Method for estimating the vehicle-distributed load of a trailer coupled to the vehicle

Abstract

Disclosed is a method for estimating the variation in the load carried by a mounted assembly on a vehicle, the variation resulting from the trailer being coupled to the vehicle, the method comprising the following steps: coupling the trailer to the vehicle; recording the internal pressure P in the fluidic cavity of an equipped mounted assembly; ascertaining the internal temperature T in the fluidic cavity of the equipped mounted assembly using a specified law of change; evaluating a variation in the volume ΔV of the equipped mounted assembly by means of the recorded internal pressure P and the ascertained internal temperature T using a model of a fluid in adiabatic transformation, the fluid having a perfect gas behavior; and estimating a variation in the load ΔZ carried by the n equipped mounted assembly using a second function comprising, as a parameter, the evaluated intermediate variation in volume ΔV and the flattening stiffness of the tire of the mounted assembly per unit volume Kp.

Description

DESCRIPTION TITLE: METHOD FOR ESTIMATING THE LOAD DISTRIBUTED ON A VEHICLE OF A TRAILER ATTACHED TO THE VEHICLE Scope of the invention

[0001] The present invention relates to the field of real-time determination of the quasi-static load applied and in particular the load variation generated by the coupling of a trailer to a vehicle, especially when the vehicle is stationary. Technological background

[0002] Obtaining the quasi-static load applied to a stationary vehicle allows us to determine if the vehicle, or each of its axles, is in a safe condition before it even starts moving. This makes the vehicle more reliable and ensures compliance with safe driving regulations. Indeed, determining the load applied to inflatable systems, such as mounted assemblies, generally requires a balancing scale. It is not easy to determine this load outside of specific loading locations, such as quarries where the trailer attached to the vehicle is loaded. To assess the load carried by the vehicle, as well as by each axle, outside of these specific locations, it is possible to evaluate the load carried by each mounted assembly by measuring the tire's contact patch on the ground.While it is possible to measure static pressure using a system that measures the tire's dimensions by placing the measuring device between the mounted tire and the ground, its implementation is not straightforward, and the accuracy of the measurement depends on the correct positioning of the measuring device. Another alternative is to assess the contact patch size under driving conditions by measuring tire deformation per wheel rotation. Using a mathematical model that links the tire type, inflation pressure, and the external dimensions of the contact patch, the load applied to the tire can then be calculated. Unfortunately, this measurement is taken under driving conditions. Therefore, the vehicle may no longer be operating within its safe operating range at the time of measurement.Moreover, the accuracy of these measurements is tricky for very heavy loads where the deformation of the tire which determines the load variations tends to stabilize along the circumferential direction on which the evolution of the measurement of the deformation of the tire casing is generally based.

[0003] The objects and methods of the invention that follow aim to solve the problem of measuring the load carried by a vehicle in the absence of an external measurement system, that is, a system that can be used at any time without a specific measuring device. Furthermore, this assessment is carried out while the vehicle is stationary, allowing for a determination of the vehicle's load safety criteria before any movement. Description of the invention

[0004] The invention relates to a method for estimating the variation in load borne by a vehicle assembly rigidly connected to a stationary trailer, comprising the following steps: • In the preliminary phase, that is, before the trailer is hitched to the vehicle • Equip at least one assembly mounted on at least one axle of the vehicle not coupled to the trailer with at least one pressure sensor, said sensor being capable of measuring the internal pressure of the fluidic cavity of the assembly delimited by a pneumatic casing and a wheel, preferably at least one assembly mounted on each axle of the vehicle, very preferably all the assemblies mounted on all the axles of the vehicle; • Determine the initial load ZI applied to at least one assembled unit equipped with the vehicle; • Determine the initial inflation pressure PI of at least one mounted assembly equipped with the vehicle; • Determine the initial internal temperature Tl of at least one assembled vehicle; • Evaluate the initial volume VI of at least one assembled unit equipped with a first function including as parameters the volume V0 of the fluidic cavity of the unloaded assembled unit inflated to the initial pressure PI and the flattening stiffness of the tire of the assembled unit per unit volume Kp • Evaluate the number of moles of fluid n in the fluidic cavity of each assembled and equipped unit from a model taking into account the inflation pressure PI, the initial volume VI, the temperature Tl; • Determine a law of evolution of the internal temperature T of the fluidic cavity from the internal pressure P during an adiabatic transformation for at least one assembled, inflated and subjected to the load Zl, equipped with at least one pressure sensor; • In the main phase, • Attach the trailer to the vehicle at a geometric point M of the vehicle; • Record the internal pressure P at the fluidic cavity of at least one mounted assembly equipped at an acquisition frequency Fl; • Determine the internal temperature T of the fluidic cavity of at least one mounted assembly equipped using the evolution law determined in the preliminary phase; • Evaluate an intermediate volume change AV of at least one assembled unit using the recorded internal pressure P and the internal temperature T determined using an adiabatic fluid model, the fluid exhibiting ideal gas behavior; and • Estimate a load variation AZ carried by each mounted assembly equipped using a second function including as a parameter the intermediate volume variation AV evaluated, the flattening stiffness of the tire per unit volume Kp.

[0005] According to a preferred embodiment, in the preliminary phase, the at least one mounted assembly equipped with at least one axle of the vehicle comprising a temperature sensor capable of measuring the temperature of the fluidic cavity, the method includes, in the main phase, a step to record the internal temperature T of the fluidic cavity of the at least one mounted assembly equipped at an acquisition frequency F2 and the method includes a second step of evaluating the intermediate volume variation AV of the at least one mounted assembly equipped taking into account the internal temperature T recorded using a fluid model having an ideal gas behavior, subjected to thermal equilibrium with the environment external to the fluidic cavity.

[0006] The process for determining the applied load variation comprises two successive phases. The first phase consists of identifying the intrinsic parameters of the assembly mounted before the trailer is coupled to the vehicle. This involves installing the vehicle's measurement system by setting up the measurement systems. At the vehicle axle level, the initial parameters of the mounted assemblies must be identified, such as the volume of the fluidic cavity, the amount of fluid contained within the closed volume defined by the fluidic cavity, the initial load applied to the assembly by the uncoupled vehicle, the internal temperature of the fluidic cavity, and the inflation pressure of the fluidic cavity for each mounted assembly. Intuitively, the nature of the fluid is assumed to be known to estimate the amount of fluid trapped within the fluidic cavity. It is also necessary to have a law describing the evolution of the internal temperature variation T associated with the inflation pressure variation P of the mounted assembly under operating conditions, particularly at the load ZI around the inflation pressure PI and temperature Tl. This evolution law can be a fixed value or derived from an experimental characterization or a numerical simulation of the mounted assembly under consideration.

[0007] The second phase represents the evaluation of the load variation applied to each assembly equipped with an electronic device due to the trailer being coupled to the vehicle. The electronic device, including the pressure sensor, manages and conditions the pressure measurement recordings. Thus, recordings of the inflation pressure of the fluidic cavity of each assembly equipped with an electronic device are made at the moment the trailer is coupled to the vehicle. The temporal evolutions, during the transient phase, of the physical quantities of the fluidic cavity are significant. Coupling the trailer causes an initial transformation corresponding to the work generated by this additional load, which is similar to an adiabatic transformation, i.e., a rapid one, and moreover, predominant compared to the second transformation.Following the rapid transformation, a slower transformation occurs, corresponding to the thermal equilibrium of the fluidic cavity with the external environment through the tire and wheel. This equilibrium is necessary due to the change in the internal temperature of the fluidic cavity associated with the work generated by the additional load. This thermal equilibrium is slower to achieve because of the thermal inertia of the tire and wheel. Furthermore, the thermal equilibrium has a smaller magnitude with respect to the volume change of the fluidic cavity than the transformation related to the work. Therefore, it is possible to use different sampling frequencies for the physical quantities, temperature and pressure. However, the same sampling frequency can also be used for both sensors. Preferably, the electronic device is mounted on the inner wall of the tire.The tire is indeed the most deformable element during the adiabatic transformation. If the process uses a temperature sensor, the sensor of... Because the temperature is further from the wheel, the relative temperature variations compared to the absolute temperature are greater, as the thermal inertia of the tire casing is lower and the wheel, especially a metallic one, inherently has greater inertia than a tire. Consequently, this improves the accuracy of the temperature measurement and therefore the quality of the load variation method.

