Method for estimating load distributed on trailer connected to vehicle

Abstract

Disclosed is a method for estimating a change in a load borne by a tire wheel assembly on a trailer resulting from attachment of the trailer to a vehicle, the method comprising the steps of: attaching the trailer to the vehicle; recording an internal temperature T in a fluid chamber of the tire wheel assembly equipped with the temperature sensor; determining the internal pressure P in the fluid chamber of the tire wheel assembly equipped with the temperature sensor using the specified variation rule; evaluating, by means of the recorded internal temperature T and the determined internal pressure P, a change in volume [Delta] V of the tire-wheel assembly equipped with the temperature sensor using a model of a fluid undergoing an adiabatic transition, the fluid having a desired gas behavior; the variation [delta] Z in the load borne by the n tire wheel assemblies equipped with temperature sensors is estimated using a second function, the parameters of which include the intermediate variation [delta] V in the evaluated volume and the flattening stiffness KP per unit volume of the tires of the tire wheel assemblies.

Description

Technical Field

[0001] This invention relates to the field of determining applied quasi-static loads in real time, and particularly to load variations arising from a trailer connected to a vehicle (especially when the vehicle is not moving). Background Technology

[0002] Obtaining the quasi-static load applied to a stationary trailer allows for the determination of whether the trailer or its axles are in a safe condition even before the trailer is started, thereby improving reliability and meeting road traffic safety requirements. Specifically, determining the load applied to an inflation system such as a tire-wheel assembly typically requires a balance scale and is difficult to determine outside of very specific loading locations (e.g., a quarry where trailers attached to vehicles are loaded). To assess the load on the trailer and its axles outside these specific locations, the load on the individual tire-wheel assemblies can be assessed by measuring the tire indentation on the ground. While this can be done using a system that quantifies static pressure by inserting a measuring system between the tire-wheel assembly and the ground, this is not a simple task, and the accuracy of the measurement depends on the correct positioning of the measuring system. An alternative approach is to determine the size of the contact patch under driving conditions by measuring the tire deformation as the wheels rotate. The load applied to the tire can be deduced by using a mathematical model that correlates tire type, inflation pressure, and the external dimensions of the ground indentation. Unfortunately, this measurement is performed under driving conditions. Therefore, the trailer may no longer be within its safe operating range when measurements are taken. Furthermore, achieving accuracy in these measurements becomes challenging under very heavy loads, where tire deformation, which determines load changes, tends to stabilize in the circumferential direction, and the changes in tire deformation measurements typically fall within this circumferential direction.

[0003] The following object and method of the present invention aims to solve the problem of measuring changes in load borne by a trailer in the absence of an external measuring system, i.e., it can be used at any time without requiring a specific measuring device. Furthermore, the assessment is performed while the trailer is stationary, so that it can be declared whether the trailer has been safely loaded before it begins to move. Summary of the Invention

[0004] This invention relates to a method for estimating the change in load on the tire and wheel assembly of a trailer caused by its connection to a stationary tractor, the method comprising the following steps: • In the preparation stage, that is, before the trailer is connected to the vehicle: • At least one temperature sensor is provided for at least one tire wheel assembly on at least one axle of a trailer not connected to a tractor, the sensor being capable of measuring the internal temperature of the fluid cavity of the tire wheel assembly defined by the tire and the wheel. Preferably, at least one temperature sensor is provided for at least one tire wheel assembly on each axle of the trailer. More preferably, at least one temperature sensor is provided for all tire wheel assemblies on all axles of the trailer. • Determine the initial load Z1 applied to at least one tire wheel assembly equipped with a temperature sensor on an unattached trailer; • Determine the initial inflation pressure P1 of at least one tire wheel assembly of the trailer equipped with a temperature sensor; • Determine the initial internal temperature T1 of at least one tire wheel assembly of the trailer equipped with a temperature sensor; • The initial volume V1 of at least one tire-wheel assembly equipped with a temperature sensor is evaluated using a first function, the parameters of which include the volume V0 of the fluid cavity of the tire-wheel assembly when unloaded and inflated to an initial pressure P1, and the flattening stiffness K of the tire per unit volume of the tire-wheel assembly. P ; • The number of fluid moles n in the fluid chamber of each tire wheel assembly equipped with a temperature sensor was evaluated using a model that takes into account inflation pressure P1, initial volume V1, and temperature T1. • Determine the evolution of the internal pressure P of the fluid cavity based on the internal temperature T during the adiabatic transition of at least one tire wheel assembly that is inflated, subjected to a load Z1, and equipped with at least one temperature sensor. • During the main phase: • Connect the trailer to the vehicle at the trailer's geometric point M; • Record the internal temperature T of the fluid cavity of at least one tire wheel assembly equipped with a temperature sensor at a sampling frequency F1; • The internal pressure P of the fluid cavity of at least one tire wheel assembly equipped with a temperature sensor is determined by utilizing the evolution law determined in the preparatory stage; • The intermediate change ΔV of the volume of at least one tire wheel assembly equipped with a temperature sensor is evaluated by using a determined internal pressure P and a measured internal temperature T, and by using a model of a fluid undergoing an adiabatic transition, wherein the fluid behaves as an ideal gas. • The load variation ΔZ borne by each tire-wheel assembly equipped with a temperature sensor is estimated using a second function, the parameters of which include the intermediate volume variation ΔV and the flattened stiffness K per unit volume of the tire. P .

[0005] According to a preferred embodiment, in the preparatory stage, at least one tire wheel assembly equipped with a temperature sensor on at least one axle of the trailer includes a pressure sensor capable of measuring the internal pressure of a fluid cavity. The method includes, in the main stage, a step of recording the internal pressure P of the fluid cavity of at least one tire wheel assembly equipped with a temperature sensor when at least the recorded internal temperature T changes direction or after a duration T0 corresponding to the end of an adiabatic transition of the fluid. The method also includes a second step of considering the recorded internal pressure P, the internal temperature T recorded during the time period corresponding to the recording of the internal pressure P, and using a model of the fluid undergoing an adiabatic transition to evaluate an intermediate change ΔV2 in the volume of at least one tire wheel assembly equipped with a temperature sensor, the fluid being an ideal gas.

[0006] The method for determining the variation of applied load comprises two consecutive stages. The first stage involves identifying the inherent parameters of the tire-wheel assembly before the trailer is connected to the vehicle. This constitutes establishing a trailer measurement system by mounting a measuring system to the trailer axle and identifying initial parameters of the tire-wheel assembly, such as the volume of the fluid chamber, the amount of fluid contained in the enclosed volume defined by the fluid chamber, the load initially applied to the tire-wheel assembly by the unconnected trailer, the internal temperature of the fluid chamber in each tire-wheel assembly, and the inflation pressure of the fluid chamber. Intuitively, when estimating the amount of fluid trapped in the fluid chamber, it is assumed that the properties of the fluid are known. It is also necessary to have an evolutionary law relating the variation of the internal pressure P of the tire-wheel assembly to the variation of the internal temperature T of the tire-wheel assembly when the tire-wheel assembly is under operating conditions (especially under load Z1, near inflation pressure P1 and temperature T1). This evolutionary law may be a default law or it may be derived from experimental characteristics or numerical simulations of the relevant tire-wheel assembly.

[0007] The second phase represents the step of assessing the changes in load applied to the individual tire-wheel assemblies equipped with electronics due to the trailer's connection to the vehicle. This includes electronic devices, including temperature sensors, managing and regulating the recording of the internal temperature of the fluid chambers. Therefore, when the trailer is connected to the vehicle, the internal temperature of the fluid chambers of the individual tire-wheel assemblies equipped with electronics is recorded. In the transient phase, the temporal evolution of physical quantities related to the fluid chambers is relatively large. The connection of the trailer triggers a first transition corresponding to the work generated by this additional load, which can be analogous to an adiabatic (i.e., rapid) transition and is dominant compared to the second transition. Then, after the rapid transition, there is a slower transition corresponding to the fluid chambers establishing thermal equilibrium with the external environment through the tires and wheels. This equilibrium is necessary after the change in the internal temperature of the fluid chambers caused by the work-related transition. This thermal equilibrium is established slowly due to the thermal inertia of the tires and wheels. Furthermore, the thermal equilibrium generally has a smaller impact on the volume change of the fluid chambers compared to the work-related transition. Preferably, the electronics are fixed to the inner wall of the tire. This is because the tire actually deforms the most during the adiabatic transition. Therefore, because the temperature sensor is farther from the wheel, the relative change in temperature measured is greater than the absolute temperature measured. This is because the tire has lower thermal inertia, while the wheel (especially one made of metal) inherently has greater inertia than the tire. As a result, the accuracy of temperature measurement is improved, thereby improving the quality of the method for measuring changes in load.

