Radio frequency reading systems mounted on transport vehicles

Abstract

1. A vehicle (2) comprising a movable assembly (1) including a tire (12) configured to rotate about an axis (102), the movable assembly (1) including a radio frequency transponder (100) and a reading system (3), the reading system (3) including: a generator coupled to a demodulator (31) of electrical signals; and a cable (32) electrically connected to the generator (31), fixed to the vehicle (2), and including a radial portion (342), wherein the projection R of the radial portion on a cylinder (104) having an axis of rotation (102) surrounding the tire (12) is less than 1 meter, the radial portion (342) including a meander (500), the curve length of the meander (500) being 0.9 to 1.1 times a half wavelength L0 associated with the communication frequency, and the distance "P" between the two ends of the meander (500) being less than a quarter wavelength.

Description

[Technical Field]

[0001] The present invention relates to a radio frequency transponder reading system mounted on a transport vehicle.Radio frequency transponders are primarily associated with moving assemblies of the transport vehicle. [Background technology]

[0002] The recent development of connected objects requires that they be equipped with radio frequency transponders. These radio frequency transponders generally operate in the UHF (Ultra High Frequency) frequency band, i.e., between 300 MHz and 3 GHz. In the case of transport vehicles, such as tire-driven vehicles, connected objects are moving parts of these transport vehicles. As a result, connected objects are mobile in operation, moving in a plane around a rotation axis that is fixed relative to the transport vehicle. These transponders therefore move in a closed loop relative to themselves in a reference frame related to the transport vehicle.

[0003] In the case of a land vehicle, US Patent Application Publication No. 2021 / 0021015 A1 presents the installation of an on-board reading system for RFID (Radio Frequency Identification) tags and TMS (Tire Mounted Sensor) sensors located in tire casings of mounted assemblies of the land vehicle. The system is formed by a radio frequency reader / transmitter galvanically connected to four transmission lines, each extending to a radio antenna covering a specific geographical area. The radio frequency antennas are firmly fixed to a fixed part of the land vehicle. This solution generally requires multiple two-dimensional flat or three-dimensional radio frequency antennas, which creates a spatial footprint within the land vehicle and negatively impacts the installation of other land vehicle components. Also, the separation of the various elements (radio frequency reader, transmission line, and radio frequency antenna) increases the number of connection points between the various elements, thus increasing the risk of reader failure due to the vibrations and shocks that vehicles are typically subjected to. Finally, the large number of assemblies mounted on a land vehicle means multiple transmission lines and radio frequency antennas, which adds cost. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent Application Publication No. 2021 / 0021015 [Patent Document 2] US Patent Application Publication No. 2016 / 0197408 Summary of the Invention [Problem to be solved by the invention]

[0005] One of the objects of the following invention is to solve the reliability and cost problems of mobile radio frequency transponder reading systems in transportation vehicles. [Means for solving the problem]

[0006] For a better understanding of the present invention, the terms circumferential direction S, axial direction A, and radial direction R herein refer to directions defined relative to a rotating reference frame of a movable assembly about its natural axis of rotation. The radial direction R is a direction extending perpendicularly away from the natural axis of rotation. The axial direction A is a direction parallel to the natural axis of rotation. Finally, the circumferential direction S forms a direct trihedron with the given radial and axial directions.

[0007] The present invention relates to a transport vehicle comprising a radio frequency transponder reading system and at least one movable assembly including a tire set to move about an axis of rotation capable of ensuring the movement of the transport vehicle relative to the ground on which it travels, the free movement of the at least one movable assembly occurring mainly in a two-dimensional plane within a cylindrical reference frame associated with the at least one movable assembly, the axial direction of the at least one movable assembly being in the direction of the axis of rotation and the tire defining a median plane perpendicular to the axis of rotation, the at least one movable assembly, preferably the tire, being equipped with a radio frequency transponder. - a generator of electrical signals transmitting at a frequency F0 included in the ultra-high frequency band, attached to the transport vehicle and coupled to a demodulator of electrical signals adapted to a frequency band around F0; - at least one partially flexible bidirectional communication cable, comprising a conductive core covered with a first dielectric element covered with a conductive assembly, one end of which is electrically connected to a reading system and having at its free end means for capacitive coupling between the conductive core and the conductive assembly via a second dielectric element adapted to the frequency band of the reading system, the length l0 of which is divided according to a metric in units of wavelength L0 defined by frequency F0; - at least one cable is rigidly fixed to the transport vehicle, is external to the at least one movable assembly and includes a radial portion; This arrangement is characterized in that the distance of the radial projection of the first continuous portion of the radial portion of at least one cable on a cylinder surrounding the tire and having an axis of rotation coaxial with the axis of rotation is not more than 1 meter, preferably not more than 0.5 meter, the distance of the axial projection of the first continuous portion of the radial portion of at least one cable on the median surface of the tire in the direction of the axis of rotation is not more than 2 meters, preferably not more than 1 meter, very preferably not more than 0.5 meter, the first continuous portion of the radial portion of at least one cable comprising at least one meander, the curve length of which is 0.9 to 1.1 times half the wavelength L0 defined by the communication frequency F0 modulo the wavelength L0, and the distance "P" separating the ends of the at least one meander is less than one-fourth of the wavelength L0.

[0008] The term "free motion" means that movement occurs without a displacement constraint, as in the case of forced displacement. For example, when a static load is applied to a mounting assembly configured to rotate, this refers to movement of material points of the mounting assembly outside the contact zone between the tire casing and the ground, commonly known as the contact area. Specifically, in this zone, movement of material points of the tire casing in contact with the ground is induced by the ground unless a sliding condition is reached, resulting in forced displacement that does not fit the definition of free motion.

[0009] First, the moveable assembly is a subassembly of the transport vehicle that is used to move the transport vehicle relative to the ground. The moveable assembly includes a tire that is driven to rotate about an axis of rotation by a non-deforming part, i.e., a part such as a rim that is stiffer than the tire.

[0010] The radio frequency transponder can be an RFID tag, another electronic device with its own power source, or passive. The radio frequency transponder is attached to a moving assembly of the transportation vehicle. For example, the radio frequency transponder can be an RFID tag in a tire casing, a TPMS (Tire Pressure Monitoring System) sensor attached to a wheel, or any electronic object that communicates by radio frequency and has a radio frequency antenna located on the moving assembly. To read this electronic object associated with the moving assembly and therefore moving within the transportation vehicle, the present invention discloses a reading system mounted on the transportation vehicle that is located outside the moving assembly. As a result, the reading system is not associated with the movement of the moving assembly. The reading system includes a first device including a transmitter / receiver of electrical signals at a fixed frequency and a demodulator of electrical signals in a frequency band around the fixed frequency. The first device is connected to a two-way communication cable. The cable consists of a hollow or solid, typically metallic, conductive core and a second conductive hollow tube coaxial with the conductive core. These conductive parts are separated by a first dielectric element. One end of the cable is connected to the transmitting / receiving electronics and the other end is free. The cable includes at least one radiating part, i.e., functionally transmits or receives radio waves to or from the outside of the hollow conductive tube. The free end of the cable is provided with means for capacitively coupling the conductive core to a conductive assembly including the conductive hollow tube via a second dielectric element adapted to the frequency band of the reading system.

[0011] This type of two-way communication cable uses surface waves via this capacitive coupling means. This allows for a two-way cable that does not contain singularities on the surface of the radial section. Therefore, even if the cable is significantly deformed during installation in a transportation vehicle, the communication function of the cable will not be affected, as it would be with a leaky feed antenna, where the distribution and shape of holes passing through the conductive tube are sensitive to deformation of the two-way cable. Furthermore, this technical solution is more economical, since drilling holes in a conductive tube is significantly more expensive than placing a device for electrical reflection by capacitive coupling at the end of a coaxial cable.

[0012] U.S. Patent Application Publication No. 2016 / 0197408 A1 describes such a cable, including at its free end a device for electrical reflection by capacitive coupling, consisting of a conductive element connected to the conductive core and separated from the conductive tube by a second dielectric material, which optionally creates capacitive coupling. The length of the conductive element is typically one-quarter of the wavelength of the radio waves transmitted and received by the cable antenna. This device generates surface propagation radio waves on the conductive tube in the opposite direction to the direction transmitted by the signal generator, up to a surface wave attenuation zone formed by magnetized rings, typically made of ferrite, attached axially to the outside of the cable.

[0013] The invention is based, first and foremost, on the specific arrangement of the reading system, in particular the radial portion of the bidirectional communication cable, relative to the path followed by the radio frequency transponder driven by the moving assembly. Specifically, to enable radio frequency communication between the reading system and the radio frequency transponder, the spatial distance between the radial portion of the cable and the radio frequency transponder must be less than a certain distance, preferably less than one meter, during the part of the loop that the radio frequency transponder describes as the moving assembly moves. This is ensured by two conditions related to the structure of the moving assembly. Specifically, since the moving assembly moves primarily in two dimensions, it is possible to define a median plane of the moving assembly's tire in a reference frame relative to the moving assembly, outside the zone of imposed displacement. This median plane is perpendicular to the moving assembly's rotation axis and has the property of separating the moving assembly into two symmetrical parts with respect to the median plane. The term "primarily bidirectional movement" means that the distance covered by a material point of the moving assembly between two moments, resolved in an orthogonal reference frame relative to the moving assembly, has one component that is smaller than the other two. Generally speaking, this component is the component carried by the direction of the rotation axis of the movable assembly. The first condition is that the continuous sub-portion of the radial portion of the communication cable does not exceed 2 m from the median plane attached to the tire of the movable assembly in the direction of the rotation axis of the movable assembly. Naturally, the shorter the distance between the continuous radial portion of the communication cable and the radio frequency transponder, the better the radio frequency communication between the two radio frequency devices.

