typical tire  12  is configured having a tread  14 , a shoulder  16 , an annular sidewall  18 , and a terminal bead  20 . An inner liner  22  is formed and defines a tire cavity  24 . The tire  12  is intended for mounted location upon an annular rim  26  having a peripheral rim flange  28  and an outer rim flange surface  30 . Rim  26  is conventionally configured and composed of a suitably strong metal such as steel.  
         [0018]     An annular antenna  32  is provided and, in the preferred embodiment, embodies a sinusoidal configuration. Antenna  32  may be alternatively configured into alternative patterns or comprise a straight wire(s) if desired and may be filament wire, or cord or stranded wire. Acceptable materials for the wire include steel, aluminum, copper or other electrically conducting wire. As mentioned previously, the wire diameter is not generally considered critical for operation as an antenna and multiple strands of fine wire is preferred. The curvilinear form of antenna  32  provides flexibility and minimizes the risk of breakage during manufacture and use of the tire.  
         [0019]     With continued reference to  FIG. 1 , a tag carrier  34  of the general type described above is provided and may include means for sensing tire parameters such as pressure and temperature. Included as part of the apparatus  10  is a carrier strip of material  36  formed into the annular configuration shown. Carrier strip  36  is formed of electrically insulating, preferably semi-rigid elastomeric material common to industry such as rubber or plastic. The strip  36  is formed to substantially encapsulate the antenna wire(s)  32  and at least a portion of the tag carrier  34 . In the post manufacturing state shown in  FIG. 1 , therefore, the apparatus  10  comprises antenna  32 , tag carrier  34 , and carrier strip  36 , in a unitary, generally circular, assembly. The diameter of the apparatus assembly  10  is a function of the size of the tire  12 . The preferred location of the antenna assembly  10  on the tire is on the tire just above the rim flange  30 . Such a location minimizes stress forces on the assembly from operation of the tire and minimizes interference to RF communication between the tag and an external reader (not shown) that might otherwise be caused by the metal rim. Other mounting locations of the antenna assembly  10  on the tire, however, may be employed if desired for specific tire applications.  
         [0020]     From  FIG. 8 , it will be apparent that an optimal manner for attaching annular assembly  10  to a tire is during the tire manufacturing process. In curing the tire, the assembly  10  will adhere directly to the liner 22  and a reliable mechanical connection results. However, for the reasons previously discussed, the tire manufacturing operation can impart significant stress to the tag  70 , and/or its leads  72 ,  74 , resulting in a failure of the electronics. The subject invention avoids the possibility of such a failure by replacing the tag  70  with a temporary assembly during the manufacturing process.  
         [0021]     Referring to  FIG. 1 , the invention utilizes a base plate  38  having a main body  40  of generally rectangular configuration formed of electrically conductive material such as copper or steel. The base plate body  40  includes a pair of spaced apart circular grommets  42 ,  44  extending therethrough. The plate  38  is disposed between free ends  46 ,  48  of the antenna wire  32  in a first stage of the assembly process. Free antenna ends  46 ,  48  are routed from an underside of the plate  38  up and through respective grommets  42 ,  44  as shown. The grommets  42 ,  44  conduct electrical signals between the antenna and a tag electronics package by means of antenna ends  46 , 48 .  
         [0022]     With regard to  FIGS. 1,2  and  3 , in a second stage of the assembly process, the antenna ends  46 ,  48 , are held in place by means of a plug member  50  coupled to the base plate  38 . The plug member  50  includes a rectangular body  52  dimensioned to substantially cover base plate  38 . Protruding from the body  52  are spaced apart prongs or protrusions  54 ,  56 , each prong having an enlarged diametric dimension at the equator  58 . Prongs  54 ,  56  are dimensioned and spaced for press insertion into apertures  42 ,  44  of base plate  38 , whereby the plug member  50  may be detachably coupled to the base plate  38 . Frictional retention force between prongs  54 ,  56  and apertures  42 ,  44  may be varied and adjusted by adjusting the diametric dimension and configuration of prongs  54 ,  56  as will be understood by those in the art. Plug member  50  may be detached from the base plate  38  by pulling the prongs  54 ,  56  out of respective apertures  42 ,  44 . Press insertion of prongs  54 ,  56  into apertures  42 ,  44  pinches the antenna ends  46 ,  48  against sides of the apertures  42 ,  44  and prevents withdrawal of the wires during the shaping and curing process.  