[0008] By utilizing the change in the internal temperature T of the fluid cavity, the change in the internal pressure P of the fluid within the cavity can be determined. This change is defined using an evolution law previously established in the preparatory stage. Therefore, this evolution law converts the measured value of the internal temperature of the fluid within the cavity into an estimated value of the internal fluid pressure resulting solely from the transformation related to the work generated by the applied additional load.

[0009] Then, the first intermediate change in volume can be assessed using a model of the fluid undergoing an adiabatic transition. Here, the term "adiabatic" means that the transition the fluid undergoes due to the trailer's connection to the vehicle occurs without external heat exchange between the fluid cavity and the outside of the tire-wheel assembly, assuming this transition is rapid. As a result, the first change in volume of the fluid cavity caused by the trailer's connection to the vehicle, where the fluid has undergone an adiabatic transition, can be estimated solely using the measured change in internal temperature and the change in internal pressure determined based on the change in internal temperature within the fluid cavity according to evolutionary laws. For air or nitrogen, it is perfectly reasonable to assume that the gaseous fluid within the fluid cavity of the tire-wheel assembly equipped with a temperature sensor is an ideal gas. Of course, for the first assessment of the volume change corresponding only to the adiabatic transition of the fluid, only the evolution associated with the adiabatic transition should be extracted from the measured change in internal temperature. The end of the adiabatic transition is characterized by the evolution of the internal temperature of the fluid cavity, which is the opposite of the adiabatic transition. Furthermore, it is entirely conceivable to estimate the duration T0 as the time when the adiabatic transition of the fluid ceases. Specifically, the event of connecting the loaded trailer to the vehicle is repeatable and reproducible, which means that the duration T0 can be set accurately and with high quality.

[0010] Preferably, a second fluid transition is used to assess a second intermediate change in volume. This second transition relates to the thermal equilibrium between the fluid and the components of the tire-wheel assembly (primarily the tire itself) and the outside. Therefore, during the transient phase associated with trailer connection, but after the adiabatic transition (i.e., when the internal temperature of the fluid cavity changes its evolution direction compared to the adiabatic transition), a second change in volume experienced by the tire-wheel assembly during the second transition is assessed using a second change in internal temperature extracted from an initial record of the internal temperature of the fluid cavity. Furthermore, after a pressure sensor is pre-installed in the tire-wheel assembly, the internal pressure of the fluid cavity in the tire-wheel assembly equipped with a temperature sensor is measured. Again, the change in volume is defined by solving a differential equation whose input data are the internal pressure P measured at the end of the first fluid transition and the measured internal temperature. Taking into account the second change in volume ensures higher accuracy in assessing the change in volume of the fluid cavity, thereby improving the measurement accuracy of the load change of each tire-wheel assembly equipped with a temperature sensor. However, the first intermediate change in volume is sufficient to estimate the overload applied to the tire-wheel assembly on a first order of magnitude.

[0011] In a preferred embodiment, this method requires distinguishing between a first transition of the fluid (characterized as an adiabatic transition) and a second transition of the same fluid (corresponding to the thermal equilibrium between the fluid cavity and the external environment via the tire and wheel) when measuring the internal temperature T of the fluid cavity. To this end, the recording of the internal temperature of the fluid cavity indicates the transition from the first to the second transition through changes in the evolution of the internal temperature. Specifically, overloading of the tire-wheel assembly causes the fluid within the fluid cavity to heat up during the adiabatic transition. Then, due to the thermal inertia of the tire and wheel, the thermal equilibrium of the fluid during the second transition will tend to decrease the temperature reached at the end of the adiabatic transition. Conversely, unloading of the tire-wheel assembly causes the fluid in the fluid cavity to expand, thereby cooling during the adiabatic transition. The subsequent thermal equilibrium will cause the temperature of the fluid in the fluid cavity to rise due to the external medium, which is assumed to be the initial temperature of the fluid before the tire-wheel assembly unloading; therefore, the external temperature is higher than the internal temperature at the end of the adiabatic transition.

[0012] Of course, considering the change in the external temperature of the tire-wheel assembly due to the thermal equilibrium of the tire-wheel assembly, it is also possible to improve the measurement of the second change in volume caused by the connection of the trailer to the vehicle at each tire-wheel assembly equipped with a temperature sensor. However, in a simplified method, since the tire-wheel assembly is preferably in a thermomechanically stable state, the initial internal temperature T1 of the fluid in the fluid cavity of the tire-wheel assembly can be used as the external temperature.

[0013] These two transformations of the fluid can occur in individual time increments or one after another over a period of measurement. The assessment of these intermediate changes in volume requires established measurements using mechanical and possible thermal equilibrium values ​​from the transient period of vehicle loading to the vehicle's tire and wheel assembly. Once these forms of equilibrium are established, the temperature and pressure changes in the fluid cavity tend to be infinitesimally small, thus reaching a further thermomechanical steady state.

[0014] Once the intermediate volume changes of each tire-wheel assembly equipped with temperature sensors have been assessed, it is necessary to evaluate the relevant changes in static load caused by the trailer connection for each tire-wheel assembly equipped with temperature sensors on the trailer. For this purpose, the intermediate volume changes of each tire-wheel assembly need to be converted into equivalent load changes. This requires considering the characteristics of the tire-wheel assembly (especially the tires), referred to as the flattening stiffness K per unit volume. PThis quantity provides the correlation between the load borne by the tire-wheel assembly and the change in volume of the fluid cavity caused by the load, where the tire-wheel assembly is flattened on a ground perpendicular to the applied load. This characteristic can, of course, be a default quantity, obtained through experimental characteristics of the tire-wheel assembly, or derived through numerical simulations of the same tire-wheel assembly. The tire-wheel assembly needs to be under operating conditions close to those observed in the preparatory phase (i.e., near the internal temperature T1 and inflation pressure P1). Typically, this flattening stiffness of the tire-wheel assembly is a quantity locally defined near the initial operating point of the tire-wheel assembly in a reference frame relating to the internal pressure P, internal temperature T, and volume V of the fluid cavity.

[0015] Preferably, prior to the main steps, at least one tire-wheel assembly equipped with a temperature sensor is in a thermomechanically stable state.

[0016] Preferably, the transient phenomena recorded by the sensors in the electronic device are caused solely by disturbances to the trailer balance resulting from the trailer's connection to the tractor. Therefore, other disturbances do not affect the sensor response, which improves the accuracy of load changes assessed using this method. However, the method remains fully relevant if the disturbance to the trailer balance occurs on a different timescale than the disturbance related to the trailer connection, or if such disturbances are expressed in a small magnitude in the sensor response of the electronic device.

[0017] Advantageously, the temperature sensor and / or pressure sensor are located in a subspace of a closed fluid cavity defined by the tire outer tube and wheel.

[0018] Advantageously, sensors measuring low-amplitude transient phenomena are located close to where these phenomena occur, preventing them from being overwhelmed by measurement noise. Therefore, for example, when a centralized tire pressure monitoring system for a tire-wheel assembly is present, it is advantageous to have the sensors located on the tire-wheel assembly rather than in the centralized system. For the same reason, measurements will be more accurate if the sensor is located on the inner surface of the tire than if it is mounted on the rim, because the latter's measurement point is farther from the location where the physical phenomenon occurs, acting on the deformation of the tire outer layer due to its transient nature. Finally, preferably, the sensors (especially temperature sensors) are located away from the wheel, which has a higher thermal inertia than the tire.

[0019] Advantageously, the temperature sensor operates with a resolution of less than one-hundredth of a degree.

[0020] Therefore, small changes in volume can be evaluated, thereby allowing for the assessment of small changes in load.

[0021] Preferably, the sampling frequency F1 is between 0.1 Hz and 10 Hz.

[0022] To capture the fluid’s rapid first transition, it is advantageous to set the sampling frequency F1 to a higher value.