[0014] Since the tire of the moving assembly is driven by a pure rotational motion about its axis of rotation, it is necessary to control the distance between the successive radial portions of the two-way communication cable and the tire of the moving assembly. For this purpose, a second projection condition must be satisfied. This condition consists in defining the maximum distance R of the radial projection of the radial portion of the two-way communication cable on the nearest surface of the tire of the moving assembly, which corresponds to the radially outer surface of the tire with respect to the axis of rotation, for the zone of the tire rotating about the axis of rotation.

[0015] If these conditions are met during the portion of the loop traced by the radio frequency transponder attached to the movable assembly as it moves, it is ensured that successive radial portions of the two-way communication cable are in potential two-way communication with the radio frequency transponder on this portion of the loop, and this communication is spatially periodic, since it is repeated on each loop. Naturally, the larger this portion of the loop, the better the communication between the two components will be in time. This condition is preferably met throughout the entire loop traced by the radio frequency transponder.

[0016] Finally, it is necessary that the continuous radial portion of the two-way communication cable in this spatial zone relative to the movable assembly includes at least one meander. The meander is defined by a width "l" and a length "L." The length "L" is defined relative to the axial direction of the radial portion of the cable outside the meander zone. One end of the length "L" begins at the change in cable curvature that initiates the meander. The other end is defined by the point of the meander that is farthest relative to the axial direction of the cable, i.e., has the largest orthogonal projection. The width "l" of the meander is defined using the axial average, in the direction of the cable, of the points of the meander that define the outward or return path of the meander, i.e., all points of the cable located between the two ends that define the meander length "L" on the outward or return path of the meander. The distance between these two axial averages in the axial direction of the cable determines the width "l" of the meander. The first point of the meander whose tangent has a main component carried by the direction of the meander length "L" in the propagation direction of the radio waves provided by the transmitting / receiving system is called the entrance end of the meander. The last point of the meander whose tangent has a main component carried by the direction of the meander length "L" in the propagation direction of the radio waves provided by the transmitting / receiving system is called the exit end of the meander. The distance "P" is measured between the entrance end and the exit end of the meander.

[0017] The meander allows for the creation of a zone of enhanced communication between the two-way communication cable and the transponder in a communication mode of radio frequency transmission from, i.e., triggered by, a reading system. As a result, it becomes possible to establish communication with the radio frequency transponder, particularly if the radio frequency transponder is passive, by providing a sufficient amount of energy for the radio frequency transponder to wake up and establish communication when the radio frequency transponder approaches the meander in the course of its movement associated with the movement of the movable assembly. Specifically, the meander allows for the creation of a narrow spatial zone located between the entrance and exit ends of the meander, in which the electric field E generated by the radial portion of the communication cable is stable and has a larger amplitude than the electric field E generated outside or within the meander.

[0018] The increase in the electric field E between the entrance and exit ends of this meander is only possible due to the specific distance P between the two points of the meander, which forms a gap—i.e., an oppositely charged system with opposite positive and negative charges, like a capacitor—when the meander's curved length is close to half a wavelength L0, associated with the communication frequency F0 of the reading system. The increase in the amplitude of the electric field E results in an increase in radio frequency energy directed toward the radio frequency transponder, thus enabling the radio frequency transponder to operate in communication mode. In the case of passive radio frequency transponders, such as passive RFID tags, the energy captured by the radio frequency transponder is used to transmit a return radio frequency message from the radio frequency transponder. During the reception phase of the radio frequency message from the radio frequency transponder, the linear radial portion of the communication cable is sufficient to receive the return message as long as the distance between the two elements remains adequate. Therefore, this meander is primarily used in zones where communication with a radio frequency transponder is difficult, such as when it is desired to interrogate a radio frequency transponder spatially distant from the radial portion of the communication cable, or when the environment of the vehicle or moving assembly is not suitable for radio frequency communication due to conductive elements, etc. Therefore, if radio frequency transponders are located both on the outside of the tire and on the outside of the vehicle, it is possible to locate the radial portion of the cable only on the radially outer side of the tire. However, in many cases, the crown of the tire, which is the radially outermost part of the tire relative to the tire's rotation axis, includes a metallic crown, which has a radial design that adversely affects radio frequency communication. Even in these specific cases, the presence of the meander still makes it possible to interrogate the radio frequency transponder of the moving assembly and receive its radio frequency response through the first continuous portion of the radial portion of the communication cable.

[0019] It should be noted that the positioning of the remaining parts of the meander, i.e., the parts other than the entrance and exit end points, only slightly modifies the electric field E. As a result, this meander can easily fit into any complex and dense environment, such as a car. To ensure that the meander performs its function of enhancing radio frequency communications, only the distance between the entrance and exit ends, the orientation of the straight line defined by these two ends, and the length of the curve between these two ends need to be controlled. Finally, this type of meander can also minimize the power consumption of the communication cable, since radio frequency radiation is localized and not widespread, thereby saving energy. Naturally, the smaller the distance "P" between the exit and entrance ends of the meander, the stronger the electric field E generated by these points, and the longer the radio frequency transponder is exposed to this enhanced electric field E. To increase the exposure time to this electric field E, it is sufficient to increase the number of meanders, especially by placing them adjacent to each other. For example, this can be achieved by bending the cable into an "S" shape and adding two adjacent meanders with opposite loops. The S shape avoids the spatial offset between the two meanders caused by the cable curvature. This method strengthens the electric field E of each meander, thereby expanding the communication zone.

[0020] Furthermore, the continuous radial portion of the two-way communication cable in the spatial zone around the movable assembly preferably has a curved length greater than one unit of cable length, where the unit of cable length is determined by the wavelength L0 associated with the transmission frequency F0 of the radio signal by the reading system propagating in a medium with a given dielectric constant. This ensures that the length of the antenna in the spatial zone bounded by one of the two geometric conditions is suitable for transmitting and receiving radio signals to and from the radio frequency transponder attached to the movable assembly. Naturally, the longer the continuous radial portion of the two-way communication cable, the better the communication between the reading device and the radio frequency transponder.

[0021] According to a specific embodiment, the radial portion of the at least one cable comprises at least one second continuous portion distinct from the first continuous portion, and the distance of the radial projection of the at least one second continuous portion of the radial portion of the at least one cable on a cylinder of a rotation axis coaxial with the rotation axis of the at least one second movable assembly surrounding the tire of the at least one second movable assembly is not more than 1 meter, preferably not more than 0.5 meter, and the distance of the axial projection of the at least one second continuous portion of the radial portion of the at least one cable on the median surface of the tire of the at least one second movable assembly in the direction of the rotation axis of the at least one second movable assembly is not more than 2 meters, preferably not more than 1 meter, very preferably not more than 0.5 meter.

[0022] This configuration allows a two-way communication cable to interrogate moving assemblies of the same transport vehicle that are far enough apart that the same continuous radial portion of the communication cable cannot interrogate both moving assemblies. A conventional solution would be to add a second two-way communication cable and place a continuous radial portion of this second cable within the appropriate geographic area of ​​the second moving assembly, which would be costly. The solution here is to limit the number of electrical connections to the reading system's electrical signal transmitter / receiver by using the same two-way communication cable. This cable then includes a second continuous radial portion that is separate from the first continuous portion, but this portion can be the same radial portion of the cable. In this way, the same cable in each case interrogates and receives information from radio frequency transponders associated with different moving assemblies. To create a large radiation space zone, the radial portion of the cable simply needs to be passed through the same space zone several times to form a continuous zone. This creates a large radiation zone, facilitating communication with the transponders of transport vehicles passing through the space zone. Naturally, this method can also be used to create multiple large radiation space zones that are separated from each other. Between these spatial zones, the cable's radiation behavior is reduced, but radio signals can still be transmitted along the cable to the reader. Of course, it is also possible to increase the number of continuous and radial portions along the length of the communication cable to communicate with multiple mobile assemblies that are geographically distant from one another, and to communicate with all radio frequency transponders on the transportation vehicle, regardless of whether they are coupled to the mobile assembly of the transportation vehicle. Similarly, successive radial portions of a two-way communication cable can communicate with different mobile assemblies, as long as they are located the correct distance from the successive radial portions of the cable.

[0023] In a specific embodiment, in the radial portion of the cable, the conductive assembly is covered by a second conductive assembly that is connected to ground.

[0024] This results in limiting electromagnetic emissions from cables within the transport vehicle as required by the desired electromagnetic compatibility of the transport vehicle.

[0025] According to a particular embodiment, at least one second continuous portion of the radial portion of the at least one cable comprises at least one meander, wherein a curved length of the at least one meander of the at least one second portion is 0.9 to 1.1 times half a wavelength L0 defined by the communication frequency F0 modulo the wavelength L0, and wherein a distance "P" separating the ends of the at least one meander of the at least one second portion is less than one-quarter of the wavelength L0.

