Abstract:
A pneumatic tire mountable of the rim of a vehicle wheel has a toroidal structure including a pair of beads for receipt on the rim of a vehicle wheel such that the pneumatic tire is secured to the vehicle wheel for rotation therewith. The pneumatic tire also includes a tread band surface at the radially outermost location of the toroidal structure for contacting a surface along which the tire rolls. A plurality of sensor elements are disposed in the tire for sensing at least one operational parameter of the tire, with at least some of the sensor elements being in sensing arrangement with the tread band surface and the sensor elements being operable to permit reading of data concerning any tire operational parameter which is sensed by the sensor elements.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a pneumatic tire mountable on the rim of a wheel. The present invention further relates to a sensor net which is vulcanized into a tire as well as a rotation measurement unit to be mounted in a tire and a vehicle monitoring system. 
   The tires on the wheels of a vehicle mediate the contact between the vehicle and the driving surface. The tires perform a wide variety of roles: they influence the rolling comfort, the resistance to the vehicle&#39;s travel, the security of the vehicle&#39;s driving operation, and much more and are, consequently, a decisive component with respect to the functioning fitness of the vehicle. Tires are subjected to considerable demands in operation. In addition to environmental driving influences such as gasses, light, and fluids, as well as mechanical demands such as vehicle loading conditions, sudden stopping and tire tracking, the filled tire pressure—that is, the air pressure operating in the interior of the tire—is a point of reference concerning the duration of the operational life and the functional conditions of the tire. In particular, too low an air pressure leads to excessive rolling energy of the tire, whereby the tire temperature in, in particular, the region of the tire shoulder, increases. A high temperature not only damages the tire rubber itself but also damages the interconnection of the tire rubber with the carcass and additional tire build-ups such as, for example, a tire belt. In total, it is important that the power loss attributable to a tire, which, in the same manner as mechanical demands, also make their presence known via an increased tire temperature, remains small. 
   SUMMARY OF THE INVENTION 
   The present invention provides a solution to the challenge of offering a possibility by which the status of the reliable functioning of a pneumatic tire mounted on the rim of a wheel can be evaluated. 
   The core concept is characterized by a pneumatic tire having a plurality of sensors mounted therein, whereupon the operational parameters of the tire such as temperature, pressure, mechanical loading, and so forth can be registered or captured and such captured operational parameter values can not only be available for evaluation for the purpose of drawing conclusions about the tire itself but, as well, can also be available for drawing conclusions therefrom concerning the operational parameters of the vehicle. 
   The present invention relates to a pneumatic tire which is mountable on the rim of a wheel on all types of vehicles including, as well, aviation transport. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The object of the present invention will appear more clearly from the following specification in conjunction with the accompanying schematic drawings, in which: 
       FIG. 1  is an enlarged radial sectional view through the upper half of a vehicle tire and showing as well portions of one embodiment of the vehicle monitoring system of the present invention; 
       FIG. 2  is a schematic view of one configuration for interrogating and receiving data concerning a tire from a tire monitoring system of the present invention; 
       FIG. 3  is a view of a portion of one configuration of a sensor net of a tire monitoring system of the present invention which would be wound about a tire in its installed disposition but being shown in a flattened, non-wound view; 
       FIG. 4  is a view of a portion of another configuration of a sensor net of a tire monitoring system of the present invention which would be wound about a tire in its installed disposition but being shown in a flattened, non-wound view; 
       FIG. 5  is a view of a portion of a further configuration of a sensor net of a tire monitoring system of the present invention which would be wound about a tire in its installed disposition but being shown in a flattened, non-wound view; 
       FIG. 6  is a schematic view of one configuration of a sensor of a tire monitoring system of the present invention; and 
       FIG. 7  is a schematic view of an autonomous or self sufficient sensor unit of a tire monitoring system of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows, in radial sectional view, an upper portion of a tire, the tire comprising a carcass  4  which has, for example, two radially extending plies formed of rayon cords and terminating radially inwardly in beads  6 . Bead cores  8  are mounted in the radially inner end regions of the beads  6  for stabilizing the beads. A belt  10  is arranged in the radially outer region of the carcass  4  and is comprised, for example, of two crossed or biased plies formed of steel cords and two completely annularly extending plies formed of nylon cords. A rubber layer  12  is vulcanized over the carcass  4 , or, respectively, the belt  10 , the rubber layer forming in its radially outermost region the tread band  14  and forming, in its lateral or side regions, relatively thin sidewalls  16 . The beads  6  are received axially inwardly of the shoulders  18  of a rim  20  which itself is integrally formed with a non-illustrated wheel. The tire is of the type having an air sealed construction so that the tire interior can be provided with pressurized air via a valve  22  extending through the rim. 
