Radio frequency reading system carried on transport vehicle

Abstract

The invention relates to a vehicle (2) equipped with a movable assembly (1) comprising a pneumatic tire (12) rotating about an axis (102), the movable assembly (1) being equipped with a radio frequency transponder (100), and a reading system (3) comprising:-a generator coupled with an electrical signal demodulator (31); -a cable (32) electrically connected to the generator (31), attached to the vehicle (2), comprising a radiating portion (342), characterized in that the projection R of the radiating portion on a cylinder (104) of the axis of rotation (102) surrounding the pneumatic tire (12) is less than 1 meter, the radiating portion (42) comprising a bend (500) having a curvilinear length between 0.9 and 1.1 times of a half-wavelength L0 associated with the communication frequency, and the distance P between the two ends of the bending part (500) is less than 1 / 4 wavelength.

Description

Technical Field

[0001] The present invention relates to a system for reading radio frequency transponders mounted on a transport vehicle. The radio frequency transponders are mainly associated with the movable components of the transport vehicle. Background Art

[0002] The latest developments of connected objects require them to be equipped with radio frequency transponders. These radio frequency transponders generally operate in the UHF (Ultra High Frequency) frequency range (in other words, between 300 MHz and 3 GHz). In the case of transport vehicles such as vehicles with tires, the connected objects are the movable components of these transport vehicles. Therefore, they are movable during operation and perform planar motion around a rotational axis fixed relative to the transport vehicle. Thus, in the reference frame associated with the transport vehicle, the transponders move in a self - enclosed loop.

[0003] Document US20210021015A1 describes the installation of an on - vehicle reading system of radio frequency identification (RFID) tags and tire - mounted sensors (TMS) located in the outer tire of the mounting assembly of a land vehicle. The system consists of a radio frequency reader / transmitter that is electrically connected to four transmission lines up to the radio frequency antennas, and each radio frequency antenna covers a specific geographical area. The radio frequency antennas are firmly fixed to the fixed part of the land vehicle. This solution requires multiple radio frequency antennas (usually two - dimensional planes or even three - dimensional). This causes space occupation inside the land vehicle and is not conducive to the installation of other land vehicle components. In addition, the separation of various elements (radio frequency reader, transmission lines, and radio frequency antennas) increases the number of connection points between various elements, which in turn increases the risk of failure of the reading system due to the vibrations and shocks usually suffered by the means of transportation. Finally, the large number of components mounted on the land vehicle means there are many transmission lines and radio frequency antennas, resulting in a high cost.

[0004] One of the objectives of the present invention is to solve the reliability and cost problems of the system for reading movable radio frequency transponders in transport vehicles.

[0005] For a better understanding of the present invention, the circumferential direction S, the axial direction A, and the radial direction R herein refer to the directions defined with respect to the rotational reference frame of the movable component around its natural rotational axis. The radial direction R is the direction perpendicular to the natural rotational axis and extending away. The axial direction A is the direction parallel to the natural rotational axis. Finally, the circumferential direction S forms a direct trihedron with the predefined radial direction and axial direction. Summary of the Invention

[0006] The present invention relates to a transport vehicle, which includes a radio frequency transponder reading system and at least one movable component capable of ensuring the movement of the transport vehicle relative to the ground on which the transport vehicle travels. The movable component includes a tire that moves around a rotation axis. The free movement of the at least one movable component occurs in a main two-dimensional plane in a cylindrical reference system associated with the at least one movable component. The axial direction of the at least one movable component is the direction of the rotation axis. The tire defines an intermediate plane perpendicular to the rotation axis. The at least one movable component, preferably the tire, is equipped with a radio frequency transponder. The reading system includes:

[0007] - An electrical signal generator that emits an electrical signal at a frequency F0 included in the ultra-high frequency band, which is connected to an electrical signal demodulator suitable for a frequency band near F0 and is installed on the transport vehicle;

[0008] - At least one partially flexible two-way communication cable, including a conductive core covered with a first dielectric element, and the first dielectric element itself is covered with a conductive component. One end of the two-way communication cable is electrically connected to the reading system, and at its free end, there is a device for capacitive coupling between the conductive core and the conductive component through a second dielectric element. The conductive core is suitable for the frequency band of the reading system, and its length l0 is divided according to a metric, and the unit of this metric is the wavelength L0 defined by the frequency F0;

[0009] - The at least one cable is firmly fixed to the transport vehicle and is located outside the at least one movable component. The at least one cable includes a radiation part.

[0010] The feature of this arrangement is that the radial projection distance of the first continuous part of the radiation part of the at least one cable on a cylinder coaxial with the rotation axis and surrounding the tire is less than or equal to 1 meter, preferably less than or equal to 0.5 meter. The axial projection distance of the first continuous part of the radiation part of the at least one cable on the intermediate plane of the tire in the direction of the rotation axis is less than 2 meters, preferably less than or equal to 1 meter, and very preferably less than or equal to 0.5 meter. The first continuous part of the radiation part of the at least one cable includes at least one bending part, and the curve length of the at least one bending part is between 0.9 times and 1.1 times of the half wavelength L0 defined by the communication frequency F0 modulo the wavelength L0, and the distance "P" separating the two ends of the at least one bending part is less than one quarter of the wavelength L0.

[0011] The term "free movement" refers to a movement that takes place without displacement constraints, as is the case with forced displacement movement. For example, in the case of the rotation of a mounting assembly under a static load, this refers to the movement of the material points of the mounting assembly outside the contact area of the outer tire with the ground (commonly referred to as the ground contact area). Specifically, in this area, as long as the sliding condition is not reached, the movement of the material points of the outer tire in contact with the ground is guided by the ground; thus, forced displacement is achieved, which does not fall within the definition of free movement.

[0012] First, the movable assembly is a sub - assembly of a transport vehicle and is used to move the transport vehicle relative to the ground. The movable assembly includes a tire that is driven to rotate about a rotation axis by a non - deformable assembly (in other words, an assembly that is harder than the tire, such as a rim).

[0013] The radio - frequency transponder can be an RFID tag or another electronic device with its own power source or passive. The radio - frequency transponder is attached to the movable assembly of the transport vehicle. For example, the radio - frequency transponder can be an RFID tag in the outer tire, a Tyre Pressure Monitoring System (TPMS) sensor attached to the wheel, or any electronic object located on the movable assembly that communicates via radio - frequency and is equipped with a radio - frequency antenna. In order to read an electronic object connected to the movable assembly and thus moving in the transport vehicle, the present invention discloses placing a reading system carried on the transport vehicle outside the movable assembly. Thus, the reading system is independent of the movement of the movable assembly. The reading system includes a first device that includes a transmitter / receiver of an electrical signal with a fixed frequency and a demodulator of electrical signals in a frequency band near the fixed frequency. The first device is connected to a two - way communication cable. The cable consists of a hollow or solid conductive core, usually made of metal, and a second hollow conductive tube coaxial with the conductive core. A first dielectric element separates the two conductive components. One end of the cable is connected to the transmit / receive electronic device, while the other end is free. The cable includes at least one radiating portion, that is, it functionally emits or receives radio waves outside the hollow conductive tube. The cable is equipped at the free end with means for capacitive coupling between the conductive core and the conductive assembly consisting of the hollow conductive tube through a second dielectric element, and the conductive core is adapted to the frequency band of the reading system.

[0014] This type of two-way communication cable utilizes surface radio waves through such a capacitive coupling device. This enables a two-way cable that has no particularity on the surface of the radiation section. Thus, in the case of significant deformation when the cable is installed in a transport vehicle, the communication function of the cable is not affected as in the case of a leaky feeder antenna, where the distribution and shape of the holes through the conductive tube are more sensitive to the deformation of the two-way cable. Additionally, this technical solution is more economical because manufacturing holes in the conductive tube is much more expensive than setting up an electrical reflection device through capacitive coupling at the end of a coaxial cable.

[0015] This type of cable is described in patent application US2016 / 0197408A1, whose free end includes an electrical reflection device for capacitive coupling, which consists of a conductive component connected to the conductive core and optionally separated from the conductive tube by a second dielectric material that generates capacitive coupling. The length of the conductive component is typically one quarter of the wavelength of the radio waves emitted and received by the cable antenna. This device generates surface-propagating radio waves on the conductive tube in a direction opposite to the direction in which the signal generator emits, up to the surface wave attenuation zone generated by a magnetic ring, which is usually made of ferrite and is mounted axially outside the cable.

[0016] The present invention is first based on a specific arrangement of a reading system (especially the radiation section of a two-way communication cable) relative to the path followed by a radio frequency transponder driven by a movable component. Specifically, during a part of the loop described by the radio frequency transponder as the movable component travels, the spatial distance between the radiation section of the cable and the radio frequency transponder must be less than a certain distance (preferably one meter) so that radio frequency communication can be established between the reading system and the radio frequency transponder. This is ensured by two conditions related to the structure of the movable component. Specifically, since the movable component has a mainly two-dimensional motion in the reference frame related to the movable component, outside the region of forced displacement, an intermediate plane can be defined for the tires of the movable component, which has the property of being perpendicular to the axis of rotation of the movable component and dividing the movable component into two parts that are symmetric with respect to the intermediate plane. The term "mainly two-dimensional motion" refers to the distance covered by a material point of the movable component between two instants, decomposed on an orthogonal reference frame related to the movable component, where one component is smaller than the other two components. Generally, this smaller component is the component in the direction of the axis of rotation of the movable component. The first condition is that the continuous sub-parts of the radiation section of the communication cable are no more than 2 meters away from the intermediate plane of the tires attached to the movable component in the direction of the axis of rotation of the movable component. Obviously, the smaller the distance between the continuous part of the radiation section of the cable and the radio frequency transponder, the better the radio frequency communication between the two radio frequency devices.