[0026] The second continuous section of the radial portion of the two-way communication cable, closer to the movable assembly, preferably includes at least one meander. The meander is defined by a width "l" and a length "L." The length "L" is defined relative to the axial direction of the radial portion of the cable outside the meander zone, within the zone defined by the radial and axial projections of the cable on the movable assembly. One end of the length "L" begins at the change in cable curvature that initiates the meander. The other end is defined by the point of the meander that is furthest along the axial direction of the cable, i.e., has the largest orthogonal projection. The width "l" of the meander is determined using the axial averages, in the direction of the cable, of all points of the cable located between the two ends that define the length "L" of the meander along the axial direction of the cable, i.e., the meander's outgoing or returning path. The distance between these two axial averages in the axial direction of the cable determines the width "l" of the meander. The first point of the meander whose tangent has a main component carried by the direction of the meander length "L" in the propagation direction of the radio waves provided by the transmitting / receiving system is called the entrance end of the meander. The last point of the meander whose tangent has a main component carried by the direction of the meander length "L" in the propagation direction of the radio waves provided by the transmitting / receiving system is called the exit end of the meander. The distance "P" is measured between the entrance end and the exit end of the meander.

[0027] The meander allows for the creation of an enhanced communication zone between the two-way communication cable and the transponder in a communication mode of radio frequency transmission from the reading system, i.e., triggered by the reading system. As a result, it becomes possible to establish communication with the radio frequency transponder, particularly if the radio frequency transponder is passive, by providing a sufficient amount of energy to wake up the radio frequency transponder and establish communication when the radio frequency transponder approaches the meander during the course of movement associated with the movement of the second movable assembly. Specifically, the meander allows for the creation of a narrow spatial zone located between the entrance and exit ends of the meander, in which the electric field E generated by the radial portion of the communication cable is stable and has a larger amplitude than the electric field E generated outside or within the meander.

[0028] Specifically, this meander allows the formation of a vast spatial zone proportional to the length "L" of the meander, where the electric field E generated by the radial portion of the communication cable is stable and has a larger amplitude than the electric field E generated outside the meander. The increase in the electric field E between the entrance and exit ends of this meander is only possible due to a certain distance P between those two points of the meander that forms a gap, i.e. an oppositely charged system where the positive and negative charges are opposite to each other, like a capacitor, when the curved length of the meander is close to half a wavelength L0 related to the communication frequency F0 of the reading system.

[0029] The increase in the amplitude of the electric field E results in an increase in radio frequency energy directed toward the radio frequency transponder, thus enabling the radio frequency transponder to operate in communication mode. In the case of passive radio frequency transponders, such as RFID tags, the energy captured by the radio frequency transponder is used to transmit a return radio frequency message from the radio frequency transponder. During the reception phase of the radio frequency message from the radio frequency transponder, the linear radial portion of the communication cable is sufficient to receive the return message as long as the distance between the two elements remains adequate. Therefore, this meander is primarily used in zones where communication with the radio frequency transponder is difficult, such as when one wishes to interrogate a radio frequency transponder that is spatially distant from the radial portion of the communication cable, or when the environment of the vehicle or moving assembly is not suitable for radio frequency communication due to conductive elements, etc. Even in these specific cases, the presence of the meander still makes it possible to interrogate the radio frequency transponder of the moving assembly and receive its radio frequency response through the second continuous radial portion of the communication cable.

[0030] It should be noted that the positioning of the remaining parts of the meander, i.e., the parts other than the entrance and exit end points, only slightly modifies the electric field E. As a result, this meander can easily fit into any complex and dense environment, such as a car. To ensure that the meander performs its function of enhancing radio frequency communications, only the distance between the entrance and exit ends, the orientation of the straight line defined by these two ends, and the length of the curve between these two ends need to be controlled. Finally, this type of meander can also minimize the power consumption of the communication cable, since radio frequency radiation is localized and not widespread, thereby saving energy. Naturally, the smaller the distance "P" between the exit and entrance ends of the meander, the stronger the electric field E generated by these points, and the longer the radio frequency transponder is exposed to this enhanced electric field E. To increase the exposure time to this enhanced electric field E, it is sufficient to increase the number of meanders, especially to place these meanders adjacent to each other. For example, this can be achieved by bending the cable into an "S" shape and adding two adjacent meanders with opposite loops. The S shape avoids the spatial offset between the two meanders caused by the curvature of the cable. This method strengthens the electric field E generated by each meander, thereby expanding the communication zone.

[0031] Furthermore, the continuous radial portion of the two-way communication cable in the spatial zone around the second movable assembly preferably has a curved length greater than one unit of cable length. The unit of cable length is determined by the wavelength associated with the transmission frequency F0 of the radio signal by the reading system propagating in a medium with a given dielectric constant. This ensures that the length of the antenna in the spatial zone bounded by one of the two geometric conditions is suitable for transmitting and receiving radio signals to and from the radio frequency transponder attached to the movable assembly. Naturally, the longer the length of the continuous radial portion of the two-way communication cable, the better the communication between the reading device and the radio frequency transponder.

[0032] According to an advantageous embodiment, the radial portion of at least one cable comprises at most seven meanders, preferably at most five meanders.

[0033] Increasing the number of meanders limits the radiation of the cable outside the zone in which the meanders are located, which has a negative impact on the interrogation of radio frequency transponders of transport vehicles that are not located within the spatial zone of the continuous radial portion of the communication cable during movement. An alternative solution to compensate for the low radiation of transmissions from this cable is to increase the power of the reading system. However, it is preferable to limit the number of meanders in order to provide the same power to the reading system and ensure sufficient radio frequency communication along the entire radial portion of the two-way communication cable.

[0034] According to another advantageous embodiment, each successive radial portion of at least one cable comprises at most three meanders, preferably at most two meanders.

[0035] By the same logic of uniformity of cable capacity, it is preferable that each successive radial section of the cable has around three meanders, and very preferably around two, so that when there are multiple different successive sections, the radiated power is distributed across these successive sections, and radio transmission power remains in areas without meanders.

[0036] Advantageously, the radio frequency transponder associated with the at least one movable assembly comprises a radio frequency antenna including at least one twisted wire defining a first longitudinal axis, and each meander of the first continuous portion and / or the at least one second continuous portion of the radial portion of the at least one cable defines a straight line D defined by two ends of the at least one meander, and the angle formed by the direction vector of the first longitudinal axis and the straight line D is less than ±30 degrees, preferably less than ±20 degrees, over at least a portion of the closed path described by the at least one movable assembly.

[0037] In certain cases where the radio frequency transponder includes a wire antenna, the direction of the first longitudinal axis and the direction of the line D must be substantially parallel to each other to ensure electromagnetic coupling between the radio frequency transponder and the active portion of the meander. Specifically, the enhanced electric field E generated by the meander is oriented along the line D. Therefore, the transponder's wire antenna is substantially aligned with the enhanced electric field E generated by the meander. Ideally, for maximum coupling effectiveness, the wire antenna should be collinear with the enhanced electric field E. However, as long as the angle formed by the two directions does not deviate by more than 30 degrees, communication between the two antennas is quite sufficient. This is preferable when the radio frequency transponder is passive, i.e., does not have its own source or generation of electrical energy. In this case, electromagnetic coupling serves to activate the radio frequency transponder by transmitting energy to it before transmission.

[0038] Of course, since the reading system is fixed relative to the transport vehicle while the radio frequency transponder is moving, the angle condition is not necessarily met over the entire path traversed by the radio frequency transponder, but it is sufficient that the angle condition be met over part of the path taken by the moving assembly for radio frequency communication between the two electronic systems to be valid.

[0039] According to a first very specific embodiment, if the at least one movable assembly is capable of describing a rotational movement about a single axis of rotation defining a cylindrical reference frame about the single axis of rotation, the first longitudinal axis of the radio frequency antenna of the radio frequency transponder associated with the at least one movable assembly has a main component oriented circumferentially in the cylindrical reference frame, and the at least one meander associated with the first continuous portion and / or the at least one second continuous portion of the radial portion of the at least one cable is arranged radially outside the movable assembly with respect to the axis of rotation, and the straight line D of the at least one meander has a main component oriented circumferentially in the cylindrical reference frame of the movable assembly.

[0040] If the first longitudinal axis of the radio frequency transponder of the movable assembly is predominantly circumferential in the cylindrical reference frame of the mounting assembly, as for example when an RFID tag is embedded in the structure of the tire in the sidewall or lower zone, and if the meander is located radially outside the tire relative to the axis of rotation of the movable assembly, it is desirable to arrange the meander so that the line D is predominantly circumferential in the cylindrical reference frame of the movable assembly. It is thus ensured that during rotational movement of the movable assembly, the first longitudinal axis of the wire antenna of the radio frequency transponder and the direction of the enhanced electric field E caused by the meander are substantially aligned with the part of the loop described by the movement of the radio frequency transponder.

[0041] A very specific realization of this first specific embodiment is that, if the radio frequency antenna of the radio frequency transponder associated with the at least one movable assembly and the at least one meander associated with the first continuous portion and / or the at least one second continuous portion of the radial portion of the cable project in the same circumferential plane, the projection of the antenna of the radio frequency transponder intersects with the projection of the straight line D of the at least one meander.

[0042] When the radio frequency transponder of the movable assembly is embedded in the rubber compound of the tire, as in the case of an RFID tag, the size of the radio frequency antenna of the radio frequency transponder, defined by the stranded wire(s) and associated with the radio communication frequency F0 of the radio frequency transponder, is small due to the relative permittivity of the rubber compound of the tire. Specifically, the relative permittivity of the rubber compound differs from that of air, which alters the wavelength of radio waves. In this case, depending on the communication frequency F0, the size of the radio frequency antenna can be smaller than the distance "P" between the entrance and exit ends of the serpentine. Therefore, the entire radiating antenna of the transponder is located within the enhanced electric field E generated by the serpentine, thereby increasing the power transmitted to the radio frequency transponder.

