Method for estimating the load distributed on a trailer attached to a vehicle

Abstract

Method for estimating the load variation carried by a mounted assembly of a trailer generated by the coupling of the trailer to the vehicle comprising the following steps: Coupling the trailer to the vehicle; Recording the internal pressure P of the fluid cavity of an equipped mounted assembly; Determining the internal temperature T of the fluid cavity of the equipped mounted assembly using a determined evolution law; Evaluating a volume variation ΔV of the 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 an ideal gas behavior; and Estimating a load variation ΔZ carried by the equipped mounted assembly using a second function comprising as parameter the intermediate volume variation ΔV evaluated and the flattening rigidity of the tire of the mounted assembly per unit of volume KP. Figure for the abstract: Fig. 3

Description

Title of the invention: Method for estimating the load distributed on a trailer attached to a vehicle Field of 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, in particular when the vehicle is stationary. Technological background

[0002] Obtaining the quasi-static load applied to a stationary trailer makes it possible to determine whether the trailer or each of the axles of the trailer is in a safe condition even before setting it in motion, which makes it more reliable and makes it possible to comply with safe traffic conditions. 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 very specific loading locations such as quarries where the loading of the trailer coupled to the vehicle takes place. In order to evaluate, outside of these specific locations, the load carried by the trailer as well as by each axle of the trailer, it is possible to evaluate the load carried by each mounted assembly of the trailer through an indication of the footprint of the tire on the ground.Although a measurement through a static pressure quantification system is possible by inserting the measuring system between the mounted assembly and the ground, its implementation is not simple and the accuracy of the measurement is subject to the correct positioning of the measuring system. Another alternative is to evaluate the dimension of the contact patch in rolling conditions through a measurement of the tire deformation at the wheel revolution in order to determine the dimension of the contact patch. Through a mathematical model, linking the type of tire, the inflation pressure and the external dimension of the footprint, we then go back to the load applied to the tire casing. Unfortunately, this measurement is in rolling conditions. As a result, the trailer may no longer be within its safe operating range at the time of the measurement.Furthermore, the precision of these measurements is delicate for very heavy loads where the deformation of the tire which determines the load variations tends to stabilize according to the circumferential direction on which the evolution of the measurement of the deformation of the tire envelope generally relates.

[0003] The objects and methods of the invention which follow aim to solve the problem of measuring the variation in load carried by the trailer in absence of a measurement system external to the trailer, i.e. usable at any time without specific measuring means. In addition, this assessment is carried out while the vehicle is stationary, making it possible to decide on the safety criterion for loading the trailer before it is moved. Description of the invention

[0004] The invention relates to a method for estimating the variation in load carried by a mounted assembly of a trailer generated by the coupling of the trailer to a stationary towing vehicle comprising the following steps: • In the preliminary phase, i.e. before coupling the trailer to the vehicle • Equip at least one assembly mounted on at least one axle of the trailer not coupled to the towing vehicle 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 trailer, very preferably all the mounted assemblies of all the axles of the trailer; • Determine the initial load ZI applied to at least one mounted assembly equipped with the uncoupled trailer; • Determine the initial inflation pressure PI of at least one mounted assembly equipped with the trailer; • Determine the initial internal temperature Tl of at least one assembled assembly equipped with the trailer; • Evaluate the initial volume VI of at least one mounted assembly equipped using a first function comprising as parameter the volume V0 of the fluid cavity of the mounted assembly unloaded and 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 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 point geometry M of the trailer; • Record the internal pressure P of the fluid cavity of at least one mounted assembly equipped with 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 each equipped assembly using a second function including as parameter the intermediate volume variation AV evaluated and the flattening rigidity of the tire per unit of volume KP.

[0005] According to a preferred embodiment, in the preliminary phase, the at least one mounted assembly equipped with the at least one axle of the trailer 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 AV of the at least one mounted assembly equipped taking into account the internal temperature T recorded using a fluid model having perfect gas behavior, subjected to thermal equilibrium with the environment outside the fluid cavity.

[0006] The method for determining the variation in applied load comprises two successive phases. The first phase consists of identifying the intrinsic parameters of the mounted assembly before coupling the trailer to the vehicle. This constitutes an installation of the trailer measurement system by means of the installation of the measurement systems at the level of the trailer axles and the identification of the initial parameters of the mounted assemblies such as the volume of the fluid cavity, the quantity of fluid contained in the closed volume defined by the fluid cavity, the load initially applied to the mounted assembly by the uncoupled trailer, the internal temperature of the fluid cavity and the inflation pressure of the fluid cavity of each mounted assembly. Intuitively, the nature of the fluid is assumed to be known in order to estimate the quantity of fluid trapped in the fluid cavity.It is also necessary to have a law of evolution of the variation of internal temperature T associated with the variation of inflation pressure P of the assembled assembly when it is in use condition, in particular with the load ZI carried around the inflation pressure PI and the temperature TL This law of evolution can be fixed or result from an experimental characterization or a numerical simulation of the assembled assembly considered.

[0007] The second phase represents the step of evaluating the load variation applied to each mounted assembly equipped with an electronic device due to the coupling of the trailer to the vehicle. The electronic device comprising the pressure sensor manages and conditions the recording of the pressure measurement. Thus, recordings of the inflation pressure of the fluid cavity of each mounted assembly equipped with an electronic device are made at the time of coupling the trailer to the vehicle. The temporal changes, in the transient phase, of the physical quantities of the fluid cavity are significant. Coupling the trailer causes a first transformation corresponding to the work generated by this additional load which is similar to an adiabatic transformation, i.e. a rapid one which is predominant compared to the second transformation.After the rapid transformation, a slower transformation follows, which corresponds to the thermal equilibrium of the fluid cavity with the external environment through the tire and the wheel. This equilibrium is necessary following the modification of the internal temperature of the fluid cavity associated with the work generated by the additional load. This thermal equilibrium is slower to be implemented due to the thermal inertia of the tire and the wheel. In addition, the thermal equilibrium is of smaller magnitude on the variation of volume of the fluid cavity than the transformation linked to the work. Therefore, it is possible to use sampling frequencies for the physical quantities, temperature and pressure, which are different. However, it is just as easy to use the same sampling frequency for both sensors.

[0008] Using the variation of the inflation pressure of the fluidic cavity, it is possible to determine the variation of the internal temperature of the fluid of the fluidic cavity which is determined, for this purpose, by the evolution law previously determined in the preliminary phase. It therefore converts the measurement of the internal pressure of the fluid of the fluidic cavity and an evaluation of the internal temperature of the fluid generated by the adiabatic transformation alone.

