Characterization of the load applied to a wheel

Abstract

The invention relates to a device (100) for characterizing a load applied to a wheel (102) of a vehicle, characterized in that said device (100) comprises: at least one means (114) for capturing a sound signal inside a cavity (108) formed by a tire (106) of said wheel (102), and at least one means (116) for analyzing said sound signal to determine at least one resonance frequency in said cavity (108), representative of said load, when an acoustic resonance is created within said cavity (108). It also relates to a wheel and a vehicle comprising at least one device according to the invention, as well as a method for characterizing a load applied to a wheel. Figure: Fig. 1

Description

Description Title of the invention: Characterization of the load applied to a wheel

[0001] — The present invention relates to the characterization of the load on a wheel of a vehicle, in particular to determine the weight of a vehicle.

[0002] = The field of the invention is more particularly the field of on-board weighing of a vehicle, whether it is stationary or moving. State of the art

[0003] — The weighing of vehicles, including but not limited to the weighing of weights- heavy, is of paramount importance, firstly to determine if the vehicle complies with current regulations and, on the other hand, to determine if the vehicle is used in accordance with design rules, in order to avoid risks of accidents.

[0004] There are currently two categories of weighing systems: weighing systems non-onboard and onboard weighing systems. The invention relates to weighing systems at least partially embedded.

[0005] — The currently known partially or fully embedded weighing systems use sensors, usually pressure sensors in the systems of suspension, allowing the vehicle's weight to be estimated. Alternatively, it is ac- It is not currently possible to estimate the weight of a vehicle by measurements, manually or via various sensors, measuring the level of deformation of the suspension and / or tires. Others Weighing systems are based on measuring the ground footprint of at least one tire of the vehicle.

[0006] — However, prior art systems do not allow the determination of the load of a wheel or the weight of the vehicle with satisfactory accuracy.

[0007] One object of the present invention is to remedy at least one of the drawbacks mentioned above.

[0008] = Another object of the present invention is to facilitate the evaluation of the load of a vehicle.

[0009] = Another object of the present invention is to allow a more precise evaluation of the load of a vehicle.

[0010] = Another object of the present invention is to improve safety vehicle usage. Description of the invention