[0043] According to a second very specific embodiment, if the mobile assembly is capable of describing a rotational movement about a single axis of rotation defining a cylindrical reference frame about the single axis of rotation, the first longitudinal axis of the radio frequency antenna of the radio frequency transponder associated with at least one mobile assembly has a main component oriented circumferentially in the cylindrical reference frame, and at least one meander associated with the first continuous portion and / or the at least one second continuous portion of the radial part of the cable is arranged axially outside and radially inside the mobile assembly with respect to the axis of rotation, and the straight line D of the at least one meander has a main component oriented circumferentially in the cylindrical reference frame of the mobile assembly.

[0044] In cases where the first longitudinal axis of the radio frequency transponder of the movable assembly is predominantly circumferential in the cylindrical reference frame of the mounting assembly, as for example when an RFID tag is embedded in the structure of the tire in the sidewall or lower zone, and where a continuous portion of the radial portion of the communication cable is located axially outside and radially inside the tire relative to the axis of rotation of the movable assembly, it is desirable to arrange the meander so that the line D is predominantly circumferential in the cylindrical reference frame of the movable assembly. It is thus ensured that during rotational movement of the movable assembly, the first longitudinal axis of the wire antenna of the radio frequency transponder and the direction of the electric field generated by the meander are substantially aligned with the portion of the loop described by the movement of the radio frequency transponder.

[0045] A very concrete realization of this second specific embodiment is that, when the radio frequency antenna of the radio frequency transponder associated with the at least one movable assembly and the at least one meander associated with the first continuous portion and / or the at least one second continuous portion of the radial portion of the cable project in the same axial plane, the projection of the antenna of the radio frequency transponder intersects with the projection of the straight line D of the at least one meander.

[0046] When the radio frequency transponder of the movable assembly is embedded in the rubber compound of the tire, as in the case of an RFID tag, the size of the radio frequency antenna of the radio frequency transponder, defined by the stranded wire(s) and associated with the radio communication frequency F0 of the radio frequency transponder, is small due to the relative permittivity of the rubber compound of the tire. Specifically, the relative permittivity of the rubber compound differs from that of air, which changes the wavelength of the radio waves. In this case, for example, depending on the communication frequency F0, the size of the radio frequency antenna can be smaller than the distance "P" between the entrance and exit ends of the serpentine. Therefore, the entire radiating antenna of the transponder is located within the electric field E generated by the serpentine, thereby increasing the communication power of the radio frequency transponder.

[0047] Advantageously, the radio frequency transponder comprises an RFID tag.

[0048] This embodiment is a specific one in which the radio frequency transponder comprises an RFID (Radio Frequency Identification) tag. This radio frequency transponder is small since it requires few components to operate and can actually be attached to the inside or outside of the tire of the moving assembly by a specific connecting patch. The main function of such an electronic system is to convey identification information that is usually encoded in a non-erasable memory of the electronic system. In a specific embodiment, the RFID tag is passive and does not have its own power source. In this specific case, the RFID tag interrogation step consists of first transferring radio frequency energy to the RFID tag to enable it and then responding to the interrogation.

[0049] When the movable assembly is capable of describing a rotational movement about an axis of rotation, it is advantageous for each continuous portion of the at least one cable to describe an angular sector about the axis of rotation that is at least greater than 30 degrees, preferably greater than 60 degrees, very preferably greater than 120 degrees.

[0050] In the case of a movable assembly rotating about a single axis of rotation, it is preferable that the continuous radial portion of the two-way communication cable, including the serpentine, extends over an angular sector of at least 30 degrees within the rotating reference frame associated with the single axis of rotation. This ensures a constant communication time between the radio frequency transponder rotating with the movable assembly and the reading system fixed to the transport vehicle, depending on the rotation speed of the movable assembly about the single axis of rotation. Naturally, the larger the angular sector, the longer the communication time at a given rotation speed.

[0051] Preferably, a continuous portion of the radial portion of the at least one cable is attached to at least one wall defining a cavity of the vehicle that receives the moveable assembly.

[0052] In the case of a moving assembly that rotates about a single axis of rotation, such as an automobile tire casing, it is preferable to attach a continuous radial portion of the two-way communication cable directly or indirectly to the wheel arch. The wheel arch defines a cavity to which the vehicle-mounted assembly is connected during use. This component is generally non-metallic, meaning that there is no shielding effect or radio wave interference. The absence of metal or conductive components between the two antennas enhances radio wave propagation between the communication cable and the transponder. Finally, the cavity naturally provides a free area for installing the communication cable within extremely confined spaces, such as the interior of an automobile.

[0053] It is highly preferred that successive radial portions of the at least one cable extend at a constant radial distance from a single axis of rotation of the movable assembly.

[0054] This condition ensures reliable radio frequency communication between the two components when a passive radio frequency transponder, such as an RFID tag, is present in the tire. In practice, it is generally accepted that RFID tags are positioned on the tire's sidewall, primarily circumferentially relative to the axis of rotation of the mounting assembly. Furthermore, the shape of the walls defining the cavity for receiving the mounting assembly generally follows this geometric condition. Therefore, communication between the two antennas is also optimized in terms of both duration and quality, while maintaining a constant spatial distance between the radio frequency transponder and the successive radial portions of the communication cable.

[0055] The radio frequency transponder preferably transmits at a subcarrier frequency.

[0056] In such applications, a radio frequency transponder transmits a response to a query using a received radio frequency transmission signal. This mode of operation is particularly common in passive radio frequency transponders, i.e., transponders that do not have their own power source for transmission, such as RFID tags. These communication modes employ various modulations depending on whether the objective is to increase the communication sensitivity of a two-way communication cable or to increase the communication speed between two radio frequency devices. The modulation is primarily characterized by two variables: the number of binary state transitions (physically, this is a change in the state of the radio frequency transponder impedance of, for example, an RFID tag's electronic chip, which induces changes in the amplitude and phase of the return signal) and the unit period for observing the transitions. To increase the sensitivity of a communication cable, it is desirable to use a large number of binary state transitions over a long unit period. For example, Miller 8 coding, applicable to UHF RFID, provides a sensitivity increase of 5 to 10 dBm. On the other hand, limiting the number of transitions to one transition per unit period over a short unit period is advantageous for, and in fact maximizes, transaction throughput between the radio frequency transponder and the two-way communication cable. FMO modulation, i.e., one transition per unit period of, for example, 7.6 μs, improves the read rate of a two-way communication cable by a factor of ten compared to Miller-8 modulation. In the case of RFID tags, it is the reading system, and in particular the electrical signal generator, that controls the modulation scheme with which the radio frequency transponder must communicate. This is not a choice of the radio frequency transponder, but a requirement imposed on it by the reading system.

[0057] It is highly preferred that the subcarrier frequency of the radio frequency transponder contains less than five transitions, preferably a single transition over a unit period of the subcarrier frequency.

[0058] It is highly preferred that the subcarrier frequency of the radio frequency transponder has a unit period of less than 10 μs, preferably less than 8 μs.

[0059] The selection of a short period and a small number of transitions is advantageous for the speed of radio frequency communication between the radio frequency transponder and the two-way communication cable, i.e., the speed of reading the continuous radial portion of the communication cable, which is preferable in the context of the envisaged arrangement. In fact, this arrangement is characterized by a reading distance of less than one meter between the two devices over a short coupling time between the two-way communication cable and the radio frequency transponder due to the relative movement of the radio frequency transponder attached to the movable assembly. The inventors have discovered that this modulation mode is particularly advantageous for vehicles when the transport vehicle is traveling at high or very high speeds, with the continuous radial portion of the communication cable directly facing the tire of the movable assembly.

[0060] The invention will be better understood on reading the following description, given by way of non-limiting example only, with reference to the accompanying drawings in which like reference numerals indicate the same parts throughout. [Brief explanation of the drawings]

[0061] [Figure 1] FIG. 1 is a perspective view of the communication space of a radial portion of a communication cable with a movable assembly consisting of an inflated tire mounted on a rim, not shown. [Figure 2] 1 shows an embodiment of a bidirectional communication cable of a reading system according to the invention; [Figure 3] 1 is a perspective view of a method for installing a reading system in a car. [Figure 4] FIG. 1 is a cross-sectional view of a tire equipped with an RFID tag. [Figure 5] FIG. 1 illustrates an example of a radio frequency transponder, in this case an RFID tag. [Figure 6a] 10A and 10B show examples of successive radial sections of cables in a movable assembly. [Figure 6b] 10A and 10B show examples of successive radial sections of cables in a movable assembly. [Figure 6c]10A and 10B show examples of successive radial sections of cables in a movable assembly. [Figure 7] FIG. 10 is a dimensional explanatory diagram of the meandering of a two-way communication cable. DETAILED DESCRIPTION OF THE INVENTION

[0062] FIG. 1 shows a tire 12 representing a deformable part of a mobile assembly 1 consisting of an inflated tire mounted on a rim (the rim is not shown). The tire 12 rotates about a natural axis of rotation 102. The tire 12 has a median plane 101 perpendicular to the axis of rotation 102, which separates the tire 12 into two sub-parts symmetrical with respect to the median plane 101. The tire 12 is equipped with an RFID-type radio frequency transponder, i.e., without its own power source, corresponding to an RFID sensor-type electronic device used to measure the inflation pressure of the mobile assembly using a pressure sensor. The tire 12 also includes an active TPMS-type sensor mounted on the rim valve. The radial, azimuthal and axial positions of these radio frequency devices are generally arbitrary within the mobile assembly.