[0009] Then, it is possible to evaluate a first intermediate volume variation using a model of a fluid undergoing an adiabatic transformation. Here, the term adiabatic is understood to mean that the transformation that the fluid undergoes due to the coupling of the trailer to the vehicle is carried out without external heat exchange between the fluid cavity and the exterior of the mounted assembly, which assumes that it is rapid. Therefore, by using only the variation in the measured inflation pressure and the internal temperature variation determined by the evolution law from the pressure variation of the fluid cavity, it is possible to estimate the first volume variation of the fluid cavity generated by the coupling of the trailer to the vehicle, the fluid having undergone an adiabatic transformation. We will make the entirely suitable assumption for air or nitrogen that the fluid, in the gaseous state, of the cavity the assembled equipped assembly is an ideal gas.

[0010] Preferably, a second intermediate volume variation is evaluated using a second transformation of the fluid. This second transformation is associated with the thermal equilibrium of the fluid with the exterior through the components of the mounted assembly, mainly the tire. The second volume variation undergone by the mounted assembly following this second transformation is then evaluated using the variation in the internal temperature recorded in the fluid cavity during the transient phase linked to the coupling of the trailer but subsequent to the first transformation of the fluid, that is to say when the inflation pressure has changed its temporal evolution. Taking into account this second volume variation guarantees better precision in the evaluation of the volume variation of the fluid cavity, which improves the precision of the measurement of the load variation at the level of each equipped mounted assembly.However, the first intermediate volume variation is sufficient to estimate, to a first order of magnitude, the overload applied to the assembled assembly.

[0011] Of course, taking into account the variation in the external temperature of the mounted assembly resulting from the thermal equilibrium of the mounted assembly also makes it possible to refine the measurement of the second variation in volume, generated by the coupling of the trailer to the vehicle, at the level of each equipped mounted assembly. However, in a simple approach, the mounted assembly being preferably in a thermomechanically stable state, it is possible to take as the external temperature the initial internal temperature Tl of the fluid of the fluidic cavity of the mounted assembly.

[0012] These two transformations can take place at each time increment or one after the other over a period of time measurements. These evaluations of the intermediate volume variation must be made with measurements during the transient period of loading of the trailer until the establishment of the mechanical and possibly thermal equilibrium of the mounted assemblies of the trailer. Once these equilibria are established, the variations in temperature and pressure of the fluidic cavity are infinitesimal, they are then in a new thermomechanically stable state.

[0013] Once the intermediate volume variation has been evaluated for each equipped mounted assembly, it is appropriate to evaluate the associated static load variation resulting from the coupling of the trailer to each equipped mounted assembly of the trailer. To do this, it is appropriate to transform the intermediate volume variation of each equipped mounted assembly into an equivalent load variation. To this end, it is appropriate to take into account a characteristic of the mounted assembly, in particular that of the tire, which is called flattening rigidity per unit of volume KP. This quantity makes it possible to link the load carried by the mounted assembly to the variation of volume of the fluid cavity generated by the load carried, the mounted assembly being crushed on a ground perpendicular to the applied load. This characteristic can of course be a fixed quantity or obtained by an experimental characterization of the mounted assembly or deduced from a numerical simulation campaign of the same mounted assembly. The mounted assembly must be in conditions of use close to those observed in the preliminary phase, that is to say around the internal temperature Tl and around the inflation pressure PI. Generally, this flattening rigidity of the mounted assembly is a quantity defined locally around the initial point of use of the mounted assembly in the reference frame associated with the internal pressure P, the internal temperature T and the volume of the fluid cavity V.

[0014] Preferably, before the main step, the at least one equipped mounted assembly is in a thermomechanically stabilized state.

[0015] It is preferable that the transient phenomena recorded at the sensors of the electronic device are only due to the disturbance of the balance of the trailer generated by the coupling of the latter to the towing vehicle. Thus, the other disturbances do not influence the response of the sensors, which improves the precision of the load variation evaluated by the method. However, if the disturbance of the balance of the trailer takes place on a different time scale than the disturbance associated with the coupling of the trailer or if this disturbance results in lower amplitudes of the responses of the sensors of the electronic device, the method remains entirely relevant.

[0016] Advantageously, 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.

[0017] It is advantageous for the sensors measuring low-amplitude transient phenomena to be placed close to the appearance of these transient phenomena so as not to be drowned in the measurement noise. Thus, in the presence, for example, of a centralized inflation pressure system for the mounted assemblies, it is advantageous for the sensors to be located at the level of the mounted assembly and not at the level of the centralized system. In the same logic, if the sensors are placed on the surface of the tire on the inside of the tire, the measurement will be more precise than if the sensors are mounted on the wheel rim due to the distance of the measurement from the appearance of the physical phenomenon which acts on the deformation of the tire casing due to the transient nature of the physical phenomenon.

[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 small 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 transformation of the fluid which is rapid. The frequency F2 being linked to the recording of the second sensor does not need such a high frequency since the second transformation of the fluid is slower by nature. However, it is quite possible to use the same acquisition frequency for both sensors by then taking the frequency Fl as a 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 a reference pressure PO, preferably the 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 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.

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

[0026] To determine this volume V0, it is necessary to know the axisymmetric geometry of the unloaded tire for a reference inflation pressure PO. It is made the realistic assumption that the geometry of the rim is not influenced by the inflation pressure of the mounted assembly. These geometries can be accessed via a tire database. Knowledge of the identity of the tire and / or the wheel rim makes it possible to isolate the correct geometries in this database. The identity of the tire can be obtained through an optical reading of the regulatory markings affixed to the sidewall of the tire.The identity can also be transmitted by radio frequency interrogation of an electronic device present on the mounted assembly such as an RFID tag (acronym in English for Radio Frequency Identification), a TMS (acronym in English for "Tyre Mounted Sensor") mounted on the internal rubber of the tire or "inner liner" or a TPMS (acronym in English for "Tyre Pressure Monitoring System") mounted on the wheel rim for example.

[0027] Preferably, the load Z of each equipped mounted assembly is estimated by a , , where KpP is the pneumatic stiffness of Z = KPp * P * A(V) = KPP *P* (71 - 70) & fh flattening of the tire of the assembled assembly per unit of volume.

[0028] This is a simple and elementary model which links the load applied to the tire to the variation in volume of the fluid cavity of the mounted assembly between a first state, for example unloaded, of volume V0 and a second state of volume VI, the inflation pressure P of the fluid cavity and the pneumatic rigidity of the mounted assembly corresponding to the flattening of the mounted assembly on a contact plane, at a global level, that is to say whatever the pressure P, the volume V and the temperature T. Through this model, it is assumed that the rigidity of a structural nature of the mounted assembly is negligible compared to that of a pneumatic nature, which is a realistic assumption for a pneumatic casing for a trailer. However, it is entirely possible to take into account the structural rigidity of the tire in the previous formula by adding it to the product of the pneumatic rigidity by the inflation pressure.