[0008] By measuring the inflation pressure of the fluidic cavity, it is possible to determine the internal temperature variation of the fluid within the fluidic cavity using the evolution law previously established in the preliminary phase. This process thus converts the internal pressure measurement of the fluid within the fluidic cavity into an evaluation of the internal fluid temperature generated solely by the adiabatic transformation.

[0009] Next, it is possible to evaluate an initial intermediate volume change using a fluid model undergoing an adiabatic transformation. Here, adiabatic means that the transformation the fluid undergoes due to the trailer being coupled to the vehicle occurs without external heat exchange between the fluidic cavity and the exterior of the assembled unit, implying that it is rapid. Therefore, using only the measured inflation pressure change and the internal temperature change determined by the evolution law based on the pressure change of the fluidic cavity, it is possible to estimate the initial volume change of the fluidic cavity generated by coupling the trailer to the vehicle, the fluid having undergone an adiabatic transformation. We will make the perfectly suitable assumption for air or nitrogen that the fluid, in its gaseous state, within the cavity of the assembled unit is an ideal gas.

[0010] Preferably, a second intermediate volume change is evaluated using a second fluid transformation. This second transformation is associated with the thermal equilibrium of the fluid with the surroundings through the components of the assembled vehicle, primarily the tire. The second volume change experienced by the assembled vehicle following this second transformation is then evaluated using the internal temperature change recorded in the fluidic cavity during the transient phase related to trailer coupling but subsequent to the fluid transformation, i.e., when the inflation pressure has reached steady state. Taking this second volume change into account ensures greater accuracy in evaluating the volume change of the fluidic cavity, which improves the accuracy of the load variation measurement for each assembled vehicle.However, the first intermediate volume variation is. sufficient for estimating, to a first order of magnitude, the surcharge applied to the assembled unit.

[0011] Of course, taking into account the variation in external temperature to the assembled unit resulting from the thermal equilibrium of the assembled unit also allows for a more precise measurement of the second volume variation, generated by coupling the trailer to the vehicle, at the level of each equipped assembled unit. However, in a simplified approach, since the assembled unit is preferably in a thermomechanically stable state, it is possible to take as the external temperature the initial internal temperature Tl of the fluid in the fluidic cavity of the assembled unit.

[0012] These two transformations can occur at each time increment, one after the other, over a period of time measurements. These assessments of the intermediate volume variation must be made with measurements during the transient period of vehicle loading until the mechanical and, potentially, thermal equilibrium of the vehicle's assembled components is established. Once these equilibria are established, the temperature and pressure variations of the fluidic cavity are infinitesimal; it is then in a new thermomechanically stable state.

[0013] Once the intermediate volume variation for each equipped assembly has been evaluated, the associated static load variation resulting from coupling the trailer to each equipped assembly of the vehicle must be assessed. To do this, the intermediate volume variation of each equipped assembly must be converted into an equivalent load variation. For this purpose, a characteristic of the assembly, particularly that of the tire, called the flat-flat rigidity per unit volume (Kp), must be taken into account. This quantity allows the load carried by the assembly to be related to the volume variation of the fluidic cavity generated by the load, with the assembly compressed onto a surface perpendicular to the applied load.This characteristic can, of course, be a fixed value or obtained through experimental characterization of the assembled unit, or deduced from a numerical simulation campaign of the same assembled unit. The assembled unit must be in operating conditions close to those observed in the preliminary phase, that is, around the internal temperature Tl and around the inflation pressure PL. Generally, this flattening rigidity of the assembled unit is a value defined locally around the initial operating point of the assembled unit in the frame of reference associated with the internal pressure P, the internal temperature T, and the volume of the fluidic cavity V.

[0014] Preferably, before the main stage, at least one assembled and equipped unit is in a thermo-mechanically stabilized state.

[0015] It is preferable that the transient phenomena recorded by the electronic device's sensors be solely due to the vehicle's equilibrium disturbance caused by the trailer coupling. This way, other disturbances do not influence the sensor response, thus improving the accuracy of the load variation evaluated by the method. However, if the vehicle's equilibrium disturbance occurs on a different timescale than the disturbance associated with the trailer coupling, or if this disturbance results in lower amplitudes in the electronic device's sensor responses, the method remains perfectly valid.

[0016] Advantageously, the pressure sensor and / or temperature sensor are placed in a subspace of the closed fluidic cavity delimited by the pneumatic casing and the wheel.

[0017] It is advantageous for sensors measuring low-amplitude transient phenomena to be placed close to the occurrence of these transient phenomena to avoid being masked by measurement noise. For example, in the presence of a centralized tire pressure monitoring system, it is advantageous for the sensors to be located on the tire assembly itself, rather than on the centralized system. Similarly, if the sensors are placed on the inner surface of the tire, the measurement will be more accurate than if they are mounted on the wheel rim. This is because the measurement point is further from the point of occurrence of the physical phenomenon that affects the tire's deformation due to the transient nature of the phenomenon.Finally, preferably, the sensors, mainly due to the temperature sensor, are positioned far away from the wheel which has a higher thermal inertia than the tire.

[0018] Advantageously, the pressure sensor operates with a resolution of less than one millibar.

[0019] Thus, it is possible to evaluate small variations in volume and therefore variations in load.

[0020] Preferably, the acquisition frequency Fl is between 0.1 Hz and 10 Hz.

[0021] Optionally, the acquisition frequency F2 is lower than the acquisition frequency Fl.

[0022] It is useful for the acquisition frequency Fl to be high to capture the first, rapid transformation of the fluid. The frequency F2, linked to the recording of the second sensor, does not require such a high frequency since the second fluid transformation is inherently slower. However, the same acquisition frequency can be used for both sensors, taking the Fl frequency as the reference.

[0023] According to a particular embodiment, the determination of the initial volume V0 takes into account the geometry of a wheel rim and the geometry of an unloaded tire, mounted on a rim and inflated to the reference pressure PO, preferably the reference pressure PO is the initial pressure PI.

[0024] Advantageously the geometry of the tire and / or the geometry of the rim is determined using an identifier of the tire and / or wheel of the assembled unit, preferably obtaining the identifier of said tire and / or wheel is achieved by a radio frequency interrogation of an electronic device located on the assembled unit.

[0025] To initiate the measurement system and in particular the determination of the initial volume VI of the fluidic cavity, it is necessary to determine the volume V0 of the fluidic cavity which corresponds to the volume delimited by the assembled unloaded assembly, that is to say that the envelope is mounted on rim with a reference inflation pressure PO which is preferably the initial pressure PI.

[0026] To determine this volume V0, the axisymmetric geometry of the unloaded tire at a reference inflation pressure PO must be known. We make the realistic assumption that the rim geometry is not influenced by the inflation pressure of the assembled tire. These geometries can be accessed via a tire database. Knowing the tire and / or wheel rim identification allows us to isolate the correct geometries in this database. The tire identification can be obtained through optical reading of the regulatory markings on the tire sidewall. The identification can also be transmitted by radio frequency interrogation of an electronic device present on the assembled tire, such as an RFID (Radio Frequency Identification) tag or a TMS (Tyre Mounted Sensor) mounted on the tire. The inner rubber of the tire, or "inner liner," or a TPMS (Tyre Pressure Monitoring System) mounted on the wheel rim, for example.