[0017] Then, since the tires of the movable component are driven by a pure rotational movement about their axis of rotation, it is necessary to control the distance between the continuous part of the radiating portion of the bidirectional communication cable and the tires of the movable component. To this end, a second projection condition must be satisfied. With respect to the region where the tire rotates about its axis of rotation, this condition includes defining the maximum radial projection distance R of the continuous part of the radiating portion of the bidirectional communication cable on the nearest surface of the tire of the movable component (corresponding to the radially outer surface of the tire with respect to its axis of rotation).

[0018] When these conditions are satisfied during a part of the loop described when the radio frequency transponder attached to the movable component travels, it can be ensured that the continuous part of the radiating portion of the bidirectional communication cable can communicate bidirectionally with the radio frequency transponder on this part of the loop. In addition, this communication is spatially periodic because it repeats on each loop. Obviously, the larger this part of the loop, the better the communication between the two components in terms of time. Preferably, this condition is satisfied on the entire loop depicting the path of the radio frequency transponder.

[0019] Finally, the continuous part of the radiating portion of the bidirectional communication cable located in this spatial region with respect to the movable component must include at least one bend. The bend is defined by a width denoted as "l" and a length denoted as "L". The length "L" is defined with respect to the axial direction of the radiating portion of the cable outside the bend region. One end of the length "L" starts at the change in the curvature of the cable where the bend begins. The other end is defined by the farthest point of the bend (in other words, the point with the maximum orthogonal projection with respect to the axial direction of the cable). The width "l" of the bend is defined using the axial average of the points of the bend that define the outward or return path of the bend in the cable direction (in other words, all points of the cable between the two ends of the length "L" of the bend located on the outward or return path defining the bend). In the axial direction of the cable, the distance between these two axial averages determines the width "l" of the bend. In the direction of the radio wave propagation provided by the transmit / receive system, the first point of the bend where the tangent has a major component in the direction of the length "L" of the bend will be called the inlet end of the bend. In the direction of the radio wave propagation provided by the transmit / receive system, the last point of the bend where the tangent has a major component in the direction of the length "L" of the bend will be called the outlet end of the bend. The distance "P" is measured between the inlet end and the outlet end of the bend.

[0020] This bent portion enables the creation of an enhanced communication area between a bidirectional communication cable and a transponder in a communication mode where the radio frequency emission of the reading system (i.e., triggered by the reading system). This enables the establishment of communication with the radio frequency transponder, especially when the radio frequency transponder is passive. When the radio frequency transponder approaches this bent portion during travel related to the movement of a movable component, by providing a sufficient amount of energy to the radio frequency transponder to wake up the radio frequency transponder and establish communication. Specifically, this bent portion enables the creation of a narrow spatial region between the inlet end and the outlet end of the bent portion, in which the electric field E generated by the radiating portion of the communication cable is stable, and its amplitude is higher than the electric field generated outside the bent portion or even inside the bent portion.

[0021] This increase in the electric field E of the bent portion between the inlet end and the outlet end is possible when the curved length of the bent portion approaches the half-wavelength L0 related to the communication frequency F0 of the reading system, simply because a specific distance P between two points of the bent portion creates a gap, that is, a system with opposite charges, positive and negative charges facing each other, like a capacitor. The increase in the amplitude of the electric field E enables an increase in the radio frequency energy to the radio frequency transponder, which enables the activation of the radio frequency transponder in the communication mode. In the case of a passive radio frequency transponder (such as a passive RFID tag), the energy captured by the radio frequency transponder is used to transmit a return radio frequency message from the radio frequency transponder. During the stage of receiving the radio frequency message from the radio frequency transponder, as long as the distance between the two elements remains reasonable, the linear radiating portion of the communication cable is sufficient to capture the return message. Therefore, this bent portion is mainly used in areas where it is difficult to communicate with the radio frequency transponder. For example, when it is necessary to interrogate a radio frequency transponder that is spatially far from the radiating portion of the communication cable, or when the environment of a vehicle or a movable component is unfavorable for radio frequency communication due to, for example, conductive elements. Therefore, the radio frequency transponder is located outside the tire and outside the transport vehicle, and only the radiating portion of the cable can be positioned radially outside the tire. However, the crown of the tire, that is, the radially outermost portion of the tire relative to its axis of rotation, includes a metal crown that is usually radially designed, which is unfavorable for radio frequency communication. In these specific cases, the presence of the bent portion can still interrogate the radio frequency transponder of the movable component and receive its radio frequency response through the first continuous portion of the radiating portion of the communication cable.

[0022] Note that the arrangement of the remaining part of the bent portion (that is, except for the points at the inlet end and the outlet end) only slightly changes the electric field E. Therefore, such a bent portion can be easily adapted to any complex and dense environment, such as a motor vehicle. It is only necessary to control the distance between the inlet end and the outlet end, the direction of the straight line defined by these two ends, and the curve length between these two ends to ensure that the bent portion plays its function in enhancing radio frequency communication. Finally, this type of bent portion can also minimize the power consumption of the communication cable. This is because the radio frequency radiation is local rather than extensive, which saves energy. Obviously, the smaller the distance "P" between the outlet end and the inlet end of the bent portion, the stronger the electric field E generated by these points, at the cost of the duration for which the radio frequency transponder is exposed to this enhanced electric field E. To increase the duration of exposure to this electric field E, it is sufficient to increase the number of bent portions, especially by making these bent portions adjacent. For example, this can be achieved by bending the cable into an "S" shape, which constitutes the addition of two adjacent bent portions with opposite loops. Due to the curvature of the cable, the "S" shape can prevent the two bent portions from being spatially offset. This technique makes it possible to expand the communication area through the enhanced electric field E of each bent portion.

[0023] Furthermore, preferably, the continuous portion of the radiating part of the bidirectional communication cable located in the spatial region around the movable component has a curve length greater than one cable length unit. The cable length unit is defined by the wavelength L0, which is related to the transmission frequency F0 of the radio signal propagated by the reading system in a medium with a given relative permittivity. This ensures that the length of the antenna in the spatial region defined by one of the two geometric conditions is suitable for transmitting radio signals to and receiving radio signals from the radio frequency transponder attached to the movable component. Of course, the longer the length of the continuous portion of the radiating part of the bidirectional communication cable, the better the communication between the reading system and the radio frequency transponder.

[0024] According to a specific embodiment, the radiating part of the at least one cable includes at least one second continuous part separated from the first continuous part, and the radial projection distance of the at least one second continuous part of the radiating part of the at least one cable on the cylinder of the tire surrounding the at least one second movable component with the rotation axis coaxial with the rotation axis of the at least one second movable component is less than or equal to 1 meter, preferably less than 0.5 meter, and the axial projection distance of the at least one second continuous part of the radiating part of the at least one cable in the direction of the rotation axis of the at least one second movable component on the middle plane of the tire of the at least one second movable component is less than 2 meters, preferably less than 1 meter, and very preferably less than 0.5 meter.

[0025] This is a configuration in which a two-way communication cable can interrogate movable components of the same transport vehicle that are so far apart that the same continuous portion of the radiating part of the communication cable cannot interrogate two movable components. Then, the traditional solution was to add a second two-way communication cable and place the continuous portion of the radiating part of this second cable in the appropriate geographical area of the second movable component, which was expensive. The solution here is to utilize the same two-way communication cable, which limits the number of current connections to the electrical signal transmitter / receiver of the reading system. Then, the cable is equipped with a second continuous radiating part separated from the first continuous part. However, this second continuous radiating part may be the same radiating part of the cable. In this way, in each case, the same cable interrogates and receives information from each radio frequency transponder associated with a different movable component. To create an extended radiating space area, it is sufficient to pass the radiating part of the cable through the same space area several times to create a continuous area. This creates an extended radiating area that enables easy communication with the transponders of the transport vehicle passing through this space area. Of course, several separate extended radiating space areas can be created using this technique. Between these space areas, the cable has a lower radiating behavior, but radio signals can still be transmitted along the cable to the reader. Of course, the number of continuous radiating parts can be increased along the length of the communication cable to communicate with several movable components that are geographically far from each other in order to communicate with all the radio frequency transponders of the transport vehicle, whether or not these transponders are connected to the movable components of the transport vehicle. Similarly, the continuous portions of the radiating part of the two-way communication cable can communicate with different movable components as long as they are at an appropriate distance from the continuous portion of the radiating part of the cable.

[0026] In a specific embodiment, in the radiating part of the cable, the conductive component is covered by a second conductive component that is grounded.

[0027] This limits the electromagnetic radiation from the cable in the transport vehicle, which may be necessary depending on the electromagnetic compatibility required for the transport vehicle.

[0028] According to a specific embodiment, the at least one second continuous portion of the radiating part of the at least one cable includes at least one bend, and the curved length of the at least one bend of the at least one second portion is between 0.9 times and 1.1 times the half-wavelength L0 defined by the communication frequency F0 modulo the wavelength L0, and the distance "P" between the two ends of the at least one bend of the at least one second portion is less than one-quarter of the wavelength L0.

