Method for estimating the variation in load distribution on a trailer at standstill

Abstract

The invention relates to a method for estimating the variation in the load carried by an inflatable system of a trailer generated by loading the loading space of the trailer at standstill, the method comprising the following steps: - loading the trailer; - recording the internal pressure P in the fluid cavity of an equipped inflatable system; - recording the internal temperature T in the fluid cavity of the equipped inflatable system; - evaluating a variation in the volume ΔV of the equipped inflatable system on the basis of the recorded internal pressure P and the recorded internal temperature T using a model of a fluid undergoing adiabatic transformation, wherein the fluid exhibits ideal gas behaviour; and - estimating a variation in the load ΔZ carried by the equipped inflatable system using a second function that comprises, as a parameter, the evaluated intermediate variation in the volume ΔV and the flattening stiffness of the inflatable system per unit volume KSG.

Description

DESCRIPTION TITLE: METHOD FOR ESTIMATING THE VARIATION IN LOAD DISTRIBUTED ON A STATIONARY TRAILER 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 loading of the loading volume of a trailer, in particular when the trailer is stationary and not coupled to a towing vehicle. 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 trailer's axles is in a safe condition before even setting it in motion, which makes it more reliable and allows for compliance 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 trailer is loaded. 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 tire's footprint on the ground.Although a measurement using a static pressure quantification system is possible by inserting the measurement system between the inflatable system and the ground, its implementation is not simple and the accuracy of the measurement is subject to the correct positioning of the measurement system. Another alternative is to evaluate the dimension of the contact patch in rolling conditions by measuring the deformation of the tire 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.In addition, the precision of these measurements is delicate for very heavy loads where the deformation of the tire which determines the load variations tends to occur. stabilize according to the circumferential direction on which the evolution of the measurement of the deformation of the pneumatic envelope generally relates.

[0003] The following objects and methods of the invention aim to solve the problem of measuring the variation in load carried by the trailer in the absence of a measurement system external to the trailer, i.e. one that can be used at any time without specific measuring means. In addition, this evaluation is carried out while the vehicle is stationary, making it possible to decide on the safety criterion for loading the trailer before any movement thereof. Description of the invention

[0004] The invention relates to a method for estimating the variation in load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary, comprising the following steps: • In the preliminary phase, i.e. before loading the trailer: • Equip at least one inflatable system serving as an interface element between the ground and the trailer, such as a mounted assembly or a pneumatic cylinder, associated with a connecting component of the trailer, such as a stand or an axle, with at least one pressure sensor, the at least one sensor being capable of measuring the internal pressure of the fluid cavity of the inflatable system delimited by at least one deformable surface of the inflatable system, preferably at least one inflatable system of each group of inflation systems linked to the same connecting component of the trailer, very preferably each inflatable system of each connecting component of the trailer; • Equip the at least one inflatable system with at least one temperature sensor, the at least one sensor being capable of measuring the internal temperature of the fluid cavity of the inflatable system; and • Determine the initial load ZI applied to at least one inflatable system equipped with the trailer, • Determine the initial inflation pressure PI of the fluid cavity of at least one inflatable system equipped with the trailer; • Determine the initial internal temperature Tl of the fluid cavity of at least one inflatable system equipped with the trailer; • Evaluate the initial volume VI of the fluid cavity of at least one equipped inflatable system using a first function comprising as parameter the volume VO of the fluid cavity of the unloaded inflatable system inflated to the initial pressure PI and the flattening rigidity of the inflatable system per unit volume KSG, • Evaluate the number of moles of fluid or of the fluidic cavity of at least one inflatable system equipped from a model taking into account the inflation pressure PI, the initial volume VI and the temperature Tl; • In the main phase, i.e. when loading the trailer: • Load the trailer loading volume; • Record the internal temperature T of the fluid cavity of at least one equipped inflatable system; • Record the internal pressure P of the fluid cavity of at least one equipped inflatable system; • Evaluate an intermediate volume variation AV of at least one inflatable system using the recorded internal pressure P and the recorded internal temperature T from a fluid model in adiabatic transformation, the fluid having a perfect gas behavior; and • Estimate a variation in load carried AZ by the at least one equipped inflatable system using at least one second function, the at least one second function including as parameter the variation in intermediate volume AV evaluated and the flattening rigidity of the inflatable system per unit of volume KSG.

[0005] According to a preferred embodiment, in the preliminary phase, the method comprises a step of determining a law of evolution of the internal pressure P of the fluidic cavity from the internal temperature T during an adiabatic transformation of the fluid of the fluidic cavity of the inflated and charged inflatable system, in the main phase, the method comprises a step of extracting the variation of internal temperature T' generated by the sole adiabatic transformation of the fluid from the recording of the internal temperature T, the method comprises a step of determining an internal pressure P' of the fluidic cavity from the internal temperature T' and the law of evolution determined in the preliminary phase and the step of evaluating the variation of volume AV comprises a first phase where the evaluation is carried out with the determined internal pressure P' and extracted internal temperature T' and at least a second phase where the evaluation is carried out with a part of the internal temperature T recorded outside a time frame corresponding to the extracted internal temperature variations T' and a part of the recorded internal pressure P outside said time frame.

[0006] Advantageously, the extraction of the internal temperature variation T' begins when the recorded internal temperature T changes, a first time, in variation speed and ends when the recorded internal temperature T changes a second time in variation speed or after a duration T0 corresponding to the end of the adiabatic transformation of the fluid, the start of the duration T0 corresponds to the first change in variation speed of the recorded internal temperature T.

[0007] According to another preferred embodiment, in the preliminary phase, the method comprises a step of determining a law of evolution of the internal temperature T of the fluidic cavity from the internal pressure P during an adiabatic transformation of the fluid of the fluidic cavity of the inflated and charged inflatable system, in the main phase, the method comprises a step of extracting the variations of internal pressure P” generated by the sole adiabatic transformation of the fluid from the recording of the internal pressure P,the method comprises a step of determining an internal temperature T” of the fluid cavity of the inflatable system from the internal pressure P” and the evolution law determined in the preliminary phase and the step of evaluating the volume variation AV comprises a first phase where the evaluation is carried out with the extracted internal temperature P” and the determined internal temperature T” and at least a second phase where the evaluation is carried out with a part of the internal pressure P recorded outside a time frame of the extracted internal pressure variations P” and a part of the recorded internal temperature T outside said time frame.,

[0008] Advantageously, the extraction of the internal pressure variation P” begins when the recorded internal pressure P changes, for the first time, its variation speed and ends when the recorded internal pressure P changes its variation speed for a second time or after a duration T0 corresponding to the end of the adiabatic transformation of the fluid, the start of the duration T0 corresponding to the first change in the variation speed of the recorded internal pressure P.

[0009] The process of determining the variation of applied load comprises two successive phases. The first phase consists of identifying the intrinsic parameters of the inflatable system before loading the trailer. This constitutes an installation of the trailer measurement system through the implementation of the measurement systems at the trailer ground connection components such as the trailer axles and the landing gear and the identification of the initial parameters of the inflatable systems 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 inflatable system by the trailer, the internal temperature of the fluid cavity and the inflation pressure of the fluid cavity of each inflatable system. Intuitively, the nature of the fluid is assumed to be known to estimate the quantity of fluid trapped in the fluid cavity.