[0023] According to a particular implementation, the determination of the initial volume V0 takes into account the geometry of the rim and the geometry of the unloaded tire mounted on the rim and inflated to a reference pressure P0, preferably, P0 is the initial pressure P1.

[0024] Advantageously, the geometry of the tire and / or the wheel is determined using the tire and / or wheel identifiers of the tire and / or wheel assembly equipped with a temperature sensor. Preferably, the tire and / or wheel identifiers are obtained by radio frequency interrogation of electronics located on the tire and wheel assembly.

[0025] In order to initialize the measurement system, and in particular to determine the initial volume V1 of the fluid cavity, the volume V0 of the fluid cavity corresponding to the volume defined by the unloaded tire wheel assembly should be determined, i.e., the tire is mounted on the rim with a reference inflation pressure P0, preferably the initial pressure P1.

[0026] To determine the volume V0, the axisymmetric geometry of the unloaded tire at a reference inflation pressure P0 is required. In practice, it is assumed that the rim geometry is unaffected by the tire-wheel assembly inflation pressure. These geometries can be obtained from a tire database. Knowing the tire and / or rim identification information allows for precise determination of the correct geometry from this database. Tire identification information can be obtained by optically reading regulatory markings attached to the tire sidewall. Identification information can also be transmitted via radio frequency interrogation of electronics present on the tire-wheel assembly, such as Radio Frequency Identification (RFID) tags, tire-mounted sensors (TMS) mounted on the tire liner, or tire pressure monitoring systems (TPMS) mounted on the rim.

[0027] Preferably, the load Z on each tire-wheel assembly equipped with a temperature sensor is estimated using the following formula: [Formula 1] , where K PP It is the aerodynamic flattening stiffness per unit volume of the tire in the tire-wheel assembly.

[0028] This is a simple and basic model that relates the load applied to the tire to the volume change of the fluid cavity of the tire-wheel assembly between a first volume state V0 (e.g., unloaded) and a second volume state V1, the inflation pressure P of the fluid cavity, and the aerodynamic stiffness corresponding to the flattening of the tire-wheel assembly on the contact plane. This model assumes that the structural stiffness of the tire-wheel assembly is negligible compared to its aerodynamic stiffness, an assumption that is realistic for pneumatic tires on trailers. However, in the previous formula, the tire's structural stiffness could be fully accounted for by adding the product of the tire's structural stiffness and its aerodynamic stiffness multiplied by the inflation pressure.

[0029] According to a favorable implementation scheme, the volume change ΔV of each tire-wheel assembly equipped with a temperature sensor is estimated by solving the following differential equation: [Formula 2] , [Formula 3] Where P is the internal pressure of the fluid cavity, V is the internal volume of the fluid cavity, and T is the internal temperature of the fluid cavity.

[0030] This differential equation shows the relationship between the parameters of the fluid inside the tire wheel assembly cavity. These parameters are determined first by the adiabatic transformation of the fluid and second by the fact that the fluid is an ideal gas.

[0031] The present invention also relates to a method for estimating the load borne by a trailer securely connected to a vehicle, comprising a method for estimating the change in load borne by the trailer's tire wheel assembly resulting from the trailer's connection to a stationary vehicle, characterized in that, in a preliminary stage, the method includes the step of determining a first load distribution on each axle of the trailer in relation to the application of an additional load applied to the attachment point M where the trailer is connected to the vehicle, preferably a first load distribution on each tire wheel assembly of the trailer; the method optionally further includes the step of determining a second load distribution on each axle of the trailer in relation to the weight of the trailer, preferably a second load distribution on each tire wheel assembly of the trailer; in a main stage, the method includes utilizing at least one tire wheel equipped with a temperature sensor. The method includes estimating the load Z borne by each tire wheel assembly of each axle i of the trailer by determining the load variation ΔZ borne by the assembly, the first load distribution related to the additional load applied at the attachment point M, and the initial load Z1i of each tire wheel assembly of the trailer; and optionally, estimating the load Z borne by each tire wheel assembly by considering a second load distribution related to the weight of the trailer. The method further includes comparing the estimated load Z borne by each axle i of the trailer and / or the total load borne by the trailer with at least one threshold S, where the total load is the sum of the loads borne by each axle i of the trailer. When the at least one threshold S is exceeded, in a secondary stage, the mass content K of the trailer is modified, and then the steps of the main stage are performed again.

[0032] By summing the loads borne by the tire wheel assemblies or axles before the trailer is connected, the total load on the trailer's tire wheel assemblies or axle i can be assessed. Therefore, assessing the total load borne by the trailer is equivalent to simply summing the static loads established on all axles i of the trailer. Thus, even before the trailer begins to move, it is possible to verify whether the load conditions of each tire wheel assembly, each axle, and of course, the trailer itself comply with road traffic safety regulations.

[0033] By understanding the first load distribution of the trailer's tire wheel assembly or axle i related to the overload applied to the attachment point M of the trailer, the overload on each tire wheel assembly or axle of the trailer associated with the trailer connection to the vehicle can be derived from individual measurements on the tire wheel assembly equipped with measuring devices. By summing the overload associated with the trailer connection and the static load experienced by each tire wheel assembly related to the trailer mass, the total load applied to each tire wheel assembly or axle i of the trailer can be estimated. Alternatively, the static load related to the trailer mass can be obtained from the second load distribution on the trailer's tire wheel assembly or axle i related to the trailer mass.

[0034] If the connected trailer does not meet safe driving conditions, the layout of the trailer contents needs to be altered, whether at the individual wheel assembly, axle, or the entire trailer, even if the trailer is disconnected from the vehicle, to shift the trailer's center of gravity. This shift in the trailer's center of gravity allows for a different distribution of the trailer's mass across the trailer's axles or the tractor unit's drawbar. Once the new layout is implemented, the method needs to be restarted from the main phase by connecting the trailers in the new layout and analyzing the loads on the individual wheel assemblies equipped with temperature sensors. For example, this new trailer layout might involve shifting the trailer's center of gravity, reducing the amount of cargo, or a combination of both.

[0035] The present invention also relates to a method for estimating the change in load borne by the tire and wheel assembly of a trailer rigidly connected to a vehicle due to the connection of the trailer to a stationary vehicle, and / or a system for estimating the load borne by a trailer rigidly connected to a stationary vehicle, the system comprising: • Trailer, with a hitch on point M, which can accommodate the towing seat of the vehicle, and each axle i of the trailer includes at least one tire wheel assembly equipped with electronic devices. The electronic device includes at least one temperature sensor, at least one electronic chip, at least one storage space capable of recording signals from the sensor, and at least one first radio frequency communication device capable of transmitting. The electronic device is preferably fixed to the inner wall of the tire, and very preferably fixed to the tread of the tire. • At least one computing device; and • At least one display device, which includes at least one second radio frequency communication device capable of receiving signals.

[0036] As described in the method, the temperature sensor should be located in the tire-wheel assembly, which rotates relative to the trailer. To keep it away from the components of the tire-wheel assembly with the greatest thermal inertia, the electronics are fixed to the inner wall of the tire, at the tire crown. Therefore, the electronics, at least those regulating the signal from the temperature sensor, should be equipped with, for example, a radio frequency communication device capable of transmitting data to easily transmit the data outside the tire-wheel assembly, at least to the location of the display device. Specifically, an alternative is to integrate a computing device that calculates the volume change of the inner cavity of the tire-wheel assembly into the tire-wheel assembly. This computing device can be integrated into the electronics or communicate with the electronics via a wired connection. The radio frequency communication device of the electronics facilitates the transmission of the calculation results outside the tire-wheel assembly. The radio frequency communication from the electronics of the tire-wheel assembly may be sent to the trailer, the vehicle, or somewhere outside of these two components, and used by devices separate from these components, such as mobile phones, tablets, and computers. These three components can represent a display device. However, the display device can also be a graphical interface of the trailer or the vehicle, such as a graphical interface on the dashboard.

[0037] Therefore, the proposed structural form can be adapted to a variety of possible technical configurations, while also having the functionality to implement the method.

[0038] Preferably, the system includes an analysis device capable of analyzing the results output by at least one computing device.