[0029] According to an advantageous embodiment, the variation in volume AV of each equipped mounted assembly is estimated by solving a differential equation according to the following form: [MATH 2] t) r , and 11 X / vi \ V|- 7 P -^*»1 TJ \Q 0 0 J With [MATH 3] [P\ U = 7 | \T / , 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 translates the link between the parameters of the fluid of the cavity of the mounted 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 trailer integrally connected to a vehicle comprising the method for estimating the variation in the load carried by a mounted assembly of a trailer generated by the coupling of the trailer to a stationary vehicle, 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 trailer, preferably on each mounted assembly of the trailer, associated with the application of an additional load exerted at the coupling point M of the trailer to the vehicle, optionally the method also comprises a step of determining a second load distribution on each axle of the trailer, preferably a second load distribution on each mounted assembly of the trailer, associated with the weight of the trailer, 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 trailer 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 trailer, 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 trailer,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 trailer and / or the total load carried of the trailer which is the summation of the loads carried by each axle i of the trailer, and when the at least one threshold value S is crossed, the mass content K of the trailer is adapted in the trailer during a secondary phase before carrying out again all the steps of the main phase.

[0032] By adding the load carried by the mounted assembly or the axle before the trailer is hitched, this makes it possible to evaluate the total load established at the level of the mounted assembly or the axle i of the trailer. The evaluation of the total load carried by the trailer then amounts to just adding the static loads established on all the axles i of the trailer. It is then possible to verify that the load conditions comply with the safety traffic instructions at the level of each mounted assembly, each axle of the trailer and of course the trailer even before the trailer starts to move.

[0033] By knowing the first load distribution at the level of the mounted assemblies or axles i of the trailer associated with an overload applied to the coupling point M of the trailer, it is possible to deduce from a single measurement on a mounted assembly equipped with the measuring device, the overloads on each mounted assembly or each axle of the trailer linked to the coupling of the trailer to the vehicle. By adding this overload linked to the coupling of the trailer to the static load linked to the mass of the trailer seen from each mounted assembly, it is possible to estimate the total load applied to each mounted assembly or each axle i of the trailer. Optionally, the static load linked to the mass of the trailer is obtained via the second load distribution on the mounted assemblies or axles i of the trailer associated with the mass of the trailer.

[0034] In the event that a safe driving condition is not obtained on the coupled trailer, whether at the level of a mounted assembly, an axle or the complete trailer. It is appropriate to modify the arrangement of its contents, even if it means uncoupling the trailer of the vehicle, with the aim of shifting the center of gravity of the trailer. This shift of the center of gravity of the trailer allows the mass of the trailer to be distributed differently, taken up by each of the axles of the trailer or by the fifth wheel of the towing vehicle. Once the new arrangement has been made, it is necessary to repeat the process at the main phase by coupling the trailer with its new arrangement and analyze the load carried by each mounted assembly equipped with the trailer. This new arrangement of the trailer can, for example, be a shift of the center of gravity of the contents of the trailer or a lightening of the contents of the trailer or a combination of the two.

[0035] The invention also relates to a system for implementing the method for estimating the variation in load carried by a mounted assembly of a trailer securely connected to a vehicle generated by the coupling of the trailer to the stationary vehicle and / or for implementing the method for estimating the load carried by a trailer securely connected to a vehicle comprising: • a trailer, equipped with a coupling device at a point M of the trailer capable of receiving the fifth wheel of a vehicle, each axle i of which comprises 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 radiofrequency communication at least in transmission; • at least one means of calculation; and • at least one display means comprising at least one second means of radio frequency communication at least in reception

[0036] As mentioned by the method, it is appropriate for the pressure sensor to be located on the mounted assembly which is driven by a rotational movement relative to the vehicle. Therefore, it is appropriate for the electronic device conditioning at least the signals from the pressure sensor to be provided with communication means, for example radio frequency, in transmission to simply transmit the data beyond the mounted assembly where at least the display means will be located. Indeed, an alternative consists of integrating the calculation means, the one which performs the calculation of the variation in volume of the internal cavity of the mounted assembly at the level of the mounted assembly. This can be integrated into the electronic device or be in wired communication with the electronic device. Then, the radio frequency communication means of the electronic device is useful for transmitting the results of calculations beyond the mounted assembly.Radio frequency communication from the electronic device of the mounted assembly may be to the trailer, the vehicle or outside the two components to a device separate from these components. such as a mobile phone, a tablet, a computer. These three elements can then represent the display means. However, the display means can also be a graphical interface of the trailer, the vehicle or at the dashboard level for example.

[0037] As a result, the proposed structural form makes it possible to adapt to several possible technical configurations while being functional for implementing said method.

[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 means is the load variation or the load carried by each mounted assembly equipped with the electronic device. If we want to compare this second quantity with respect to a threshold S, it is appropriate to carry out an operation before sending a message to the display means. This optional element of the system making it possible to provide a service for the user of the convoy consisting of the towing vehicle and the trailer must be positioned between the calculation means and the display means. Structurally, it can be associated with one and / or the other by a wired connection or be physically dissociated from these elements by means of radiofrequency communication means.

[0040] According to a first particular embodiment, the at least one calculation means comprises at least one third radiofrequency transmission / reception communication means.

[0041] In the case where the calculation means is physically dissociated on the one hand from the electronic device and on the other hand from the display means, it is appropriate for the latter to be able to communicate with the other two elements. This is the case for example when the calculation means is on the vehicle, it recovers the pressure data from the electronic device through a radio frequency communication with the latter. On the other hand, if the display means is on a mobile telephone, it transmits the calculation results to the display means by this radio frequency communication.

[0042] According to a second particular embodiment, the at least one analysis means comprises at least a fourth radiofrequency transmission / reception communication means.

[0043] In the case where the analysis means is physically dissociated on the one hand from the calculation means and on the other hand from the display means, it is appropriate that the latter can communicate with the other two elements. This is the case for example when the analysis means is on a server remote from the vehicle, it recovers the load variations or the loads applied to the various mounted assemblies of the vehicle coming from the calculation means present on the vehicle through a radiofrequency communication with the latter. On the other hand, if the display means is on a mobile telephone, or any other electronic device equipped with a screen, it transmits the messages resulting from the comparison to the display means by radio frequency communication.

[0044] According to a third particular embodiment, the system comprises at least one reading means capable of at least reading data contained in the at least one memory space of the electronic device, comprising at least a fifth radiofrequency transmission / reception communication means.