[0010] The second phase represents the step of evaluating the load variation applied to an inflatable system of the trailer equipped with an electronic device due to the loading of the trailer's loading volume, in a single step or using several successive steps. The electronic device comprising the pressure sensor and a temperature sensor, manages and conditions the recording of the measurement of the fluid parameters. Thus, recordings of the inflation pressure and the internal temperature of the fluid cavity of the inflatable system equipped with an electronic device are made at the time of loading of the trailer. The temporal evolutions, in transient phase, of the physical quantities of the fluid cavity are important.The trailer loading step results in 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 in front of 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 external surfaces of the inflatable system. 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 components of the inflatable system. In addition, the thermal equilibrium is generally 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 different sampling frequencies for the physical quantities, temperature and pressure. However, the same sampling frequency can also be used for both sensors.

[0011] Optionally, if the evolution of the internal temperature is not suitable for observing the first transformation of the fluid linked, for example to a too low temperature sampling frequency, 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. This evolution law links the variation of internal temperature T associated with the variation of internal pressure P of the inflatable system during an adiabatic transformation of the fluid when it is in use condition, in particular to the load ZI carried around the inflation pressure PI and the temperature Tl. This evolution law can be fixed or derived from an experimental characterization or a numerical simulation of the inflatable system considered.

[0012] It therefore converts the internal pressure measurement of the fluid in the fluid cavity and a determination of the internal temperature of the fluid generated by the adiabatic transformation alone.

[0013] Then, it is possible to evaluate a first intermediate volume variation using a fluid model undergoing an adiabatic transformation. Here, the term adiabatic means that the transformation that the fluid undergoes due to the trailer loading step is carried out without heat exchange between the fluid cavity and the exterior of the inflatable system, which assumes that it is rapid. Therefore, using only the variation in the measured inflation pressure and the internal temperature variation determined using the measurement of the internal pressure variation and the evolution law linking the internal temperature variation T associated with the internal pressure variation P of the mounted assembly, it is possible to estimate the first volume variation of the fluid cavity generated by the loading or unloading of the trailer.We will make the entirely suitable assumption for air or nitrogen that the fluid, in the gaseous state, of the cavity of the inflatable system equipped with the trailer is an ideal gas.

[0014] Then, a second intermediate volume variation is evaluated using a second fluid transformation. This second transformation is associated with the thermal equilibrium of the fluid with the exterior through the components of the inflatable system, mainly the deformable surface. The second volume variation undergone by the inflatable system following this second transformation is then evaluated using the internal temperature variation and the pressure variation recorded in the fluid cavity during of the transient phase linked to the trailer loading step but subsequent to the first transformation of the fluid, i.e. when the inflation pressure has changed its temporal evolution a second time. 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 the equipped inflatable system. However, the first intermediate volume variation is sufficient for the estimation, to a first order of magnitude, of the first overload applied to the inflatable system. Then a possible second loading or unloading step is carried out at the level of the trailer loading volume. This second step can be divided into two successive transformations of the fluid as during the previous loading step.Continuous measurement during the various loading or unloading stages of the trailer allows the volume variation of the fluid cavity of the equipped inflatable system to be estimated precisely since the starting point before the new loading stage is measured with respect to the internal pressure and the internal temperature of the fluid and the internal volume of the fluid cavity can be determined. Therefore, knowing the initial point and recording the parameters of the fluid during the new loading stage, the internal volume variation during the second loading stage up to a new loading stage or the thermomechanical equilibrium of the fluid of the fluid cavity can be determined without difficulty.

[0015] Optionally, if the evolution of the internal pressure is not suitable for observing the first transformation of the fluid, linked for example to a sampling frequency of the internal pressure that is too low, using the variation of the internal temperature of the fluidic cavity, it is possible to determine the variation of the internal pressure of the fluid of the fluidic cavity which is determined, for this purpose, by the evolution law previously determined in the preliminary phase. This evolution law links the variation of internal temperature T associated with the variation of internal pressure P of the inflatable system when it is in use condition, in particular to the load ZI carried around the inflation pressure PI and the temperature TL This evolution law can be fixed or derived from an experimental characterization or a numerical simulation of the inflatable system considered.

[0016] It therefore converts the internal temperature measurement of the fluid in the fluid cavity and a determination of the internal pressure of the fluid generated by the adiabatic transformation alone.

[0017] As before, it is possible to evaluate a first intermediate volume variation using a fluid model undergoing an adiabatic transformation. Therefore, using only the variation of the measured internal temperature and the internal pressure variation determined by the evolution law from the temperature variation of the fluid cavity, it is possible to estimate the first volume variation of the fluid cavity generated by the work related to loading or unloading the trailer, the fluid having undergone an adiabatic transformation.

[0018] Preferably, a second intermediate volume variation is evaluated using a second fluid transformation. This second transformation is associated with the thermal equilibrium of the fluid with the exterior through the components of the inflatable system, mainly the deformable surface. The second volume variation undergone by the inflatable system following this second transformation is then evaluated using the internal temperature variation recorded in the fluid cavity during the transient phase linked to the loading of the trailer but subsequent to the first fluid transformation, i.e. when the internal temperature has changed its temporal evolution a second time. Taking this second volume variation into account guarantees better accuracy in evaluating the volume variation of the fluid cavity, which improves the accuracy of the load variation measurement at the equipped inflatable system.However, the first intermediate volume variation is sufficient to estimate, to a first order of magnitude, the first overload applied to the inflatable system.

[0019] 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 loading of the trailer, at the level of the equipped inflatable systems. However, in a simple approach, the inflatable system 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 inflatable system.

[0020] 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 inflatable systems of the trailer. Once these equilibria are established, the variations temperature and pressure of the fluid cavity are infinitesimal, they are then in a new thermomechanically stable state. Generally, when the loading of the trailer is done by a succession of operations, the thermomechanical equilibrium does not have time to establish itself, it is then appropriate to follow the continuous evolution throughout the loading of the trailer by taking as a starting point before a new work associated with a loading operation, the thermomechanical state of the fluid. This being evaluated continuously, the variation in volume of the equipped inflatable system is correct.

[0021] Therefore, if the internal pressure and internal temperature variations are satisfactory to identify all the phenomena, it is possible to evaluate the intermediate volume variation associated with a loading step of the trailer loading by directly using the measured internal pressure variation and the measured internal temperature variation by solving a differential equation taking into account that the fluid is a perfect gas, that the fluid undergoes an adiabatic transformation and that the fluid is in thermal equilibrium with the external environment through the components of the inflatable system.

[0022] Finally, it should be noted that the determination of the first transformation of the fluid linked to the work associated with the additional load, its beginning and its end, is carried out by calculating the derivative and / or the second derivative of the variation of the parameter of the fluid in order to detect the change in the speed of evolution of these parameters.