[0039] The result of the calculation device is the change in load and / or the load borne by each tire wheel assembly equipped with electronic devices. If this second quantity is to be compared with a threshold S, an operation needs to be performed before the message is sent to the display device. Optional components of the system capable of serving users of a semi-trailer truck unit consisting of a tractor and a trailer need to be located between the calculation device and the display device. Structurally, it can be associated with one and / or the other via a wired connection, or it can be physically separated from these components via radio frequency communication devices.

[0040] According to a first specific embodiment, the at least one computing device includes at least one third radio frequency communication device capable of transmitting / receiving.

[0041] When a computing device is physically separated from its electronic and display components, it needs to be able to communicate with the other two. This is the case, for example, when the computing device is on a trailer and / or vehicle: it collects temperature data from the electronic device via radio frequency communication. On the other hand, if the display device is on a mobile phone, it sends the calculation results to the display device via the same radio frequency communication.

[0042] According to a second specific embodiment, the at least one analysis device includes at least one fourth radio frequency communication device capable of transmitting / receiving.

[0043] When the analysis device is physically separated from the computing and display devices, it needs to be able to communicate with the other two components. This is the case, for example, when the analysis device is located on a server far from the trailer: it collects information from the computing device, via radio frequency communication, about the load variations or loads applied to the individual tire and wheel assemblies of the trailer. On the other hand, if the display device is on a mobile phone or any other electronic device with a screen, the analysis device sends the comparison-generated messages to the display device via radio frequency communication.

[0044] According to a third specific embodiment, the system includes at least one reading device capable of reading data contained in at least one storage space of the electronic device, the at least one reading device including at least a fifth radio frequency communication device capable of transmitting / receiving.

[0045] When the communication range of an electronic device is insufficient to provide communication for a display device, a reading device should be used to collect data from the electronic device. This reading device performs the function of capturing measurement data. It then transmits this data via radio frequency communication to the display device or any other component in the system that requires the data, preparing for the remainder of the method. The reading device acts as an information relay, thereby optimizing communication coverage relative to the electronic devices present in the tire-wheel assembly. Specifically, to reduce the mass of the electronics at the tire, the energy source required for data transmission should be limited; data transmission is an energy-consuming function of the electronics.

[0046] Preferably, a portion of the communication performed by the communication device between the device and an element included in the group comprising an electronic device, at least one computing device, at least one display device, at least one analysis device, and at least one reading device is performed using UHF radio waves, and preferably using Bluetooth Low Energy (BLE).

[0047] Ultra-High Frequency (UHF) bands enable high-volume data transmission at favorable bit rates, particularly at higher frequencies within the UHF band, such as the BLE band. UHF bands are commonly used in transportation applications, meaning that the system's communication equipment can share resources with existing communication equipment in trailers and / or vehicles or roadside infrastructure.

[0048] Advantageously, the at least one display device is included in the group comprising a telephone, a computer, and a human-machine interface located on a trailer and / or vehicle, preferably on a vehicle dashboard.

[0049] The display device is used to warn personnel operating the semi-trailer truck unit of the safety status of the trailer, whether that personnel is the driver in the cab or someone else responsible for the compliance of the semi-trailer truck unit.

[0050] According to an advantageous embodiment, a portion of the at least one reading device is located on the trailer.

[0051] According to another advantageous embodiment, a portion of the at least one computing device and / or a portion of the at least one analysis device is located on the trailer, preferably on the tire wheel assembly.

[0052] The trailer acts as a natural information relay because the tire and wheel assembly is connected to the trailer, and safety conditions apply to the trailer. Therefore, while it is ideal for the system's structural components to be located on the trailer, alternatives are possible. However, the trailer provides a degree of data confidentiality, unlike communication with, for example, a server, unless a secure communication protocol is established. Of course, to minimize the system's impact on the trailer's environment (modern trailers are complex and heavily loaded), positioning the functionality on the tire and wheel assembly limits interference with other structural components of the trailer and / or vehicle. Attached Figure Description

[0053] The invention will be better understood by reading the following description, which is given by way of non-limiting example only and with reference to the accompanying drawings, in which the same reference numerals always denote the same parts, wherein: Figure 1 The invention illustrates a method for estimating the load variation borne by a tire wheel assembly of a trailer rigidly connected to a tractor, and / or a system for estimating the load borne by a trailer rigidly connected to a vehicle, according to a first embodiment of the invention. Figure 2 Another configuration of the system according to a second embodiment of the present invention is shown; Figure 3 A block diagram is shown of a method according to the invention for estimating the variation of load and / or the load borne by a tire wheel assembly of a trailer securely connected to a vehicle. Figure 4 The time evolution of the internal temperature of the fluid cavity, as output by the temperature sensor, is shown. Figure 5 The time evolution of the internal pressure of the fluid cavity output by the pressure sensor is shown; Figure 6 An estimate of the volume change of a fluid cavity relative to time according to the present invention is shown; Figure 7The diagram shows an estimate of the load variation of the trailer's tire and wheel assembly relative to time in relation to the trailer's connection to the vehicle. Detailed Implementation

[0054] Figure 1 An example of system 2000 is shown, which implements a method for estimating the variation of loads borne by the tire wheel assembly of a trailer rigidly connected to a tractor and / or for estimating the loads borne by the tire wheel assembly of a trailer rigidly connected to a tractor. System 2000 includes a trailer 2001, which includes three axles of tire wheel assemblies 2006 distributed on the trailer 2001. The trailer 2001 includes a point M located at the front of the trailer for connecting a towing seat (not shown) of the tractor. However, the tractor applies an external force ΔZ to the trailer 2001 at point M. The trailer 2001 has a center of gravity G, to which the weight P of the trailer is applied, corresponding to the force generated by the total mass of the trailer taking into account gravity. This weight P is balanced by reaction forces applied to the tire wheel assembly 2006 of the trailer, which are designated Z1 to Z3 according to the axles to which the tire wheel assembly 2006 is connected. An external force ΔZ exists at point M on the vehicle (corresponding to the connection between the trailer 2001's coupling device and the vehicle), resulting in additional reaction forces, denoted as ΔZ1 to ΔZ3, being applied to the tire and wheel assemblies 2006 of the respective axles. When a steady state is reached, these reaction forces stabilize to balance the external force ΔZ. The additional reaction forces ΔZ1 to ΔZ3 take into account the reaction force exerted by the ground on the outriggers of the trailer 2001, which are not shown here.

[0055] The purpose of the method is to determine the reaction forces on the individual tire wheel assemblies of a trailer that will become stable when a steady state is reached.

[0056] Here, at least one tire wheel assembly 2006 on each axle of vehicle 2001 is equipped with an electronic device 2007. The electronic device 2007 is located within a fluid chamber of the tire wheel assembly 2006. Specifically, the electronic device 2007 is located on the inner wall of the tire, aligned with the tire surface of the tire that provides contact between the tire and the ground. The electronic device can be mounted on the rim of the tire wheel assembly while remaining within the fluid chamber of the tire wheel assembly 2006. For example, the electronic device can be integrated into the rim valve, similar to some tire pressure monitoring systems (TPMS).

[0057] The electronic device 2007 includes a temperature sensor associated with a microcontroller and at least a radio frequency (RF) device capable of transmitting. Therefore, the RF device includes a radio wave generator and a radio communication antenna for transmitting the generated radio waves. The RF device may also optionally include a radio wave receiver for receiving instructions from an external source, such as initiating a measurement. The electronic device 2007 also includes storage space for storing measurement data from the temperature sensor before transmitting it in the form of radio waves. The electronic device can transmit raw measurement data or data filtered by the microcontroller. Here, the electronic device 2007 transmits radio waves in the Ultra High Frequency (UHF) band, and more specifically, in the Bluetooth Low Energy (BLE) band.

[0058] Here, the exterior of the tire wheel assembly includes at least a trailer 2001. The trailer 2001 first includes a radio data reader 2005 operating in the UHF band, whose antenna 2105 is located near the tire wheel assembly 2006 during rotation to collect measurement data generated by the electronic device 2007. The data is then transmitted here via a wired connection to a computing device 2002 located within the trailer 2001. Radio frequency transmission may also be performed using a specific communication device. The computing device 2002 includes storage space and a processor for performing the following tasks: identifying quantities of the tire wheel assembly corresponding to an initial state; solving differential equations to determine the volume changes of the fluid cavities of the individual tire wheel assemblies equipped with the electronic device 2007; and finally, after pre-collecting the tire quantities required for this final task, calculating the load changes related to the volume changes.