[0027] Preferably, the Z load of each assembled and equipped unit is estimated by a first relation according to the following formula: [MATH1] Z = K P p * P * A(V) = Kpp * P * (VI - PO) , where Kpp is the flattening pneumatic stiffness of the assembled tire per unit volume.

[0028] This is a simple and elementary model that relates the load applied to the tire to the volume change of the fluidic cavity of the assembly between an unloaded state of volume V0 and a loaded state of volume VI. The inflation pressure P of the fluidic cavity and the pneumatic stiffness of the assembly correspond to the assembly lying flat on a plane. This model assumes that the structural stiffness of the assembly is negligible compared to its pneumatic stiffness, which is a realistic assumption for a tire on a passenger vehicle. However, it is perfectly possible to incorporate the structural stiffness of the tire into the previous formula by adding it to the product of the pneumatic stiffness and the inflation pressure.

[0029] According to an advantageous embodiment, the volume variation AV of each assembled unit is estimated by solving a differential equation of the form next: [MATH 2] With [MATH 3] , where P is the internal pressure, V is the internal volume and T is the internal temperature of the fluid cavity.

[0030] This differential equation reflects the link between the fluid parameters of the cavity of the assembled assembly, which are controlled on the one hand by an adiabatic transformation of the fluid and on the other hand by the fact that the fluid is a perfect gas.

[0031] The invention also relates to a method for estimating the load carried by a vehicle rigidly connected to a trailer, comprising a method for estimating the variation in the load carried by a vehicle assembly generated by the trailer coupling when stationary. The method is characterized in that, in a preliminary phase, the method comprises a step of determining a first load distribution on each axle of the uncoupled vehicle, preferably on each vehicle assembly, associated with the application of an additional load exerted at the coupling point M of the trailer on the uncoupled vehicle. Optionally, the method also comprises a step of determining a second load distribution on each axle of the uncoupled vehicle, preferably a second load distribution on each vehicle assembly, associated with the weight of the uncoupled vehicle. In that, in the main phase,The method includes a step of estimating the load Z carried by each mounted assembly on each axle i of the vehicle using the load variation AZ carried by at least one equipped mounted assembly, the first load distribution associated with the application of an additional load at the coupling point M, and the determination of the initial loads Zli of each mounted assembly of the uncoupled vehicle. Optionally, the step of estimating the load Z carried by each mounted assembly takes into account the second load distribution associated with the weight of the uncoupled vehicle. The method includes a step of comparing the estimated load Z carried by each axle i of the coupled vehicle and / or the total load carried by the coupled vehicle, which is the sum of the loads carried by each axle i of the vehicle, to at least one threshold value S. When at least one threshold value S is exceeded,The mass K content of the trailer is adjusted within the trailer during a secondary phase before repeating all the steps of the main phase.

[0032] By adding the load carried by the vehicle assembly or the front axle before the trailer coupling, the total load on the vehicle assembly or axle i of the vehicle can be calculated. Evaluating the total load on the vehicle then simply involves summing the static loads on all the vehicle's axles i. It is then possible to verify that the load conditions comply with the vehicle's safety guidelines for each vehicle assembly, each axle of the vehicle, and indeed for the vehicle as a whole, even before the vehicle begins to move.

[0033] Knowing the initial load distribution at the vehicle's axles (i) associated with an overload applied to the vehicle's coupling point (M), it is possible to deduce, from a single measurement on an assembly equipped with the device The measurement involves calculating the overloads on each mounted assembly or each axle of the vehicle related to the trailer coupling. By summing this trailer coupling overload to the static load associated with the mass of the uncoupled vehicle as seen from each mounted assembly, it is possible to estimate the total load applied to each mounted assembly or each axle i of the vehicle. Optionally, the static load associated with the mass of the uncoupled vehicle is obtained via the second load distribution on the mounted assemblies or axles i of the uncoupled vehicle, combined with the mass of the uncoupled vehicle.

[0034] If a safe driving condition cannot be achieved on the trailer, whether at the level of a single vehicle combination, an axle, or the entire vehicle, the arrangement of its contents must be modified, even if it means uncoupling the trailer, in order to shift the trailer's center of gravity. This shift allows for a different distribution of the trailer's weight on the vehicle. Once the new arrangement is in place, the procedure must be repeated at the main stage by coupling the trailer with its new configuration and analyzing the load carried by each vehicle combination. This new trailer arrangement could, for example, involve shifting the center of gravity of the trailer's contents, lightening the trailer's load, or a combination of both.

[0035] The invention also relates to a system for implementing the method of estimating the load carried by an assembly consisting of a vehicle rigidly connected to a trailer comprising: • a vehicle, equipped with a tow hook at a point M of the vehicle suitable for receiving the attachment of a trailer, each axle i of which includes at least one mounted assembly equipped with an electronic device; • the electronic device comprising at least one pressure sensor, at least one electronic chip, at least one memory space capable of recording the sensor signals, and at least one first means of radio frequency communication at least in transmission, preferably, the electronic device is fixed on the inner wall of the tire, very preferably at the top of the tire; • At least one means of calculation; and • at least one display device including at least one second radio frequency communication device, at least for reception

[0036] As described in the procedure, the pressure sensor must be located on the assembly, which rotates relative to the vehicle. To avoid the components of the assembly with the highest thermal inertia, the electronic device is fixed to the inner wall of the tire at the crown, especially if the device includes a temperature sensor. Therefore, the electronic device that at least conditions the pressure sensor signals must be equipped with a means of communication, such as radio frequency, to transmit data beyond the assembly, where at least the display unit will be located. Alternatively, the calculation unit, which performs the calculation of the volume change of the internal cavity of the assembly, can be integrated directly into the assembly itself.This can be integrated into the electronic system or connected via a wired connection. In this case, the electronic system's radio frequency communication is useful for transmitting calculation results beyond the vehicle's immediate area. Radio frequency communication from the electronic system can be directed to the vehicle itself or externally to a device separate from the vehicle, such as a mobile phone, tablet, or computer. These three devices can then serve as the display. However, the display can also be a graphical user interface on the vehicle's dashboard, for example.

[0037] Therefore, the proposed structural form allows it to adapt to several possible technical configurations while being functional for implementing the said process.

[0038] Preferably, the system comprises an analysis means capable of analyzing a result output from at least one calculation means.

[0039] The result of the calculation method is the load carried by each assembled unit equipped with the electronic device. If this value is to be compared to a threshold S, an operation must be performed before sending a message to the display. This optional system element, which provides a service to the vehicle user, must be positioned between the calculation method and the display. Structurally, it can be connected to one or both via a wired connection or be physically separated from these elements using radio frequency communication.

[0040] According to a first particular embodiment, the at least one computing means includes at least one third radio frequency communication means in transmitting / receiving.

[0041] If the calculation method is physically separate from both the electronic device and the display, it must be able to communicate with both. For example, if the calculation method is located in the vehicle, it retrieves pressure data from the electronic device via radio frequency communication. Conversely, if the display is on a mobile phone, it transmits the calculation results to the display via this same radio frequency communication.

[0042] According to a second particular embodiment, the at least one analysis means comprises at least a fourth radio frequency communication means for transmitting / receiving

[0043] In cases where the analysis means is physically separated from both the computing means and the display means, it must be able to communicate with the other two elements. This is the case, for example, when the analysis means is located on a server distant from the vehicle; it retrieves the loads applied to the various vehicle assemblies from the computing means located on the vehicle via radio frequency communication. Conversely, if the display means is on a mobile phone or any other electronic device equipped with a screen, it transmits the messages resulting from the comparison to the display means via radio frequency communication.