[0029] Preferably, the second continuous portion of the radiating portion of the bidirectional communication cable close to the movable component includes at least one bent portion. The bent portion is defined by a width denoted as "l" and a length denoted as "L". The length "L" is defined with respect to the axial direction of the radiating portion of the cable outside the bent portion area, and the cable is located within the area defined by the radial projection and the axial projection of the cable on the movable component. One end of the length "L" starts at the change in the curvature of the cable where the bent portion begins. The other end is defined by the farthest point of the bent portion (in other words, the point having the maximum orthogonal projection with respect to the axial direction of the cable). The width "l" of the bent portion is defined by the axial average value of the points of the bent portion that define the outward or return path of the bent portion in the cable direction (in other words, all points of the cable between the two ends of the length "L" of the bent portion that are located on the outward or return path defining the bent portion). In the axial direction of the cable, the distance between these two axial average values determines the width "l" of the bent portion. In the radio wave propagation direction provided by the transmitting / receiving system, the first point of the bent portion whose tangent has a main component in the direction of the length "L" of the bent portion will be called the inlet end of the bent portion. In the radio wave propagation direction provided by the transmitting / receiving system, the last point of the bent portion whose tangent has a main component in the direction of the length "L" of the bent portion will be called the outlet end of the bent portion. The distance "P" is measured between the inlet end and the outlet end of the bent portion.

[0030] Such a bent portion enables the creation of an enhanced communication area between the bidirectional communication cable and the transponder in the communication mode of the radio frequency transmission of the reading system (i.e., triggered by the reading system). This enables the establishment of communication with the radio frequency transponder, especially when the radio frequency transponder is passive. When the radio frequency transponder approaches this bent portion during the travel related to the movement of the second movable component, the radio frequency transponder can be woken up and communication can be established by providing a sufficient amount of energy to wake up the radio frequency transponder. Specifically, such a bent portion enables the creation of a narrow spatial area between the inlet end and the outlet end of the bent portion, in which the electric field E generated by the radiating portion of the communication cable is stable and its amplitude is higher than the electric field generated outside the bent portion and even inside the bent portion.

[0031] Specifically, such a bent portion can create an extended spatial area proportional to the length "L" of the bent portion, in which the electric field E generated by the radiating portion of the communication cable is stable and its amplitude is higher than the electric field generated outside the bent portion. When the curved length of the bent portion approaches the half-wavelength L0 related to the communication frequency F0 of the reading system, this increase in the electric field E of the bent portion between the inlet end and the outlet end is possible only because a specific distance P between the two points of the bent portion creates a gap, that is, a system with opposite charges, where the positive and negative charges face each other like a capacitor.

[0032] An increase in the amplitude of the electric field E results in an increase in the RF energy to the RF transponder, which enables the activation of the RF transponder in the communication mode. In the case of a passive RF transponder (such as an RFID tag), the energy captured by the RF transponder is used to transmit a returned RF message from the RF transponder. During the phase of receiving the RF message from the RF transponder, as long as the distance between the two elements remains reasonable, the linear radiation portion of the communication cable is sufficient to receive the returned message. Therefore, such a bent portion is mainly used in areas where it is difficult to communicate with the RF transponder. For example, when it is necessary to interrogate an RF transponder that is spatially far from the radiation portion of the communication cable, or when the environment of a vehicle or a movable component is unfavorable for RF communication due to, for example, conductive elements. In these specific cases, the presence of the bent portion can still interrogate the RF transponder of the movable component and receive its RF response through the second continuous portion of the radiation portion of the communication cable.

[0033] Note that the arrangement of the remaining part of the bent portion (that is, except for the points at the inlet end and the outlet end) only slightly changes the electric field E. Therefore, such a bent portion can be easily adapted to any complex and dense environment, such as a motor vehicle. It is only necessary to control the distance between the inlet and outlet ends, the direction of the straight line defined by these two ends, and the curve length between these two ends to ensure that the bent portion plays its role in enhancing RF communication. Finally, this type of bent portion can also minimize the power consumption of the communication cable. This is because the RF radiation is local rather than extensive, which saves energy. Obviously, the smaller the distance "P" between the outlet and inlet ends of the bent portion, the stronger the electric field E generated by these points, at the cost of the duration for which the RF transponder is exposed to this enhanced electric field E. To increase the duration of exposure to this electric field E, it is sufficient to increase the number of bent portions, especially by making these bent portions adjacent. For example, this can be achieved by bending the cable into an "S" shape, which constitutes the addition of two adjacent bent portions with opposite loops. Due to the curvature of the cable, the "S" shape can prevent the two bent portions from being spatially offset. This technique enables the expansion of the communication area through the enhanced electric field E generated by each bent portion.

[0034] In addition, preferably, the continuous portion of the radiation portion of the two-way communication cable located in the spatial region around the second movable component has a curve length greater than one cable length unit. The cable length unit is defined by the wavelength, which is related to the transmission frequency F0 of the radio signal propagated by the reading system in a medium with a given relative permittivity. This ensures that the length of the antenna in the spatial region defined by one of the two geometric conditions is suitable for transmitting radio signals to and receiving radio signals from the RF transponder attached to the movable component. Of course, the longer the length of the continuous portion of the radiation portion of the two-way communication cable, the better the communication between the reading system and the RF transponder.

[0035] According to an advantageous embodiment, the radiating portion of the at least one cable includes at most 7 bends, preferably at most 5 bends.

[0036] Increasing the number of bends limits the radiation properties of the cable outside the region where the bends are located, which may have an adverse effect on the interrogation of a radio frequency transponder of a transport vehicle in a spatial region that is not within the continuous portion of the radiating portion of the communication cable during movement. An alternative to compensating for this low transmission radiation of the cable is to increase the electrical power of the reading system. However, with the same power supplied to the reading system, it is preferable to limit the number of bends to ensure sufficient radio frequency communication over the entire length of the radiating portion of the two-way communication cable.

[0037] According to another advantageous embodiment, each continuous portion of the radiating portion of the at least one cable includes at most 3 bends, preferably at most 2 bends.

[0038] According to the same logic of the cable communication capacity consistency, preferably, each continuous portion of the radiating portion of the cable has no more than 3 bends, and very preferably, no more than 2 bends. Thus, if there are multiple continuous portions, the radiation power is distributed over the respective continuous portions. In addition, the radio transmission power remains in the regions without bends.

[0039] Advantageously, the radio frequency transponder associated with the at least one movable component includes a radio frequency antenna that includes at least one strand defining a first longitudinal axis. Each bend of the first continuous portion and / or at least one second continuous portion of the radiating portion of the at least one cable defines a straight line D defined by the two ends of the at least one bend. On at least a part of the closed path described by the at least one movable component, the angle formed by the direction vector of the first longitudinal axis and the direction vector of the straight line D is less than + / - 30 degrees, preferably less than + / - 20 degrees.

[0040] In the specific case where the radio frequency transponder is equipped with a wired antenna, the direction of the first longitudinal axis and the direction of the straight line D must be substantially parallel to each other to ensure electromagnetic coupling between the radio frequency transponder and the effective portion of the bend. Specifically, the enhanced electric field E generated by the bend is oriented along the straight line D. Therefore, the wired antenna of the transponder is substantially aligned with the enhanced electric field E generated by the bend. Ideally, the wired antenna should be collinear with the enhanced electric field E to maximize the coupling efficiency. However, as long as the angle formed by the two directions does not exceed 30 degrees, the communication level between the two antennas is completely sufficient. This is preferred when the radio frequency transponder is passive (i.e., without its own power source or electrical energy generation). In this case, electromagnetic coupling is used to activate the radio frequency transponder by transmitting energy to it before the radio frequency transponder transmits.

[0041] Of course, since the RF transponder is in a moving state and the reading system is fixed relative to the transport vehicle, the angular condition may not be satisfied along the entire path described by the RF transponder. However, it is sufficient for the angular condition to be satisfied along a partial path of the movable component for the RF communication between the two electronic systems to be effective.

[0042] According to a first very specific embodiment, the at least one movable component is capable of depicting a rotational movement about a single axis of rotation defining a cylindrical reference system about the single axis of rotation, the main component of the first longitudinal axis of the RF antenna of the RF transponder associated with the at least one movable component is circumferentially oriented in the cylindrical reference system, and at least one bend associated with the first continuous portion and / or at least one second continuous portion of the radiating portion of the at least one cable is arranged radially outside the movable component relative to the axis of rotation, the main component of the straight line D of the at least one bend being circumferentially oriented in the cylindrical reference system of the movable component.

[0043] When the first longitudinal axis of the RF transponder of the movable component is mainly circumferential in the cylindrical reference system of the mounting component, for example in the case where an RFID tag is embedded in the sidewall or lower region of a tyre structure, and when the bend is located radially outside the axis of rotation of the movable component, it is advisable to position the bend such that the straight line D has a mainly circumferential direction within the cylindrical reference system of the movable component. Thus, it is certain that during the rotational movement of the movable component, the direction of the first longitudinal axis of the wired antenna of the RF transponder and the direction of the enhanced electric field E generated by the bend are substantially aligned with a part of the loop described by the movement of the RF transponder.