[0059] The results (especially the final data) are sent to the analysis unit 2004. Here, this data is transmitted via wired connection, but radio frequency communication can also be established. The analysis unit 2004 compares the results from the calculation unit 2002 with pre-input thresholds. These thresholds (such as the maximum permissible load per axle of the trailer, the total maximum load of the trailer, or the maximum permissible load per tire wheel assembly) can be transmitted either by hard-coding the data within the trailer 2001 or by querying a database located outside the trailer 2001. Of course, the analysis unit 2004 can be integrated into the calculation unit 2002.

[0060] Finally, various output data from the analysis device 2004 are transmitted to the display device 2003 via the fourth communication device 2104 (specifically, by the radio communication antenna of the trailer 2001) and the second communication device 2102 present on the display device 2003.

[0061] These communication devices 2104 and 2102 transmit data via a communication network to a tablet or smartphone 2003 to notify whether the trailer's load meets the thresholds allowed by current regulations for the trailer 2001.

[0062] If the trailer's load does not meet requirements, the trailer needs to be disconnected from the vehicle to allow for load reconfiguration (either by reducing the load's mass or by changing its position within the trailer), thereby reducing the load on the trailer 2001's axles when the trailer is connected to the tractor. Then, the main phase of the method used to estimate the load borne by the trailer's wheel assemblies, which are securely connected to the vehicle, needs to be repeated to verify that the trailer's load complies with current regulations. While disconnecting the trailer to reconfigure its load is preferred, this operation is still optional. Measurement signals from the electronic device 2007 can be continuously recorded while the trailer's load is being reconfigured, and then the connected trailer 2001 can be allowed to reach overall equilibrium before estimating the load borne by the individual wheel assemblies 2006 on the trailer 2001 equipped with the electronic device 2007. These new loads are then compared to previously used thresholds to verify that the trailer 2001 complies with current regulations.

[0063] Figure 2 Another configuration of system 2000 is shown. System 2000 includes a trailer 2001, which includes three axles of a tire wheel assembly 2006 distributed on the trailer, numbered 1 to 3 in the direction of forward travel of trailer 2001. The trailer includes a point M located at the front of the trailer for connecting a towing vehicle (not shown). However, the towing vehicle applies an external force ΔZ to trailer 2001 at point M.

[0064] At least one tire wheel assembly 2006 on each axle of the trailer 2001 is equipped with an electronic device 2007. This electronic device 2007 is located within a fluid chamber of the tire wheel assembly 2006. Here, the electronic device 2007 is located on the inner wall of the tire, aligned with the tread pattern of the tire that provides contact between the tire outer layer and the ground. The electronic device can be mounted on the rim of the tire wheel assembly while remaining within the fluid chamber of the tire wheel assembly 2006. For example, the electronic device can be integrated into the rim valve, similar to some tire pressure monitoring systems (TPMS).

[0065] The electronic device 2007 includes a temperature sensor associated with a microcontroller and at least a radio frequency (RF) device capable of transmission. Therefore, the RF device includes a radio wave generator and a radio communication antenna for transmitting the generated radio waves. The RF device may also optionally include a radio wave receiver for receiving instructions from an external source to, for example, initiate a measurement. The electronic device 2007 also includes storage space for storing measurement data from the temperature sensor before transmitting it in the form of radio waves. The electronic device can transmit raw measurement data or data filtered by the microcontroller. Here, the electronic device 2007 transmits radio waves in the Ultra High Frequency (UHF) band, and more specifically, in the Bluetooth Low Energy (BLE) band.

[0066] Here, the exterior of the tire wheel assembly includes at least a tractor and a trailer 2001. The trailer 2001 first includes a radio data reader 2005 operating in the UHF band, whose receiving antenna 2105 is located near the tire wheel assembly 2006 during rotation to collect measurement data generated by the electronic device 2007. The data, after processing, is then transmitted wiredly to the transmitting antenna of a communication device 2104 located in the trailer 2001. Radio frequency transmission can also be performed using a specific communication device. The computing device 2002 includes storage space and a processor for performing the following tasks: identifying quantities of the tire wheel assembly corresponding to an initial state; solving differential equations to determine the volume changes of the fluid cavities of the individual tire wheel assemblies equipped with the electronic device 2007; and finally, after pre-collecting the tire quantities required for this final task, calculating the load changes related to the volume changes.

[0067] The data is then transmitted via wired connection to the computing device 2002 located in the trailer 2001. However, the data can also be transmitted to a physical device located outside the trailer 2001.

[0068] The first device is a computing device 2002, which includes communication devices capable of transmitting / receiving. These communication devices are... Figure 2 In configurations other than those described above, radio waves transmitted by the transmitting communication device 2105 can be received and converted into digital data that can be used by the computing device 2002. The computing device 2002 includes storage space and a processor for performing the following tasks: identifying quantities of the tire-wheel assembly corresponding to an initial state; solving differential equations to determine changes in the volume of the fluid chambers of the individual tire-wheel assemblies equipped with the electronic device 2007; and finally, after pre-collecting the tire quantities required for this final task, calculating the change in load related to the volume change.

[0069] The results (especially the final data) are sent to a second device corresponding to the analysis device 2004. Here, this data is transmitted via wired communication. The analysis device 2004 compares the results collected by the computing device 2002 (which may be radio frequency transmission from the computing device 2002 using the receiving communication device 2104) with pre-input thresholds. These thresholds (such as the maximum permissible load per axle of the vehicle, the total maximum load of the vehicle, or the maximum permissible load per tire wheel assembly) can be transmitted by querying a remote database containing data related to the trailer 2001. Of course, the analysis device 2004 is integrated into the computing device 2002 here.

[0070] Finally, various output data from the analysis device 2004 are transmitted to the display device 2003 via a fourth communication device 2104 and a second communication device 2102 located on the display device 2003. Here, the display device consists of a digital tablet computer 2003, which may be located remotely from the trailer 2001, and a human-machine interface within the trailer 2001, which may include a display screen. These display devices may also be screens on the tractor's dashboard, with radio frequency transmission of the data to be displayed.

[0071] The purpose of the display device 2003 is to notify whether the load of the trailer meets the thresholds permitted by current laws.

[0072] Of course, these two embodiments of the system for implementing a method for estimating the changes in load and / or the load borne by the tire-wheel assembly of a vehicle securely connected to a trailer are merely illustrative examples of the system and are not limited to these two configurations. The first extreme configuration integrates all calculation and analysis devices into an electronic device mounted on the tire-wheel assembly, which transmits the results to a display device remote from the trailer. The other extreme configuration transmits the measurement data recorded on the electronic device via radio waves and performs other steps of the method on a device remote from the vehicle, without passing through the trailer or tractor unit.

[0073] Figure 3 A block diagram is shown of a method for estimating the variation in load and / or the load borne by the tire and wheel assembly of a trailer securely connected to a stationary tractor. The method comprises several stages.