[0023] Once the intermediate volume variation has been evaluated for the equipped inflatable systems, the associated static load variation resulting from the trailer loading on each inflatable system equipped with the trailer must be evaluated. To do this, the intermediate volume variation of each equipped inflatable system must be transformed into an equivalent load variation. To this end, a characteristic of the inflatable system must be taken into account, in particular that of the deformable surface of the inflatable system, which is called flattening stiffness per unit volume KSG. This quantity makes it possible to link the load variation carried by the inflatable system to the volume variation of the fluid cavity generated by the load variation carried, the inflatable system being crushed on a plane perpendicular to the applied load.This characteristic can of course be a fixed quantity or obtained by an experimental characterization of the inflatable system or deduced from a numerical simulation campaign of the same inflatable system. The inflatable system 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 inflatable system is a quantity defined locally around the initial point of use of the inflatable system in the frame associated with the internal pressure P, the internal temperature T and the volume of the fluid cavity V.

[0024] Preferably, before the main step, the at least one equipped inflatable system is in a thermomechanically stabilized state.

[0025] It is preferable that the transient phenomena recorded at the level of the sensors of the electronic device are only due to the disturbance of the balance of the trailer generated by the loading of the latter before the start of the recordings. 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 loading 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.Once the various successive loading operations have been carried out, it is advisable to wait until the equipped inflatable system is thermomechanically stable in order to have the best possible precision on the load variation and therefore the load carried by the inflatable system.

[0026] Advantageously, the temperature sensor and the pressure sensor are fixed on the at least one deformable surface of the equipped inflation system.

[0027] It is advantageous for the sensors measuring low amplitude transient phenomena to be placed close to the occurrence 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 inflatable systems, it is advantageous for the sensors to be located at the level of the inflatable system and not at the level of the centralized system. In the same logic, if the sensors are placed on the deformable surface of the inflatable system on the inside of the fluid cavity, the measurement will be more precise than if the sensors are mounted on the less deformable surfaces of the inflatable system due to the distance of the measurement from the occurrence of the physical phenomenon which acts on the deformable surface due to the transient nature of the physical phenomenon.

[0028] Advantageously, the at least one pressure sensor operates with a resolution of less than one millibar.

[0029] Advantageously, the at least one temperature sensor operates with a resolution of less than one hundredth of a degree.

[0030] Thus, it is possible to evaluate small variations in volume and therefore small variations in load.

[0031] Preferably, the acquisition frequency of the sensor is between 0.1 Hz and 10 Hz.

[0032] It is useful for the acquisition frequency to be high to capture the first transformation of the fluid which is rapid. It is quite possible to use the same acquisition frequency for both sensors but this is not mandatory thanks to the alternatives for estimating the adiabatic transformation of the fluid.

[0033] According to a particular embodiment, the determination of the initial volume V0 takes into account the geometry of the unloaded inflatable system inflated to a reference pressure PO, preferably the pressure PO is the initial pressure PI.

[0034] Advantageously, the geometry of the inflatable system is determined using an identifier of the equipped inflatable system, preferably obtaining the identifier of said inflatable system is carried out by radiofrequency interrogation of an electronic device located on the inflatable system.

[0035] To initiate the measurement system and in particular the determination of the initial volume VI of the fluid cavity, it is necessary to determine the volume V0 of the fluid cavity which corresponds to the volume delimited by the unloaded inflatable system, i.e. the inflatable system with a reference inflation pressure PO which is preferably the initial pressure PI.

[0036] To determine this volume V0, the geometry of the inflatable system for a reference inflation pressure PO must be known. It is realistically assumed that the geometry of the non-deformable parts of the inflatable system is not influenced by the inflation pressure. These geometries can be accessed via an inflatable system database. Knowing the identity of the inflatable system makes it possible to isolate the correct geometry in this database. The identity of the inflatable system can be obtained through optical reading of the regulatory markings affixed to the external surface of the inflatable system. The identity can also be transmitted by radiofrequency interrogation of an electronic device present on the inflatable system such as an RFID tag (acronym in English for Radio Frequency Identification), a TMS (acronym in English for "Tyre Mounted Sensor"), in the case of a tire, 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 of a mounted assembly for example.

[0037] Preferably, the load variation Z of the at least one equipped inflatable system is estimated by a relationship according to the following formula [MATH 1] , where K P SG is the flattening pneumatic stiffness of the inflatable system per unit volume.

[0038] This is a simple and elementary model that links the load applied to the inflatable system to the variation in volume of the fluid cavity of the inflatable system between a first state, for example unloaded, of volume Vi and a second state of volume Vi+i, the inflation pressure P of the fluid cavity and the pneumatic stiffness of the inflatable system corresponding to the flattening of the inflatable system 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, we make the assumption that the rigidity of the structural nature of the inflatable system is negligible compared to that of the pneumatic nature, which is a realistic assumption for a pneumatic envelope for a trailer. However, it is quite possible to take into account the structural rigidity of the inflatable system in the previous formula by adding it to the product of the pneumatic stiffness by the inflation pressure.If one of the states of the inflatable system corresponds to a zero load applied to the inflatable system, the variation in load carried then corresponds directly to the load carried by the inflatable system in the other volume state.

[0039] According to an advantageous embodiment, the variation in volume AV of the at least one equipped inflatable system is estimated by solving a differential equation according to the following form: [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.

[0040] This differential equation translates the link between the parameters of the fluid in the cavity of the inflatable system 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. The thermal equilibrium with the external environment is taken into account by the direct measurement of the internal temperature of the fluid cavity and possibly the temperature of the environment external to the mounted assembly.

[0041] The invention also relates to a method for estimating the variation in the load carried by a trailer generated by the loading of the loading volume of the unhitched trailer when stationary, comprising the method for estimating the variation in the load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary, in which, in the preliminary phase, at least one inflatable system of each component for connection with the ground of the trailer, preferably each inflatable system of each component for connection with the ground of the trailer, is equipped and the method comprises a step of estimating the variation in load carried by an inflatable system not equipped with a component for connection with the ground of the trailer from the estimated variations in load carried by the equipped inflatable systems, in the main phase,the method comprises a step of determining the variation in load carried by the trailer constituting the sum of the variations in load carried by each inflatable system of each component connecting with the ground of the trailer.

[0042] Here, the objective is no longer to estimate the variation in load carried at the level of a single inflatable system associated with a component connecting to the trailer floor, but to determine the variation in overall load carried at the level of the trailer. To this end, each component connecting to the trailer floor must be equipped with an inflatable system equipped with pressure and temperature sensors. This then makes it possible to estimate the location of the additional load carried within the loading volume of the trailer, both longitudinally and laterally according to the dimensions of the trailer. Then, a distribution law of the additional load estimated according to its location is required to estimate the additional loads applied to the inflatable systems not equipped with measurement sensors for each component connecting to the trailer floor.Of course, if each inflatable system of each component connecting to the trailer floor is equipped, this distribution is not essential. It then preferentially robustifies the process by providing a point. of checking the measurements made against the theory. It is then possible to estimate the variations in load carried applied to each inflatable system of each component of connection with the ground of the trailer. The last step therefore consists of summing the variations in load carried by all of these inflatable systems to estimate the variation in load carried at the level of the trailer overall. The summation of the variations in load carried at the level of the trailer at each stage of loading of the trailer makes it possible to estimate the overall load carried by the trailer especially if the initial load of the trailer is determined before the first loading stage if this is relevant for the operation of the trailer. For example, the empty load of the trailer is not necessarily relevant data for estimating the weight of the load transported by the trailer. But it becomes useful for estimating the overall load carried by the various axles of the trailer.