   The afore-described tire construction is conventional and is not further described herein. The afore-described tire construction is to be understood as only an exemplary description of a tire. The invention can also be deployed for tires of a different construction. 
   In accordance with the present invention, a sensor system or net  24  is disposed between the belt  10  and the carcass  4  by, for example, lamination or vulcanization of the sensor net into the tire and the sensor net comprises sensor units which are not illustrated in  FIG. 1 . The sensor units can be interrogated by an antenna  26  fixedly secured to the vehicle and connected to a control device  28  which itself can be provided with vehicle sensors or with inputs  30 , outputs  32 , and a data connector  34  connected to a bus system. 
     FIG. 2  schematically shows three antennas  26  arranged at circumferential spacings from one another around a fender of a vehicle and, as required, arranged as well offset to one another relative to the transverse direction of the vehicle, the antennas  26  communicating with at least one transponder  36  contained in the sensor net  24  or connected to a node of the sensor net. In correspondence with the arrangement of the transponder(s), a greater or lesser number of vehicle-secured antennas can be provided. 
     FIGS. 3–5  each show, as viewed in the tire interior, a portion of a respective configuration of the sensor net  24  with the belt  10  being shown thereunder, wherein both the sensor net and the belt are shown in a flattened, non-wound view. 
   In the configuration shown in  FIG. 3 , the sensor units  38  contained in the sensor net  24  are each connected via a respective connector  40  with a node  42  which itself contains the transponder  36 . 
   In the configuration shown in  FIG. 4 , a plurality of sensors  38 , arranged in angularly serially-following manner with one another around the tire, are each connected to a single common connector  40  which itself is connected with the transponder  36 . 
     FIG. 5  shows a configuration in which the connectors  40  form a rhombus-shaped net  41  to which is connected the node  42  with the transponder  36 . 
   The cord-like connectors  40  are preferably comprised of steel cable, carbon, conductive plastic or other electrically conductive connectors such as, for example, those conventionally known in the vehicle environment, which, for the purpose of providing the necessary insulation and tension or strain relief, are combined with additional materials or fibers such as, for example, carbon, aramid, steel cord synthetic material, conductive plastic ceramic fibers, and so forth, whereby the connection material cords or, respectively, the connectors, must be chemical and heat resistant in order that such components are not damaged during the vulcanization of the tire, and such components must possess mechanical properties which can survive the operational demands of the tire. In accordance with the respective deployed data processing technology, each sensor unit  38  is connected, via one or several connectors electrically insulated from one another, to the central node  42 , or the individual sensor units can be connected in a net via connectors, if the sensor units comprise, for example, their own processors and can be individually queried by the transponder  36  via multi-plex or bus technology. Within the connector- or, respectively, the cord-, net  41 , the switching arrangements can be realized as are illustrated in  FIG. 2  or in  FIG. 3 . 
   The requisite connectors  40  collectively configure, as a function of the desired number of sensors or, respectively, the mounting of sensor units into the tire, a connector net  41  which, together with the sensor units  38 , forms the sensor net  24  which is disposed between the belt  10  and the carcass  4  and is vulcanized into the tire during the production of the tire. The width of the sensor net, which, in  FIG. 1 , is somewhat larger than the width of the belt  10 , can, depending upon the desired sensor units extend into the sidewalls  16  or can extend in less-than-full width coverage over the belt  10 . In the same vein, the sensor net  24  need not necessarily extend around the entire periphery of the tire (as viewed in its rolling direction). The individual cords of the net can be configured with multiple strands. A reference measure or mass for all of the sensor units  38  and the transponder  36  can be provided by the steel ply of the belt  10  to which each sensor unit and the transponder  36  is connected. In the illustrated embodiments, the node  42  forms, for example, a base substrate with connective paths for connecting, on the one hand, the connectors  40  and, on the other hand, the elements connected to the base substrate of the transponder such as a processor, a memory, antennas, and, as may be optionally provided, an energy supply. In accordance with the respective configuration of the monitoring arrangement, mechanically stable cords can extend through the entire substrate or can be connected with extension elements operable to measure the application of force, such extension elements being integrated into the substrate. 