[0045] In the case where the electronic device has a communication range that is not sufficient to ensure communication to the display means, it is appropriate to use a reading means to recover the data from the electronic device. This reading means ensures the function of capturing the measurement data. It then transfers them to the display means or any other element of the system requiring the data by radiofrequency communication for the rest of the process. This is a role of relaying the information by optimizing the communication coverage in relation to the electronic device present in the mounted assembly. Indeed, in order to reduce the mass of the electronic device at the tire, it is appropriate to limit the energy source necessary for the transmission of the data which is the energy-consuming 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 (acronym for Ultra High Frequencies) allows significant data transmission with an interesting flow rate, this is even more true in the high frequencies of the UHF band such as the BLE band (acronym in English for "Bluethooth Low Emission"). It is classically used in transport applications, which makes it possible to share the system's communication means with those already present on the vehicle or in the road infrastructure.

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

[0049] The display means is used to warn the individual who is conducting operations on the convoy of the securing of the trailer of his convoy, whether he is the driver behind his driving position or another person having responsibility for the conformity of the convoy.

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

[0051] According to another advantageous embodiment, a part of the at least one calculation means and / or a part of the at least one analysis means is located on the trailer, preferably located on the mounted assembly.

[0052] The trailer is a natural information relay instrument since the mounted assembly is connected to it and the security condition is applied to it. Consequently, that the structural devices of the system are located on the trailer is entirely desirable although the alternative is just as possible. However, the trailer allows to ensure a certain confidentiality of the data unlike communications to servers for example, unless secure communication protocols are put in place. Of course, in order to minimize the impact of this system in the trailer environment which is today complex and loaded, the localization of the functions at the level of the mounted assembly makes it possible to limit interference with the other structural components of the trailer and / or the vehicle. Brief description of the drawings

[0053] The invention will be better understood on reading the following description given solely by way of 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.l] presents a system for implementing the method for estimating the variation in load carried by a mounted assembly of a trailer securely connected to a towing vehicle and / or for implementing the method for estimating the load carried by a trailer securely connected to a vehicle 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 synopsis of the process of estimating the variation of load carried and / or the load carried by a mounted assembly of a trailer securely connected to a vehicle 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 temporal evolution of the internal temperature of the fluid cavity; • [Fig.6] presents a temporal estimate of the volume variation of the fluidic cavity according to the invention; • [Fig.7] presents a time estimate of the load variation of a trailer mounted assembly associated with the coupling of the trailer to the vehicle. Detailed description of the embodiments

[0054] [Fig. 1] illustrates an example of a system 2000 enabling the implementation of the method for estimating the variation in load carried and / or the method for estimating the load carried by a mounted assembly of a trailer integrally connected to a towing vehicle. This system 2000 comprises a trailer 2001 comprising three axles of mounted assemblies 2006 distributed over the trailer 2001. The trailer 2001 comprises a point M on the front part of the trailer which enables the attachment of a fifth wheel of the towing vehicle not shown in the figure. However, this towing vehicle exerts an external force AZ on the axle M on the trailer 2001. The trailer 2001 comprises a center of gravity G where the weight P of the trailer is applied which corresponds to the force generated by the total mass of the trailer taking into account the gravity of the Earth.This weight P is balanced by reaction forces exerted on the mounted assemblies 2006 of the trailer which are called Zi to Z3 depending on the axle where the mounted assembly 2006 is connected. The presence of an external force AZ on the point M of the vehicle, which corresponds to the attachment of the coupling device of the trailer 2001 to the vehicle, causes the appearance of additional reaction forces noted respectively AZi to AZ3 on the mounted assemblies 2006 of each respective axle which stabilize when the permanent regime is reached to balance the external force AZ. The additional reaction forces AZi to AZ3 take into account the reaction force exerted by the ground on the crutch device of the trailer 2001.

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

[0056] At least one mounted assembly 2006 per axle of the vehicle 2001 is here equipped with an electronic device 2007. This electronic device 2007 is located in the fluid cavity of the mounted assembly 2006. Here, the electronic device 2007 is placed on the internal wall of the tire in line with the tread of the tire casing which ensures contact between the ground and the tire casing. It would have been possible to install the electronic device at the wheel rim of the mounted assembly, while remaining in the fluid cavity of the mounted assembly 2006. For example, the electronic device could have been integrated into the rim valve like certain TPMS systems (acronym in English for Tire Pressure Monitoring System).

[0057] This electronic device 2007 comprises a pressure sensor associated with a microcontroller and a radiofrequency device at least in transmission. The radiofrequency device therefore comprises a radio wave generator and a radiocommunication antenna for transmitting the generated radio waves. The radiofrequency device may also, optionally, comprise a radio wave receiver for receiving instructors from outside in order, for example, to launch a measurement. This electronic device 2007 also includes a memory space for storing the measurement data from the pressure sensor before transmitting them in the form of radio waves. The electronic device can transmit the raw measurement data or the data filtered by the microcontroller. Of course, it is common for the pressure sensor to be accompanied by a temperature sensor. At this time, the electronic device 2007 transmits both types of data, pressure and temperature, to the outside of the mounted assembly 2006. Here, the electronic device 2007 transmits radio waves in the UHF frequency band (acronym in English for Ultra High Frequency) and particularly in the BLE band (acronym in English for Bluetooth Low Emission)

[0058] Here, the exterior comprises at least the trailer 2001. This trailer 2001 firstly comprises a radio data reader 2005, operating in the UHF range, the antennas 2105 of which are located close to the mounted assemblies 2006 during the rotation of these in order to recover the measurement data generated by the electronic device 2007. The data are then transferred, here by wire, to the calculation means 2002 located in the trailer 2001. A radiofrequency transmission using specific means of communication would also have been possible.This calculation means 2002 includes memory space and a processor to carry out its tasks: identify the quantities of the assembled assembly corresponding to the initial state, solve the differential equation which leads to the determination of the variation in volume of the fluidic cavity of each assembled assembly equipped with an electronic device 2007, and finally calculate the variation in load associated with the variation in volume having previously recovered the quantities of the tires necessary for this final task.

[0059] The results and in particular the last data are sent to an analysis means 2004. Here, the transmission of this data is done by wire but a radio frequency communication could have been set up. The analysis means 2004 makes comparisons between the results of the calculation means 2002 and threshold values ​​previously entered. These threshold values ​​such as the maximum authorized load per axle of the trailer or the maximum total load of the trailer or the maximum authorized load per mounted assembly are possibly transmitted by the hard entry of this data within the trailer 2001 or by the interrogation of a database remote from the trailer 2001. Of course the analysis means 2004 can be integrated into the calculation means 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, among other things, by the radiocommunication antenna of the trailer 2001 and a second communication means 2102 present on the means 2003 display.

[0061] These communication means 2104 and 2102 transfer their data via a communication network to a tablet or smartphone 2003 in order to prevent compliance or non-compliance of the trailer loading with respect to the threshold values ​​admissible by the trailer 2001 according to the legislation in force.