[0043] The invention also relates to a method for estimating the load carried by an inflatable system of a trailer comprising the method for estimating the variation in the load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary, the method is characterized in that the method comprises a step of estimating the load Z carried by the at least one equipped inflatable system using the load variation AZ carried by the at least one equipped inflatable system and determining the initial load ZI of the at least one equipped inflatable system of the trailer.

[0044] By adding the initial load ZI carried by the inflatable system, or the inflatable systems of the trailer connection component, or all the inflatable systems connected to the trailer connection components, before loading the trailer load volume to the loaded variation AZ evaluated at the same inflatable system, this makes it possible to evaluate the total load established at the inflatable system, or the trailer connection component or the trailer. The evaluation of the total load carried by the trailer then amounts to just adding the static loads established on all the trailer connection components. It is then possible to compare the loading conditions between the trailer connection components or the inflatable systems of the same trailer connection component even before the trailer is coupled to a towing vehicle and then starts to move.This checks the correct distribution of the total load or the load variation generated by the loading of the trailer on the various connecting components of the trailer or the trailer as a whole.

[0045] The invention also relates to a system for implementing the method for estimating the variation in load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary and / or for implementing the method for estimating the variation in the load carried by a trailer generated by the loading of the loading volume of the unhitched trailer when stationary and / or for implementing the method for estimating the load carried by an inflatable system of a trailer comprising: • a trailer, fitted with at least one inflatable system equipped with an electronic device on at least one connecting component of the trailer; • the electronic device comprising at least one pressure sensor, at least one temperature sensor, at least one electronic chip, at least one memory space capable of recording the signals from the sensors, 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 radiofrequency communication means at least in reception.

[0046] As mentioned by the method, the sensors should be located on the inflatable system which is potentially driven by a rotational movement relative to the trailer as in the case of a mounted assembly. Therefore, the electronic device conditioning at least the signals from the sensors should be provided with a means of communication, for example radio frequency, in transmission to simply transmit the data beyond the inflatable system 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 inflatable system at the level of the inflatable system. 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 calculation results beyond the inflatable system.Radio frequency communication from the inflatable system's electronic device can 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, or 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 as well as at the dashboard level for example.

[0047] Therefore, the proposed structural form allows it to adapt to several possible technical configurations while being functional for implementing the said process.

[0048] Preferably, the system comprises an analysis means capable of analyzing a result output from at least one calculation means.

[0049] The result of the calculation means is the volume variation or the load variation or the load carried by each inflatable system equipped with the electronic device. If these quantities are to be compared or ordered for presentation on the display means, one or more tasks may need to be performed before sending a message to the display means. This optional element of the system, which provides a service to the trailer operator, must be positioned between the calculation means and the display means. Structurally, it may be associated with one and / or the other by a wired connection or be physically separated from these elements by means of radio frequency communication means.

[0050] According to a first particular embodiment, the at least one calculation means comprises at least one third radiofrequency transmission / reception communication means.

[0051] In the case where the calculation means is physically separated from the electronic device on the one hand and from the display means on the other hand, it is appropriate that the latter can communicate with the other two elements. This is the case, for example, when the calculation means is on the trailer; it retrieves the data on the physical parameters of the fluid from the electronic device through 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 via this radio frequency communication.

[0052] According to a second particular embodiment, the at least one analysis means comprises at least a fourth radiofrequency transmission / reception communication means.

[0053] In the case where the analysis means is physically separated 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 trailer; it retrieves, for example, load variations or loads applied to the various inflatable systems of the trailer from the calculation means present on the trailer through radio frequency communication with the latter. On the other hand, 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 by radio frequency communication.

[0054] 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 communication means at least in reception.

[0055] In the case where the electronic device has a communication range that is not sufficient to ensure communication to the calculation means, or the display means, it is appropriate to use a reading means to retrieve 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 inflatable system. Indeed, in order to reduce the mass of the electronic device at the level of the inflatable system, it is appropriate to limit the energy source necessary for the transmission of data which is the energy-consuming function of the electronic device.

[0056] 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”).

[0057] The UHF band (acronym for Ultra High Frequencies) allows for significant data transmission with an interesting throughput, 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 allows to share the system's communication resources with those already present on the vehicle, trailer or in road infrastructure.

[0058] 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.

[0059] The display means is used to warn the operator who is carrying out operations on the trailer, whether he is the driver of the convoy which will consist of the trailer behind his driving position or another person responsible for the quality of loading of the trailer.

[0060] According to an advantageous embodiment, a part of the at least one reading means is located on the trailer.

[0061] According to another advantageous embodiment, part of the at least one calculation means and / or part of the at least one analysis means is located on the trailer, preferably located on the inflatable system.

[0062] The trailer is a natural information relay instrument since the inflatable system is connected to it. Therefore, it is entirely desirable for the structural devices of the system to be located on the trailer, although the alternative is also possible. However, the trailer ensures a certain confidentiality of the data, unlike communications to servers, for example, unless secure communication protocols are implemented. Of course, in order to minimize the impact of this system in the trailer environment, which is today complex, locating the functions at the inflatable system level limits interference with other structural components of the trailer and / or vehicle. Brief description of the drawings

[0063] 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. 1 presents a system for implementing the method for estimating the variation in load carried by an inflatable system of a trailer and / or for implementing of the method for estimating the load carried by an inflatable system of a trailer when stationary 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 block diagram of the method for estimating the variation in load carried and / or the load carried by an inflatable system of a trailer during loading of the 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 temporal evolution of the internal temperature of the fluidic cavity; • Fig. 6 presents a temporal estimate of the variation in volume of the fluidic cavity according to the invention; • Fig. 7 shows a time estimate of the load variation of a mounted trailer assembly associated with the loading of the trailer's cargo volume. Detailed description of the embodiments

[0064] 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 an inflatable system of a trailer connected to a connecting component of the trailer. This system 2000 comprises a trailer 2001 here comprising three axles of mounted assemblies 2006 distributed over the trailer 2001. The trailer 2001 comprises a pair of stands 2008 located on the front of the trailer, one stand on each side of the trailer along the trailer 2001. The pair of stands 2008 and the three axles represent the components connecting the trailer to the ground. The trailer 2001 comprises a point M on the front part of the trailer which allows the attachment of a fifth wheel of the towing vehicle.The trailer 2001 includes a center of gravity G where the weight P of the trailer with its load in the loading volume is applied, which corresponds to the force generated by the total mass of the trailer and its initial load, taking into account the gravity of the Earth. This weight P is balanced by reaction forces exerted on the one hand on the mounted assemblies 2006 of the trailer, which are called Zi to Z3 depending on the axle where the mounted assembly is connected. 2006 and on the other hand on the 2008 stand which is called Z4. The reaction force is observed here at the level of the inflatable system 2006 of the 2008 stand which is located at the interface between the 2008 stand and the structure of the trailer. It is quite possible to imagine that the inflatable system of the stand is located at the interface between the ground and the stand or is inserted along the stand. The presence of an additional load on the trailer, which corresponds to the loading of the loading volume of the 2001 trailer, causes the appearance of additional reaction forces noted respectively AZi to AZ3 on the mounted assemblies 2006 of each respective axle and AZ4 which stabilize when the permanent regime is reached to balance the additional load.