[0044] Very specifically, for this first specific embodiment, the RF antenna of the RF transponder associated with the at least one movable component and at least one bend associated with the first continuous portion and / or at least one second continuous portion of the radiating portion of the cable are projected in the same circumferential plane, and the projection of the antenna of the transponder intersects at least the projection of the straight line D of the at least one bend.

[0045] In the case where the RF transponder of the movable component is embedded in the rubber compound of a tyre, as in the case of an RFID tag, due to the relative permittivity of the rubber compound of the tyre, the size of the RF antenna of the RF transponder defined by the strands and associated with the radio communication frequency F0 of the RF transponder is smaller. Specifically, the relative permittivity of the rubber compound is different from that of air, which changes the wavelength of the radio waves. In this case, depending on the communication frequency F0, the size of the RF antenna may be smaller than the distance "P" between the inlet and outlet ends of the bend. Thus, the entire radiating antenna of the transponder may be located in the enhanced electric field E generated by the bend, which increases the power transmitted to the RF transponder.

[0046] According to a second very specific embodiment, the movable component is capable of depicting a rotational movement about a single axis of rotation that defines a cylindrical reference system about the single axis of rotation, a major component of a first longitudinal axis of a radiofrequency antenna of a radiofrequency transponder associated with the at least one movable component being circumferentially oriented in the cylindrical reference system, and at least one bend associated with a first continuous portion and / or at least one second continuous portion of a radiating portion of a cable being arranged axially outside and radially inside the movable component relative to the axis of rotation, a major component of a straight line D of the at least one bend being circumferentially oriented in the cylindrical reference system of the movable component.

[0047] When the first longitudinal axis of the radiofrequency transponder of the movable component is mainly circumferential in the cylindrical reference system of the mounting component, such as in the case where an RFID tag is embedded in the sidewall or lower region of a tire structure, and when the continuous portion of the radiating portion of the communication cable is located axially outside and radially inside the tire relative to the axis of rotation of the movable component, it is advisable to position the bend such that the straight line D has a mainly circumferential direction within the cylindrical reference system of the movable component. Thus, it is certain that during the rotational movement of the movable component, the direction of the first longitudinal axis of the wired antenna of the radiofrequency transponder and the direction of the electric field generated by the bend are substantially aligned with a part of the loop depicted by the movement of the radiofrequency transponder.

[0048] Very specifically, for this second specific embodiment, the radiofrequency antenna of the radiofrequency transponder associated with the at least one movable component and at least one bend associated with a first continuous portion and / or at least one second continuous portion of a radiating portion of a cable are projected in the same axial plane, and the projection of the antenna of the transponder intersects at least the projection of the straight line D of the at least one bend.

[0049] In the case where the radiofrequency transponder of the movable component is embedded in the rubber compound of a tire, such as in the case of an RFID tag, due to the relative permittivity of the rubber compound of the tire, the size of the radiofrequency antenna of the radiofrequency transponder defined by the strands and associated with the radio communication frequency F0 of the radiofrequency transponder is smaller. Specifically, the relative permittivity of the rubber compound is different from that of air, which changes the wavelength of the radio wave. In this case, for example, depending on the communication frequency F0, the size of the radiofrequency antenna may be smaller than the distance "P" between the inlet end and the outlet end of the bend. Thus, the entire radiating antenna of the transponder may be located in the electric field E generated by the bend, which increases the communication power transmitted to the radiofrequency transponder.

[0050] Advantageously, the radiofrequency transponder includes an RFID tag.

[0051] This is a specific implementation where the radio frequency transponder includes a Radio Frequency Identification (RFID) tag. Since the RFID tag requires very few components to operate, it is very small in size, which allows it to be actually mounted inside or on the outer surface of the tire of a movable component through a specific connection patch. The main function of this electronic system is to transmit identification information that is usually encoded in the non-erasable memory of the electronic system. In a specific implementation, the RFID tag is passive and has no power source of its own. In this specific case, the interrogation phase of the RFID tag first includes transmitting radio frequency energy to it to make it operable, and then responding to the interrogation.

[0052] Advantageously, the movable component is capable of depicting a rotational movement about a rotational axis, and each successive portion of the at least one cable depicts an angular sector about the rotational axis, which angular sector is at least greater than 30 degrees, preferably greater than 60 degrees, and very preferably greater than 120 degrees.

[0053] In the case of a movable component rotating about a single rotational axis, preferably, in a rotational reference frame associated with the single rotational axis, successive portions (including bends) of the radiating portion of the two-way communication cable extend over an angular sector of at least 30 degrees. In this way, depending on the rotational speed of the movable component about its single rotational axis, a certain communication duration is ensured between the radio frequency transponder rotating with the movable component and the reading system fixed in the transport vehicle. Of course, the larger the angular sector, the longer the communication time at a given rotational speed.

[0054] Preferably, successive portions of the radiating portion of the at least one cable are attached to at least one wall defining a chamber of a transport means that houses the movable component.

[0055] In the case of a movable component rotating about a single rotational axis, such as a movable component including an outer tire in an automobile, preferably, successive portions of the radiating portion of the two-way communication cable are directly or indirectly attached to the wheel arch. The wheel arch defines a chamber to which the vehicle mounting component will be connected under use conditions. Generally, this component is non-metallic, which means there is no shielding effect or radio interference. Since there are no metal or conductive components between the two antennas, the radio wave propagation between the communication cable and the transponder is enhanced. Finally, the chamber naturally provides a free area for installing the communication cable in an extremely limited space, such as the space of a motor vehicle.

[0056] Very preferably, successive portions of the radiating portion of the at least one cable extend at a constant radial distance from the single rotational axis of the movable component.

[0057] In the case of using a passive radio frequency transponder (such as an RFID tag) in a tire, this condition ensures reliable radio frequency communication between the two components. In fact, it is usually allowed to position the RFID tag relative to the axis of rotation of the mounting component in the main circumferential direction on the tire sidewall. In addition, the shape of the wall defining the chamber for accommodating the mounting component generally follows this geometric condition. Therefore, the communication between the two antennas is also optimized in terms of duration and quality, and the spatial distance between the continuous parts of the radio frequency transponder and the radiating part of the communication cable is kept constant.

[0058] Preferably, the radio frequency transponder transmits at a subcarrier frequency.

[0059] In these applications, the radio frequency transponder uses the radio frequency transmission signal it receives to transmit a response to its interrogation. This operating mode is particularly common in passive radio frequency transponders such as RFID tags (i.e., transponders without their own power source for transmission). These communication modes employ various modulation methods depending on whether their purpose is to improve the communication sensitivity of a two-way communication cable or to increase the communication speed between two radio frequency devices. The main characteristics of modulation are two variables: the number of transitions of the binary state - physically, this is, for example, a change in the state of the radio frequency transponder impedance of the electronic chip of an RFID tag, which causes changes in the amplitude and phase of the return signal - and the unit period for observing the transitions. To improve the sensitivity of the communication cable, it is recommended to have a large number of transitions of the binary state within a long unit period. For example, the Miller 8 coding applicable to UHF RFID provides a sensitivity gain of 5 dBm to 10 dBm. On the other hand, limiting the number of transitions to a single transition per unit period within a short unit period is beneficial for the transaction throughput between the radio frequency transponder and the two-way communication cable, in fact maximizing it. The FMO modulation, i.e., one transition per unit period of, for example, 7.6 μs, increases the reading rate of the two-way communication cable by a factor of 10 compared to the Miller 8 modulation. In the case of an RFID tag, it is the reading system, especially the electrical signal generator, that controls the modulation scheme by which the radio frequency transponder must communicate. This is not a choice of the radio frequency transponder, but an obligation imposed on it by the reading system.

[0060] Very preferably, the subcarrier frequency of the radio frequency transponder includes a number of transitions less than 5, and preferably, there is a single transition within the unit period of the subcarrier frequency.

[0061] Very preferably, the unit period of the subcarrier frequency of the radio frequency transponder is less than 10 μs, and preferably, less than 8 μs.

[0062] Selecting a short period and fewer transitions is beneficial for the radio frequency communication rate between the radio frequency transponder and the two-way communication cable, i.e., the reading rate of the continuous part of the radiating portion of the communication cable, which is advantageous in the envisaged arrangement. In fact, this arrangement is characterized in that, due to the relative movement of the radio frequency transponder mounted on the movable component, the reading distance between the two-way communication cable and the radio frequency transponder is less than 1 meter within the short coupling time between the two devices. The inventors have found that this modulation method is particularly advantageous for a transport vehicle in which the continuous part of the radiating portion of the communication cable is directly opposite the tire of the movable component when the vehicle is traveling at high or very high speeds. Description of the Drawings

[0063] The present invention will be better understood after reading the following description given by way of non-limiting example and with reference to the drawings, in which the same reference numerals denote the same components, where:

[0064] Figure 1 A perspective view showing the communication space between the radiating portion of the communication cable and the movable component, the movable component consisting of a tire mounted on a rim (not shown) and inflated.

[0065] Figure 2 An embodiment of a two-way communication cable of a reading system according to the present invention is shown.

[0066] Figure 3 A perspective view showing how the reading system is installed in a motor vehicle is shown.

[0067] Figure 4 A cross-sectional view of a tire equipped with an RFID tag is shown.