[0074] The first stage is the preparatory stage, which includes at least actions 1 to 6, depicted in solid lines, where the connecting system follows each other. This preparatory stage, focusing on the unconnected trailer, obviously involves equipping and thus loading the trailer by installing temperature sensors at the tire wheel assembly (ideally), capable of measuring the internal temperature of the fluid cavity defined by the inner surface of the tire and the rim, using dedicated electronics. Steps 1 and 2 involve determining physical quantities related to the fluid cavity of the tire wheel assembly equipped with the measuring device, such as inflation pressure P1 and internal temperature T1. Preferably, these determinations can be made with default values ​​or by capturing specific measurements. Step 3 involves determining the load Z1 borne by the tire wheel assembly equipped with the measuring device in the unconnected state. This determination can be made with default values, assuming the total load of the trailer is distributed among its axles; the total load of the trailer is, for example, data given by the trailer manufacturer and corresponds, for example, to the unloaded mass of the trailer specified in the trailer manufacturer's technical specifications. Of course, this determination can also include the loading of the trailer. Step 4 corresponds to obtaining specific quantities of the tire wheel assembly equipped with the measuring device. One of these quantities is the volume V0, which corresponds to the volume occupied by the fluid cavity of the tire wheel assembly when it is inflated to pressure P1 (strictly speaking, at internal temperature T1) but without any applied load (i.e., not even on the ground). The second quantity is the flattening stiffness Kp per unit volume of the tire outer casing of the tire wheel assembly, which may depend on the inflation pressure P1, internal temperature T1, and the load Z1 applied. Finally, the third set of quantities relates to the ideal gas behavior laws concerning the properties of the gas contained in the fluid cavity of the tire wheel assembly. Furthermore, the penultimate step of the preparatory stage (labeled 5) is the step of determining the volume V1 occupied by the fluid cavity of the instrumented tire wheel assembly under load Z1, inflation pressure P1, and temperature T1. Finally, the last step of the preparatory stage (labeled 6) is to assess the amount of gas contained in the fluid cavity of the instrumented tire wheel assembly by determining the number of gas moles n present in volume V1. Here, while the assumptions related to the ideal gas state do apply, it is still necessary to identify the nature of the gas composition, i.e., whether the gas is a single type of gas or a mixture of gases. Furthermore, in this preliminary stage, even if not shown, it is crucial to determine the evolution of the relationship between changes in the internal pressure P and internal temperature T of the fluid in the fluid cavity of the relevant tire wheel assembly during the adiabatic transition near the operating point (i.e., pressure P1, temperature T1, and load Z1) of the tire wheel assembly. Finally, in the preliminary stage, even if not shown, it is necessary to determine the load distribution on each axle of the trailer, preferably on each tire wheel assembly of the trailer, which is related to the load applied at the trailer connection point M.Alternatively, a second load distribution can be envisioned on the individual axles of the trailer, preferably on the individual wheel assemblies of the trailer, when the trailer is not connected. This second load distribution is related to the total mass of the trailer in the unconnected state.

[0075] The method then proceeds to the main steps, which begin with connecting the trailer to the tractor. The temporal variation of the internal temperature T(t) of each instrumented tire wheel assembly of the trailer must be recorded; for example, in the case of passenger cars and trailers suitable for this type of vehicle, this variation is approximately one-hundredth of a degree. These records are then stored in storage so that the raw data can first be filtered using a low-pass filter to eliminate high-frequency phenomena, corresponding to step 11. Next, the temporal variation of the internal pressure P(t) of the fluid cavity is determined using the evolution law determined in the preliminary steps, corresponding to step 12. Optionally, a second variation of the internal temperature corresponding to a second transition of the fluid in thermal equilibrium with the external environment is extracted from the recording of the temporal variation of the internal temperature T(t) of each instrumented tire wheel assembly of the vehicle. Simultaneously, for this option, the variation of the internal pressure of the fluid in the fluid cavity of the tire wheel assembly equipped with a measuring device, the tire wheel assembly previously equipped with a pressure sensor, is recorded. This recording must at least include the variation of the internal pressure corresponding to the time frame after the first transition of the fluid. In this option, the recorded changes in internal temperature T(t) and internal pressure P(t) are used to assess the second transition of the fluid in the fluid cavity corresponding to the establishment of thermal equilibrium between the fluid cavity and the external environment, which is necessary for the first transition of the fluid associated with trailer connection. The connection system between optional steps and steps indispensable to the method is represented by gray lines instead of black. However, connection lines belonging to the main stages are shown as dashed lines, while connection lines for the preparatory stages are shown as solid lines. Finally, as will be seen later, the secondary stages have a connection system depicted as broken lines (dashed lines).

[0076] One of the key steps in the main phase is to determine the volume change ΔV of the fluid cavity in each instrumented tire wheel assembly via step 13. This corresponds to at least considering the adiabatic transition of the fluid in the fluid cavity due to the instantaneous attachment of the trailer to the tractor, which alters the thermomechanical balance of all tire wheel assemblies of the trailer, and thus the thermomechanical balance of the fluid trapped in the fluid cavities of the tire wheel assemblies. Furthermore, it is assumed that the fluid behaves as an ideal gas. Based on the change in the internal temperature T(t) of each instrumented tire wheel assembly, the change in internal pressure P(t) can be determined using the evolution law determined in the preparatory phase for the adiabatic transition of the fluid.

[0077] The changes in internal pressure and internal temperature can be substituted into a differential equation that takes into account the above assumptions. Solving the differential equation in time increments yields an estimate of the time-varying volume ΔV(t) of the fluid cavity, corresponding to step 13. Alternatively, this method can be supplemented by measurements of a second change in the internal temperature T and the change in internal pressure P(t) of the fluid cavity to assess the second change in the fluid cavity volume associated with the transition caused by heat exchange between the fluid cavity of the tire-wheel assembly and the external environment through the components of the tire-wheel assembly (i.e., the tire and the wheel). This second transition typically follows an adiabatic transition, as the temperature change resulting from the adiabatic transition is the root cause of the lack of thermal equilibrium between the fluid cavity and the external environment.

[0078] Another important step in the main phase is to evaluate the change in load ΔZ, which is only related to the previously evaluated change in volume ΔV. This corresponds to step 14. For this, the flattening stiffness K per unit volume of the tire-wheel assembly needs to be considered again. P This stiffness can include both aerodynamic and structural components. Only the aerodynamic component K is considered. PP This may be sufficient to provide a reliable estimate of the load variation ΔZ.

[0079] Based on the change in load ΔZ, an initial load Z1 needs to be added to obtain the load borne by the instrumented tire-wheel assembly in step 15. From this value at the tire-wheel assembly scale, the load borne by each axle i of the trailer can be easily deduced, thus deducing the total load borne by the trailer. For this purpose, assuming that only one or a few (but not all) of the trailer's tire-wheel assemblies are equipped with measuring devices, the method includes: estimating the load distribution on each tire-wheel assembly or axle of the trailer in a preliminary stage, which is related to the overload applied at the trailer connection point M. Optionally, a second load distribution can be used to estimate the initial load on each tire-wheel assembly or axle of the trailer, which is only related to the total mass of the trailer.

[0080] The final step (marked 16) is to compare the load Z borne by each tire and wheel assembly with the threshold S, and in the same way, compare each axle i of the trailer, and finally the entire trailer. Generally, these thresholds S can be safety conditions specific to the roadworthiness of semi-trailer truck units consisting of a tractor and trailer, as stipulated by national regulations.

[0081] Based on the comparison results, the semi-trailer truck unit can be driven on the road with the trailer connected to the tractor unit because all safety conditions have been met according to step 17 of the main phase. If this is not the case, the method loops to a secondary phase that includes at least step 20, in which the load of the connected trailer is changed. This change of load can occur while the trailer remains connected. It is also conceivable that the trailer can be decoupled from the vehicle while the change of trailer load is being performed. The change of load includes changing the position of the load in the trailer and / or changing the contents of the load to, for example, reduce the mass of the load. Once step 20 is completed, the main phase needs to be restarted, and if necessary, the trailer is reconnected to the vehicle, and the temperature of the fluid chambers of the instrumented tire wheel assemblies of the trailer is recorded, corresponding to step 11 of the block diagram; optionally, the internal pressure corresponding to step 12 is measured, particularly for the second transition of the fluid related to thermal equilibrium. This secondary phase is repeated as long as the criteria for allowing the execution of step 17 have not been met.

[0082] Figure 4 The diagram shows the time evolution of temperature transmitted by a temperature sensor located on the tire wheel assembly of the trailer. The curve consisting of point 10 represents the raw measurement from the temperature sensor, while curve 11 corresponds to the time evolution of the filtered internal temperature, eliminating high-frequency noise. Then, in... Figure 3 The second curve is used in the block diagram.

[0083] This time-based recording of the internal temperature of the fluid cavity in the tire-wheel assembly begins in the preparatory phase before the trailer is connected to the tractor. The moment of trailer connection corresponds to the abscissa value of point 100, marking the start of the main phase. It can be seen that from point 100, the internal temperature of the fluid cavity rapidly decreases until point 101, at which point the temperature decrease stops, and the temperature even rises slightly. Point 101 marks the transition between the fluid work associated with trailer connection and the heat exchange with the outside; the former corresponds to the first transition of the fluid, which can be analogous to an adiabatic transition, and the latter corresponds to the second transition of the fluid. Considering that the time origin is the abscissa value of point 100, the abscissa value of point 101 corresponds to the duration T0. Therefore, the preparatory phase 50 ends at the abscissa value of point 100. This phase precedes the main phase, which is divided into two consecutive phases. The first phase 51 can be analogous to the adiabatic transition of the fluid, corresponding to the work done by the fluid after trailer connection. The second phase 52 corresponds to the heat exchange between the fluid and the outside.