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

[0045] If the electronic device has insufficient communication range to reach the display, a reading device must be used to retrieve the data from the electronic device. This reading device captures the measurement data and then transfers it to the display or any other system component requiring the data via radio frequency communication for subsequent processing. It acts as an information relay, optimizing communication coverage relative to the electronic device within the assembly. This is also necessary to reduce the device's mass. electronics at the pneumatic level, it is necessary to limit the energy source required for data transmission, which is the energy-intensive function of the electronic device.

[0046] Preferably, part of the communication carried out by the communication means from and to the elements included in the group comprising the electronic device, the at least one calculation means, the at least one display means, the at least one analysis means and the at least one reading means is carried out by UHF radiofrequency waves, preferably in BLE (acronym in English for “Bluetooth Low Emission”).

[0047] The UHF band (short for Ultra High Frequency) allows for significant data transmission at a high data rate, and this is even more true in the higher frequencies of the UHF band, such as the BLE band (short for Bluetooth Low Emission). It is commonly used in transportation applications, allowing the system's communication resources to be shared with those already present on the vehicle or in road infrastructure.

[0048] Advantageously, at least one means of display is included in the group comprising, a telephone, a computer, a human-machine interface located on the vehicle, preferably located on the vehicle's instrument cluster.

[0049] The display means is used to warn the individual conducting the operations on the vehicle of the need to secure their convoy, whether they are the driver behind their driving position or another person with responsibility for the conformity of the convoy.

[0050] According to an advantageous embodiment, part of at least one reading means is located on the vehicle.

[0051] According to another advantageous embodiment, part of at least one calculation means and / or part of at least one analysis means is located on the vehicle, preferably located on the assembled unit.

[0052] The vehicle acts as a natural information relay, since the entire system is connected to it and security measures are in place. Therefore, locating the system's structural components on the vehicle is highly desirable, although alternative solutions are equally feasible. However, the vehicle offers a degree of data confidentiality, unlike communications to servers, for example, unless secure communication protocols are implemented. Of course, in order to To minimize the impact of this system in the vehicle environment, which is now complex and busy, locating the functions at the level of the assembled unit helps to limit interference with other structural components of the vehicle. Brief description of the drawings

[0053] The invention will be better understood on reading the following description, given solely as a non-limiting example and made with reference to the appended figures in which the same reference numbers designate identical parts throughout and in which: • Fig. 1 presents a system for implementing the method of estimating the load carried by an assembly of a vehicle rigidly connected to a trailer according to the first embodiment of the invention; • Fig. 2 shows another system configuration according to the second embodiment of the invention; • Fig. 3 presents a synoptic diagram of the method for estimating the load carried by an assembly of a vehicle rigidly connected to a trailer according to the invention; • Fig. 4 shows a temporal evolution of the internal pressure of the fluid cavity at the outlet of the pressure sensor; • Fig. 5 shows a time evolution of the internal temperature of the fluidic cavity according to the invention; • Fig. 6 presents a temporal estimate of the variation in volume of the fluidic cavity according to the invention; • Fig. 7 presents a time estimate of the load variation of a vehicle assembly associated with the trailer coupling on the vehicle. Detailed description of the implementation methods

[0054] Fig. 1 illustrates an example of a system 2000 for implementing the method of estimating the load carried by a vehicle assembly rigidly connected to a trailer. This system 2000 comprises a vehicle 2001 with four assemblies 2006 distributed across the vehicle's two axles, the front axle and the rear axle, following the direction of the vehicle 2001 when moving forward. The vehicle includes a point M at the rear for attaching a trailer (not shown in the figure). However, this The trailer exerts an external force AZ on the axle M of vehicle 2001. Vehicle 2001, when not coupled to the trailer, has a center of gravity G where the weight P of the vehicle is applied. This weight P corresponds to the force generated by the total mass of the uncoupled vehicle, taking into account the Earth's gravity. This weight P is balanced by reaction forces exerted on the vehicle's axle assemblies 2006, designated ZAV and ZAR depending on the axle to which the axle assembly 2006 is connected. The presence of an external force AZ on point M of the vehicle, which corresponds to the ball joint of the trailer coupling of vehicle 2001, causes an additional reaction force AZAV and AZAR to appear on the axle assemblies 2006 of each respective axle. These reaction forces stabilize when a steady state is reached, thus balancing the external force AZ.

[0055] The objective of the process is to determine the reaction forces on each mounted assembly of the vehicle which are stabilized when the steady state is reached.

[0056] At least one tire assembly (2006) per axle of the vehicle (2001) is equipped with an electronic device (2007). This electronic device (2007) is located within the fluidic cavity of the tire assembly (2006). Here, the electronic device (2007) is positioned on the inner sidewall of the tire, directly above the tread of the tire casing that provides contact between the road and the tire casing. It would have been possible to install the electronic device at the wheel rim of the tire assembly, while remaining within the fluidic cavity of the tire assembly (2006). For example, the electronic device could have been integrated into the rim valve, similar to certain TPMS (Tyre Pressure Monitoring System) systems.

[0057] This 2007 electronic device includes a pressure sensor connected to a microcontroller and a radio frequency device (RFID) for transmission. The RFID includes a radio wave generator and a radio communication antenna for transmitting the generated radio waves. Optionally, the RFID may also include a radio wave receiver for receiving external instructions, for example, to initiate a measurement. This 2007 electronic device also includes memory to store the pressure sensor's measurement data before transmitting it as radio waves. The electronic device can transmit either the raw measurement data or data filtered by the microcontroller. Naturally, it is standard practice for the pressure sensor to be accompanied by a temperature sensor.At that moment, the electronic device 2007 transmits both types of data, pressure and temperature, to the outside of the assembled unit 2006. Here, the. electronic device 2007 emits radio waves in the UHF frequency band (acronym for Ultra High Frequency) and particularly in the BLE band (acronym for Bluetooth Low Emission)

[0058] Here, the exterior includes at least vehicle 2001. This vehicle 2001 includes, first of all, a radio data reader 2005, operating in the UHF range, whose antennas are located near the mounted assemblies 2006 in order to retrieve the measurement data generated by the electronic device 2007. The data is then transferred, here by wire, to the computing means 2002 located in vehicle 2001. Radio frequency transmission using a specific means of communication would also have been possible.This 2002 calculation method includes memory space and a processor to perform its tasks: identify the quantities of the assembled unit corresponding to the initial state, solve the differential equation which leads to the determination of the volume variation of the phiidic cavity of each assembled unit equipped with an electronic device 2007, and finally calculate the load variation associated with the volume variation by having previously retrieved the tire quantities necessary for this final task.

[0059] The results, and particularly the last data point, are sent to an analysis unit 2004. Here, the data transmission is wired, but radio frequency communication could have been implemented. The analysis unit 2004 compares the results from the calculation unit 2002 with previously entered threshold values. These threshold values, such as the maximum permissible axle load, the maximum total vehicle load, or the maximum permissible load per assembled vehicle, are transmitted either by hardcoding the data into vehicle 2001 or by querying a database located remotely from vehicle 2001. Of course, the analysis unit 2004 can be integrated with the calculation unit 2002.

[0060] Finally, the various output data from this analysis means 2004 are transmitted to display means 2003 via a fourth communication means 2104, which is materialized in part by the radio communication antenna of the vehicle 2001, and a second communication means 2102 present on the display means 2003.

[0061] These means of communication 2104 and 2102 transfer its data through a communication network to a tablet or smartphone 2003 in order to warn of the conformity or non-conformity of the vehicle's load with respect to the threshold values ​​permissible by the vehicle 2001 according to the legislation in force.