   The sensor units  38  can each monitor a respectively different physical metric or operational parameter of the tire. The sensor units  38  can comprise several sensor elements including, for example, one for measuring the temperature, one for measuring the air pressure, and one for measuring the pressure or stress applied by the belt, as well as extension measurement cells for measuring the pressure applied by the cords or for measuring the extensions of the cords ( FIG. 5 ) which are a reference measure for the respective localized extension of the tire structure. 
   Via a distribution of the sensor units over the tire road surface contacting surfaces (contact surfaces) sufficient to provide sensing coverage, the respective components of information are available in a form which permits the creation of an illustrative representation of the respective measured metrics across the respective surface. This illustrative representation can, as is described hereinafter in more detail, be advantageously exploited in numerous ways. 
   Pressure measurements can, for example, be undertaken by pressure-sensitive foils or micro measurement cells having piezo elements or capacitors. Extension or expansion of the tire structure can be measured by extension-insensitive foils or micro measurement cells (piezo-electrically or per the capacitor principle). The temperature evaluation can, in similar manner, be evaluated in a piezo-electric manner by means of resistance measurement elements, and so forth. The measurement principles are conventionally known and are not further described herein in detail. 
     FIG. 6  shows a schematic view of a sensor unit  38  having a temperature measurement element  44 , a pressure measurement element  46 , and two extension measurement elements  48  and  50  disposed perpendicularly to one another. 
   To effect the passing over or transmission of the data registered or captured by the sensor units  38 , numerous different possibilities are available. One advantageous possibility is the possibility of transmission of the data via the transponder  36 , which is associated with the node  42 , with which the sensor units  38  themselves are connected. The transponder is inductively provided with electrical energy by movement of the transponder past the antennas  26 . It is to be understood that the transponder  36  can, in an advantageous manner, be arranged at a spacing which is not immediately underneath the belt  10  but which is, instead, a spacing of the transponder laterally adjacent the belt so that the transponder is not shielded off or blocked from the antennas  26  by the belt. The data transmission from the transponder  36  to the control device  28  via the single antenna  26  or, respectively, the antennas  26 , can be effected online, in that each of the sensor units is individually interrogated; in another process, a memory controlled by a processor of the transponder can cyclically interrogate and read the data of the individual sensor units, intermediately store such data, and can then itself be interrogated via, for example, a conventional sample-hold process. The interrogation and reading of the sensor units can be undertaken in a time-controlled manner or in a per-rotation controlled manner. The transponder and the therewith-associated transmission technology are conventionally known whereupon such is not further described in detail herein. 
   As an example of the sensing operation, during each rotation of the wheel, a value such as a temperature value, a pressure value, an extension or expansion value, and so forth captured by a sensor can be read so that, following a corresponding count of revolutions of the wheel, a complete picture of the tire is formed. In correspondence with the available data processing capacity, several measurement values can be simultaneously interrogated and read so that a complete picture (footprint) of the tire is rapidly produced. In this connection, those metrics which are relatively less dynamic such as, for example, temperatures, can be interrogated and read with less frequency as compared to the reading frequency of rapidly changing metrics such as, for example, the pressure and extension metrics. It is to be understood that the mounting of the temperature sensor elements is effected, above all else, in the edge region of the belt  10  in the tire shoulder as these are the respective locations of the tires at which will occur, when the air pressure is too low or the tire is subjected to relatively high loading, the relatively highest temperatures which may possibly damage the tire. 
   The interrogation and reading via a transponder of the data, which is effected via corresponding electronic components (memory, processor) providing a data processing capacity, is not indispensable. The individual sensor elements can, for example, be comprised of series circuits with sensor-specific resonance frequencies so that the sensors can be immediately interrogated and read in correspondence with their frequency specification. The measurement signal can be provided by detuning the resonance frequency or can be a modulation of the resonance frequency. The central nodes with their therewith-connected transponder  36  are not required in this manner of data transmission. 
   The cord or connector net  41  is not an indispensable component of the inventive device. In view of the increasing miniaturization of transponders in which sensor elements are integrated and which are, in their overall configuration, bendable or, respectively, flexible, and their lower costs, it is possible to dispose a plurality of individual sensor units with integrated transponders as well as, if optionally provided, additional dedicated energy supplies, in function-appropriate locations in tires and to interrogate and read data from such sensor units in a non-contact manner. Such bendable synthetic chips with sufficient temperature stability and resistance are described, for example, in the article by F. Miller “Polytronic: Chips von der Rolle”,  Fraunhofer Magazine  4, 2001, pages 8–12. Such chips can be individually mounted in the tire or can be mounted as a pre-assembled component group in a cord net. 