[0062] In the event of non-compliance of the trailer load, it is appropriate to uncouple the trailer from the vehicle in order to modify the load, whether it is a reduction in the mass of the load or a modification of the positioning of the load in the trailer in order to load the axles of the trailer 2001 less when the trailer is coupled to the towing vehicle. It is then appropriate to restart the main phase of the process of estimating the load carried by a mounted assembly of a trailer integrally connected to a vehicle in order to check the conformity of the trailer loads with the legislation in force. If uncoupling the trailer is preferred to modify the trailer load, this operation remains optional.It is perfectly possible to continue recording the measurement signals from the electronic device 2007 while the trailer load is being modified and then wait for the overall balance of the attached trailer 2001 to estimate the load carried by each mounted unit 2006 equipped with an electronic device 2007 of the trailer 2001. Then compare these new loads with the threshold values ​​previously used in order to check the conformity of the trailer 2001 with the legislation in force.

[0063] [Fig.2] shows another configuration of the system 2000. This system 2000 comprises a trailer 2001 comprising three axles of mounted assemblies 2006 distributed on the trailer, the axles are numbered from 1 to 3 according to the direction of the trailer 2001 in forward motion. The trailer comprises a point M on the front part of the trailer which allows the attachment of the fifth wheel of a towing vehicle not shown in the figure. However, this towing vehicle exerts an external force AZ on the axle M on the trailer 2001.

[0064] At least one mounted assembly 2006 per axle of the trailer 2001 is equipped with an electronic device 2007. This electronic device 2007 is located in the fluid cavity of the mounted assembly 2006. Here, the electronic device 2007 is placed on the internal wall of the tire in line with the tread of the tire casing which ensures contact between the ground and the tire casing. It would have been possible to install the electronic device at the wheel rim of the mounted assembly, while remaining in the fluid cavity of the mounted assembly 2006. For example, the electronic device could have been integrated into the rim valve like certain TPMS systems (acronym in English for Tire Pressure Monitoring System).

[0065] This electronic device 2007 comprises a pressure sensor associated with a microcontroller and a radiofrequency device at least in transmission. The radiofrequency device therefore comprises a radio wave generator and a radiocommunication antenna for transmitting the generated radio waves. The radiofrequency device can also, optionally, comprise a radio wave receiver for receiving instructors from the outside in order, for example, to launch a measurement. This electronic device 2007 also comprises a memory space for storing the measurement data from the pressure sensor before transmitting them in the form of radio waves. The electronic device can transmit the raw measurement data or the data filtered by the microcontroller. Of course, it is conventional for the pressure sensor to be accompanied by a temperature sensor.At this time, the electronic device 2007 transmits the two types of data, pressure and temperature, to the outside of the mounted assembly 2006. Here, the electronic device 2007 transmits radio waves in the UHF frequency band (acronym in English for Ultra High Frequency) and particularly in the BLE band (acronym in English for Bluetooth Low Emission).

[0066] Here, the exterior comprises at least the towing vehicle and the trailer 2001. This trailer 2001 firstly comprises a radio data reader 2005, operating in the UHF range, the receiving antennas 2105 of which are located near the mounted assemblies 2006 during the rotation thereof, in order to recover the measurement data generated by the electronic device 2007. The data are then transferred after processing, here by wire, to the transmitting antenna of the communication means 2104 located in the trailer 2001. A radio frequency transmission using specific communication means would also have been possible.This calculation means 2002 includes memory space and a processor to carry out its tasks: identify the quantities of the assembled assembly corresponding to the initial state, solve the differential equation which leads to the determination of the variation in volume of the fluidic cavity of each assembled assembly equipped with an electronic device 2007, and finally calculate the variation in load associated with the variation in volume having previously recovered the quantities of the tires necessary for this final task.

[0067] The data is then transferred, here by wire, to the calculation means 2002 located in the trailer 2001. However, the data could have been transmitted to physical means remote from the trailer 2001.

[0068] The first means is a calculation means 2002 comprising transmission / reception communication means. These communication means in a configuration other than that of [Fig.2] could receive the radio waves transmitted by the transmission communication means 2105 to transform them into digital data usable by the calculation means 2OO2. The calculation means 2002 includes memory space and a processor to carry out its tasks: identify the quantities of the assembled assembly corresponding to the initial state, solve the differential equation which leads to the determination of the variation in volume of the fluidic cavity of each assembled assembly equipped with an electronic device 2007, and finally calculate the variation in load associated with the variation in volume having previously recovered the quantities of the tires necessary for this final task.

[0069] The results and in particular the last data are sent to a second means which corresponds to an analysis means 2004. Here, the transmission of these data is done by means of a wired communication. The analysis means 2004 makes comparisons between the results of the calculation means 2002 which they recover, this communication could be a radiofrequency transmission from the calculation means 2002 using reception communication means 2104, and threshold values ​​previously entered. These threshold values ​​such as the maximum authorized load per axle of the vehicle or the maximum total load of the vehicle or the maximum authorized load per mounted assembly are possibly transmitted by querying a remote database containing data on the trailer 2001. Of course, here, the analysis means 2004 is 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 consist of a digital tablet 2003 possibly remote from the trailer 2001 and possibly a man-machine interface within the trailer 2001 comprising a display screen. These display means could also be a screen on the dashboard of the towing vehicle with radiofrequency transmission of the data to be displayed.

[0071] The display means 2003 aim to warn of the conformity or non-conformity of the trailer loading in relation to the admissible threshold values ​​according to the legislation in force.

[0072] Of course, these two embodiments of the system for implementing the method for estimating the variation in load carried and / or the load carried by a mounted assembly of a vehicle securely connected to a trailer are only illustrative examples of the system which are not limited to these two configurations. A first extreme configuration consists of integrating all of the calculation and analysis means within the electronic device on board the mounted assembly which transmits the results to a display means remote from the trailer. The other extreme configuration consists of transferring the measurement data recorded by radio waves recorded at the electronic device level and to carry out the other steps of the process on means remote from the vehicle, without ever going through the trailer or the towing vehicle.

[0073] [Fig. 3] shows a block diagram of the method for estimating the variation in load carried and / or the method for estimating the load carried by a mounted assembly of a trailer securely connected to a stationary towing vehicle. This method comprises several phases.