[0062] If the vehicle's load is not compliant, the trailer must be uncoupled to modify the load. This may involve reducing the load's mass or repositioning the load within the trailer to lessen the vehicle's load at the time the trailer was coupled. The main phase of the load estimation procedure for a vehicle and trailer combination must then be repeated to verify that the vehicle's load complies with current regulations. While uncoupling the trailer is the preferred method for modifying the trailer's load, this operation remains optional.We can perfectly continue recording the measurement signals of the electronic device 2007 during the modification of the trailer load and then wait for the overall balance of the coupled vehicle 2001 to estimate the load carried by each mounted unit 2006 equipped with an electronic device 2007 of the vehicle 2001. Then compare these new loads with the threshold values ​​previously used in order to verify the conformity of the vehicle 2001 with the legislation in force.

[0063] Fig. 2 shows another configuration of the 2000 system. This 2000 system comprises a vehicle 2001 with four mounted assemblies 2006 distributed across the vehicle's two axles, the front axle and the rear axle, following the direction of travel of the vehicle 2001 when moving forward. The vehicle includes a point M at the rear that allows for the attachment of a trailer (not shown in the figure). However, this trailer exerts an external force AZ on the axle M acting on the vehicle 2001.

[0064] At least one tire assembly (2006) per axle of the vehicle (2001) is equipped with an electronic device (2007). This electronic device (2007) is located within the fluidic cavity of the tire assembly (2006). Here, the electronic device (2007) is positioned on the inner sidewall of the tire, directly above the tread of the tire casing that provides contact between the road and the tire casing. It would have been possible to install the electronic device at the wheel rim of the tire assembly, while remaining within the fluidic cavity of the tire assembly (2006). For example, the electronic device could have been integrated into the rim valve, similar to certain TPMS (Tyre Pressure Monitoring System) systems.

[0065] This 2007 electronic device includes a pressure sensor associated with a microcontroller and a radio frequency device, at least in transmit mode. The radio frequency device therefore includes a radio wave generator and a radio communication antenna to transmit the generated radio waves. The device Radio frequency can also optionally include a radio wave receiver to receive instructions from outside the device, for example, to initiate a measurement. This 2007 electronic device also includes memory to store the pressure sensor measurement data before transmitting it as radio waves. The electronic device can transmit the raw measurement data or the data filtered by the microcontroller. It is common for the pressure sensor to be accompanied by a temperature sensor. In this case, the 2007 electronic device transmits both types of data, pressure and temperature, to the outside of the 2006 assembly. Here, the 2007 electronic device transmits radio waves in the UHF (Ultra High Frequency) frequency band, and specifically in the BLE (Bluetooth Low Emission) band.

[0066] Here, the exterior includes at least vehicle 2001. This vehicle 2001 includes, firstly, a radio data reader 2005, operating in the UHF range, whose receiving antennas 2105 are located near the mounted assemblies 2006 in order to retrieve the measurement data generated by the electronic device 2007. The data is then transferred, here via a wired connection, to the transmitting antenna of the communication device 2105 associated with the data reader 2005 located in vehicle 2001. Radio frequency transmission using a specific communication device would also have been possible between the transmitting communication device 2105 and the data reader 2005.

[0067] The data is then transmitted to physical means distant from the vehicle 2001.

[0068] The first means is a computing means 2002 comprising transmitting / receiving communication means 2102. These communication means 2102 receive the radio waves emitted by the transmitting communication means 2105 to transform them into digital data usable by the computing means 2002. The computing means 2002 includes memory space and a processor to perform its tasks: identify the quantities of the assembled unit corresponding to the initial state, solve the differential equation which leads to the determination of the volume variation of the fluidic cavity of each assembled unit equipped with an electronic device 2007, and finally calculate the load variation associated with the volume variation by having previously retrieved the tire quantities necessary for this last task.

[0069] The results, and especially the last data point, are sent to a second method, which corresponds to a 2004 analysis method. Here, the transmission of this data takes place via radio frequency communication. The analysis means 2004 performs comparisons between the results from the calculation means 2002, which it retrieves via radio frequency transmission from the calculation means 2002 using receiving communication means 2104, and pre-defined threshold values. These threshold values, such as the maximum permissible axle load of the vehicle, the maximum total vehicle load, or the maximum permissible load per assembled vehicle, are optionally transmitted by querying a remote database containing data on the vehicle 2001. Of course, according to another embodiment, the analysis means 2004 can be integrated into the calculation means 2002.

[0070] Finally, the various output data from this analysis means 2004 are transmitted to display means 2003 via a fourth communication means 2104 in transmission and a second communication means 2102 present on the display means 2003. Here, the display means are twofold. First, a digital tablet 2003, possibly located remotely from the vehicle 2001, and a human-machine interface 2003 within the vehicle 2001, comprising a display screen on the dashboard of the vehicle 2001.

[0071] The 2003 display means are intended to warn of the conformity or non-conformity of the vehicle's load with respect to the threshold values ​​permissible for the vehicle in 2001 according to the legislation in force.

[0072] Of course, these two implementation methods for estimating the load carried by a vehicle assembly rigidly connected to a trailer are merely illustrative examples of the system, which is not limited to these two configurations. One extreme configuration involves integrating all the calculation and analysis tools within the electronic device mounted on the vehicle assembly, which then transmits the results to a display device located away from the vehicle. The other extreme configuration involves transferring the measurement data recorded by the electronic device via radio waves and performing the remaining steps of the process remotely from the vehicle, without ever involving the vehicle itself.

[0073] Figure 3 shows a diagram of the method for estimating the load carried by a vehicle assembly rigidly connected to a stationary trailer. This method comprises several phases.

[0074] The first is a preliminary phase that includes at least actions 1 through 6, which follow one another through a continuous line linking system. This preliminary phase, which... Focusing on the vehicle not coupled to the trailer, this obviously includes the vehicle's equipment, ideally at the level of the mounted assemblies, by installing a pressure sensor capable of measuring the fluidic cavity pressure delimited by the inner surface of the tire and the wheel rim via a dedicated electronic device. The first steps, labeled 1 and 2, consist of determining the physical parameters of the fluidic cavity of the mounted assemblies equipped with the measuring device, such as the inflation pressure PI and the internal temperature Tl. Preferably, these determinations can be made using a standard method or through a specific measurement. Step 3 consists of determining the load ZI carried by the mounted assembly equipped with the measuring device on the uncoupled vehicle. This determination can be made using a standard method by assuming the distribution of the total vehicle load between the various axles.The total vehicle load, being a given, for example from the manufacturer, corresponds to the vehicle's unladen mass as specified in the manufacturer's technical documentation. Of course, it is also possible to include a full tank of fuel and luggage in the trunk. Step 4 involves obtaining specific measurements of the assembled tire equipped with a measuring device. One of these measurements is the volume VO, which corresponds to the volume occupied by the fluidic cavity of the assembled tire when it is inflated to pressure PI, strictly speaking, at internal temperature Tl, but without any load, i.e., not resting on the ground. The second measurement is the flattening stiffness of the tire's casing per unit volume Kp, which may depend on the inflation pressure PI, the internal temperature Tl, and the load ZI.Finally, a third set of quantities are those associated with the ideal gas laws for the nature of the gas contained in the fluidic cavity of the assembled system. The penultimate step of the preliminary phase, referenced as 5, is a step to determine the volume occupied VI by the fluidic cavity of the instrumented assembled system subjected to the load ZI and under the inflation pressure PI and temperature TL. Finally, the last step, noted as 6, of the preliminary phase is the evaluation of the quantity of gas contained in the fluidic cavity of the instrumented assembled system by determining the number of moles of gas n present within the volume VL. Here, the assumptions associated with the ideal gas condition apply; it is still necessary to identify the nature of the gas composition, that is, a monatomic gas or a gaseous mixture.Furthermore, it is important in this preliminary phase, although not shown, to determine the evolution law linking the variation of internal pressure P to the variation of internal temperature T for the fluid of the fluidic cavity. of the assembled unit under consideration during an adiabatic transformation around the operating point of the assembled unit, i.e., the pressure PI, the temperature Tl, and the load Zl. Finally, in a preliminary phase, it is necessary, although not shown, to determine the load distribution on each axle of the vehicle, preferably on each assembled unit of the vehicle, associated with a load applied at the coupling point M of the vehicle. Optionally, a second load distribution on each axle of the vehicle, preferably on each assembled unit of the vehicle, with the vehicle uncoupled, can be considered. This second load distribution is related to the total mass of the uncoupled vehicle.