   The data captured by the afore-described measurement technology, which is captured by virtue of the sensors units distributed within the “intelligent” tire, can be evaluated in numerous ways. The control device comprises, in this connection, a microprocessor and storage units so that the operation of an interrogation and evaluation unit contained in the control device is controlled and the results are displayed at a display unit. The temperature course or path of the tire can be stored in that, with respect to the length of the tire operational life or, respectively, damage to the tire, there is criticality associated with how long a location on the tire shoulder has been subjected to a temperature lying above a threshold value. The presence of unallowably high temperatures can permit a conclusion that the tire has an inadequate air pressure. In combination with the mechanical demands on the tire there occurs, for example, extensions or, respectively, deformations, in the plane of the road surface contact surface which can lead to false sudden stopping and tire tracking so that a corresponding false display is displayed by the display device. Also, due to the non-symmetrical distribution of temperatures in the tire, feedback concerning defective vehicle conditions can be generated such as, for example, feedback concerning locally heated locations showing a defective exhaust gas location, false axle alignment positions, and so forth. The footprint of the extension and/or pressure distribution within the tire road contact surface (contact surface) permits observations concerning the overloaded frictional forces (longitudinal and transverse), the axle alignment positions, the wear, the rolling resistance, the aqua-planing relationships, and so forth. In addition to offering diagnosis possibilities (for example, the axle alignment positions, ply defects, and so forth), the evaluated pressure oscillations can lead to an observation concerning mechanical or structural tire defects. 
   Additionally, one can forward the evaluated values to vehicle control and warning systems such as, for example, a vehicle stability system or comfort system, while taking into account, if optionally provided, information about the vehicle speed and the instantaneous motor performance, whereupon such systems can adjust the vehicle suspension characteristics in correspondence with the road and vehicle conditions. 
   In total, the invention not only provides the possibility to register the static and dynamic demands on the tire and, thereby, to determine the influence thereof on power loss, to monitor the function fitness of the tire, and venture a prognosis of the duration of its operating life, but the invention provides, as well, the possibility to evaluate the captured detailed tire data to draw conclusions concerning vehicle defects and to monitor the condition of the vehicle. 
     FIG. 7  shows an autonomous or self sufficient rotation measurement unit  52  which can be integrated into the sensor net  24  or can be separately disposed in the tire, by vulcanization into the tire, as a self-standing component. The rotation measurement unit  52  comprises a sensor element  54  which emits a signal during each rotation of the tire. The sensor element  54  can, for example, comprise a piezo element which is pressed against with oscillating force by a suspended mass during rotation of the tire so that a voltage signal emitted by the sensor element  54  correspondingly oscillates. The output signal of the sensor element  54  permits an evaluation of the energy supply condition of the sensor element with the requisite energy to be supplied being correspondingly made ready in an energy supply unit  56  and the output signal of the sensor element, in addition, permits the generation of a signal integrated into the rotation of the tire, in that, as a result of each oscillation of the output signal caused by a rotation of the tire, the count status maintained in a memory unit  58  increments by a single count. 
   Via the autonomous rotation measurement unit  52  integrated into the tire, the tire itself generates a signal which is independent from that produced by the vehicle concerning the count of the tire rotations. The count status of the memory unit  58  can be, consequently, interrogated and read in a repair station. For the purposes of preventing manipulation of the actual tire rotation count, a setting back of the memory unit  58  can be prevented or permitted by only an unauthorized user. 
   Alternatively, the rotation measurement unit can be integrated into a valve such as, for example, the valve  22  shown in  FIG. 1 , fixedly secured to the wheel rim. 
   In a similar manner to the energization of the rotation measurement unit  52 , the sensors  38  and/or the transponder  36  can be provided with energy generated by rotation of the tire as well. Moreover, memory elements can be provided having pre-set capability to record critical metrics relating to the tire so that such critical metrics are stored in the tire itself, whereupon a quality monitoring of the tire concerning, for example, flank damage or excessive mechanical demands on the tire, can be registered via interrogation and reading of the corresponding memory elements. 
   The specification incorporates by reference the disclosure of German priority document 102 18 781.9 filed Apr. 26, 2002. 
   The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawings, but also encompasses any modifications within the scope of the appended claims.