[0063] The tire 12 is circumscribed by a cylinder 108 having an axis of rotation 102 at the radially outermost position of the crown of the tire casing relative to the axis of rotation 102. Here, the tire 12 is inflated but not under static load, and the cylinder 108 rests on a number of points on the crown that are evenly distributed around the circumference of the crown.

[0064] The installation space 104 of the successive radial portions of the two-way communication cable can then be defined as a cylinder having an axis of rotation coaxial with the axis 102 and extending radially from the outer surface of the cylinder 108 to the axis 102 at a distance R embodied by the gray arrows shown in the median plane 101. This cylinder 104 is linear because it is bounded by plane faces collinear with the median plane 101, located on both sides of the median plane 101 at an axial distance A from the median plane 101 in the direction of the axis 102. These axial distances A are visualized by gray arrows on the axis 102. It is essential to arrange the successive radial portions of such a two-way communication cable within the linear cylinder 104 so that the radio frequency device of the mobile assembly can communicate with a reading system installed on the vehicle using a two-way communication cable, preferably having a cable length of at least one unit determined by the transmission frequency F0 of the reading system.

[0065] FIG. 2 shows the two-way communication cable 32 in a first configuration that works perfectly well for, but not limited to, RFID tag applications.

[0066] The cable 32 includes an elongated bipolar coaxial conductive structure 312 having a conductive inner conductor 314 and a conductive sheath conductor 316 coaxially surrounding the inner conductor 314. In the illustrated example, the inner conductor 314 is cylindrical and the sheath conductor 316 is hollow cylindrical.

[0067] Both the inner conductor 314 and the sheath conductor 316 are formed of a metallic material, and advantageously, an electrically insulating intermediate layer (e.g., plastic) is radially present between the inner conductor 314 and the sheath conductor 316 along the length of the conductive structure 312.

[0068] A first end 318 of the conductive structure 312 is provided for connecting a transmitter and / or receiver of a reading system so that antenna signals are transmitted using or received by the cable 32. The cable 32 is provided at this first end 318 with a conventional coaxial plug 320 which forms an electrical connector for the inner conductor 314 and the sheath conductor 316 in a conventional manner.

[0069] In this configuration, an extension 324 of the inner conductor 314 is provided at a second, opposite end 322 of the conductive structure 312, which in the illustrated example is integrally formed with, and therefore electrically connected to, the inner conductor 314. This extension 324 originates at the second end 322 of the conductive structure 312 and extends away from the sheath conductor 316 in a linear manner and coaxially with the path of the inner conductor 314 and sheath conductor 316 immediately prior to the second end 322.

[0070] The inner conductor extension 324 extends to a free end 326 of the inner conductor extension 324, and depending on the length of the inner conductor extension 324, there is some capacitive coupling of the free end 326 or the inner conductor extension 324 to the sheath conductor 316 in the region of the second end 322 of the sheath conductor 316.

[0071] In one transmission mode of cable 32, i.e., when an antenna signal to be transmitted is introduced at coaxial plug 320 at first end 318, this antenna signal travels through conductive structure 312 to end 322, where it is more or less reflected and flows back as a bound progressive wave that propagates from second end 322 along sheath conductor 316 towards first end 318.

[0072] In an operating mode appropriately selected, for example with respect to the frequency and power of the injected antenna signal, the cable 32 generates an alternating electromagnetic field around it, but the amount of radiation can be relatively small. In the "coupling mode," the cable 32 acts like a progressive-wave antenna, and therefore the range of the cable 32 is well controlled.

[0073] 2, a surface wave damping device 330 is disposed on the outer periphery of the sheathed conductor 316 at a point between the ends 318 and 322, a fixed distance from the second end 322. In the illustrated example, this device is formed by a number of ferrite rings 332, 334, 336, and 338, each of which surrounds the outer periphery of the sheathed conductor 316.

[0074] The ferrite rings 332-338 are spaced apart from one another in the longitudinal direction of the conductive structure 312 and advantageously attenuate the traveling waves emerging from the second end 322 of the conductive structure 312 when they reach the position of the attenuation device 330.

[0075] The attenuation device 330 formed by the ferrite rings 332-338 or their arrangement location within the path of the coaxial conductive structure 312 divides the length of the conductive structure 312 into a signal-conducting section 340 and a radiating section 342, and during operation of the cable 32, section 340 is used to conduct antenna signals extending from or towards the first end 318, and section 342 is used to transmit information and / or power extending from or towards the cable 32.

[0076] The number of ferrite rings and the respective distances between the ferrite rings can be adapted to each application or operating parameters of the cable 32 .

[0077] Additionally, in the case of multiple ferrite rings, at least one ferrite ring, preferably at least the "first" ferrite ring closest to second end 322, i.e., ferrite ring 332 in the illustrated example, may be positioned so as to be movable along conductive structure 312.

[0078] As a result, the properties of the damping device thus formed can be influenced or adapted to suit the actual application.

[0079] Instead of or in addition to the ferrite rings 332-338, the damping device 330 may deviate from the illustrated example and include various damping components, such as an electrical network structure consisting of capacitive and / or inductive and / or resistive elements arranged at relevant points along the path of the conductive structure 312 and connected on both sides to sections 340, 342 of the conductive structure 312 leading to the first end 318 and the second end 322.

[0080] The main cable component 32 is formed by a coaxial conductive structure 312 which may be a flexible or semi-rigid cable having an "open end" or inner conductor extension 324 as described above.

[0081] In the area of ​​the inner conductor extension 324, the sheath conductor 316 that forms the shield is removed to some extent in the remaining area of ​​the conductive structure, so that a dipole antenna is formed with one arm formed by the inner conductor extension 324 and the other arm formed by the sheath conductor 316. There are other ways to implement capacitive coupling that are not presented here.

[0082] A surface wave attenuator 330 , here formed by one or more ferrite rings, limits the effective antenna length for transmission / reception to section 342 .

[0083] In addition to adjusting this antenna length, the position of the damping device 330, here particularly the position of the first ferrite ring 332, also affects the characteristics of the damping device 330 and therefore the characteristics of the returning progressive waves.

[0084] Generally, it is advantageous with respect to generating the desired feedback traveling wave if the length of the inner conductor extension 324 represents at least approximately one-quarter wavelength of the associated antenna signal.

[0085] In a suitable configuration and corresponding operating mode of the cable 32, the majority of the transmitted signal can travel as sheath current along the "signal transmitter / receiver section" 342, with relatively little radio frequency energy being radiated ("coupled mode").

[0086] The length of the inner conductor extension 324 may be selected to define a desired impedance in combination with the position of the first ferrite ring 332 to achieve the highest possible return loss for the cable 32 .

[0087] The length of the cable 32 and the lengths of its individual sections described above can be adapted to suit the intended application.

[0088] In FIG. 2, l1 is the length of the signal conducting section 340, l2 is the length of the surface wave attenuator 330, l3 is the length of the signal transmitting / receiving section 342, and l4 is the length of the inner conductor extension.

[0089] The distance d1 represents the distance between the ferrite rings 332 and 334. The distance d1 is, for example, 5 mm to 20 mm.

[0090] The sheath conductor 316 of the coaxial conductive structure 312 has at least one opening, depicted by a dotted line and referenced 339, for example. The distance of the opening 339 from the attenuation device 330 is denoted by d2 and is in the range of 1 to 5 m. However, multiple openings 339 may be distributed along the length of the signal transmitting / receiving section 342, with a mutual spacing of 0.1 to 5 times the signal wavelength.

[0091] FIG. 3 is a perspective view showing a method for installing a reading device 3 on a transport vehicle 2 such as an automobile.

[0092] Here, the automobile 2 is represented by a transparent volume representing a closed equipped body corresponding to the complete vehicle minus the axles and drivetrain. Nevertheless, this vehicle 2 is depicted with four cavities 21a-1, 21a-2, 21b-1 and 21b-2, each designed to receive a mounting assembly of the vehicle. The mounting assemblies in this case include radio frequency devices of the RFID tag and / or TPMS sensor type in the tire casing.

[0093] The vehicle 2 also includes a reading system 3 that allows communication with the radio frequency device of the mounting assembly. The reading system 3 includes a first device 31 for transmitting and reading electrical signals, located in a firewall within the vehicle 2, which is the wall separating the engine compartment from the passenger compartment of the vehicle, generally perpendicular to the ground along which the vehicle travels, here located at the front of the vehicle 2. The device 31 therefore includes both an electrical signal transmitter and an electrical signal demodulator.

[0094] Two bidirectional communication cables 32a and 32b extend from the device 31 to the left and right of the vehicle 2, respectively. These communication cables are traveling wave cables as shown in Figure 2, and are attached to the device 31 to form electrical connections. Each cable 32a, 32b extends within the structure of the vehicle 2 to reach the vicinity of at least one cavity 21a-1, 21a-2, 21b-1, 21b-2 for receiving a mounting assembly. Each cable has a signal transmission part that radiates from the device 31.