         [0023]     The annular assembly, with plug member  50 , shown in  FIG. 2  is thereafter shaped to conform to a tire and positioned against the tire liner as explained above and illustrated in  FIG. 8 . The tire is cured and the annular antenna assembly is thereby cured into the tire. The plug member  50  throughout the procedure maintains the fixed relationship between the antenna wire ends  42 ,  44  and the base plate  38 .  
         [0024]     The tag carrier is illustrated in detail by  FIGS. 5, 6 , and  7 . As shown, carrier  60  comprises a carrier body  62  formed of any suitable material such as plastic. The body  62  has inwardly and upwardly tapering sides  61  that lead to an upper cylindrical socket  63 . Depending from the body  62  are spaced apart prongs or protrusions  64 ,  66 . Prongs  64 ,  66  are formed to have an enlarged equatorial diameter  68 . Seated and secured within the socket  63  is an electronic tag  70 . The invention is not intended to be tag specific and any suitable electronic tag available in the industry may be employed. Typical tag packages have sensor means for measuring the temperature and pressure within a tire cavity. Such tags may further have stored therein an identification code for identifying the tire associated therewith. Tags of the subject general type may be powered by a local source such as a battery. More useful, however, are tags that are powered by an external RF energy source transmitted to the tag by means of an antenna. Such configurations do not require battery replacement and are therefore considered preferable. Typically, tags communicate by RF signal through an antenna to an external reader on a vehicle. Connection between the tag and the antenna is by means of conductor leads  72 ,  74 . As best seen from  FIG. 7 , the leads  72 ,  74  are extended through the carrier body  62  to terminal ends  76  located at an outside surface of each carrier prong  64 ,  66 , proximate to the equatorial plane  68 . The leads  72 ,  74  are stabilized by the carrier body  62  so that the terminal ends  76  are fixed in their intended orientation outboard of prongs  64 ,  66  substantially at the equatorial plane  68 .  
         [0025]     In a post-cure operation, the plug member  50  is removed from attachment with the base plate  38  by extraction of prongs  54 ,  58  from apertures  42 ,  44 . The antenna ends  46 ,  48  will remain within grommets  42 ,  44 . In a next step, the tag carrier of  FIG. 5  is inserted into mating engagement with the base plate  38  by the press insertion of carrier prongs  64 ,  66  into the grommet apertures  42 ,  44 . The prongs  64 ,  66  replace the prongs  54 ,  56  of the plug member  50  and are of like configuration, having an enlarged equatorial diameter  68 . The prongs  64 ,  66  pressure the antenna leads  42 ,  44  against sides of apertures  42 ,  44  and ensure that positive electrical contact is established and maintained between the antenna ends  42 ,  44  and the base plate  38 . See  FIG. 6 .  
         [0026]     With reference to  FIGS. 6 and 7 , it will further be noted that insertion of prongs  64 ,  66  into grommet apertures  42 , 44  also establishes and maintains electrical contact between the terminal ends  76  of tag leads  72 ,  74  and the base plate  38 . Preferably prongs  64 ,  66  and  54 ,  58  are formed of resilient plastics material. As they are press inserted into the base plate grommets, the prongs will be compressed and exert radially directed outward force against the ends of the antenna. The terminal ends  76  of the tag  70  are disposed at the oversized equatorial plane of each prong such that when the prongs  64 ,  66  are fully inserted into their respective grommet, the ends  76  of each lead will be pressured against sidewalls defining each grommet. Positive electrical continuity is thereby established between the tag  70  and the base plate  38  through leads  72 ,  74 . The antenna is likewise electrically in contact with the base plate  38  as the same carrier prongs  64 ,  66  serve to pressure antenna ends  46 ,  48  against the grommet sidewalls. Resultantly, there is established and maintained an electrical continuity between tag  70  and the antenna  32 .  
         [0027]     From the foregoing, it will be appreciated that the subject invention accomplishes the needs outlined above. First, the subject method allows the annular antenna and carrier strip to be incorporated within the tire during the tire building operation, resulting in a mechanical connection of high integrity. The tag  70 , however, is spared from exposure to stresses associated with the tire building operation by the substitution of plug member  60 . The plug member  60  is conveniently inserted into the annular antenna apparatus and serves to maintain the antenna ends at their designated locations within base plate grommets. In a post-cure operation, the plug member may be conveniently removed and replaced with the tag carrier. Replacement effectively establishes electrical continuity between the tag electronics and the annular antenna wire without the need for extensive labor or parts. The tag electronics are thereby incorporated into the annular antenna assembly at a final stage.  
         [0028]     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.