[0084] Figure 5 The time evolution of the internal pressure of the fluid cavity is shown. Here, this time evolution is entirely transmitted by the pressure sensor of the electronic device located on the trailer's tire wheel assembly, as shown in curve 12.

[0085] The evolution of the internal pressure 12 of the fluid cavity in the tire-wheel assembly begins in the preparatory stage before the trailer is connected to the tractor. The moment of trailer connection corresponds to the abscissa value of point 100, which marks the start of the main stage. It can be seen that from point 100, the internal pressure of the fluid cavity rapidly decreases until point 101, at which point the pressure decrease stops, and the pressure even increases to some extent. Point 101 marks the transition between the fluid work associated with trailer connection and the heat exchange with the outside; the former corresponds to the first transition of the fluid, which can be analogous to an adiabatic transition, and the latter corresponds to the second transition of the fluid. Considering that the time origin is the abscissa value of point 100, the abscissa value of point 101 corresponds to the duration T0. Therefore, the preparatory stage 50 ends at the abscissa value of point 100. This stage precedes the main stage, which is divided into two consecutive stages. The first stage 51 can be analogous to the adiabatic transition of the fluid, corresponding to the work done by the fluid after trailer connection. The second stage 52 corresponds to the heat exchange between the fluid and the outside.

[0086] Figure 6 The time evolution of the internal volume of the fluid cavity is shown. Here, this time evolution, represented by the curve, is the output of the volume change calculated using the proposed differential equation, which also takes into account the thermal equilibrium with the external environment.

[0087] This evolution of the internal volume of the fluid cavity in the tire-wheel assembly begins in the preparatory stage before the trailer is connected to the tractor. The moment of trailer connection corresponds to the abscissa value of point 100, marking the start of the main stage. It can be seen that from point 100, the internal volume of the fluid cavity rapidly increases until point 101, at which point the increase in internal volume stops, and the volume even decreases to some extent. Point 101 marks the transition between the fluid work associated with trailer connection and the heat exchange with the outside; the former corresponds to the first transformation of the fluid, which can be analogous to an adiabatic transition, and the latter corresponds to the second transformation of the fluid. Considering that the time origin is the abscissa value of point 100, the abscissa value of point 101 corresponds to the duration T0. Therefore, the preparatory stage 50 ends at the abscissa value of point 100. This stage precedes the main stage, which is divided into two consecutive stages. The first stage 51 can be analogous to the adiabatic transition of the fluid, corresponding to the work done by the fluid after trailer connection. The second stage 52 corresponds to the heat exchange between the fluid and the outside.

[0088] It is noted that by the end of stage 51, a good estimate of the volume change of the tire-wheel assembly has been obtained, clearly demonstrating that the work generated by the change in load on the tire-wheel assembly occurs primarily during stage 51. The observed changes or oscillations correspond to fluctuations in the transient phase corresponding to the establishment of thermal equilibrium. Therefore, the method described herein produces a continuous measurement of the change in the internal volume of the tire-wheel assembly in the time domain.

[0089] Figure 7 The temporal evolution of the load applied to the electronically equipped tire-wheel assembly is shown. Here, this temporal evolution, represented by curve 14, is the output of calculating the volume change using the proposed differential equation and multiplying it by the flattened stiffness of the tire-wheel assembly, a calculation that takes into account thermal equilibrium with the external environment. The stiffness used here is based on the initial pressure on the tire-wheel assembly, the initial load applied to the tire-wheel assembly, and the locally identified stiffness corresponding to the initial temperature. The overall stiffness defined by the proposed formula can be used, which has already given a good order of magnitude.

[0090] The evolution 14 of the load in the fluid cavity of the tire wheel assembly begins in the preparatory stage before the trailer is connected to the tractor. The moment of trailer connection corresponds to the abscissa value of point 100, which marks the beginning of the main stage. It can be seen that from point 100, the applied load decreases rapidly until point 101, at which point the load reduction stops, and thereafter decreases to a certain extent. Point 101 marks the transition between the fluid work associated with trailer connection and the heat exchange with the outside; the former corresponds to the first transition of the fluid, which can be analogous to an adiabatic transition, and the latter corresponds to the second transition of the fluid. Considering that the time origin is the abscissa value of point 100, the abscissa value of point 101 corresponds to the duration T0. Therefore, the preparatory stage 50 ends at the abscissa value of point 100. This stage precedes the main stage, which is divided into two consecutive stages. The first stage 51 can be analogous to the adiabatic transition of the fluid, corresponding to the work done by the fluid after trailer connection. The second stage 52 corresponds to the heat exchange between the fluid and the outside.

[0091] It is noted that by the end of stage 51, a good estimate of the change in load applied to the tire-wheel assembly has been obtained, clearly indicating that the work generated by the load change occurs primarily during stage 51. The observed changes or oscillations correspond to fluctuations in the transient phase corresponding to the establishment of thermal equilibrium. Therefore, the method described herein can generate continuous measurements of the temporal change in load applied to the tire-wheel assembly in the time domain. Curve 80 corresponds to the measurement of the overload applied to the tire-wheel assembly of the trailer by the ground weighbridge, which ensures that the estimate of the overload applied to the electronically equipped tire-wheel assembly is a reasonable estimate. In summary, the proposed method captures the change in applied load very well.

Claims

1. A method for estimating the change in load on the tire and wheel assembly of a trailer caused by its connection to a stationary tractor, the method comprising the steps of: In the preparatory stage - Equip at least one temperature sensor for at least one tire wheel assembly on at least one axle of a trailer not connected to a tractor, the sensor being capable of measuring the internal temperature of the fluid cavity of the tire wheel assembly defined by the tire and wheel. Preferably, at least one temperature sensor is provided for at least one tire wheel assembly on each axle of the trailer. More preferably, at least one temperature sensor is provided for all tire wheel assemblies on all axles of the trailer. - Determine the initial load Z1 applied to at least one tire wheel assembly equipped with a temperature sensor on an unattached trailer; - Determine the initial inflation pressure P1 of the fluid chamber of at least one tire wheel assembly of the trailer equipped with a temperature sensor; - Determine the initial internal temperature T1 of the fluid cavity of at least one tire wheel assembly of the trailer equipped with a temperature sensor; - The initial volume V1 of at least one tire-wheel assembly equipped with a temperature sensor is evaluated using a first function, the parameters of which include the volume V0 of the fluid cavity of the tire-wheel assembly when unloaded and inflated to an initial pressure P1, and the flattening stiffness K of the tire per unit volume of the tire assembly. P ; - The number of fluid moles n in the fluid chamber of each tire wheel assembly equipped with a temperature sensor is evaluated using a model that takes into account inflation pressure P1, initial volume V1, and temperature T1. - Determine the evolution of the internal pressure P of the fluid cavity based on the internal temperature T during the adiabatic transition of at least one tire wheel assembly that is inflated, subjected to a load Z1, and equipped with at least one temperature sensor. During the main phase: - Connect the trailer to the vehicle at the trailer's geometric point M; - Record the internal temperature T of the fluid cavity of at least one tire wheel assembly equipped with a temperature sensor at a sampling frequency F1; - The internal pressure P of the fluid cavity of at least one tire wheel assembly equipped with a temperature sensor is determined by utilizing the evolution law determined in the preparatory stage; - By utilizing the recorded internal temperature T and the determined internal pressure P, the intermediate change ΔV of the volume of at least one tire wheel assembly equipped with a temperature sensor is evaluated using a model of a fluid undergoing an adiabatic transition, where the fluid behaves as an ideal gas. - The load variation ΔZ borne by at least one tire-wheel assembly equipped with a temperature sensor is estimated using a second function, the parameters of which include the intermediate volume variation ΔV of the assessed volume and the flattened stiffness K per unit volume of the tire of the tire-wheel assembly. P .