[0075] Next, we move on to the main step, which begins with the coupling of the trailer to the vehicle. We necessarily record the temporal variation of the inflation pressure P(t) of each instrumented vehicle assembly, which is on the order of millibars for passenger vehicles and trailers adapted to this type of vehicle. These recordings are then stored in memory. First, the raw data is filtered using a low-pass filter to eliminate high-frequency phenomena, which corresponds to step 11. Then, we determine the temporal variation of the internal temperature T(t) of the fluid cavity using the temporal variation of the internal pressure P(t), employing the evolution law determined in the preliminary step, which corresponds to step 12.Optionally, the temporal variation of the internal temperature T(t) of each instrumented vehicle assembly is recorded, if the vehicle is equipped with a temperature sensor, which also corresponds to step 12. In this option, the recorded internal temperature variation T(t) is used to evaluate the isobaric or monobaric transformation of the fluid in the fluidic cavity, corresponding to the establishment of thermal equilibrium between the fluidic cavity and the external environment. This equilibrium is necessitated by the adiabatic transformation of the fluid associated with the trailer coupling. The linking systems between optional steps and essential process steps are illustrated with gray lines instead of black. However, the linking systems of the main phase are illustrated with dashed lines, while those of the preliminary phase are solid lines.Finally, as we will see later, the secondary phase has a linking system in the form of dashed lines.

[0076] One of the important steps in the main phase is the determination of the volume variation AV of the fluidic cavity of each instrumented mounted assembly through step 13. This corresponds to taking into account at least the adiabatic transformation The fluid in the fluidic cavity is affected by the instantaneous attachment of the trailer to the vehicle, which alters the thermomechanical equilibrium of all the vehicle's mounted assemblies and, consequently, of the fluid trapped within each fluidic cavity of the mounted assemblies. Furthermore, the fluid is assumed to behave like an ideal gas. From the internal pressure variation P(t) of each instrumented mounted assembly, it is possible to determine the internal temperature variation T(t) using the evolution law identified in the preliminary phase for an adiabatic transformation of the fluid.

[0077] Using the variation in internal pressure and temperature, it is possible to generate a differential equation that incorporates the previous assumptions. Solving this differential equation incrementally allows us to estimate the associated temporal variation of the fluidic cavity volume AV(t). Optionally, the process can be supplemented by measuring the internal temperature T of the fluidic cavity to evaluate a second volume variation associated with the isobaric or monobaric transformation of the fluid due to heat exchange between the fluidic cavity of the assembled system and the external environment through the components of the assembly; that is, the tire and the wheel.This second transformation is generally subsequent to the adiabatic transformation since it is the temperature variation generated by the adiabatic transformation that is at the origin of the thermal imbalance between the fluidic cavity and the external environment.

[0078] Another important step in the main phase is evaluating the load variation AZ associated with the single volume variation previously evaluated AV, which corresponds to step 14. This requires again considering the flattening stiffness of the assembled unit Kp per unit volume. This stiffness may include a pneumatic component and a structural component. Considering a single pneumatic component Kpp may be sufficient for a reliable estimation of the load variation AZ.

[0079] From this variation in load AZ, the initial load ZI must be added to obtain the load carried by the instrumented assembly in step 15. From this value at the scale of the assembly, it is easy to calculate the load carried by axle i of the vehicle and therefore the total load carried by the vehicle. To do this, assuming that only one or a few assemblies, but not all, of the vehicle are equipped with measuring devices, the procedure includes, in a preliminary phase, an estimation of the load distribution on each assembly or each axle of the vehicle associated with an overload applied to the coupling point M of the uncoupled vehicle. Optionally, a second load distribution can be used to estimate the initial load of each mounted unit or each axle of the uncoupled vehicle associated with the mass of the uncoupled vehicle alone.

[0080] The final step, noted as 16, is the comparison of the load carried Z against a threshold S at the level of each assembled unit, but also similarly for each axle i of the vehicle, and finally at the level of the complete vehicle. Generally, these thresholds S can be the safety conditions specific to each national legislation for vehicle operation.

[0081] Based on the results of this comparison, the vehicle is deemed fit to travel with the trailer attached, as all safety conditions are met according to step 17 of the main phase. Otherwise, a secondary phase is initiated, including at least step 20, in which the load of the attached trailer is adjusted. This load adjustment can take place while the trailer remains attached. Alternatively, the trailer can be uncoupled from the vehicle during this load adjustment. Load adjustment involves modifying the location of the load within the trailer and / or changing the contents of the load, for example, to reduce its weight.Once step 20 is completed, the main step must be repeated, reattaching the trailer to the vehicle if necessary, and recording the inflation pressure and, if applicable, the internal temperature of each instrumented assembly on the vehicle, corresponding to steps 11 and 12 of the diagram. This secondary phase is repeated until the criteria for carrying out step 17 are met.

[0082] Figure 4 shows the time evolution of the pressure from the pressure sensor of the electronic device mounted on a vehicle assembly. The curve consisting of points 10 represents the raw measurement from the pressure sensor, while curve 11 corresponds to the time evolution of the filtered pressure, which has been cleaned of high-frequency noise. This second curve will then be used in the diagram in Figure 3.

[0083] This time-domain recording of the internal pressure of the fluidic cavity of the assembled unit begins in the preliminary phase before the trailer is coupled to the vehicle. The moment the trailer is coupled corresponds to the x-coordinate of point 100, which marks the beginning of the main phase. From this point 100, a rapid drop in the internal pressure of the fluidic cavity is observed until point 101, where the pressure drop stops. to grow to a lesser extent. This point 101 marks the transition between the work done by the fluid associated with the coupling of the trailer, which corresponds to a first transformation of the fluid similar to an adiabatic transformation, and the heat exchange with the outside, which corresponds to a second transformation of the fluid. The x-coordinate of this point 101 corresponds to the time interval T0, taking the x-coordinate of point 100 as the origin of time. Thus, the preliminary phase 50 ends at the x-coordinate of point 100. It precedes the main phase, which is divided into two successive phases. The first phase 51 is similar to an adiabatic transformation of the fluid, corresponding to the work done by the fluid following the coupling of the trailer. The second phase 52 corresponds to a heat exchange of the fluid with the outside.

[0084] Figure 5 shows the temporal evolution of the internal temperature of the fluid cavity. Here, this temporal evolution is either provided by a temperature sensor of the electronic device mounted on a vehicle assembly, as illustrated by curve 12. An alternative, in the absence of a temperature sensor measurement, is an estimation of the internal temperature, illustrated by curve 12', based on, firstly, the recorded internal pressure and a law relating the internal temperature to the internal pressure during an adiabatic transformation of the fluid, and secondly, the external temperature of the assembly, which serves as the basis for heat exchange between the fluid in the fluid cavity and the external environment via a heat transfer coefficient. This heat transfer coefficient takes into account the thermal characteristics of the assembly.In this alternative, curve 70 illustrates the evolution of the outside temperature of the assembled unit.