[0074] The first is a preliminary phase which comprises at least actions 1 to 6 which follow one another through a continuous line link system. This preliminary phase which focuses on the unhitched trailer obviously includes the equipment of the trailer, including its loading, ideally at the level of the mounted assemblies, by the installation of a pressure sensor capable of measuring the pressure of the fluid cavity delimited by the internal surface of the tire and the wheel rim by means of a dedicated electronic device. The first steps, noted 1 and 2, consist of determining the physical quantities of the fluid 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 as a lump sum or through a specific measurement.Step 3 consists of determining the load carried ZI by the assembled assembly equipped with the measuring device of the uncoupled vehicle. This determination can be made on a flat-rate basis by making assumptions about the distribution of the total load of the trailer between the various axles of the latter. The total load of the trailer being a given, for example from the trailer manufacturer, corresponds for example to the unladen mass of the trailer as specified in the technical instructions of the trailer manufacturer. Of course, it is also possible to integrate the loading of the trailer. Step 4 corresponds to obtaining specific quantities of the assembled assembly equipped with a measuring device.One of these quantities is the volume V0 which corresponds to the volume occupied by the fluid cavity of the mounted assembly when the mounted assembly is inflated to pressure PI, strictly speaking, under the internal temperature Tl, but in the absence of any load carried, i.e. not resting on the ground. The second quantity is the flattening rigidity of the pneumatic envelope of the mounted assembly per unit of volume Kp, possibly depending on the inflation pressure PI, the internal temperature Tl and the load carried ZI. Finally, a third set of quantities are those associated with the ideal gas behavior laws for the nature of the gas contained in the fluid cavity of the mounted assembly.And the penultimate step of the preliminary phase, referenced 5, is a step of determining the volume occupied VI by the fluidic cavity of the instrumented mounted assembly subjected to the load ZI and under the inflation pressure PI and the temperature TL. Finally the last step, noted 6, of the preliminary phase is. the evaluation of the quantity of gas contained in the fluidic cavity of the instrumented mounted assembly by determining the number of moles of gas n present within volume VI. Here, the hypotheses associated with the ideal gas condition apply well, it is still necessary to identify the nature of the composition of the gas, i.e. a monatomic gas or a gas mixture. In addition, 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 mounted assembly considered during an adiabatic transformation around the operating point of the mounted assembly, i.e. the pressure PI, the temperature Tl and the load Zl.Finally, in the preliminary phase, it is necessary, although not shown, to determine the load distribution on each axle of the trailer, preferably on each mounted assembly of the trailer, associated with a load applied to the coupling point M of the trailer. Optionally, a second load distribution on each axle of the trailer, preferably on each mounted assembly of the trailer, the trailer being uncoupled, can be envisaged. This second load distribution is linked to the total mass of the uncoupled trailer.

[0075] Then we move on to the main step, the beginning of which corresponds to the coupling of said trailer to the towing vehicle. Necessarily, we record the temporal variation of the inflation pressure P(t) of each instrumented mounted assembly of the trailer, which are of the order of milibar for trailers adapted to a light vehicle. These recordings are then stored in a memory space to firstly filter the raw data using a low-pass filter to eliminate high-frequency phenomena, which corresponds to step referenced 11. Then we determine the temporal variation of internal temperature T(t) of the fluid cavity using the temporal variation of internal pressure P(t) by using the evolution law determined in the preliminary step, which corresponds to step 12.Optionally, the time variation of the internal temperature T(t) of each instrumented mounted assembly of the vehicle is recorded, if it 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 which is made necessary by the adiabatic transformation of the fluid associated with the coupling of the trailer. The connection system between optional steps and the steps essential to the process are illustrated with gray lines instead of being black. However, the connection systems of the main phase are illustrated by dotted lines, while those of the preliminary phase are solid lines. Finally, as will be seen later, the se- phase. secondary has a linking system in the form of dashed lines.

[0076] One of the important steps of the main phase is the determination of the volume variation AV of the fluid cavity of each instrumented mounted assembly through step 13. This corresponds to taking into account at least the adiabatic transformation of the fluid of the fluid cavity due to the instantaneous attachment of the trailer to the towing vehicle which modifies the thermomechanical equilibrium of all the mounted assemblies of the trailer and consequently of the fluid trapped in each fluid cavity of the mounted assemblies. In addition, the fluid is assumed to follow the behavior of a perfect gas. From the internal pressure variation P(t) of each instrumented mounted assembly, it is possible to determine the internal temperature variation T(t) by means of the evolution law identified in the preliminary phase for an adiabatic transformation of the fluid.

[0077] Using the variation of the internal pressure and the internal temperature, it is possible to feed a differential equation taking into account the preceding hypotheses. The resolution by time increment of the differential equation makes it possible to obtain an estimate of the associated time variation of the volume of the fluidic cavity AV(t) corresponding to step 13. Optionally, the method can be completed by a measurement of the internal temperature T of the fluidic cavity in order to evaluate a second variation of volume of the fluidic cavity associated with the isobaric or monobaric transformation of the fluid due to the heat exchange which takes place between the fluidic cavity of the mounted assembly and the external environment through the components of the mounted assembly; that is to say the pneumatic envelope and the wheel.This second transformation is generally subsequent to the adiabatic transformation since it is the temperature variation generated by the adiabatic transformation which is at the origin of the thermal imbalance between the fluidic cavity and the external environment.

[0078] Another important step of the main phase is the evaluation of the variation in load carried AZ associated with the single variation in volume previously evaluated AV which corresponds to step 14. For this, it is necessary to take into account again the flattening rigidity of the assembled assembly KP per unit of volume. This rigidity can comprise a pneumatic component and a structural component. Taking into account a single pneumatic component KPP can be sufficient for a reliable estimation of the variation in load carried AZ.

[0079] From this variation in load carried AZ, the initial load carried ZI must be added to obtain the load carried by the instrumented mounted assembly in step 15. From this quantity on the scale of the mounted assembly, it is easy to go back to the load carried by axle load i of the trailer and therefore to the total load carried by the trailer. For this, on the assumption that only one or a few assemblies mounted, but not all, of the trailer are equipped with a measuring device, the method comprises in a preliminary phase an estimation of the load distribution on each mounted assembly or each axle of the trailer associated with an overload applied to the coupling point M of the trailer. Optionally, a second load distribution can be used to estimate the initial load of each mounted assembly or each axle of the trailer associated with the total mass of the trailer alone.

[0080] The last step, noted 16, is the comparison of the load carried Z with respect to a threshold S at the level of each mounted assembly, but also in the same way for each axle i of the trailer and finally at the level of the complete trailer. Generally, these thresholds S can be the safety conditions specific to each national legislation for the circulation of a convoy consisting of a tractor vehicle and a trailer.

[0081] According to the result of this comparison, the convoy is able to take the road with the trailer coupled to the towing vehicle since all the safety conditions are respected according to step 17 of the main phase. Otherwise, a secondary phase is followed comprising at least step 20 in which the loading of the coupled trailer is adapted. This adaptation of the loading can take place while the trailer remains coupled. It may also be envisaged to uncouple the trailer from the vehicle during this adaptation of the loading of the trailer. The adaptation of the loading consists of a modification of the location of the load in the trailer and / or a modification of the contents of the load in order, for example, to reduce the mass of the load.Once step 20 is completed, the main step should be repeated, if necessary reattaching the trailer to the vehicle and recording the inflation pressure and possibly the internal temperature of each instrumented assembly of the vehicle, which corresponds respectively to steps 11 and 12 of the synopsis. This secondary phase is repeated until the criteria authorizing the completion of step 17 are met.