[0068] Figure 5 An example of a radio frequency transponder, in this case an RFID tag, is shown.

[0069] Figures 6a to 6c An example of the continuous part of the radiating portion of the cable at the movable component is shown.

[0070] Figure 7 A dimensional description of the bent portion of the two-way communication cable is shown. Detailed Description of the Invention

[0071] Figure 1Shows the tire 12, which presents the deformable part of the movable assembly 1 composed of a tire mounted on a rim and inflated, where the rim is not shown here. The tire 12 rotates about the natural rotation axis 102. The tire 12 defines a median plane 101 perpendicular to the rotation axis 102, dividing the tire 12 into two sub-parts symmetric with respect to the median plane 101. The tire 12 is equipped with an RFID-type radio frequency transponder, i.e., without its own energy source, for measuring the inflation pressure of the movable assembly using a pressure sensor, which corresponds to an electronic device of the RFID sensor type. The tire 12 also includes an active TPMS-type sensor mounted on the rim valve. The radial position, azimuthal position, and axial position of these radio frequency devices are generally arbitrary in the movable assembly.

[0072] The tire 12 is surrounded by a cylinder 108 having a rotation axis 102, which is located at the radially outermost position of the crown of the outer tire with respect to the rotation axis 102. Here, the tire 12 is inflated but without a static load, and the cylinder 108 is located at multiple points on the crown, and these points are evenly distributed around the perimeter of the crown.

[0073] Then, the installation space 104 of the continuous part of the radiating part of the two-way communication cable can be defined as a cylinder having a rotation axis coaxial with the axis 102, which extends radially from the outer surface of the cylinder 108 at a distance R with respect to the axis 102, and the distance R is represented by the gray arrow depicted in the median plane 101. The cylinder 104 is a straight cylinder because it is defined by a plane collinear with the median plane 101, and the plane is located on both sides of the median plane 101 and is axially spaced from the median plane 102 by an axial distance A along the direction of the axis 102. These axial distances A are represented by the gray arrows on the axis 102. The continuous part of the radiating part of the two-way communication cable (preferably, its length is at least one unit of the cable length, defined by the transmission frequency F0 of the reading system) must be positioned in the straight cylinder 104 so that the radio frequency devices of the movable assembly can communicate with the reading system mounted on the vehicle using the two-way communication cable.

[0074] Figure 2 Shows the two-way communication cable 32 in the first configuration, which performs excellently and is not only suitable for RFID tag applications.

[0075] The cable 32 includes an elongated bipolar coaxial conductive structure 312, which has a conductive inner conductor 314 and a conductive sheath conductor 316 coaxially surrounding the inner conductor 314. In the shown example, the inner conductor 314 is cylindrical and the sheath conductor 316 is a hollow cylinder.

[0076] The inner conductor 314 and the sheath conductor 316 are both made of metallic material, and an electrically insulating intermediate layer (e.g., plastic) advantageously exists radially between the inner conductor 314 and the sheath conductor 316 over the length of the conductive structure 312.

[0077] The first end 318 of the conductive structure 312 is arranged to connect to a transmitter and / or a receiver of a reading system to transmit or receive an antenna signal via the cable 32. The cable 32 is provided with a conventional coaxial plug 320 which forms electrical connectors for the inner conductor 314 and the sheath conductor 316 in a conventional manner at this first end 318.

[0078] In this configuration, at the opposite second end 322 of the conductive structure 312, an extension 324 of the inner conductor 314 is provided which is integrally formed with the inner conductor 314 in the illustrated example and is thus electrically connected to the inner conductor 314. The extension 324 starts from the second end 322 of the conductive structure 312 and extends linearly away from the sheath conductor 316 and coaxially with the paths of the inner conductor 314 and the sheath conductor 316 before the second end 322.

[0079] The inner conductor extension 324 extends to the free end 326 of the inner conductor extension 324, where some capacitive coupling of the free end 326 or the inner conductor extension 324 with the sheath conductor 316 exists in the region of its second end 322, depending on the length of the inner conductor extension 324.

[0080] In one transmission mode of the cable 32, i.e., if the antenna signal to be transmitted is introduced at the coaxial plug 320 at the first end 318, this antenna signal travels through the conductive structure 312 to the end 322 and is more or less reflected there to return as a bound traveling wave along the sheath conductor 316 towards the first end 318.

[0081] For a correspondingly selected operating mode, e.g., with respect to the frequency and power of the injected antenna signal, it is possible to achieve that the cable 32 generates an alternating electromagnetic field around it, but with relatively little radiation. The cable 32 operates like a traveling wave antenna in "coupling mode", and thus the range of the cable 32 can be well controlled.

[0082] In Figure 2 In the illustrated example, a surface wave attenuation device 330 is arranged on the outer periphery of the sheath conductor 316 at a certain distance from the second end 322, at a point between the two ends 318 and 322. In the illustrated example, the device consists of a plurality of ferrite rings 332, 334, 336 and 338, each ferrite ring surrounding the outer periphery of the sheath conductor 316.

[0083] When viewed in the longitudinal direction of the conductive structure 312, the ferrite rings 332 to 338 are arranged at a certain distance from each other, and when the traveling wave from the second end 322 of the conductive structure 312 reaches the position of the attenuation device 330, the ferrite rings 332 to 338 can advantageously attenuate these traveling waves.

[0084] The attenuation device 330 constituted by the ferrite rings 332 to 338 or their arrangement positions in the path of the coaxial conductive structure 312 divides the total length of the conductive structure 312 into a signal conduction part 340 and a radiation part 342. During the operation of the cable 32, the signal conduction part 340 is used to conduct the antenna signal emitted from or to the first end 318, and the radiation part 342 is used to transmit the information and / or energy emitted from or to the cable 32.

[0085] The number of ferrite rings and the individual distance between the ferrite rings can be adjusted according to the corresponding application or operating parameters of the cable 32.

[0086] It can also be stipulated that in the case of multiple ferrite rings, at least one ferrite ring (preferably, at least the "first" ferrite ring closest to the second end 322, i.e., the ferrite ring 332 in the illustrated example) is arranged so that it can move along the conductive structure 312.

[0087] Therefore, the performance of the thus constituted attenuation device can be affected or adjusted by the actual application.

[0088] As an alternative or supplement to the ferrite rings 332 to 338, different from the illustrated example, the attenuation device 330 can also include various attenuation components, such as a grid structure composed of capacitive components and / or inductance and / or resistance elements, which are arranged at relevant points on the path of the conductive structure 312 and are connected to the parts 340, 342 of the conductive structure 312 leading to the first end 318 and the second end 322 on both sides.

[0089] The main cable assembly 32 is constituted by a coaxial conductive structure 312, which can be a flexible or semi-rigid cable with an "open end" or the above-mentioned inner conductor extension 324.

[0090] In the region of the inner conductor extension 324, the shielded sheath conductor 316 is removed to a certain extent in the remaining region of the conductive structure, thereby forming a dipole antenna, one arm of which is constituted by the inner conductor extension 324 and the other arm is constituted by the sheath conductor 316. There are also other methods of realizing capacitive coupling not shown here.

[0091] The surface wave attenuation device 330 constituted by one or more ferrite rings here limits the effective antenna length for transmission / reception to the radiation part 342.

[0092] In addition to adjusting the length of the antenna, the position of the attenuation device 330 (in this case, especially the position of the first ferrite ring 332) also affects the characteristics of the attenuation device 330, and thus affects the characteristics of the reflected traveling wave.

[0093] If the length of the inner conductor extension 324 is at least approximately equal to a quarter wavelength of the relevant antenna signal, it is generally advantageous for the generation of the desired reflected traveling wave.

[0094] For a suitable geometry of the cable 32 and the corresponding operating mode, most of the transmitted signal can be made to migrate as sheath current along the "signal transmitter / receiver section" 342, and relatively little high-frequency energy is radiated ("coupling mode").

[0095] The length of the inner conductor extension 324 can be selected such that, in combination with the position of the first ferrite ring 332, the desired impedance is defined to achieve the highest possible reflection loss of the cable 32.

[0096] The length of the cable 32 and the lengths of its various parts described above can be adjusted to suit the application involved.

[0097] In Figure 2 , l1 is the length of the signal conducting section 340, l2 is the length of the surface wave attenuation device 330, l3 is the length of the signal transmitter / receiver section 342, and l4 is the length of the inner conductor extension.

[0098] The distance d1 refers to the distance between the ferrite ring 332 and the ferrite ring 334. This distance d1 is, for example, between 5 mm and 20 mm.

[0099] The sheath conductor 316 of the coaxial conductive structure 312 has at least one opening, which is drawn as an example in dashed lines and labeled 339. The distance between the opening 339 and the attenuation device 330 is labeled d2 and is in the range of 1 m to 5 m. However, a plurality of openings 339 can also be arranged along the length of the signal transmitter / receiver section 342, with the distance between each other being between 0.1 times and 5 times the signal wavelength.

[0100] Figure 3 A perspective view shows how the reading system 3 is installed in a transport vehicle 2 such as a motor vehicle.

[0101] The motor vehicle 2 is represented here by a transparent volume that represents the closed, assembled bodywork, corresponding to the complete vehicle with the axles and the powertrain removed. However, the vehicle 2 depicts four chambers 21a-1, 21a-2, 21b-1 and 21b-2, each chamber being designed to house a mounting assembly of the vehicle. In this case, the mounting assembly includes radio frequency devices of the RFID tag of the outer tyre and / or the TPMS sensor type.