[0095] In practice, as shown in FIG. 3 , each cable 32a, 32b reaches the vicinity of two cavities for receiving mounting assemblies, one for the front axle and one for the rear axle of the vehicle 2. The cable 32a has a continuous portion 32a-1 in the first cavity 21a-1, located at the height of the wheel arch, representing a 120-degree angular sector around the axis of the front axle. This portion 32a-1 of the communication cable 32a is located within the communication zone of the radio frequency device of the mounting assembly received in the cavity 21a-1. Therefore, this portion 32a-1 of the communication cable 32a communicates with the radio frequency device of the mounting assembly present in the cavity 21a-1. In this case, the continuous portion 32a-1 of the cable is located radially outside the mounting assembly. Thus, although not shown in FIG. 3, continuous portion 32a-1 includes a serpentine whose median direction extends axially relative to the natural axis of rotation of the mounting assembly received within cavity 21a-1 as the mounting assembly moves linearly.

[0096] However, the same cable 32a then extends toward a second cavity 21a-2 located at the left rear axle of the vehicle 2. In this cavity 21a-2, the cable 32a has a continuous radiating second part 32a-2 located within the communication zone of the radio frequency device of the mounting assembly received within the cavity 21a-2. The second continuous radial part 32a-2 extends angularly over a 90-degree angular sector around the axis of rotation of the rear axle. In this case, the rear axle is non-directional, and therefore the mounting assembly undergoes little angular movement while driving. As a result, radio frequency communication between the continuous radial parts 32a-2 of the two-way communication cable 32a is easier than with the part 32a-1, where the axle is directional and angular movement of the mounting assembly occurs, such as during cornering. These two continuous radial parts 32a-1 and 32a-2 are separate and each is capable of communicating with only one mounting assembly. However, in the case of a twin-wheeled axle, such as a commercial vehicle in traction mode, the continuous portion 32a-2 located near the cavity 21a-2 allows communication with various twin-mounted assemblies located on the same side of the same axle of the vehicle 2.

[0097] Similarly, due to the symmetry of the vehicle 2, the communication cable 32b includes a radial portion having two separate continuous portions that communicate with mounting assemblies located on the front and rear axles, respectively. The cable 32b has a meander in the first continuous portion 32b-1, similar to the cable 32a located on the left side of the vehicle 2. Because the continuous portion 32b-1 is located radially outward of the mounting assemblies, the direction of the midline of the meander extends primarily in the axial direction defined by the axis of the front axle of the vehicle 2.

[0098] In this example, the total length of the two-way communication cables 32a and 32b does not exceed 5 meters. The length of the successive radial portions 32a-1, 32a-2, 32b-1, and 32b-2 is greater than 50 centimeters, which corresponds to one-quarter of the expansion of a passenger car tire casing. This length exceeds the cable length unit for 920 MHz or 2.4 GHz UHF radio frequency communication.

[0099] 4 is a detailed view of a tire casing forming a tire of a moving assembly, represented by a mounting assembly formed by an inflated tire casing mounted on a rim. The rim represents the non-deforming part of the moving assembly. The view focuses on the bead 84 of the tire casing. The view shows the position of an RFID tag type radio frequency transponder 100 in the outer zone of the tire casing relative to the carcass ply 87.

[0100] The bead portion 84 consists of a bead wire 85 around which the carcass ply 87 is wound and a folded part 88 located in the outer zone of the tire casing. The folded part 88 of the carcass ply 87 terminates at a free edge 881. Radially outward of the bead wire 85, adjacent to the bead wire 85, there is a rubber mass 91 called a bead wire filler. The rubber mass 91 has a radially outer free end 911 that presses against the surface of the carcass ply 87 (more precisely, against the outer calendering of the carcass ply; there is no direct contact between the cord of the carcass ply and the radio frequency transponder 100). Adjacent to the rubber mass 91 is a second rubber mass 92 called a "reinforcing filler." The second rubber mass 92 has two free ends. A first free end 921 is located radially inward of the carcass ply and presses against the turned-up portion 88 of the carcass ply. The other free end 922 is located radially outward of the carcass ply 87 and terminates on the surface of the carcass ply 87. Finally, a sidewall portion 83 covers both the reinforcing filler 92 and the carcass ply 87. The sidewall portion has a free end 831 located radially inward of the carcass ply and terminates on the turned-up portion 88 of the carcass ply.

[0101] In this configuration, an airtight inner liner 90 is located in the inner zone of the tire casing, adjacent to the carcass ply 87. The airtight inner liner 90 terminates at a free end 901 adjacent to the carcass ply 87. Finally, a protective bead 93 protects the carcass ply 87, the radially inner ends 901, 921, and 831 of the airtight inner liner 90, the reinforcing filling rubber 92, and the sidewall 83, respectively. The outer surface of this protective bead 93 is adapted to be in direct contact with the rim flange when the tire casing is mounted on a wheel. This protective bead 93 has two radially outer free ends. The first free end 931 is located in the inner zone of the tire casing 1. The second free end 932 is located in the outer zone of the tire casing 1.

[0102] The bead part 84 of this tire casing comprises two RFID tags 100 and 100bis located in the outer zone of the tire casing. The first radio frequency transponder 100 is pre-sealed in an electrically insulating encapsulating rubber and is placed on the outer surface of the bead wire filler 91. The first radio frequency transponder 100 is located 20 mm from the free end 881 of the carcass ply turn-up part 88, which constitutes the mechanical singularity. This position ensures a mechanical stability zone for the electronic element 100, which is beneficial for its mechanical durability. Furthermore, embedding it within the structure of the mechanical casing provides good protection against mechanical attacks from outside the tire.

[0103] The second radio frequency transponder 100bis is pre-sealed with electrically insulating sealing rubber that is the same or similar to the material of the sidewall portion 83 and is placed on the outer surface of the sidewall. The similarity in material between the sidewall portion 83 and the sealing rubber ensures that the RFID tag 100bis is installed inside and around the sidewall portion 83 during the curing process. The RFID tag 100bis is simply placed on the uncured outer surface of the sidewall portion 83 during the tire casing's manufacture. Pressurizing the green body in a curing mold ensures that the RFID tag 100bis is positioned in the cured state as shown. This RFID transponder 100bis is located away from the free ends of the tire casing's rubber components. Specifically, the RFID transponder 100bis is located at a certain distance from the protective bead free end 932, the carcass ply free end 881, and the filler rubber free ends 911 and 922. The location of the RFID transponder 100bis on top of the bead ensures improved communication performance with an external radio frequency reader.

[0104] 5 is a diagram of a radio frequency transponder 100 operating in the frequency range of 860-960 MHz, intended to be integrated into a tire casing via an identification patch made of elastomeric material. In order to improve the wireless communication performance and the physical integrity of the radio frequency transponder 100 inside the tire casing, the axis of rotation of the radiating antenna 10 is preferably arranged parallel to the direction U, i.e. perpendicular to the thread of the carcass ply of the tire casing of radial construction, especially if the thread is made of metal.

[0105] Here, a radio frequency transponder 100 includes a radiating antenna 10 and an electronic section located inside the radiating antenna 10. The electronic section includes an electronic chip connected to a printed circuit board. A primary antenna made of conductive lines is connected to the printed circuit board. The printed circuit board on the opposite side of the primary antenna includes a meander-shaped galvanic circuit. Finally, the diameter of the cylinder surrounding the primary antenna is 0.8 millimeters. The primary antenna and the electrical circuit on the opposite side of the printed circuit board can match the impedance of the primary antenna to the impedance of the circuit board.

[0106] The circuit board thus formed is embedded in an epoxy resin mass 300 to ensure the mechanical reliability of the electronic components and the electrical insulation of the circuit board. The cylinder surrounding the hard mass 300 has a diameter of 1.15 mm and a length of 6 mm.

[0107] Here, the length L of the radiating antenna 10 is 45 mm, which corresponds to half the wavelength of a radio wave with a frequency of 915 MHz in a medium with a relative dielectric constant equal to about 5. The radiating antenna 10 is manufactured using a steel wire 120 with a diameter of 0.225 mm, the surface of which is coated with a brass layer. This steel wire 120 is a wire strand of the radiating antenna of the radio frequency transponder 100, which defines a first longitudinal axis of the radio frequency transponder 100.

[0108] In this case, the radiating antenna 10 is divided into two main regions: the first region 201 corresponds to the section of the radiating antenna that is not aligned perpendicular to the electronics, and includes two sub-regions 201a and 201b located on either side of the rigid, electrically insulating mass 300.

[0109] Each subregion 201a, 201b has a length L1 of 19 millimeters and includes 12 circular turns with a constant winding diameter D1 of 1.275 millimeters. These define an inner diameter of 1.05 millimeters and an outer diameter of 1.5 millimeters, respectively. The helical pitch P1 of the circular turns is 1.55 millimeters. Therefore, the ratio of the helical pitch P1 of the turns to the winding diameter D1 is 1.21. The axially outer ends of each subregion 201a, 201b terminate with two adjacent turns. This high ratio ensures that the effectiveness of the radio wave characteristics of the radiating antenna 10 is maximized in this region 201. Furthermore, the contact between the outermost turns of the radiating antenna 10 prevents the helical spring from tangling during handling of the radio frequency transponder. Because the majority of the turns in the first region 201 of the radiating antenna 10 have a ratio higher than 0.8, the improvement in the radio wave performance of the radio frequency transponder 100 is evident.