[0085] These changes in the internal temperature 12 and 12' of the fluidic cavity of the assembled unit begin in a preliminary phase before the trailer is coupled to the vehicle. The moment the trailer is coupled corresponds to the abscissa of point 100, which marks the beginning of the main phase. From this point 100, a rapid drop in the internal temperature of the fluidic cavity is observed until point 101, where the temperature drop stops and then increases to a certain extent. This point 101 marks the transition between the work done by the fluid associated with coupling the trailer, which corresponds to a first transformation of the fluid similar to an adiabatic transformation, and the heat exchange to the outside, which corresponds to a second transformation of the fluid. The abscissa of this point 101 corresponds to the duration T0, taking the abscissa of point 100 as the origin of time. Thus, the preliminary phase 50 ends at the abscissa of point 100.It precedes the main phase, which is divided into two successive phases. The first phase, 51, is similar to a transformation. The adiabatic process of the fluid corresponds to the work done by the fluid following the coupling of the trailer. The second phase, 52, corresponds to a heat exchange of the fluid with the outside.

[0086] Here, we observe a difference between the recorded curve 12 and the estimated curve 12' of the internal temperature, which illustrates, on the one hand, the inherent inertia of the temperature sensor. On the other hand, the assumption that the relationship between internal pressure and internal fluid temperature during an adiabatic transformation is also perhaps overestimated. However, the trend between these curves 12 and 12' is quite similar. Finally, here we are not measuring the external temperature of the assembled system; we are determining it by extrapolating the internal temperature of the fluidic cavity in the preliminary phase, which is also a source of potential errors. This estimate corresponds to the linear line 70 in Figure 5.The heat transfer coefficient of the assembled system can initially be approximated solely by the characteristics of the tire casing. This can be achieved, for example, by estimating the tire's surface area in contact with the external environment (representing the external surface of the tire casing) and a heat transfer coefficient X. This coefficient depends on the thermal characteristics of the tire's material properties, including the distribution of different types of heat transfer within the tire casing, such as radiation, conduction, and convection. X can be estimated by observing the evolution of the internal temperature of the fluidic cavity during the preliminary phase, just before the main phase, for example.

[0087] Figure 6 shows the temporal evolution of the internal volume of the fluid cavity. Here, this temporal evolution, represented by the curve, is the output of the volume variation calculation using the proposed differential equation, also taking into account thermal equilibrium with the external environment.

[0088] This evolution of the internal volume of the fluidic cavity of the assembled system begins in a preliminary phase before the trailer is coupled to the vehicle. The moment the trailer is coupled corresponds to the x-coordinate of point 100, which marks the beginning of the main phase. From this point 100, a rapid increase in the internal volume of the fluidic cavity is observed until point 101, where the increase in internal volume stops and then decreases to a certain extent. This point 101 marks the transition between the work done by the fluid associated with coupling the trailer, which corresponds to a first transformation of the fluid similar to an adiabatic transformation, and the heat exchange to the outside, which corresponds to a second transformation of the fluid. The x-coordinate of this point 101 corresponds to the time interval T0, taking the x-coordinate of point 100 as the origin of time. Thus, the phase Preliminary phase 50 ends at the abscissa of point 100. It precedes the main phase, which is divided into two successive phases. The first phase 51 resembles an adiabatic transformation of the fluid, corresponding to the work done by the fluid following the coupling of the trailer. The second phase 52 corresponds to a heat exchange of the fluid with the surroundings.

[0089] It is observed that at the end of phase 51, a good estimate of the volume change of the assembled unit is obtained, clearly demonstrating that the work generated by the load variation applied to the assembled unit occurs primarily during phase 51. The observed variations or oscillations correspond to the fluctuations of the transient phase corresponding to thermal equilibrium. Therefore, the process described here provides a continuous measurement of the internal volume change of the assembled unit in the time domain.

[0090] Figure 7 shows the time evolution of the load variation applied to a mounted assembly equipped with the electronic device. Here, this time evolution, represented by curve 14, is the output of the volume variation calculation using the proposed differential equation, taking into account thermal equilibrium with the external environment, which is multiplied by the flattening stiffness of the mounted assembly. Here, the stiffness used is that which is locally identified at the initial pressure of the mounted assembly, the initial load applied to the assembly, and corresponding to the initial temperature. The overall stiffness defined by the proposed formula could have been used, which would have already provided a good order of magnitude.

[0091] This evolution of the applied load variation 14 of the fluidic cavity of the assembled system begins in a preliminary phase before the trailer is coupled to the vehicle. The moment the trailer is coupled corresponds to the abscissa of point 100, which marks the beginning of the main phase. From this point 100, a rapid decrease in the applied load is observed until point 101, where the decrease stops and then increases to a certain extent. This point 101 marks the transition between the work done by the fluid associated with coupling the trailer, which corresponds to a first transformation of the fluid similar to an adiabatic transformation, and the heat exchange to the outside, which corresponds to a second transformation of the fluid. The abscissa of this point 101 corresponds to the time interval T0, taking the abscissa of point 100 as the origin of time. Thus, the preliminary phase 50 ends at the abscissa of point 100.It precedes the main phase, which is divided into two successive phases. The first phase, 51, resembles an adiabatic transformation of the fluid, corresponding to the work done by the fluid following the coupling of the trailer. The second phase, 52, corresponds to a heat exchange of the fluid with the surroundings.

[0092] It is observed that at the end of phase 51, a good estimate of the load variation applied to the assembled unit is obtained, clearly demonstrating that the work generated by the load variation occurs primarily during phase 51. The observed variations or oscillations correspond to the fluctuations of the transient phase corresponding to thermal equilibrium. Therefore, the method described here produces a continuous measurement of the temporal load variation of the assembled unit in the time domain. Curve 80 corresponds to the measurement, on a ground scale, of the overload applied to the assembled trailer. In conclusion, the applied load variation is accurately captured by the proposed method.

Claims

CLAIMS 1. Method for estimating the variation in load carried by a mounted assembly of a vehicle generated by the coupling of a trailer when stationary, comprising the following steps: In the preliminary phase, - Equip at least one mounted assembly of at least one axle of the vehicle not coupled to the trailer with at least one pressure sensor, said sensor being capable of measuring the internal pressure of the fluid cavity of the mounted assembly delimited by a pneumatic casing and a wheel, preferably at least one mounted assembly of each axle of the vehicle, very preferably all the mounted assemblies of all the axles of the vehicle; - Determine the initial load ZI applied to at least one mounted assembly equipped with the uncoupled vehicle, - Determine the initial inflation pressure PI of the fluid cavity of at least one mounted assembly equipped with the vehicle; - Determine the initial internal temperature Tl of the fluid cavity of at least one mounted assembly equipped with the vehicle; - Evaluate the initial volume VI of at least one equipped mounted assembly using a first function comprising as parameter the volume VO of the fluid cavity of the unloaded mounted assembly inflated to the initial pressure PI and the flattening rigidity of the tire of the mounted assembly per unit of volume Kp, - Evaluate the number of moles of fluid n in the fluid cavity of each assembled assembly equipped from a model taking into account the inflation pressure PI, the initial volume VI, the temperature Tl; - Determine a law of evolution of the internal temperature T of the fluidic cavity from the internal pressure P during an adiabatic transformation for the at least one assembled assembly, inflated and subjected to the load Zl, equipped with at least one pressure sensor; In the main phase: - Attach the trailer to the vehicle at a geometry point M of the vehicle - Record the internal pressure P in the fluid cavity of at least one mounted assembly equipped at an acquisition frequency Fl; - Determine the internal temperature T of the fluid cavity of at least one equipped assembly using the evolution law determined in the preliminary phase; - Evaluate an intermediate volume variation AV of at least one equipped mounted assembly using the recorded internal pressure P and the internal temperature T determined using a fluid model in adiabatic transformation, the fluid having perfect gas behavior; and - Estimate a load variation AZ carried by the at least one mounted assembly equipped using a second function comprising as parameter the intermediate AV volume variation evaluated and the flattening rigidity of the tire of the mounted assembly per unit of volume Kp.