[0102] The vehicle 2 also includes a reading system 3 capable of communicating with the radio frequency devices of the mounting assembly. The reading system 3 includes first means 31 for transmitting and reading electrical signals, which are located at the bulkhead in the vehicle 2, the bulkhead being a wall that is substantially perpendicular to the ground on which the vehicle travels and that separates the vehicle engine compartment located at the front of the vehicle 2 from the passenger compartment. Thus, the means 31 includes an electrical signal transmitter and an electrical signal demodulator.

[0103] Starting from this means 31, two bidirectional communication cables 32a and 32b extend respectively to the left and right sides of the vehicle 2. These communication cables are Figure 2 as shown travelling-wave cables, mounted on the means 31 to form an electrical connection. Each cable 32a, 32b passes through the structure of the vehicle 2 and reaches near at least one of the chambers 21a-1, 21a-2, 21b-1, 21b-2 for housing the mounting assembly. Each cable has a signal transmission portion that starts from the means 31 and then becomes a radiating section.

[0104] In fact, as Figure 3 shown, each cable 32a, 32b reaches near two chambers for housing the mounting assembly, each chamber corresponding to the front axle and the rear axle of the vehicle 2. In the first chamber 21a-1, the cable 32a has a continuous portion 32a-1 that is located at the wheel arch and forms a 120-degree angular sector around the front axle axis. This portion 32a-1 of the communication cable 32a is located in the communication area of the radio frequency device of the mounting assembly to be housed in the chamber 21a-1. Thus, this portion 32a-1 of the communication cable 32a will communicate with the radio frequency device of the mounting assembly present in the housing chamber 21a-1. In this case, the continuous portion 32a-1 of the cable is located radially outside the mounting assembly. Thus, although Figure 3 not shown in, the continuous portion 32a-1 includes a bend whose median line direction extends axially with respect to the natural rotation axis of the mounting assembly to be housed in the chamber 21a-1 when the mounting assembly travels in a straight line.

[0105] However, the same cable 32a then extends to a second receiving chamber 21a-2 located on the left side of the vehicle 2 and at the rear axle. In this chamber 21a-2, the cable 32a has a second continuous radiating portion 32a-2, which is located in the communication area of the radio frequency device of the mounting assembly to be accommodated in the chamber 21a-2. The second continuous radiating portion 32a-2 extends angularly over a 90-degree angular sector about the axis of rotation of the rear axle. In this case, the rear axle is not oriented, so the mounting assembly hardly moves angularly during driving. Therefore, radio frequency communication between the continuous radiating portions 32a-2 of the bidirectional communication cable 32a is easier than radio frequency communication of the portion 32a-1 with shaft orientation (e.g., generating angular movement of the mounting assembly during turning). These two continuous radiating portions 32a-1 and 32a-2 are separated and can only communicate with one mounting assembly in each case. However, in the case of a double-wheel axle, such as in the case of a commercial vehicle in towing mode, the continuous portion 32a-2 near the chamber 21a-2 can communicate with various double mounting assemblies located on the same axle and the same side of the vehicle 2.

[0106] Similarly, due to the symmetry of the motor vehicle 2, the communication cable 32b includes a radiating portion having two separate continuous portions, each continuous portion communicating with a mounting assembly located on the front axle and the rear axle respectively. Like the cable 32a located on the left side of the vehicle 2, the cable 32b has a bend in the first continuous portion 32b-1. Since the continuous portion 32b-1 is located radially outside the mounting assembly, the direction of the midline of the bend mainly extends in the axial direction defined by the axis of the front axle of the vehicle 2.

[0107] In this case, the total length of the bidirectional communication cables 32a and 32b does not exceed 5 meters. The lengths of the continuous radiating portions 32a-1, 32a-2, 32b-1 and 32b-2 are greater than 50 cm, corresponding to one quarter of the deployed length of the outer tire of a passenger car. This length exceeds the cable length unit for 920 MHz or 2.4 GHz UHF radio frequency communication.

[0108] Figure 4 A detailed view of the outer tire of the tire constituting the movable assembly is shown, and the movable assembly is represented by a mounting assembly composed of an outer tire in an inflated state mounted on a rim. The rim represents the non-deformable part of the movable assembly. This schematic diagram highlights the bead 84 of the outer tire. This diagram shows the position of the RFID tag type radio frequency transponder 100 relative to the carcass ply 87 in the outer area of the outer tire.

[0109] The bead 84 consists of bead wires 85, the carcass ply 87 is wound around the bead wires, and the folded portion 88 is located in the outer region of the tire. The folded portion 88 of the carcass ply 87 terminates at the free edge 881. A rubber block 91, called bead wire filler, is located radially outside and adjacent to the bead wires 85. The rubber block 91 has a radially outer free edge 911 that bears on the surface of the carcass ply 87 (more precisely, on the outer calendered surface of the carcass ply, with no direct contact between the cords of the carcass ply and the RFID transponder 100). Adjacent thereto is a second rubber block 92 called "reinforcing filler". The second rubber block 92 has two free edges. The first free edge 921 is located radially inside and bears on the folded portion 88 of the carcass ply. The other free edge 922 is located radially outside and terminates at the surface of the carcass ply 87. Finally, the sidewall 83 covers the reinforcing filler 92 and the carcass ply 87. The sidewall has a free edge 831 located radially inside and terminating at the folded portion 88 of the carcass ply.

[0110] In this configuration, the airtight inner liner 90 adjacent to the carcass ply 87 is located on the inner region of the tire. The airtight inner liner 90 terminates at the free edge 901 adjacent to the carcass ply 87. Finally, the bead protector 93 protects the carcass ply 87 and the radial inner ends 901, 921, and 831 of the airtight inner liner 90, the reinforcing filler rubber 92, and the sidewall 83, respectively. When the tire is mounted on a wheel, the outer surface of the bead protector 93 is adapted to come into direct contact with the rim flange. The bead protector 93 has two radially outer free edges. The first free edge 931 is located in the inner region of the tire 1. The second free edge 932 is located in the outer region of the tire 1.

[0111] The bead 84 of the tire is equipped with two RFID tags 100 and 100bis, which are located in the outer region of the tire. The first RFID transponder 100, pre-encapsulated in electrically insulating encapsulating rubber, is located on the outer surface of the bead wire filler 91. The first RFID transponder 100 is located at a distance of 20 millimeters from the free edge 881 of the folded portion 88 of the carcass ply that forms a mechanical singularity. This position ensures a region of mechanical stability for the electronic component 100, which is beneficial for its mechanical durability. In addition, embedding the first RFID transponder 100 in the structure of the mechanical housing provides good protection against mechanical attacks from outside the tire.

[0112] A second radio frequency transponder 100bis, pre-encapsulated in an electrically insulating encapsulation rubber compatible or similar to the material of the sidewall 83, is located on the outer surface of the sidewall. The material similarity between the sidewall 83 and the encapsulation rubber ensures the installation of the RFID tag 100bis inside and around the sidewall 83 during the curing process. During the production of the outer tire, the RFID tag 100bis is simply placed on the uncured outer surface of the sidewall 83. Pressurizing the green tire in a curing mold ensures the positioning of the RFID tag 100bis in the cured state (as shown in the figure). The RFID transponder 100bis is located at a position away from any free edge of the rubber components of the outer tire. In particular, the RFID transponder 100bis is spaced a certain distance from the free edge 932 protecting the bead, the free edge 881 of the carcass ply, and the free edges 911 and 922 of the filler rubber. The RFID transponder 100bis is located in the upper part of the bead, ensuring improved communication performance with an external radio frequency reader.

[0113] Figure 5 is a schematic diagram of a radio frequency transponder 100 operating in the frequency range of 860 MHz to 960 MHz, which is designed to be integrated into an outer tire through an identification patch made of an elastic material. To improve the radio communication performance and physical integrity of the radio frequency transponder 100 inside the outer tire, preferably, the rotation axis of the radiating antenna 10 is placed parallel to the direction U (i.e., along the direction perpendicular to the cords of the carcass ply of the radially structured outer tire, especially if the cords are made of metal).

[0114] The radio frequency transponder 100 here includes a radiating antenna 10 and an electronic part located inside the radiating antenna 10. The electronic part includes an electronic chip connected to a printed circuit board. A main antenna composed of wires is connected to the printed circuit board. The side of the printed circuit board opposite to the main antenna includes a bent current circuit. Finally, the diameter of the cylinder surrounding the main antenna is 0.8 mm. Both the main antenna and the current circuit on the opposite side of the printed circuit board can achieve impedance matching between the impedance of the main antenna and the impedance of the circuit board.

[0115] The printed circuit board thus formed is embedded in an epoxy resin block 300, ensuring the mechanical reliability of the electronic components and the electrical insulation of the circuit board. The diameter of the cylinder surrounding the rigid block 300 is 1.15 mm and the length is 6 mm.

[0116] The length L of the radiating antenna 10 here is 45 mm, corresponding to half the wavelength of a radio wave with a frequency of 915 MHz in a medium with a relative dielectric constant of approximately 5. The radiating antenna 10 is manufactured using a steel wire 120 with a diameter of 0.225 mm and a surface coated with a layer of brass. The steel wire 120 is a strand of the radiating antenna of the radio frequency transponder 100, which defines the first longitudinal axis of the radio frequency transponder 100.