2. The method for estimating the change in load on the tire and wheel assembly of a trailer caused by its connection to a stationary tractor, as described in claim 1, wherein, In the preparatory phase, at least one tire wheel assembly equipped with a temperature sensor on at least one axle of the trailer includes a pressure sensor capable of measuring the internal pressure of a fluid cavity. The method includes, in the main phase, recording the internal pressure P of the fluid cavity of at least one tire wheel assembly equipped with a temperature sensor when at least the recorded internal temperature T changes direction or after a duration T0 corresponding to the end of an adiabatic transition of the fluid. The method also includes, in the second step, taking into account the recorded internal pressure P, the internal temperature T recorded during the time period corresponding to the recording of the internal pressure P, and using a model of the fluid undergoing an adiabatic transition, evaluating an intermediate change ΔV2 of the volume of at least one tire wheel assembly equipped with a temperature sensor, the fluid being an ideal gas.

3. The method for estimating the change in load on the tire and wheel assembly of a trailer caused by its connection to a stationary tractor, according to any one of claims 1 to 2, wherein, Prior to the main steps, at least one tire-wheel assembly equipped with a temperature sensor is in a state of thermomechanical stability.

4. The method for estimating the change in load on the tire and wheel assembly of a trailer caused by its connection to a stationary tractor, according to any one of claims 1 to 3, wherein, Temperature and / or pressure sensors are located in a subspace of a closed fluid cavity defined by the tire outer tube and wheel.

5. The method for estimating the change in load on the tire and wheel assembly of a trailer caused by its connection to a stationary tractor, according to any one of claims 1 to 4, wherein, The sampling frequency F1 is between 0.1 Hz and 10 Hz.

6. The method for estimating the change in load on the tire and wheel assembly of a trailer caused by its connection to a stationary tractor, according to any one of claims 1 to 5, wherein, The determination of the initial volume V0 takes into account the geometry of the rim and the geometry of the unloaded tire mounted on the rim and inflated to a reference pressure P0. Preferably, P0 is the initial pressure P1.

7. The method for estimating the change in load on the tire and wheel assembly of a trailer caused by its connection to a stationary tractor, as described in claim 6, wherein, The geometry of the tire and / or the rim is determined using the tire and / or wheel identifiers of the tire and / or wheel assembly equipped with a temperature sensor. Preferably, the tire and / or wheel identifiers are obtained by radio frequency interrogation of electronics located on the tire and wheel assembly.

8. The method for estimating the change in load on the tire and wheel assembly of a trailer caused by its connection to a stationary tractor, according to any one of claims 1 to 7, wherein, The load Z on each tire-wheel assembly equipped with a temperature sensor can be estimated using the following formula: [Formula 1] , Among them, K PP It is the aerodynamic flattening stiffness per unit volume of the tire in the tire-wheel assembly.

9. The method for estimating the change in load on the tire and wheel assembly of a trailer caused by its connection to a stationary tractor, according to any one of claims 1 to 8, wherein, The volume change ΔV of each tire-wheel assembly equipped with a temperature sensor is estimated by solving the following differential equation: [Formula 2] , [Formula 3] , Where P is the internal pressure of the fluid cavity, V is the internal volume of the fluid cavity, and T is the internal temperature of the fluid cavity.

10. A method for estimating the load borne by a trailer securely connected to a vehicle, comprising a method for estimating the change in load borne by the tire wheel assembly of the trailer resulting from the trailer being connected to a stationary vehicle, according to any one of claims 1 to 9, characterized in that, in a preliminary stage, the method includes determining a first load distribution on each axle of the trailer in relation to the application of an additional load applied to the attachment point M where the trailer is connected to the vehicle, preferably, the first load distribution on each tire wheel assembly of the trailer; the method optionally further includes determining a second load distribution on each axle of the trailer in relation to the weight of the trailer, preferably, the second load distribution on each tire wheel assembly of the trailer; in a main stage, the method includes utilizing at least one equipped with a temperature... The method involves estimating the load Z borne by each tire wheel assembly of each axle i of the trailer by determining the change ΔZ of the load borne by the tire wheel assembly of the speed sensor, the first load distribution related to the application of additional load at the attachment point M, and the initial load Z1i of each tire wheel assembly of the trailer. Optionally, the method further includes estimating the load Z borne by each tire wheel assembly by considering a second load distribution related to the weight of the trailer. The method also includes comparing the estimated load Z borne by each axle i of the trailer and / or the total load borne by the trailer with at least one threshold S, where the total load is the sum of the loads borne by each axle i of the trailer. When the at least one threshold S is exceeded, in a secondary stage, the mass content K of the trailer is modified, and then the steps of the main stage are performed again.

11. A system (2000) for implementing the method for estimating the change in load borne by a tire and wheel assembly of a trailer rigidly connected to a vehicle as caused by the connection of a trailer to a stationary vehicle, according to any one of claims 1 to 9, and / or for implementing the method for estimating the load borne by a trailer rigidly connected to a stationary vehicle according to claim 10, the system comprising: - Trailer (2001), with a hook-up device installed at point M on the trailer, the hook-up device being able to accommodate the towing seat of the vehicle, and each axle i of the trailer including at least one tire wheel assembly (2006) equipped with an electronic device (2007). - The electronic device (2007) includes at least one temperature sensor, at least one electronic chip, at least one storage space capable of recording signals from the sensor, and at least one first radio frequency communication device (2101) capable of transmitting. - At least one computing device (2002); and - At least one display device (2003) includes at least one second radio frequency communication device (2102) capable of receiving.

12. The method for estimating the load variation borne by a tire-wheel assembly of a trailer rigidly connected to a stationary vehicle, and / or the system for estimating the load borne by a trailer rigidly connected to a stationary vehicle, as described in claim 11 (2000), wherein, The system (2000) includes an analysis device (2004) capable of analyzing the results output by the at least one computing device (2002).

13. The method for estimating the load variation borne by a tire-wheel assembly of a trailer rigidly connected to a stationary vehicle according to any one of claims 11 to 12 and / or the system for estimating the load borne by a trailer rigidly connected to a stationary vehicle (2000), wherein, The at least one computing device (2002) includes at least one third radio frequency communication device (2103) capable of transmitting / receiving.

14. The method for estimating the load variation borne by a tire-wheel assembly of a trailer rigidly connected to a stationary vehicle, and / or the system for estimating the load borne by a trailer rigidly connected to a stationary vehicle, as described in claim 13 (2000), wherein, The at least one analysis device (2004) includes at least one fourth radio frequency communication device (2104) capable of transmitting / receiving.

15. The method for estimating the load variation borne by a tire-wheel assembly of a trailer rigidly connected to a stationary vehicle according to any one of claims 11 to 14 and / or the system for estimating the load borne by a trailer rigidly connected to a stationary vehicle (2000), wherein, The system (2000) includes at least one reading device (2005) capable of reading data contained in at least one storage space of the electronic device (2007), and includes at least one fifth communication device (2105) capable of receiving data.

16. A method for estimating the load variation borne by a tire-wheel assembly of a trailer rigidly connected to a stationary vehicle, as claimed in any one of claims 11 to 15, and / or a system for estimating the load borne by a trailer rigidly connected to a stationary vehicle (2000), wherein, Communication performed by the communication devices (2101, 2102, 2103, 2104, 2105) between a portion of the communication and the elements included in the group comprising the electronic device (2007), the at least one computing device (2002), the at least one display device (2003), the at least one analysis device (2004), and the at least one reading device (2005) is performed using UHF radio waves, preferably using BLE.

17. A system (2000) for implementing a method for estimating the load variation borne by a tire-wheel assembly of a trailer rigidly connected to a stationary vehicle according to any one of claims 11 to 16, wherein, The at least one display device (2003) is included in the group comprising a telephone, a computer, and a human-machine interface located on a trailer (2001) and / or vehicle, preferably on a vehicle dashboard.

18. A system (2000) for implementing a method for estimating the load variation borne by a tire-wheel assembly of a trailer rigidly connected to a stationary vehicle, according to any one of claims 11 to 17, wherein, A portion of the at least one reading device (2005) is located on the trailer (2001).

19. A system (2000) for implementing a method for estimating the load variation borne by a tire-wheel assembly of a trailer rigidly connected to a stationary vehicle, according to any one of claims 11 to 18, wherein, A portion of the at least one computing device (2002) and / or a portion of the at least one analysis device (2004) is located on the trailer (2001), preferably on the tire and wheel assembly (2006).

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