[0082] [Fig.4] shows the time evolution of the pressure of the pressure sensor of the electronic device arranged on a mounted assembly of the trailer. The curve consisting of points 10 is the raw measurement of the pressure sensor while curve 11 corresponds to the temporal evolution of the filtered pressure, which is cleaned of high-frequency noise. It is this second curve which will then be used in the synoptic of [Fig.3].

[0083] This time recording of the internal pressure of the fluid cavity of the mounted assembly begins in the preliminary phase before the trailer is coupled to the towing vehicle. The moment of coupling of the trailer corresponds to the abscissa of point 100 which marks the start of the main phase. From this point 100, a rapid drop in the internal pressure of the fluid cavity is then observed until the point 101 where the pressure drop stops and even increases to a lesser extent. This point 101 marks the transition between the work of the fluid associated with the hitching of the trailer, which corresponds to a first transformation of the fluid similar to an adiabatic transformation, and the heat exchange towards 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 the times. Thus, the preliminary phase 50 ends at the abscissa of point 100. It precedes the main phase, which is separated into two successive phases. The first phase 51 is similar to an adiabatic transformation of the fluid corresponding to the work of the fluid following the hitching of the trailer. The second phase 52 corresponds to a heat exchange of the fluid with the outside.

[0084] [Fig.5] shows the temporal evolution of the internal temperature of the fluid cavity. Here, this temporal evolution is either delivered by a temperature sensor of the electronic device arranged on a mounted assembly of the trailer as illustrated by curve 12. An alternative, in the absence of measurement by a temperature sensor, is an estimation of the internal temperature, illustrated by curve 12' from, on the one hand, the recorded internal pressure and an evolution law linking the internal temperature to the internal pressure during an adiabatic transformation of the fluid and, on the other hand, the temperature outside the mounted assembly serving as a basis for the heat exchange of the fluid of the fluidic cavity with the environment outside the mounted assembly through a heat exchange coefficient. This heat exchange coefficient takes into account the thermal characteristics of the mounted assembly.In this alternative, curve 70 illustrates the evolution of the external temperature of the assembled assembly.

[0085] These changes in the internal temperature 12 and 12' of the fluid cavity of the mounted assembly begin in the preliminary phase before the trailer is coupled to the towing vehicle. The moment of coupling of the trailer corresponds to the abscissa of point 100 which marks the start of the main phase. From this point 100, a rapid drop in the internal temperature of the fluid cavity is then observed up to point 101 where the drop in temperature stops and then increases to a certain extent. This point 101 marks the transition between the work of the fluid associated with the coupling of the trailer which corresponds to a first transformation of the fluid which is similar to an adiabatic transformation and the heat exchange towards the outside which corresponds to a second transformation of the fluid. The abscissa of this point 101 corresponds to the duration T0 taking as the origin of the times the abscissa of point 100. Thus, the preliminary phase 50 ends at the abscissa of point 100.It preceded the main phase which is separated into two successive phases. The first phase 51 is similar to an adiabatic transformation of the fluid corresponding to the work of the . fluid following the coupling of the trailer. The second phase 52 corresponds to a thermal exchange of the fluid with the exterior.

[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 inertia specific to the temperature sensor. On the other hand, the hypothesis that the evolution law linking the internal pressure to the internal temperature of the fluid during an adiabatic transformation is also perhaps overestimated. However, the trend between these curves 12 and 12' is quite similar. Finally, here we do not measure the temperature outside the mounted assembly, we determine it by extrapolation of the internal temperature of the fluid cavity in the preliminary phase, which is also a source of potential errors. This estimate corresponds to the linear line 70 in [Fig.5].The heat exchange coefficient of the assembled assembly can be approximated by the sole characteristics of the tire casing initially through, for example, an estimation of the exchange surface of the tire with the external environment, which represents the external surface of the tire casing and a heat exchange coefficient X which depends on the thermal characteristics of the material properties of the tire with a distribution of the different types of heat exchange of the tire casing such as radiation, conduction and convection. This coefficient X can be estimated using the evolution of the internal temperature of the fluidic cavity in the preliminary phase, just before the main phase for example.

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

[0088] This evolution of the internal volume 13 of the fluid cavity of the mounted assembly begins in the preliminary phase before the trailer is coupled to the towing vehicle. The moment of coupling of the trailer corresponds to the abscissa of point 100 which marks the start of the main phase. From this point 100, a rapid increase in the internal temperature of the fluid cavity is then observed up to point 101 where the rise in temperature stops and then decreases to a certain extent. This point 101 marks the transition between the work of the fluid associated with the coupling of the trailer which corresponds to a first transformation of the fluid which is similar to an adiabatic transformation and the heat exchange towards the outside which corresponds to a second transformation of the fluid. The abscissa of this point 101 corresponds to the duration T0 taking as the origin of the times the abscissa of point 100. Thus, the preliminary phase 50 ends at the abscissa of point 100.It preceded the main phase which is separated into two successive phases. The first phase 51 is similar to an adiabatic transformation of the fluid corresponding to the work of the fluid following the coupling of. the trailer. The second phase 52 corresponds to a thermal exchange of the fluid with the exterior.

[0089] It is noted that at the end of phase 51, a good estimate of the variation in volume of the mounted assembly is obtained, which clearly shows that the work generated by the variation in load subjected to the mounted assembly occurs mainly during phase 51. The variations or oscillations observed correspond to the fluctuations of the transient phase corresponding to thermal equilibrium. As a result, the method described here produces a continuous measurement of the temporal load variation of the mounted assembly in the time domain.

[0090] [Fig.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 calculation of the volume variation by the proposed differential equation taking into account the thermal equilibrium with the external environment which is multiplied by the flattening rigidity of the mounted assembly. Here, the rigidity taken is that which is locally identified at the level of the initial pressure of the mounted assembly, of the initial load applied to the mounted assembly and corresponding to the initial temperature. We could have taken into account the global rigidity defined by the proposed formula which would already have given a good order of magnitude.