[0117] In this case, the radiating antenna 10 is divided into two main areas. A first area 201 corresponds to the part of the radiating antenna that is not directly opposite the electronic part. The first area 201 comprises two sub-areas 201a and 201b located on both sides of the rigid electrically insulating block 300.

[0118] The length L1 of each sub-region 201a, 201b is 19 mm, including 12 circular coils with a constant winding diameter D1 of 1.275 mm. This defines an inner diameter and an outer diameter of 1.05 mm and 1.5 mm, respectively. The pitch P1 of the circular coil is 1.55 mm. Therefore, the ratio of the pitch P1 to the winding diameter D1 of the coil is 1.21. The axial outer ends of each sub-region 201a and 201b terminate at two adjacent coils. Therefore, this high ratio ensures that the efficiency of the radio performance of the radiating antenna 10 in this region 201 is maximized. In addition, the contact between the outermost coils of the radiating antenna 10 prevents the coil springs from being wound around each other during the RF transponder processing. Since most of the coils of the first region 201 of the radiating antenna 10 have a ratio higher than 0.8, the radio performance of the RF transponder 100 is significantly improved.

[0119] In the second region 202 of the radiating antenna 10 (which corresponds to the portion of the radiating antenna 10 that is directly opposite to the electronic part), the radiating antenna 10 has a length of 7 mm. The coil spring has a constant pitch P2 of 1 mm and a constant winding diameter D2 of 1.575 mm. Therefore, the inner diameter of the coil spring of the second region of the radiating antenna is 1.35 mm. This allows the ratio of the pitch to the winding diameter to be maintained at about 0.63. This ratio maximizes the inductance of the second region 202 of the radiating antenna 10 relative to the first region 201, which makes it possible to improve the efficiency of the electromagnetic coupling with the electronic part.

[0120] In this particular case, in the first zone 201, the inner diameter of the radiating antenna 10 is equal to 1.05 mm, which is smaller than the diameter of the block 300 represented by the cylinder surrounding the electronic part (equal to 1.15 mm). Therefore, the sub-zones 201a and 201b of the first zone 201 of the radiating antenna 10 constitute mechanical stops that limit the axial movement of the block 300 inside the radiating antenna 10. In the first embodiment, the electronic part is mounted by sliding the rigid insulating block 300 into the radiating antenna 10.

[0121] Figure 6a , Figure 6b and Figure 6cAre various two - dimensional views of the communication area 104 of a radio transponder of a mounting assembly. In this example, the radio transponder is mainly attached to the tire 12, and the reading system is mounted on a transport vehicle. The tire 12 is mounted on a rim, which is not shown. The resulting movable assembly defines a natural axis of rotation 102 and a median plane 101. The movable assembly is mounted on an axle of the vehicle. The movable assembly located at the right rear side of the transport vehicle is shown here. The vehicle can move on the ground 600 via the tire 12. The tire 12 here includes two radio transponders, located on both sides of the lower region of the tire 12 respectively. Thus, one side is located inside the vehicle, while the other side is open to the outside of the vehicle when no body element of the transport vehicle obstructs the opening. During the rotational movement of the movable assembly, the radio transponders respectively depict approximately circular closed loops 601 - 1 and 601 - 2, whose axis of rotation corresponds to the natural axis of rotation 102 of the tire 12.

[0122] Figure 6a Is a view of the YZ plane of a motor vehicle, which corresponds to the front view of the movable assembly. Figure 6b Corresponds to a view of the XY plane, which corresponds to the top view of the movable assembly, Figure 6c Shows a view of the XZ plane, which corresponds to the side of the movable assembly. The radio - communication cylinder 104 is shown in the three figures between the radio transponders of the movable assembly and the reading system represented by the radiating part of the two - way communication cable 32a. When the communication cable 32a enters the communication volume 104, this cable becomes the continuous part 32a - 2 of the radiating part of the cable 32a of the movable assembly located at the right rear side of the vehicle. The fact that the cable 32a does not emerge from the volume 104 again once it enters the volume 104 indicates that there is a single continuous part 32a - 2 of the radiating part of the cable 32a associated with this movable assembly. The continuous part 32a - 2 first extends along the inner side of the tire 12 relative to the vehicle, depicting a part of a first circle centered on the natural axis of rotation 102 of the movable assembly. Then, after the bend of this cable 32a, the cable 32a moves along the direction Y of the vehicle to the other side of the median plane 101 of the movable assembly, that is, moves to the outer side of the tire 12 and the vehicle. Finally, the continuous part 32a - 2 partly depicts a second circle, which is again centered on the natural axis of rotation 102 of the movable assembly, and then the cable terminates at an end (in this particular case, this end is located within the volume 104). This end can be located outside the volume defined by the cylinder 104.

[0123] The first circle depicted by the continuous part 32a - 2 is located axially outside the movable assembly. In this case, the radius of the first circle is smaller than the maximum radius of the movable assembly; it could be larger. On the arc depicted by the continuous part 32a - 2 of the communication cable, there is a bend 501, as Figure 6cAs shown, it extends perpendicular to the arc, in other words, it extends radially in the reference frame of the movable component. The surface defined by the bent portion extends radially inwards to the first circle such that it intersects the loop 601-2 depicted by the movement of the radio frequency transponder present inside the tyre 12. In Figure 6c this, the loop is shown as a dashed circle. For an RFID tag operating at a UHF frequency of 920 MHz, when the RFID tag is embedded in the tyre structure, the length of the radio frequency antenna of the RFID tag is approximately 5 cm. Generally, the radio tag is mainly oriented in the circumferential direction. The bent portion 501 has a distance separating the outward path and the return path, here approximately 8 cm, which enables improved radio frequency communication between the bent portion 501 and the antenna of the RFID tag since the entire radiating antenna of the radio tag lies in the enhanced electric field generated by the entry end and the exit end of the bent portion at a given time.

[0124] The second circle depicted by the continuous portion 32a-2 of the communication cable 32a is located radially outside the tyre 12 with respect to the axis of rotation 102. In the example shown in FIG. 6 of this movable component, the cable 32a outside the vehicle is mainly located axially outside the tyre 12, except for the bent portion 500-2 that extends axially inwards with respect to the tyre 12. Specifically, as Figure 6a and Figure 6b shown, the bent portion 500-1 is located axially outside the tyre 12. However, the loop 601-1 depicted by the pseudo-periodic movement of the radio frequency transponder of the tyre is positioned axially close to the second circle of the communication cable 32a, which optimizes the radio frequency communication between the two antennas. In this case, the bent portion 500-2 will enable interrogation of another radio frequency transponder mounted on the movable component, which has a smaller width in the axial direction, or is positioned facing the crown of the tyre 12, which radially covers the tyre 12 externally. In this case, since the exit end of the bent portion 500-1 does not coincide with the entry end of the bent portion 500-2, the bent portion 500-1 and the bent portion 500-2 are not adjacent. However, they are still close enough to enable the creation of two different improved communication areas. In the case of adjacent bent portions in the shape of, for example, an "S", the two bent portions will form an improved communication area. In the current case, the curve lengths of the bent portions 500-1 and 500-2 are approximately 15 cm, and the spacing P between the entry end and the exit end of each bent portion is approximately 4 cm. In contrast, the bent portion 501 has a curve length of 14 cm, but the spacing P is approximately 6 cm.

[0125] This continuous portion 32a-2 of the radiating portion of the communication cable 32a is firmly fixed to the transport vehicle, in particular to the surface defining a chamber for receiving the movable component, so that communication can be carried out by radio waves with a radio frequency transponder mounted on the movable component (in particular the tire 12). This radio frequency communication remains operational regardless of which side of the tire 12 the radio frequency transponder is located on and regardless of the size, in particular the width, of the movable component mounted on the transport vehicle. However, this is not necessarily the only configuration for achieving the radio frequency communication objective, but merely an illustrative example.

[0126] Figure 7 is an example of a bend 500 in the continuous portion of the radiating portion of a two-way communication cable. The bend 500 is defined in the orthogonal plane UV associated with the bend. The axis U is defined by the tangent of the two-way communication cable located upstream and / or downstream of the bend 500; if these two directions are not parallel, the intermediate direction is taken. The bend 500 follows an outward path 511 and a return path 512, which are connected to each other at the second end by a section 513. The first ends of the return path 512 and the outward path 511 are respectively connected to the two-way communication cable located downstream or upstream of the bend 500. The direction change between the two-way communication cable and the outward path 511 or the return path 513 of the bend 500 is achieved by the flexible characteristic of the communication cable, which allows the communication cable to be bent more or less significantly. Of course, the same direction change also occurs between the outward path 511 or the return path 512 of the bend 500 and the section 513. The flexibility of the cable also allows the direction to be changed by the bending potential of the communication cable.