[0065] The objective of the process is to determine the reaction forces on each inflatable system of the trailer which are stabilized when the permanent regime is reached to go back to the variation of load carried by the loading, including unloading for example of the trailer.

[0066] Preferably, here each inflatable system 2006 of the trailer 2001 is here equipped with an electronic device 2007. This electronic device 2007 is located in the fluid cavity of the inflatable system 2006. Here, the electronic device 2007 is placed on the internal wall of the inflatable system 2006 at the right of the deformable surface. It would have been possible to install the electronic device at the level of the rigid surfaces of the inflatable system, while remaining inside the fluid cavity of the inflatable system 2006. For example for a pneumatic mounted assembly, the electronic device could have been integrated into the rim valve like certain TPMS systems (acronym in English for Tyre Pressure Monitoring System).

[0067] This electronic device 2007 comprises a pressure sensor and a temperature 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 sensors 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. The electronic device 2007 transmits both types of data, pressure and temperature, to the outside of the mounted assembly 2006.Here, the 2007 electronic device. emits radio waves in the UHF frequency band (acronym for Ultra High Frequency) and particularly in the BLE band (acronym for Bluetooth Low Emission)

[0068] 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 near the inflatable systems 2006 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 radio frequency 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 inflatable system 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 inflatable system 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 inflatable system necessary for this final task.

[0069] 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 radio frequency communication could have been set up. The analysis means 2004 makes comparisons between the results of the calculation means 2002 and orders the results to feed the display means. Of course, the analysis means 2004 could 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 which is embodied, among other things, by the radiocommunication antenna of the trailer 2001 and a second communication means 2102 present on the display means 2003.

[0071] These means of communication 2104 and 2102 transfer their data through a communication network to a tablet or smartphone 2003 in order to inform how the load distribution of the trailer loading is carried out.

[0072] If the distribution of the load on the trailer is not satisfactory, a modification of the load should be made, whether it be a reduction in the mass of the load or a modification of the positioning of the load in the trailer in order to better distribute the load on the connecting components such as the axles of the trailer 2001 when loading the trailer. It is perfectly possible to continue recording the measurement signals of the electronic device 2007 during the modification of the trailer loading to estimate the new load carried by each inflatable system 2006 equipped with an electronic device 2007 of the trailer 2001.

[0073] 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 2001, the axles, which here correspond to components for connecting the trailer with the ground, are numbered from 1 to 3 according to the direction of the trailer 2001 in forward motion. The trailer 2001 comprises a point M on the front part of the trailer which allows the attachment of the fifth wheel of a towing vehicle. And the trailer 2001 being stationary, it rests on its front part on a pair of stands 2008, each stand being located on one side of the trailer along the main direction of the trailer. Each 2008 stand includes a 2006 inflatable system. Here, the 2006 inflatable system, which is similar to an air suspension, is inserted between the upper end of the 2008 stand and the structure of the 2001 trailer.This inflatable system could have been installed directly between the ground and the lower end of the stand or inserted between the two previously mentioned ends of the stand. The stand 2008 and / or the inflatable system 2006 are capable of pivoting around an axis in a transverse direction relative to the main dimension of the trailer 2001 mounted on the structure of the trailer in the event of the trailer being hitched to a towing vehicle.

[0074] Preferably, here each inflatable system 2006 of each component connecting the trailer 2001 with the ground, such as an axle or a stand, is equipped with an electronic device 2007. This electronic device 2007 is located in the fluid cavity of the inflatable system 2006. Here, the electronic device 2007 is placed on the internal wall of the deformable surface of the inflatable system. It would have been possible to install the electronic device at the rigid surface of the inflatable system, while remaining located inside the fluid cavity of the inflatable system 2006. For example, the electronic device could have been integrated into the rim valve like certain TPMS (Tire Pressure Monitoring System) systems for a mounted assembly which is an inflatable system of an axle.

[0075] This 2007 electronic device includes a pressure sensor and a temperature 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 emitting the generated radio waves. The radiofrequency device may also, optionally, comprise a radio wave receiver for receiving instructions from the outside in order, for example, to initiate a measurement. This electronic device 2007 also comprises a memory space for storing the measurement data from the sensors before emitting them in the form of radio waves. The electronic device may transmit the raw measurement data or the data filtered by the microcontroller. The electronic device 2007 transmits both types of data, pressure and temperature, to the outside of the inflatable system 2006.Here, the electronic device 2007 emits 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).

[0076] Here, the exterior comprises at least the trailer 2001. This trailer 2001 firstly comprises a radio data reader 2005, operating in the UHF range, whose reception antennas 2105 are located near the inflatable systems 2006 of the various components connecting the trailer 2001 to the ground 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 calculation means 2002 and the transmission antenna of the communication means 2104 located in the trailer 2001. A radiofrequency transmission using specific communication means would also have been possible.This calculation means 2002 includes memory space and a processor to carry out certain tasks: assignments of the quantities of the inflatable system corresponding to the initial state for example, solving the differential equation which leads to the determination of the variation in volume of the fluidic cavity of each inflatable system 2006 equipped with an electronic device 2007. But here, part of the tasks of the calculation means 2002 are located in the cloud such as the calculation of the variation in load associated with the variation in volume having previously recovered the quantities of the inflatable system 2006 necessary for this final task as well as the first results of the calculation means 2002 located on the trailer 2001 and previously passed through the analysis means 2004 for ordering the first results.

[0077] Here the data is transferred by wire to a first computing means 2002 located in the trailer 2001. However, the data could all have been transmitted to computing means 2002 remote from the trailer 2001.

[0078] The first calculation means 2002 comprising transmission / reception communication means. These communication means in a configuration other than that of figure 2 could receive the radio waves emitted by the transmission communication means 2105 to transform them into digital data usable by the first calculation means 2002. The first calculation means 2002 comprises memory space and a processor to carry out its tasks: identify the quantities of the inflatable system 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 inflatable system equipped with an electronic device 200. These first results, possibly ordered or completed by a first analysis means 2004 on the trailer, are transferred in a cloud to a second calculation means 2002.This second calculation means 2002 equipped with means of communication 2102 in transmission for this purpose carries out for example the calculation of the variation of load associated with the variation of volume by having previously recovered the quantities of the inflatable system necessary for this final task.

[0079] These second results are sent to a second analysis means 2004. Here, the transmission of these data is done by means of radio communication. The second analysis means 2004 orders and makes comparisons between the second results of the second calculation means 2002.

[0080] Finally, the various output data from this second 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.