[0110] In the second region 202 of the radiating antenna 10, which corresponds to the portion of the radiating antenna 10 positioned perpendicular to the electronic part, the radiating antenna 10 has a length of 7 millimeters. The helical spring has a constant helical pitch P2 of 1 millimeter and a constant winding diameter D2 of 1.575 millimeters. Therefore, the inner diameter of the helical spring in the second region of the radiating antenna is 1.35 millimeters. This allows for a constant ratio of pitch to winding diameter of approximately 0.63. This ratio allows the inductance of the second region 202 of the radiating antenna 10 to be maximized relative to the first region 201, thereby improving the effectiveness of electromagnetic coupling to the electronic part.

[0111] In this particular case, the inner diameter of the radiating antenna 10, represented by a cylinder surrounding the electronic part, of the first region 201, equal to 1.05 millimeters, is smaller than the diameter of the mass 300, equal to 1.15 millimeters. The sub-regions 201a and 201b of the first region 201 of the radiating antenna 10 therefore form mechanical stops that limit the axial movement of the mass 300 inside the radiating antenna 10. In the first embodiment, the electronic part is attached by sliding the rigid insulating mass 300 into the radiating antenna 10.

[0112] 6a, 6b, and 6c are various two-dimensional views of the communication zone 104 of the radio frequency transponder of the mounting assembly, which in this example is primarily mounted on a tire 12, and a reading system mounted on a transport vehicle. The tire 12 is mounted on a rim (not shown). The mobile assembly thus formed defines a natural rotation axis 102 and a median plane 101. This mobile assembly is attached to the axle of the vehicle. Here, the mobile assembly is shown located on the rear right side of the transport vehicle. The vehicle can move on the ground 600 with the tire 12. Here, this tire 12 includes two radio frequency transponders, each located in a lower zone on one side of the tire 12. Thus, one side is located inside the vehicle, and the other side opens to the outside of the vehicle if not obstructed by bodywork elements of the transport vehicle. During the rotational movement of the mobile assembly, the radio frequency transponder describes a closed loop 601-1 or 601-2, similar to a circle, with an axis of rotation corresponding to the natural rotation axis 102 of the tire 12.

[0113] FIG. 6a is a view in plane YZ of the automobile corresponding to a front view of the movable assembly. FIG. 6b is a view in plane XY corresponding to a top view of the movable assembly, and FIG. 6c is a view in plane XZ corresponding to a side view of the movable assembly. These three figures show a radio frequency communication cylinder 104 between the radio frequency transponder of the movable assembly and a reading system represented by a radial portion of two-way communication cable 32a. When communication cable 32a enters communication volume 104, this cable becomes a continuation portion 32a-2 of the radial portion of cable 32a for the movable assembly located on the rear right side of the vehicle. The fact that cable 32a does not re-emerge from volume 104 after entering volume 104 indicates that there is only one continuation portion 32a-2 of the radial portion of cable 32a associated with this movable assembly. The continuous portion 32a-2 first extends along the inside of the tire 12 relative to the vehicle, describing a portion of a first circle centered on the natural axis of rotation 102 of the movable assembly. Then, after bending of this cable 32a, the cable moves on the opposite side of the median plane 101 of the movable assembly, in the direction Y of the vehicle, i.e., toward the outside of the tire 12 and the vehicle. Finally, the cable describes a portion of a second circle centered on the natural axis of rotation 102 of the movable assembly, before terminating in a tip located in this specific case within the volume 104. This tip can also be located outside the volume defined by the cylinder 104.

[0114] The first circle described by the continuous portion 32a-2 is located axially outside the movable assembly. In this example, the first circle has a radius smaller than the maximum radius of the movable assembly, but it could also be larger. As shown in FIG. 6c, a meander 501 extends perpendicular to the arc of the circle described by the continuous portion 32a-2 of the communication cable, i.e., radially within the reference frame of the movable assembly, on the arc of the circle described by the continuous portion 32a-2 of the communication cable. The surface defined by the meander extends radially inward of the first circle, intercepting a loop 601-2 described by the movement of a radio frequency transponder present inside the tire 12. This loop is shown as a dotted circle in FIG. 6c. For an RFID tag operating at a UHF frequency of 920 MHz, the length of the RFID tag's radio frequency antenna is approximately 5 cm when the RFID tag is embedded in the tire structure. Typically, this radio tag is oriented primarily in the circumferential direction. The serpentine 501 has a distance, here about 8 centimeters, separating the outbound and inbound paths, which allows for improved radio frequency communication between the serpentine 501 and the antenna of the RFID tag, as the entire radiating antenna of the radio tag is located within the enhanced electric field generated by the entrance and exit ends of the serpentine at any given time.

[0115] The second circle described by the continuous portion 32a-2 of the communication cable 32a is located radially outside the tire 12 relative to the rotation axis 102. In the example of this moving assembly shown in FIG. 6, the cable 32a on the vehicle's exterior is primarily located axially outside the tire 12, except for a serpentine 500-2 that extends axially inward relative to the tire 12. Specifically, the serpentine 500-1 is located axially outside the tire 12, as shown in FIGS. 6A and 6B. However, the loop 601-1 described by the quasi-periodic movement of the tire's radio frequency transponder is located axially close to the second circle of the communication cable 32a, thereby optimizing radio frequency communication between the two antennas. In this case, the serpentine 500-2 allows for interrogation of another radio frequency transponder attached to a moving assembly having a smaller axial width or positioned perpendicular to the crown of the tire 12, which radially surrounds the tire 12 from the outside. In this example, serpentines 500-1 and 500-2 are not adjacent because the exit end of serpentine 500-1 does not coincide with the entrance end of serpentine 500-2. However, they are still close together and can still form two distinct enhanced communication zones. For example, in the case of adjacent "S"-shaped serpentines, the two serpentines form a single enhanced communication zone. In this example, the curve length of serpentines 500-1 and 500-2 is 15 centimeters, and the spacing P between the entrance and exit of each serpentine is 4 centimeters. Conversely, for serpentine 501, the curve length is 14 centimeters, but the spacing P is approximately 6 centimeters.

[0116] Such a continuous portion 32a-2 of the radial portion of the communication cable 32a is fixedly secured to the transport vehicle, in particular to a surface defining a cavity for receiving the movable assembly, and enables radio wave communication with a radio frequency transponder attached to the movable assembly, in particular to the tire 12. This radio communication remains operable regardless of the side of the tire 12 on which the radio transponder is located, and also regardless of the dimensions, in particular the width, of the movable assembly attached to the transport vehicle. However, this is merely an example and not necessarily the only configuration that achieves the purpose of this radio frequency communication.

[0117] FIG. 7 shows an example of a meander 500 in a continuous radial portion of a two-way communication cable. The meander 500 is defined in an orthogonal plane UV associated with the meander. An axis U is defined by a tangent to the two-way communication cable located immediately upstream and / or downstream of the meander 500; if these two directions are not parallel, the median direction is used. The meander 500 follows an outgoing path 511 and a returning path 512, which are connected to each other by a segment 513 at the second end. A first end of the outgoing path 511 or the returning path 512 is connected to the two-way communication cable located downstream or upstream of the meander 500. The change of direction between the two-way communication cable on the one hand and the outgoing path 511 or the returning path 513 of the meander 500 on the other hand is made possible by the flexible nature of the communication cable, which allows for more or less pronounced bending of the communication cable. Naturally, this same change of direction also occurs between the outgoing path 511 or the returning path 512 of the meander 500 on the one hand and the segment 513. The flexibility of the cable also allows this change in direction through the bending potential of the communication cable.

[0118] The meander 500 is defined by the average spacing or width between the outgoing path 511 and the returning path 512, indicated by "l", on the one hand, and the length L of the meander 500. The length "L" of the outgoing path 511 or the returning path 512 of the meander 500 is defined as the distance in a direction V perpendicular to the direction U of the bidirectional communication cable between the starting point 521 of the outgoing path 511 or the arrival point 522 of the returning path 512 and the second end 523 of the outgoing path 511 or the second end 524 of the returning path 512. The second end 523 or 524 is determined by two conditions. The first condition is that the second end 523 or 524 is the highest coordinate in the direction V of a point on the communication cable 32 from the first end 521 of the outgoing path 511 or the first end 522 of the returning path 512. Note that the origin of the axis V is defined at the point 521 or 522. The second condition is that the tangent to a point on the communication cable 32 at this second end 523 or 524 has its maximum component carried by the direction V. Finally, the segment 513 is bounded by the second ends 523 and 524 of the outbound path 511 and the inbound path 512.

[0119] Finally, the mean spacing "l" of the meanders is determined by taking the distance in direction U between the outgoing path 511 and the returning path 512. The position of the outgoing path 511 or the returning path 512 in direction U corresponds to the mean value UA or UB in direction U of the coordinates of the points of the outgoing path 511 or the returning path 512, and the distribution of the points along the cable 32 is homogeneous. The outgoing path 511 is bounded by points 521 and 523, and the returning path 512 is bounded by points 522 and 524. Points 521 and 522 are the start and end points of the meander 500, respectively. Points 521 and 522 each correspond to the direction of the cable downstream or upstream of the meander 500, i.e., the change in the curvature of the cable relative to the direction of vector U.

[0120] Additionally, the curve length of serpentine 500 is defined as the distance between entrance end 525 and exit end 526 of serpentine 500 along the bidirectional communication cable. Each of points 525 or 526 is determined by the following condition: they are the points on the communication cable originating from start point 521 or arrival point 522, whose tangent has the largest component carried by direction V.