[0127] The bend 500 is defined by the average spacing or average width (denoted as "l") between the outward path 511 and the return path 512 and the length L of the bend 500. The length "L" of the outward path 511 or the return path 512 of the bend 500 is defined as the distance between the starting point 521 (or the end point 522 of the return path 512) of the outward path 511 and the second end 523 (or the second end 524 of the return path 512) in the direction V perpendicular to the direction U of the two-way communication cable. The second end 523 or 524 is determined by two conditions. The first condition is that it is the highest coordinate in the direction V of the point of the communication cable 32 starting from the first end 521 (or the first end 522 of the return path 512) of the outward path 511. Note that the origin of the axis V is defined at the point 521 or 522. The second condition is that the tangent of the communication cable 32 at the point of the second end 523 or 524 has the largest component in the direction V. Finally, the section 513 is defined by the second ends 523, 524 of the outward path 511 and the return path 512.

[0128] Finally, the average pitch "l" of the bent portion is determined by taking the distance in the direction U between the outward path 511 and the return path 512. The position of the outward path 511 (or the return path 512) in the direction U corresponds to the average value U of the coordinates of each point of the outward path 511 (or the return path 512) in the direction U A (or U B ), and the points are evenly distributed along the cable 32. The outward path 511 is defined by points 521 and 523, while the return path 512 is defined by points 522 and 524. Points 521 and 522 are the starting and ending points of the bent portion 500, respectively. Each of points 521 and 522 corresponds to a change in the curvature of the cable relative to the cable direction (i.e., the direction of the vector U) downstream or upstream of the bent portion 500.

[0129] In addition, the curve length of the bent portion 500 is defined as the distance along the two-way communication cable between the inlet end 525 and the outlet end 526 of the bent portion 500. Each of points 525 or 526 is determined by the following condition. It is the point of the communication cable starting from the starting point 521 or the ending point 522, and its tangent has the maximum component in the direction V.

[0130] The curve length of the cable must be between 0.9 times and 1.1 times the half-wavelength L0 related to the communication frequency of the reader system. In the case of communicating at a frequency F0 of 900 MHz, the half-wavelength is approximately 15 cm, so the curve length of the bent portion 500 must be between 13.5 cm and 16.6 cm.

[0131] Finally, the distance "P" corresponds to the pitch between points 525 and 526 of the two-way communication cable. These two points 525 and 526 define the straight line D, and the distance D corresponds to the length of the line segment between the material points 525 and 526. Necessarily, the straight line D is substantially parallel to the axis U. In the case of communicating at a frequency F0 of 900 MHz, the half-wavelength is approximately 15 cm, and the distance "P" must be less than one-quarter of the wavelength, i.e., 7.5 cm.

Claims

1. A transport vehicle (2) comprising a radio transponder reading system (3) and at least one movable component (1) capable of ensuring the movement of the transport vehicle relative to the ground (600) on which the transport vehicle (2) travels, said movable component (1) comprising a tire (12) moving about a rotation axis (102), the free movement of said at least one movable component (1) occurring in a main two-dimensional plane in a cylindrical reference system associated with said at least one movable component, the axial direction of said at least one movable component being the direction of the rotation axis (102), the tire (12) defining a median plane (101) perpendicular to the rotation axis (102), said at least one movable component (1), preferably the tire (12), being equipped with a radio transponder (100, 100bis), said reading system (3) comprising: - an electrical signal generator (31) emitting an electrical signal at a frequency F0 included in the ultra-high frequency band, connected to an electrical signal demodulator (31) adapted to a frequency band near F0 and mounted on the transport vehicle; - at least one partially flexible two-way communication cable (32) comprising a conductive core (314) covered with a first dielectric element, said first dielectric element itself being covered with a conductive component (316), one end (318) of said two-way communication cable (32) being electrically connected to the reading system (3) and having means for capacitive coupling between the conductive core (314) and the conductive component (316) through a second dielectric element at the free end (322), the conductive core (314) being adapted to the frequency band of the reading system (3); - at least one two-way communication cable (32) firmly fixed to the transport vehicle (2) and located outside said at least one movable component (1), said at least one two-way communication cable (32) comprising a radiation part (342), Characterized in that, the radial projection distance of the first continuous portion (32a-1, 32b-1) of the radiating portion (342) of at least one cable (32) on a cylinder (104) coaxial with the rotation axis and surrounding the tire (12) is less than or equal to 1 meter, preferably less than or equal to 0.5 meter; the axial projection distance of the first continuous portion (32a-1, 32b-1) of the radiating portion (342) of at least one cable (32) on the intermediate plane (101) of the tire (12) and in the direction of the rotation axis (102) is less than 2 meters, preferably less than or equal to 1 meter, and very preferably less than or equal to 0.5 meter; the first continuous portion (32a-1, 32b-1) of the radiating portion (342) of at least one cable (32) includes at least one bending portion (500, 500-1, 500-2, 501), the curved length of the at least one bending portion is between 0.9 times and 1.1 times of the half wavelength L0 defined by the communication frequency F0 modulo the wavelength L0, and the distance "P" separating the two ends (525, 526) of the at least one bending portion (500, 500-1, 500-2, 501) is less than one quarter of the wavelength L0.

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

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

4. The transport vehicle (2) according to any one of claims 1 to 3, wherein, the radiating portion (342) of the at least one cable (32) includes at most 7 bends (500, 501), preferably at most 5 bends (500-1, 500-2, 501).

5. The transport vehicle (2) according to any one of claims 1 to 4, wherein, the radio frequency transponder (100, 100bis) associated with the at least one movable component (1) includes a radio frequency antenna, the radio frequency antenna includes at least one strand defining a first longitudinal axis, and each bend of the first continuous portion (32a-1, 32b-1) and / or at least one second continuous portion (32a-2, 32b-2) of the radiating portion of the at least one cable (32) defines a straight line D defined by the two ends (521, 522) of the at least one bend (500, 500-1, 500-2, 501), on at least a part of the closed path described by the at least one movable component (1), the angle formed by the direction vector of the first longitudinal axis and the direction vector of the straight line D is less than + / -30 degrees, preferably less than + / -20 degrees.

6. The transport vehicle (2) according to claim 5, wherein, the at least one movable component (1) is capable of depicting a rotational movement around a single rotational axis (102) that defines a cylindrical reference system around the single rotational axis (102), the main component of the first longitudinal axis of the radio frequency antenna of the radio frequency transponder (100, 100bis) associated with the at least one movable component (1) is circumferentially oriented in the cylindrical reference system, and at least one bend (500-1, 500-2) associated with the first continuous portion (32a-1, 32b-1) and / or at least one second continuous portion (32a-2, 32b-2) of the radiating portion (342) of the at least one cable (32) is arranged radially outside the movable component (1) relative to the rotational axis (102), and the main component of the straight line D of the at least one bend is circumferentially oriented in the cylindrical reference system of the movable component (1).

7. The transport vehicle (2) according to claim 6, wherein, The radio-frequency antenna of the radio-frequency transponder (100, 100bis) associated with the at least one movable component (1) and at least one bend (500-1) associated with the first continuous portion and / or at least one second continuous portion of the radiating portion of the cable are projected in the same circumferential plane, and the projection of the antenna of the radio-frequency transponder intersects at least the projection of the straight line D of the at least one bend.

8. The transport vehicle (2) according to claim 5, wherein, the movable component (1) is capable of depicting a rotational movement about a single axis of rotation (102) defining a cylindrical reference system about the single axis of rotation (102), the main component of the first longitudinal axis of the radio-frequency antenna of the radio-frequency transponder (100, 100bis) associated with the at least one movable component (1) is circumferentially oriented in the cylindrical reference system, and at least one bend (501) associated with the first continuous portion and / or at least one second continuous portion of the radiating portion of the cable is arranged axially outside and radially inside the movable component (1) relative to the axis of rotation (102), and the main component of the straight line D of the at least one bend is circumferentially oriented in the cylindrical reference system of the movable component (1).

9. The transport vehicle (2) according to claim 8, wherein, the radio-frequency antenna of the radio-frequency transponder (100, 100bis) associated with the at least one movable component (1) and at least one bend (500-1) associated with the first continuous portion and / or at least one second continuous portion of the radiating portion of the cable are projected in the same axial plane, and the projection of the antenna of the radio-frequency transponder intersects at least the projection of the straight line D of the at least one bend.

10. The transport vehicle (2) according to any one of claims 1 to 9, wherein, the radio-frequency transponder includes an RFID tag (100).

11. The transport vehicle (2) according to any one of claims 1 to 10, wherein, the movable component (1) is capable of depicting a rotational movement about the axis of rotation (102), and each continuous portion of the at least one cable depicts an angular sector about the axis of rotation (102), and the angular sector is at least greater than 30 degrees, preferably greater than 60 degrees, and very preferably greater than 120 degrees.

12. The transport vehicle (2) according to any one of claims 1 to 11, wherein, the continuous portions of the radiating portion of the at least one cable are attached to at least one wall defining a chamber (21a-1, 21a-2, 21b-1, 21b-2) of the transport vehicle (2) that houses the movable component (1).

13. The transport vehicle (2) according to any one of claims 11 and 12, wherein, the first continuous portion (32a-1, 32b-1) and / or at least one second continuous portion (32a-2, 32b-2) of the radiating portion of the at least one cable extend at a constant radial distance from the axis of rotation (102) of the movable component.

14. The transport vehicle (2) according to any one of claims 1 to 13, wherein, The radio frequency transponder (100, 100bis) transmits at a subcarrier frequency.

15. The transport vehicle (2) according to claim 14, wherein the subcarrier frequency of the radio frequency transponder includes less than 5 transition times, preferably, there is a single transition within the unit period of the subcarrier frequency.

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