[0081] The display means 2003 are intended to inform the operator of the trailer 2001 of the state of the loading of the trailer 2001, in particular the distribution of the load between the various components connecting the trailer 2001 to the ground.

[0082] 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 an inflatable system of 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 the calculation and analysis means within the electronic device on board the inflatable system which transmits the results to a display means remote from the trailer. The other extreme configuration consists of transferring by radio waves the measurement data recorded at the level of the electronic device and carrying out the other steps of the process on means remote from the trailer, without ever passing through the trailer or the towing vehicle.

[0083] 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 an inflatable system of a trailer generated by the loading of the trailer's loading volume when stationary. This method comprises several phases.

[0084] The first is a preliminary phase which includes 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 initial loading, ideally at the level of the inflatable systems such as for example the mounted assemblies, by the installation of a pressure sensor and a temperature sensor capable of measuring the physical parameters, such as the inflation pressure and the internal temperature, of the fluid cavity delimited by the deformable surface of the inflatable system by means of a dedicated electronic device.The first steps, marked 1 and 2, consist of determining the physical quantities of the fluid cavity of the inflatable systems 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 marked 3 consists of determining the load carried ZI by the inflatable system equipped with the measuring device of the unhitched trailer. This determination can be made as a lump sum by making assumptions about the distribution of the total load of the trailer between the various ground connection components of the latter. The total unladen 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 by the technical instructions of the trailer manufacturer.Of course, it is also possible to integrate the initial loading of the trailer coming for example from a previous evaluation, ideally the last one carried out. The step referenced 4 corresponds to obtaining specific quantities of the inflatable system equipped with a measuring device. One of these quantities is the volume V0 corresponds to the volume occupied by the fluid cavity of the inflatable system when. the inflatable system is inflated to pressure PI, strictly speaking, under internal temperature Tl, but in the absence of any load carried, i.e. not resting on the ground for a mounted assembly for example. The second quantity is the flattening rigidity of the inflatable system per unit volume KSG, possibly dependent on the inflation pressure PI, the internal temperature Tl and the load carried Zl. 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 inflatable system. And the penultimate step of the preliminary phase, referenced 5, is a step of determining the volume occupied VI by the fluid cavity of the equipped inflatable system subjected to the load Zl 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 equipped inflatable system by determining the number of moles of gas ni present within the 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, that is to say a monatomic gas or a gas mixture. Optionally, 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 the internal temperature T for the fluid of the fluidic cavity of the inflatable system considered during an adiabatic transformation around the operating point of the inflatable system, that is to say the pressure PI, the temperature Tl and the load Zl.Optionally, a load distribution on each connecting component of the trailer, preferably on each inflatable system of the trailer, the trailer being unhitched, can be considered.

[0085] Then we move on to the main step, the beginning of which corresponds to the first step of loading or unloading the loading volume of the unhitched trailer when stationary. Necessarily, we record the temporal variation of the inflation pressure P(t) of each instrumented inflatable system of the trailer, which are of the order of a millibar for trailers adapted to a light vehicle. These recordings are then stored in a memory space to first filter the raw data using a low-pass filter to eliminate high-frequency phenomena, which corresponds to step referenced 11. At the same time, we record the temporal variation of the internal temperature T(t) of the fluid cavity of each instrumented inflatable system of the trailer, which are of the order of a hundredth of a degree for trailers adapted to a light vehicle.These recordings are then stored in a memory space to first filter the raw data using a low-pass filter to eliminate high-frequency phenomena, which corresponds to step 12.

[0086] Optionally, in the case where the sampling of the internal temperature measurement T(t) is not sufficient, for example, to capture the adiabatic transformation of the fluid associated with the work related to the trailer loading step, the temporal variation of the internal temperature T'(t) of the fluid cavity is determined using the temporal variation of the internal pressure P'(t) resulting from the recording of P(t) using the evolution law determined in the preliminary step, which then also corresponds to step 12. In this option, the recorded internal pressure variation P'(t) is used to evaluate the adiabatic transformation of the fluid in the fluidic cavity corresponding to the work related to the trailer loading step.Then, the recording of the internal temperature T(t) and the internal pressure P(t) beyond the adiabatic transformation determined by the length of P'(t) serves to establish the thermal equilibrium between the fluid cavity and the external environment which is made necessary by the adiabatic transformation of the fluid associated with the loading of the trailer.

[0087] The same would apply if the internal pressure measurement P(t) is not satisfactory for identifying the first transformation of the fluid, unlike the internal temperature measurement T(t). At this point, the internal temperature recording T(t) would be used to determine the limits of the adiabatic transformation of the fluid and extract a recording T”(t) between these limits. An internal pressure P”(t) would then be determined between the same two limits using an evolution law linking the internal pressure and the internal temperature of the fluid during an adiabatic transformation previously obtained in the preliminary phase. The connection system between optional steps and the essential steps in 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

[0088] One of the important steps of the main phase is the determination of the volume variation AV of the fluid cavity of each instrumented inflatable system through step 13. This corresponds to the resolution of the differential equation by feeding the differential equation using the appropriate internal pressure and internal temperature variations for the same instrumented inflatable system. The resolution by successive time increment then makes it possible to identify the time variation of the volume of the fluid cavity at each time increment. At a minimum, the resolution of the differential equation takes into account the adiabatic transformation of the fluid linked to the loading of the trailer. Preferably, it takes into account part of the thermal equilibrium of the fluid of the fluid cavity with the external environment until ideally the steady state. But, in most of the time, the steady state is not reached and a new loading step occurs which then generates a new adiabatic transformation of the fluid followed inevitably by a new thermal equilibrium cycle. This is continuous until the steady state in the thermal equilibrium phase appears or until the last loading event of the trailer.

[0089] Using the variation of the internal pressure and the internal temperature, it is possible to feed the differential equation taking into account the previous 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.

[0090] Another important step in the main phase is the evaluation of the load variation AZ associated with the single volume variation previously evaluated AV which corresponds to step 14. For this, it is necessary to take into account again the flattening rigidity of the inflatable system KSG per unit of volume. This rigidity can include a pneumatic component and a structural component. Taking into account a single pneumatic component K P SG may be sufficient for a reliable estimation of the load variation carried AZ.

[0091] From this variation in load carried AZ, the initial load carried ZI must be added to obtain the load carried by the instrumented inflatable system in step 15. From this quantity on the scale of each instrumented inflatable system, it is easy to work up to the load carried by each connecting component of the trailer and therefore to the total load carried by the trailer.

[0092] Fig. 4 shows the time evolution of the pressure of the pressure sensor of the electronic device placed 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 time 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 figure 3. Here, the measurement time frame only takes into account the first step of loading the loading volume of the trailer which is sufficient to explain the method.

[0093] This time recording of the internal pressure of the fluid cavity of the assembled assembly begins in the preliminary phase before loading the trailer loading volume. The time of the first loading step of the trailer 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 pressure of the fluid cavity is observed until point 101 where the pressure drop slows down very sharply and even increases to a lesser extent. This point 101 marks the transition between the work of the fluid associated with loading 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 linked to the first loading step 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 loading of the trailer. The second phase 52 corresponds to a heat exchange of the fluid with the exterior. During this second phase 52, a second step of loading or unloading the trailer can be initiated taking as a starting point, in terms of internal pressure, the internal pressure P associated with this starting point on curve 11.