[0121] The length of the cable curve must be 0.9 to 1.1 times the half wavelength L0 associated with the reader system's communication frequency. When communicating at a frequency F0 of 900 MHz, the half wavelength is approximately 15 centimeters, so the length of the meander 500 curve must be 13.5 to 16.6 centimeters.

[0122] Finally, distance "P" corresponds to the spacing between points 525 and 526 of the bidirectional communication cable. These two points 525 and 526 define a line D, and distance D corresponds to the length of the segment of material between points 525 and 526. Necessarily, line D is substantially parallel to axis U. When communicating at a frequency F0 of 900 MHz, half a wavelength is approximately 15 centimeters, so distance "P" must be equal to or less than one-quarter of a wavelength, or 7.5 cm. [Explanation of symbols]

[0123] 2. Transport vehicles 3 Reading device 21a-1, 21a-2, 21b-1, 21a-2 Cavity 31 First Device 32a-1, 32a-2, 32b-1, 32b-2 communication cables

Claims

1. A transport vehicle (2) comprising a radio frequency transponder reading system (3) and at least one movable assembly (1) capable of ensuring the movement of the transport vehicle (2) relative to a ground (600) on which the transport vehicle (2) travels, the movable assembly (1) comprising a tire (12) configured to move about an axis of rotation (102), the free movement of the at least one movable assembly (1) occurring mainly in a two-dimensional plane within a cylindrical reference frame associated with the at least one movable assembly (1), the axial direction of the at least one movable assembly (1) being in the direction of the axis of rotation (102), the tire (12) defining a median plane (101) perpendicular to the axis of rotation (102), the at least one movable assembly (1), preferably the tire (12), comprising a radio frequency transponder (100, 100bis), the reading system (3) comprising: a generator of an electrical signal (31) transmitted at a frequency F0 included in the ultra-high frequency band, attached to the transport vehicle and coupled to a demodulator (31) of the electrical signal adapted to a frequency band around F0; and at least one partially flexible bidirectional communication cable (32), comprising a conductive core (314) covered by a first dielectric element covered by a conductive assembly (316), having one end (318) electrically connected to said reading system (3), and having means at its free end (322) for capacitive coupling between said conductive core (314) and said conductive assembly (316) via a second dielectric element compatible with the frequency band of said reading system (3); the at least one bidirectional communication cable (32) is fixedly secured to the transport vehicle (2), is external to the at least one movable assembly (1), and includes a radial portion (342); The distance of the radial projection of the first continuous portion (32a-1, 32b-1) of the radial portion (342) of the at least one cable (32) on a cylinder (104) surrounding the tire (12) and having a rotation axis coaxial with the rotation axis (102) is 1 meter or less, preferably 0.5 meters or less, and the distance of the axial projection of the first continuous portion (32a-1, 32b-1) of the radial portion (342) of the at least one cable (32) on the median surface (101) of the tire (12) in the direction of the rotation axis (102) is 2 meters or less, preferably said first continuous portion (32a-1, 32b-1) of said radial portion (342) of said at least one cable (32) is equal to or shorter than 1 meter, very preferably equal to or shorter than 0.5 meters, said first continuous portion (32a-1, 32b-1) of said radial portion (342) of said at least one cable (32) comprising at least one meander (500, 500-1, 500-2, 501), the curved length of said at least one meander being between 0.9 and 1.1 times half a wavelength L0 as determined by a communication frequency F0 modulo said wavelength L0, and the distance "P" separating the two ends (525, 526) of said at least one meander (500, 500-1, 500-2, 501) being less than one-quarter of said wavelength L0; A transport vehicle (2).

2. The radial portion (342) of the at least one cable (32) includes at least one second continuous portion (32a-2, 32b-2) separate from the first continuous portion (32a-1, 32b-1), and the at least one second continuous portion (32a-2, 32b-2) of the radial portion (342) of the at least one cable (32) is arranged on a cylinder of a rotation axis coaxial with the rotation axis (102) of the at least one second movable assembly (1) surrounding the tire (12) of the at least one second movable assembly (1). ) is less than or equal to 1 meter, preferably less than 0.5 meter, and the distance of the axial projection of the at least one second continuous portion (32a-2, 32b-2) of the radial portion of the at least one cable on the median plane (101) of the tire (12) of the at least one second movable assembly (1) in the direction of the axis of rotation (102) of the at least one second movable assembly (1) is less than or equal to 2 meters, preferably less than or equal to 1 meter, very preferably less than or equal to 0.5 meters, A transport vehicle (2) according to claim 1.

3. the at least one second continuous portion (32a-2, 32b-2) of the radial portion (342) of the at least one cable (32) comprises at least one meander (500, 500-1, 500-2, 501), wherein a curved length of the at least one meander of the at least one second portion is 0.9 to 1.1 times half a wavelength L0 defined by a communication frequency F0 modulo the wavelength L0, and a distance "P" between both ends (525, 526) of the at least one meander (500, 500-1, 500-2, 501) of the at least one second portion is less than one-fourth of the wavelength L0; A transport vehicle (2) according to claim 2.

4. the radial portion (342) of the at least one cable (32) comprises at most seven meanders (500, 501), preferably at most five meanders (500-1, 500-2, 501); A transport vehicle (2) according to one of claims 1 to 3.

5. the radio frequency transponder (100, 100bis) associated with the at least one movable assembly (1) comprises a radio frequency antenna including at least one strand defining a first longitudinal axis, and each meander of the first continuous portion (32a-1, 32b-1) and / or the at least one second continuous portion (32a-2, 32b-2) of the radial portion of the at least one cable (32) defines a straight line D defined by two ends (521, 522) of the at least one meander (500, 500-1, 500-2, 501), and the angle formed by the direction vector of the first longitudinal axis and the straight line D is less than ±30 degrees, preferably less than ±20 degrees, over at least a part of the closed path described by the at least one movable assembly (1); A transport vehicle (2) according to one of claims 1 to 4.

6. wherein the at least one movable assembly (1) is capable of describing a rotational movement about a single axis of rotation (102) defining a cylindrical reference frame about the single axis of rotation (102), the first longitudinal axis of the radio frequency antenna of the radio frequency transponder (100, 100bis) associated with the at least one movable assembly (1) has a main component oriented in the circumferential direction in the cylindrical reference frame, the at least one meander (500-1, 500-2) associated with the first continuous portion (32a-1, 32b-1) and / or the at least one second continuous portion (32a-2, 32b-2) of the radial portion (342) of the at least one cable (32) is arranged radially outside the movable assembly (1) with respect to the axis of rotation (102), and the straight line D of the at least one meander has a main component oriented in the circumferential direction in the cylindrical reference frame of the movable assembly (1). A transport vehicle (2) according to claim 5.

7. when the radio frequency antenna of the radio frequency transponder (100, 100bis) associated with the at least one movable assembly (1) and the at least one meander (500-1) associated with the first continuous portion and / or the at least one second continuous portion of the radial portion of the cable project in the same circumferential plane, the projection of the antenna of the radio frequency transponder intersects the projection of the straight line D of the at least one meander, A transport vehicle (2) according to claim 6.

8. wherein the movable assembly (1) is capable of describing a rotational movement about a single axis of rotation (102) defining a cylindrical reference frame about the single axis of rotation (102), the first longitudinal axis of the radio frequency antenna of the radio frequency transponder (100, 100bis) associated with the at least one movable assembly (1) has a main component oriented in the circumferential direction in the cylindrical reference frame, the at least one meander (501) associated with the first continuous portion and / or the at least one second continuous portion of the radial portion of the cable is arranged axially outside and radially inside the movable assembly (1) with respect to the axis of rotation (102), and the straight line D of the at least one meander has a main component oriented in the circumferential direction in the cylindrical reference frame of the movable assembly (1). A transport vehicle (2) according to claim 5.

9. when the radio frequency antenna of the radio frequency transponder (100, 100bis) associated with the at least one movable assembly (1) and the at least one meander (501) associated with the first continuous portion and / or the at least one second continuous portion of the radial portion of the cable project in the same axial plane, the projection of the antenna of the radio frequency transponder intersects the projection of the straight line D of the at least one meander, A transport vehicle (2) according to claim 8.

10. The radio frequency transponder comprises an RFID tag (100). A transport vehicle (2) according to one of claims 1 to 9.

11. when said movable assembly is able to describe a rotational movement about a rotation axis (102), each continuous portion of said at least one cable describes an angular sector about said rotation axis (102) that is at least greater than 30 degrees, preferably greater than 60 degrees, very preferably greater than 120 degrees, A transport vehicle (2) according to one of claims 1 to 10.

12. the continuous portion of the radial portion of the at least one cable is attached to at least one wall defining a cavity (21a-1, 21a-2, 21b-1, 21b-2) of the transport vehicle (2) that receives the movable assembly (1); A transport vehicle (2) according to one of claims 1 to 11.

13. the first continuous portion (32a-1, 32b-1) and / or the at least one second continuous portion (32a-2, 32b-2) of the radial portion of the at least one cable extend at a constant radial distance from the rotation axis (102) of the movable assembly; A transport vehicle (2) according to claim 11 or 12.

14. said radio frequency transponder (100, 100bis) transmitting at a subcarrier frequency; A transport vehicle (2) according to one of claims 1 to 13.

15. the subcarrier frequency of the radio frequency transponder comprises less than five transitions, preferably a single transition over a unit period of the subcarrier frequency; A transport vehicle (2) according to claim 14.

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