2. Method for estimating the variation in the load carried by a mounted assembly of a vehicle generated by the coupling of a trailer when stationary according to claim 1 in which, in the preliminary phase, the at least one mounted assembly equipped with the at least one axle of the vehicle comprising a temperature sensor capable of measuring the temperature of the fluid cavity, the method comprises, in the main phase, a step for recording the internal temperature T in the fluid cavity of the at least one mounted assembly equipped at an acquisition frequency F2 and the method comprises a second step of evaluating the intermediate volume variation AV2 of the at least one mounted assembly equipped taking into account the internal temperature T recorded using a fluid model having a perfect gas behavior, subjected to thermal equilibrium with the environment outside the fluid cavity.

3. Method for estimating the variation in load carried by a mounted assembly of a vehicle generated by the coupling of a trailer when stationary according to one of claims 1 to 2 in which, before the main step, the at least one equipped mounted assembly is in a thermomechanically stabilized state.

4. Method for estimating the variation in load carried by a mounted assembly of a vehicle generated by the coupling of a trailer when stationary according to one of claims 1 to 3 in which the pressure sensor and / or the temperature sensor are placed in a sub-space of the closed fluid cavity delimited by the pneumatic casing and the wheel.

5. Method for estimating the variation in load carried by a mounted assembly of a vehicle generated by the coupling of a trailer when stationary according to one of claims 1 to 4 in which the acquisition frequency Fl is between 0.1 Hz and 10 Hz.

6. Method for estimating the variation in load carried by a mounted assembly of a vehicle generated by the coupling of a trailer when stationary according to one of claims 2 to 5 in which the acquisition frequency F2 is lower than the acquisition frequency Fl.

7. Method for estimating the variation in load carried by a mounted assembly of a vehicle generated by the coupling of a trailer when stationary according to one of claims 1 to 6 in which the determination of the initial volume V0 takes into account the geometry of a wheel rim and the geometry of an unloaded tire, mounted on a rim and inflated to the reference pressure PO, preferably the reference pressure PO is the initial pressure PI.

8. Method for estimating the variation in load carried by a mounted assembly of a vehicle generated by the coupling of a trailer when stationary according to claim 7 in which the geometry of the tire and / or the geometry of the rim is determined using an identifier of the tire and / or the wheel of the equipped mounted assembly, preferably obtaining the identifier of said tire and / or said wheel is carried out by a radiofrequency interrogation of an electronic device located on the mounted assembly.

9. Method for estimating the variation in load carried by a mounted assembly of a vehicle generated by the coupling of a trailer when stationary according to one of claims 1 to 8 in which the load Z of each equipped mounted assembly is estimated by a relationship according to the following formula: [MATH1] Z = K PP * P * â(F) = K PP * P * (Fl - FO) ? Where Kpp is the flat tire stiffness of the assembled tire per unit volume.

10. Method for estimating the variation in load carried by a mounted assembly of a vehicle securely connected to a trailer according to one of claims 1 to 9 in which the AV volume variation of each equipped mounted assembly is estimated by solving the following differential equation: [MATH 2] , And With [MATH 3] where P is the internal pressure, V is the internal volume and T is the internal temperature of the fluid cavity.

11. Method for estimating the load carried by a vehicle integrally connected to a trailer comprising the method for estimating the variation in the load carried by a mounted assembly of a vehicle generated by the coupling of the trailer when stationary according to one of claims 1 to 10, the method is characterized in that, in the preliminary phase, the method comprises a step of determining a first load distribution on each axle of the uncoupled vehicle, preferably on each mounted assembly of the vehicle, associated with the application of an additional load exerted at the coupling point M of the trailer on the uncoupled vehicle, optionally the method also comprises a step of determining a second load distribution on each axle of the uncoupled vehicle, preferably a second load distribution on each mounted assembly of the vehicle, associated with the weight of the uncoupled vehicle, in that, in the main phase,the method comprises a step of estimating the load Z carried by each mounted assembly of each axle i of the vehicle using the load variation AZ carried by the at least one equipped mounted assembly, the first load distribution associated with the application of an additional load to the coupling point M and the determination of the initial loads Zli of each mounted assembly of the uncoupled vehicle, optionally the step of estimating the load Z carried by each mounted assembly takes into account the second load distribution associated with the weight of the uncoupled vehicle, in that the method comprises a step of comparing to at least one threshold value S the load carried Z estimated at each axle i of the coupled vehicle and / or the total load carried by the coupled vehicle which is the summation of the loads carried by each axle i of the vehicle, and when the at least one threshold value S is crossed, the mass content K of the, trailer is fitted into the trailer during a secondary phase before performing all the steps of the main phase again.

12. System (2000) for implementing the method (1000) for estimating the variation in load carried by a mounted assembly of a vehicle securely connected to a trailer according to one of claims 1 to 10 and / or the method for estimating the load carried by a mounted assembly of a vehicle securely connected to a trailer according to claim 11 comprising: - a vehicle (2001), provided with a towing hook at a point M of the vehicle capable of receiving the attachment of a trailer, each axle i of which comprises at least one mounted assembly (2006) equipped with an electronic device (2007); the electronic device (2007) comprising at least one pressure sensor, at least one electronic chip, at least one memory space capable of recording the signals from the sensor, and at least one first radiofrequency communication means (2101) at least in transmission; at least one calculation means (2002); and at least one display means (2003) comprising at least one second radiofrequency communication means (2102) at least in reception 13. System (2000) for implementing the method (1000) for estimating the variation in load and the load carried by a mounted assembly of a vehicle securely connected to a trailer according to claim 12 in which the system (2000) comprises an analysis means (2004) capable of analyzing a result output from the at least one calculation means (2002).

14. System (2000) for implementing the method (1000) for estimating the variation in load and the load carried by a mounted assembly of a vehicle securely connected to a trailer according to one of claims 12 to 13 in which the at least one calculation means (2002) comprises at least a third radiofrequency transmission / reception communication means (2103).

15. System (2000) for implementing the method (1000) for estimating the variation in load and the load carried by a mounted assembly of a vehicle securely connected to a trailer according to claim 14 in which the at least one analysis means (2004) includes at least a fourth means of communication (2104) radiofrequency transmission / reception 16. System (2000) for implementing the method (1000) for estimating the variation in load and the load carried by a mounted assembly of a vehicle securely connected to a trailer according to one of claims 12 to 15 in which the system (2000) comprises at least one reading means (2005) capable of at least reading data contained in the at least one memory space of the electronic device (2007) comprising at least one fifth communication means (2105) at least in reception.

17. System (2000) for implementing the method (1000) for estimating the load variation and the load carried by a mounted assembly of a vehicle securely connected to a trailer according to one of claims 12 to 17 in which part of the communication carried out by the communication means (2101, 2102, 2103, 2104, 2105) from and to the elements included in the group comprising the electronic device (2007), the at least one calculation means (2002), the at least one display means (2003), the at least one analysis means (2004) and the at least one reading means (2005) is carried out by UHF radiofrequency waves, preferably in BLE.

18. System (2000) for implementing the method (1000) for estimating the variation in load and the load carried by a mounted assembly of a vehicle securely connected to a trailer according to one of claims 12 to 18 in which the at least one display means (2003) is included in the group comprising a telephone, a computer, a human-machine interface located on the vehicle (2001), preferably located on the instrument cluster of the vehicle (2001).

19. System (2000) for implementing the method (1000) for estimating the variation in load and the load carried by a mounted assembly of a vehicle securely connected to a trailer according to one of claims 12 to 18 in which a part of the at least one reading means (2005) is located on the vehicle (2001).

20. System (2000) for implementing the method (1000) for estimating the variation in load and the load carried by a mounted assembly of a vehicle securely connected to a trailer according to one of claims 12 to 19 in which a part of the at least one calculation means (2002) and / or a part of the at least one analysis means (2004) is located on the vehicle (2001), preferably located on the mounted assembly (2006).

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