[0094] Fig. 5 shows the time evolution of the internal temperature of the fluid cavity corresponding to the first stage of loading of the trailer. Here, this time evolution is delivered by the 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 a quality measurement by a temperature sensor in particular for the adiabatic transformation phase, 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 assembled assembly. In this alternative, curve 70 illustrates the estimated evolution of the external temperature of the assembled assembly.

[0095] These changes in the internal temperature 12 and 12' of the fluid cavity of the assembled assembly begin in the preliminary phase before the first loading step of the trailer. The starting time of the first loading step of the trailer 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 fluid cavity is observed until 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 loading 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 of the first stage of loading the trailer 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 loading of the trailer. The second phase 52 corresponds to a heat exchange of the fluid with the exterior. During this second phase 52, a second stage of loading or unloading the trailer can be initiated taking as a starting point, in terms of internal temperature, the internal temperature T measured on the curve 12 associated with this starting point. Indeed, the curve 12' only replaces the curve 12 on the first phase 51 according to the method.

[0096] Here, we observe a difference between the recorded curve 12 and the estimated curve 12' of the internal temperature, even on the first phase 51 of the main phase, 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 assembled 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 Figure 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 fluid cavity in the preliminary phase, just before the main phase for example.

[0097] Fig. 6 presents the determined 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 on the first stage of loading the trailer before any other stage of loading or unloading of the trailer.

[0098] This evolution of the internal volume 13 of the fluid cavity of the assembled assembly begins in the preliminary phase before loading the trailer. The time of the start of the first stage of loading 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 volume of the fluid cavity is observed up to point 101 where the rise in the internal volume slows down considerably and then stabilizes to a certain extent. This point 101 marks the transition between the work of the fluid associated with the first stage of loading the trailer, 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 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 by loading or unloading step. The first phase 51 is similar to an adiabatic transformation of the fluid corresponding to the work of the fluid following the loading of the trailer. The second phase 52 corresponds to a heat exchange of the fluid with the exterior. During this second phase 52, a second step of loading or unloading of the trailer can be initiated having as a starting point, in terms of volume of the fluid cavity, the volume of the fluid cavity estimated on the curve 13 associated with this starting point.

[0099] We note that at the end of phase 51, a good estimate of the variation in volume of the assembled assembly is obtained, which clearly shows that the work generated by the variation in load subjected to the assembled assembly occurs mainly during phase 51. The variations or oscillations observed correspond to the fluctuations of the transient phase corresponding at thermal equilibrium. Therefore, the method described here produces a continuous measurement of the temporal load variation of the assembly mounted in the time domain.

[0100] Fig. 7 shows the time evolution of the load variation applied to a mounted assembly equipped with the electronic device. The observed time frame corresponds to the first loading stage of the trailer. Here, this time evolution, represented by curve 14, is the output of the calculation of the volume variation by the proposed differential equation 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, from the origin, defined by the proposed formula which would already have given a good order of magnitude.

[0101] This evolution of the load variation 14 carried by the mounted assembly begins in the preliminary phase before loading the trailer. The time of the start of the first stage of loading the trailer corresponds to the abscissa of point 100 which marks the start of the main phase. We then observe from this point 100 a rapid drop in the load up to point 101 where the drop slows down considerably and then stabilizes to a certain extent. This point 101 marks the transition between the work of the fluid associated with loading 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 by loading stage. The first phase 51 is similar to an adiabatic transformation of the fluid corresponding to the work of the fluid following the loading of the trailer. The second phase 52 corresponds to a thermal exchange of the fluid with the exterior until the start of a second stage of loading or unloading of the trailer or the permanent regime of the thermodynamic equilibrium of the fluid.

[0102] 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 load variation time domain of the assembled assembly. Curve 80 corresponds to the measurement on a ground scale of the overload applied to the assembled assembly of the trailer during the first stage of loading the trailer. In conclusion, the variation of the applied load is well captured by the proposed method.

Claims

CLAIMS 1. Method for estimating the variation in load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary, comprising the following steps: In the preliminary phase, • Equip at least one inflatable system serving as an interface element between the ground and the trailer, such as a mounted assembly or a pneumatic cylinder, associated with a connecting component of the trailer, such as a stand or an axle, with at least one pressure sensor, the at least one sensor being capable of measuring the internal pressure of the fluid cavity of the inflatable system delimited by at least one deformable surface of the inflatable system, preferably each inflatable system of each connecting component of the trailer; • Equip the at least one inflatable system with at least one temperature sensor, the at least one sensor being capable of measuring the internal temperature of the fluid cavity of the inflatable system; and • Determine the initial load ZI applied to at least one inflatable system equipped with the trailer, • Determine the initial inflation pressure PI of the fluid cavity of at least one inflatable system equipped with the trailer; • Determine the initial internal temperature Tl of the fluid cavity of at least one inflatable system equipped with the trailer; • Evaluate the initial volume VI of the fluid cavity of at least one equipped inflatable system using a first function comprising as parameter the volume VO of the fluid cavity of the unloaded inflatable system inflated to the initial pressure PI and the flattening rigidity of the inflatable system per unit volume KSG, • Evaluate the number of moles of fluid or of the fluidic cavity of at least one inflatable system equipped from a model taking into account the inflation pressure PI, the initial volume VI and the temperature Tl; In the main phase: • Load the trailer loading volume; • Record the internal temperature T of the fluid cavity of at least one equipped inflatable system; • Record the internal pressure P of the fluid cavity of at least one equipped inflatable system; • Evaluate an intermediate volume variation AV of at least one inflatable system using the recorded internal pressure P and the recorded internal temperature T from a fluid model in adiabatic transformation, the fluid having a perfect gas behavior; and • Estimate a load variation AZ carried by the at least one equipped inflatable system using at least one second function, the at least one second function including as parameter the intermediate volume variation AV evaluated and the flattening rigidity of the inflatable system per unit of volume KSG.

2. Method for estimating the variation of the load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary according to claim 1 in which, in the preliminary phase, the method comprises a step of determining a law of evolution of the internal pressure P of the fluidic cavity from the internal temperature T during an adiabatic transformation of the fluid of the fluidic cavity of the inflated and loaded inflatable system, in the main phase, the method comprises a step of extracting the variation of internal temperature T' generated by the sole adiabatic transformation of the fluid from the recording of the internal temperature T,the method comprises a step of determining an internal pressure P' of the fluid cavity from the internal temperature T' and the evolution law determined in the preliminary phase and the step of evaluating the volume variation AV comprises a first phase where the evaluation is carried out with the determined internal pressure P' and the extracted internal temperature T' and at least a second phase where the evaluation is carried out with a part of the internal temperature T recorded outside a time frame corresponding to the extracted internal temperature variations T' and a part of the recorded internal pressure P outside said time frame., 3. Method for estimating the variation in the load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary according to claim 2 in which the extraction of the variation in internal temperature T' begins when the recorded internal temperature T changes, for the first time, in variation speed and ends when the recorded internal temperature T changes its variation rate a second time or after a duration TO corresponding to the end of the adiabatic transformation of the fluid, the start of the duration TO corresponds to the first change in the variation rate of the recorded internal temperature T.