[0091] This evolution of the internal volume 14 of the fluid cavity of the mounted assembly begins in the preliminary phase before the trailer is coupled to the towing vehicle. The moment of coupling of the trailer corresponds to the abscissa of point 100 which marks the start of the main phase. From this point 100, a rapid increase in the internal temperature of the fluid cavity is then observed up to point 101 where the rise in temperature stops and then decreases to a certain extent. This point 101 marks the transition between the work of the fluid associated with the coupling of the trailer which corresponds to a first transformation of the fluid which is similar to an adiabatic transformation and the heat exchange towards the outside which corresponds to a second transformation of the fluid. The abscissa of this point 101 corresponds to the duration T0 taking as the origin of the times the abscissa of point 100. Thus, the preliminary phase 50 ends at the abscissa of point 100.It precedes the main phase which is separated into two successive phases. The first phase 51 is similar to an adiabatic transformation of the fluid corresponding to the work of the fluid following the coupling of the trailer. The second phase 52 corresponds to a thermal exchange of the fluid with the exterior.

[0092] It is noted that at the end of phase 51, a good estimate of the load variation applied to the assembled assembly is obtained, which clearly shows that the work generated by the load variation occurs mainly during phase 51. The variations or oscillations observed 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 mounted assembly in the time domain. Curve 80 corresponds to the measurement on a ground scale of the overload applied to the mounted assembly of the trailer. In conclusion, the applied load variation is well captured by the proposed method.

Claims

1. Claims Method for estimating the variation in load carried by a mounted assembly of a trailer generated by the coupling of the trailer to the stationary towing vehicle comprising the following steps: In the preliminary phase, • Equip at least one mounted assembly of at least one axle of the trailer not coupled to the towing vehicle 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 trailer, very preferably all the mounted assemblies of all the axles of the trailer; • Determine the initial load ZI applied to at least one mounted assembly equipped with the uncoupled trailer, • Determine the initial inflation pressure PI of the fluid cavity of at least one mounted assembly equipped with the trailer; • Determine the initial internal temperature Tl of the fluid cavity of at least one mounted assembly equipped with the trailer; • Evaluate the initial volume VI of the fluid cavity of the 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 at least one assembled assembly, inflated and subjected to the load Zl, equipped with at least one pressure sensor; In the main phase: • Hitch the trailer to the vehicle at a geometry point M of the trailer; • Record the internal pressure P of the fluid cavity of the at least one equipped mounted assembly at an acquisition frequency Fl; • Determine the internal temperature T of the fluid cavity of the at least one equipped mounted assembly using the evolution law determined in the preliminary phase; • Evaluate an intermediate volume variation AV of the 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 an ideal gas behavior; and • Estimate a load variation AZ carried by the at least one equipped mounted assembly using a second function comprising as parameter the intermediate volume variation AV 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 trailer generated by the coupling of the trailer to a stationary towing vehicle 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 trailer 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 the load carried by a mounted assembly of a trailer generated by the coupling of the trailer to a stationary towing vehicle 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 the load carried by a mounted assembly of a trailer generated by the coupling of the trailer to a stationary towing vehicle 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 the load carried by a mounted assembly of a trailer generated by the coupling of the trailer to a stationary towing vehicle 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 the load carried by a mounted assembly of a trailer generated by the coupling of the trailer to a stationary towing vehicle 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 the load carried by a mounted assembly of a trailer generated by the coupling of the trailer to a stationary towing vehicle 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 pressure PO, preferably the pressure PO is the initial pressure PI.

8. Method for estimating the variation in the load carried by a mounted assembly of a trailer generated by the coupling of the trailer to a stationary towing vehicle 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 the load carried by a mounted assembly of a trailer generated by the coupling of the trailer to a stationary towing vehicle 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: [Math.l] Z = KPP * P * AfV) = KPP *P* (VI - V0) Where KPP is the flattening pneumatic stiffness of the tire of the assembled assembly per unit volume.

10. Method for estimating the variation in the load carried by a mounted assembly of a trailer generated by the coupling of the trailer to a stationary towing vehicle according to one of claims 1 to 9 in which the variation in volume AV of each equipped mounted assembly is estimated by solving the following differential equation: [Math.2] / opc \ M( U) * dU = 0 and M h' = ( FP -n * R -h '0 0 0 / , and With [MATH 3] / P\ U = K 1 w 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 trailer integrally connected to a vehicle comprising the method for estimating the variation in the load carried by a mounted assembly of a trailer generated by the coupling of the trailer to a stationary vehicle 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 trailer, preferably on each mounted assembly of the trailer, associated with the application of an additional load exerted at the coupling point M of the trailer to the vehicle, optionally the method also comprises a step of determining a second load distribution on each axle of the trailer, preferably a second load distribution on each mounted assembly of the trailer, associated with the weight of the trailer, 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 trailer using the load variation AZ carried by the at least one mounted assembly, equipped with 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 trailer, 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 trailer, in that the method comprises a step of comparison with at least one threshold value S of the load carried Z estimated at each axle i of the trailer and / or of the total load carried of the trailer which is the summation of the loads carried by each axle i of the trailer, and when the at least one threshold value S is crossed, the mass content K of the trailer is adapted in the trailer during a secondary phase before carrying out again all the steps of the main phase.

12. System (2000) for implementing the method for estimating the variation in load carried by a mounted assembly of a trailer securely connected to a vehicle generated by the coupling of the trailer to the stationary vehicle according to one of claims 1 to 10 and / or for implementing the method for estimating the load carried by a trailer securely connected to a vehicle according to claim 11 comprising: • A trailer (2001), equipped with a coupling device at a point M of the trailer capable of receiving the fifth wheel of a vehicle, 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 means of calculation (2002); and • at least one display means (2003) comprising at least a second means of communication (2102) radiofrequency at least in reception

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

15. System (2000) for implementing the method for estimating the variation in load carried by a mounted assembly of a vehicle securely connected to a trailer and / or for implementing the method for estimating the load carried by a trailer securely connected to a vehicle according to claim 14 in which the at least one analysis means (2004) comprises at least a fourth radiofrequency transmission / reception communication means (2104)

16. System (2000) implementing the method for estimating the variation in load carried by a mounted assembly of a vehicle securely connected to a trailer and / or for implementing the method for estimating the load carried by a trailer securely connected to a vehicle 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) implementing the method for estimating the variation in load carried by a mounted assembly of a vehicle securely connected to a trailer and / or for implementing the method for estimating the load carried by a trailer securely connected to a vehicle according to one of claims 12 to 16 wherein 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 means of reading (2005) is carried out by UHF radiofrequency waves, preferably in BLE (Bluetooth Low Emission).

18. System (2000) for implementing the method for estimating the variation in load carried by a mounted assembly of a vehicle securely connected to a trailer and / or for implementing the method for estimating the load carried by a trailer securely connected to a vehicle according to one of claims 12 to 17 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 trailer (2001) and / or the vehicle, preferably located on the instrument cluster of the vehicle

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

20. System (2000) implementing the method for estimating the variation in load carried by a mounted assembly of a vehicle securely connected to a trailer and / or for implementing the method for estimating the load carried by a trailer securely connected to a vehicle 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 trailer (2001), preferably located on the mounted assembly (2006).

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