4. Method for estimating the variation of the load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary according to claim 1 in which, in the preliminary phase, the method comprises a step of determining a law of evolution of the internal temperature T of the fluid cavity from the internal pressure P during an adiabatic transformation of the fluid of the fluid cavity of the inflated and loaded inflatable system, in the main phase, the method comprises a step of extracting the variations of internal pressure P” generated by the sole adiabatic transformation of the fluid from the recording of the internal pressure P,the method comprises a step of determining an internal temperature T” of the fluid cavity of the inflatable system from the internal pressure P” and the evolution law determined in the preliminary phase and the step of evaluating the volume variation AV comprises a first phase where the evaluation is carried out with the extracted internal temperature P” and the determined internal temperature T” and at least a second phase where the evaluation is carried out with a part of the internal pressure P recorded outside a time frame of the extracted internal pressure variations P” and a part of the recorded internal temperature T outside said time frame., 5. Method for estimating the variation in the load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary according to claim 4 in which, the extraction of the variation in internal pressure P” begins when the recorded internal pressure P changes, a first time, in variation speed and ends when the recorded internal pressure P changes a second time in variation speed or at the end of a duration TO corresponding to the end of the adiabatic transformation of the fluid, the start of the duration TO corresponds to the first change in variation speed of the recorded internal pressure P.

6. Method for estimating the variation in the load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary according to one of claims 1 to 5 wherein the temperature sensor and the pressure sensor are fixed on the at least one deformable surface of the equipped inflatable system.

7. Method for estimating the variation in the load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary according to one of claims 1 to 6 in which the at least one pressure sensor operates with a resolution of less than one millibar.

8. Method for estimating the variation in the load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary according to one of claims 1 to 7 in which the variation in load Z of the at least one equipped inflatable system is estimated by a relationship according to the following formula: [MATH1] where K PSG is the flattening pneumatic stiffness of the inflatable system per unit volume.

9. Method for estimating the variation in the load carried by a trailer generated by the loading of the loading volume of the unhitched trailer when stationary, comprising the method for estimating the variation in the load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary according to one of claims 1 to 8, in which, in the preliminary phase, at least one inflatable system of each component for connection with the ground of the trailer, preferably each inflatable system of each component for connection with the ground of the trailer, is equipped and the method comprises a step of estimating the variation in load carried by an inflatable system not equipped with a component for connection with the ground of the trailer from the estimated variations in load carried by the equipped inflatable systems, in the main phase,the method comprises a step of determining the variation in load carried by the trailer constituting the sum of the variations in load carried by each inflatable system of each component connecting with the ground of the trailer.

10. Method for estimating the load carried by an inflatable system of a trailer comprising the method for estimating the variation of the load carried by an inflatable system of a trailer generated by loading the loading volume of the trailer when stationary according to one of claims 1 to 8, the method is characterized in that the method comprises a step of estimating the load Z carried by the at least one equipped inflatable system using the load variation AZ carried by the at least one equipped inflatable system and determining the initial load ZI of the at least one equipped inflatable system of the trailer.

11. System (2000) for implementing the method for estimating the variation in load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary according to one of claims 1 to 8 and / or for implementing the method for estimating the variation in the load carried by a trailer generated by the loading of the loading volume of the unhitched trailer when stationary according to claim 9 and / or for implementing the method for estimating the load carried by an inflatable system of a trailer according to claim 10 comprising: • a trailer (2001), equipped with at least one inflatable system (2006) equipped with an electronic device (2007) on at least one connecting component of the trailer; • the electronic device (2007) comprising at least one pressure sensor, at least one temperature sensor, at least one electronic chip, at least one memory space capable of recording the signals from the sensors, and at least one first means of radiofrequency communication (2101) at least in transmission; • at least one means of calculation (2002); and • at least one display means (2003) comprising at least one second radiofrequency communication means (2102) at least in reception 12. System (2000) for implementing the method for estimating the variation in load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary and / or for implementing the method for estimating the variation in the load carried by a trailer generated by the loading of the loading volume of the unhitched trailer when stationary and / or for implementing the method for estimating the load carried by an inflatable system of a trailer according to claim 11 in which the system (2000) comprises an analysis means (2004) capable of analyzing a result at the output of the at least one calculation means (2002).

13. System (2000) for implementing the method for estimating the variation in load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary and / or for implementing the method for estimating the variation in the load carried by a trailer generated by the loading of the loading volume of the unhitched trailer when stationary and / or for implementing the method for estimating the load carried by an inflatable system of a trailer according to one of claims 11 to 12 in which the at least one calculation means (2002) comprises at least one third radiofrequency transmission / reception communication means (2103).

14. System (2000) for implementing the method for estimating the variation in load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary and / or for implementing the method for estimating the variation in the load carried by a trailer generated by the loading of the loading volume of the unhitched trailer when stationary and / or for implementing the method for estimating the load carried by an inflatable system of a trailer according to claim 12 wherein the at least one analysis means (2004) comprises at least a fourth radiofrequency transmission / reception communication means (2104) 15. System (2000) for implementing the method for estimating the variation in load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary and / or for implementing the method for estimating the variation in the load carried by a trailer generated by the loading of the loading volume of the unhitched trailer when stationary and / or for implementing the method for estimating the load carried by an inflatable system of a trailer according to one of claims 11 to 14 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 radiofrequency communication means (2105) at least in reception.

16. System (2000) for implementing the method for estimating the variation in load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary and / or for implementing the method for estimating the variation in the load carried by a trailer generated by the loading of the volume of loading the unhitched trailer when stationary and / or for implementing the method for estimating the load carried by an inflatable system of a trailer according to one of claims 11 to 15 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 (Bluetooth Low Emission).

17. System (2000) for implementing the method for estimating the variation in load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary and / or for implementing the method for estimating the variation in the load carried by a trailer generated by the loading of the loading volume of the unhitched trailer when stationary and / or for implementing the method for estimating the load carried by an inflatable system of a trailer according to one of claims 11 to 16 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.

18. System (2000) for implementing the method for estimating the variation in load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary and / or for implementing the method for estimating the variation in the load carried by a trailer generated by the loading of the loading volume of the unhitched trailer when stationary and / or for implementing the method for estimating the load carried by an inflatable system of a trailer according to claim 15 or according to one of claims 16 or 17 in combination with claim 15 in which a part of the at least one reading means (2005) is located on the trailer (2001).

19. System (2000) for implementing the method for estimating the variation in load carried by an inflatable system of a trailer generated by the loading of the loading volume of the trailer when stationary and / or for implementing the method for estimating the variation of the load carried by a trailer generated by the loading of the loading volume of the unhitched trailer when stationary and / or for implementing the method for estimating the load carried by an inflatable system of a trailer according to one of claims 11 to 18 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 inflatable system. (2006).

Images