[0011] = The invention makes it possible to achieve at least one of these goals by means of a device of character- scaling of a load applied to a wheel of a vehicle, characterized in that said The device includes: at least one means of capturing a sound signal inside a cavity formed by a tire of said wheel, and at least one means of analyzing said sound signal to determine at least a resonance frequency in said cavity, representative of said load, when an acoustic resonance is created within said cavity. The device according to the invention makes it possible to characterize the load applied to a wheel from the resonance frequency or frequencies inside said wheel when an acoustic resonance is created within the cavity of the wheel. Thus, it is possible to characterize the load applied to the wheel without having to manually measure the deformation level of a suspension and / or a tire. These manual measurements are difficult to perform and do not allow for accurate characterization of the load. Consequently, the device according to the invention facilitates and improves the accuracy of characterizing the load applied to the wheel. Furthermore, the device according to the invention allows for the characterization of the load applied to the wheel independently of the rest of the vehicle's architecture. Indeed, the characterization device does not require measurements to be taken on other vehicle components, such as, for example, the internal pressure of a suspension. Consequently, the characterization device according to the invention is more versatile and can be more easily implemented on any type of road vehicle. Analyzing a sound signal during acoustic resonance in the cavity of a wheel allows us to identify at least one resonance frequency. If the tire is free and undeformed, for example if no load is applied to the wheel, then only one resonant frequency, called the fundamental frequency, can be identified. However, when a load is applied to the wheel, the tire is deformed. Consequently, the fundamental frequency is replaced by two other resonant frequencies, f₁ and f₂, called induced frequencies. Numerous tests carried out during development demonstrated that it was possible to characterize the load applied to a wheel by determining the force applied to said wheel as a function of one or each of the induced resonance frequencies f, and / or f,, as well as as a function of parameters known and / or determinable by calibration. According to a non-limiting example, the force in Newtons, denoted Fz, applied to the wheel can be determined according to the following relationship: [Math.1] F,- qe _ fa. Lo with: c is the speed of sound in m / s, f, and f. the induced resonance frequencies in Hz, Ly is the perimeter in meters of the circle centered on the wheel axis and for radius the centroid of the undeformed section of the tire profile, and K is a constant of the tire in m / N / , defined as a function of the stiffness Kya of the tire tread, the K stiffness, the tire sidewalls, and of the height of the cavity formed by the tire. Thus, the force F; can be determined with one and / or the other of the induced resonance frequencies f, and f,. This force F; allows us to deduce the load, or weight, applied to the wheel as a function of the acceleration due to gravity. Alternatively, according to another, by no means limiting, embodiment, the load, the force F, can be determined according to the following relationship: [Math.2] Fz = 4 -#,) Numerous tests conducted during development demonstrated that this alternative allows for a more precise characterization of the force F, and therefore a more precise characterization of the load. However, this alternative necessarily requires determining the two induced resonance frequencies f, and f. The characterization device does not necessarily require an excitation means to function. Acoustic resonance can, for example, be created within this cavity when the vehicle is moving. Indeed, when the vehicle is moving, the interactions between the tire and the road surface can create resonance. Alternatively, when the vehicle is stationary, acoustic resonance within said cavity can be created by manual excitation, for example by impacting the tire with a hammer-type tool or similar. According to yet another alternative, an acoustic resonance can be created within the cavity by ambient noise around said wheel. By means of capture we mean any sensor capable of measuring a vibration, a sound and / or a level of acoustic pressure. The device according to the invention can further determine if the vehicle is overloaded by comparing the value of the force or load measured to a predetermined threshold value. This threshold value can, for example, be recorded in the device, for example for each vehicle. According to one embodiment, at least one vehicle load characterization device can be programmed to: determine if the vehicle is overloaded, and send an alert message to the driver in case of overload. To achieve this, the device according to the invention may include a means of light signaling, for example a warning light on the dashboard of the vehicle, configured to warn the driver when an overload is detected. Alternatively or in addition, the device according to the invention may include an audible signaling means, using for example speakers included in the vehicle's passenger compartment, configured to warn the driver when an overload is detected. Advantageously, the device according to the invention may further include at least one excitation means for creating an acoustic resonance within said cavity. Thus, it is possible to better control the excitation, which facilitates the creation of acoustic resonance within the cavity. Since the acoustic resonance is generated more reliably, the characterization of the load applied to a wheel by the device is therefore more precise. Advantageously, at least one means of excitation can be mechanical and arranged to create acoustic resonance in the cavity by mechanical contact with the tire. At least one mechanical means can thus include an element for impacting the tire, once or several times, for example at regular intervals, in particular at a frequency between 10 Hz and 300 Hz. Alternatively or in addition, at least one mechanical means may include an element that can be brought into contact with the tire and then deform it by applying a force to it, once or several times, for example at regular intervals, in particular at a frequency between 10 Hz and 300 Hz. Thus, it is possible to create an acoustic resonance in the cavity reliably and easily reproducibly. Consequently, the characterization of the load applied to a wheel by the device is more reliable and precise. Advantageously, at least one means of excitation can be acoustic and arranged to create acoustic resonance in the cavity by emission of a sound wave. Thus, it is possible to create acoustic resonance within the cavity without requiring contact with the wheel tire. Consequently, the device generates less tire wear, thereby increasing its lifespan. Moreover, when compared to a mechanical excitation method, an acoustic excitation method is less bulky. Furthermore, an acoustic excitation method comprising fewer moving parts and is therefore less susceptible to wear, which in turn allows for better repeatability of the creation of acoustic resonances than a mechanical excitation method. Advantageously, at least one means of capture can be a microphone, or a piezoelectric sensor. Advantageously, the device according to the invention may include an acoustic means which can be used selectively as an excitation means and as a capture means. Thus, a single acoustic device can be used to create a resonance in the cavity and then capture that resonance. Consequently, the total number of required excitation and capture devices can be reduced. As a result, the characterization device is less expensive to produce. Such an acoustic means of selectively capturing and arousing sound could, for example, be a piezoelectric sensor. Alternatively, such a means could be a speaker with reversible operation, thus enabling sound capture according to the same operating principle as a microphone. Advantageously, the signal analysis means can be configured to determine two resonance frequencies representative of the load. Thus, it is possible to characterize the load more precisely. Advantageously, the device according to the invention may further include at least one means for sensing pressure and / or temperature inside said cavity. Thus, it is possible to measure experimental conditions inside the cavity formed by a tire of said wheel in which the sound signal is captured. Therefore, it is possible to adapt the characterization of the charge to the measured experimental conditions in order to improve the accuracy of said characterization. According to a non-limiting example, the force in Newtons, denoted F, applied to the wheel can be determined as a function of: of each of the induced resonance frequencies f, and f3, of a pressure P measured within the wheel cavity, of a temperature T measured within said cavity, and of at least one dimension of the tire, such as the width of the tire tread, the ratio between tire height and tread, inner diameter of the wheel etc. Alternatively, according to another, by no means limiting, example, the force in Newtons, denoted F, applied to the wheel can be determined as a function of: of only one of the two induced resonance frequencies f, and f, of a predetermined reference frequency, allowing in particular to de- to complete a frequency shift between said reference frequency and pre- determined and said induced resonance frequency, f; or f>, following a variation in the load applied to the tire, of a pressure P measured within the wheel cavity, of a temperature T measured within said cavity, and of at least one dimension of the tire, such as the width of the tire tread, the ratio between tire height and tread, inner diameter of the wheel etc. Alternatively or in addition, the device can be configured to receive at least one measurement of an experimental condition taken by a sensor installed as standard in the wheel for which the applied load is characterized. According to another aspect of the invention, a vehicle wheel is proposed comprising a rim, a tire forming a cavity, characterized in that said wheel is equipped with a characterization device according to the invention. Thus, it is possible to achieve better integration of the device according to the invention within the vehicle, and particularly within the wheel. Consequently, measurements are facilitated and their quality is improved. According to one embodiment, the characterization device may include a capture means disposed outside the cavity. Advantageously, the characterization device may include at least one capture means disposed inside said cavity, or opening into said cavity of said wheel. Thus, it is possible to capture the acoustic resonance directly from inside the cavity. Consequently, it is possible to obtain better capture and therefore a more precise characterization of the load. Furthermore, measurements can be taken while the wheel is rolling. Indeed, at least one recording device placed inside the cavity allows for the capture of acoustic resonance even when the wheel is rotating. The characterization device may include at least one capture means disposed, at least partially, in the wheel tire. Advantageously, the characterization device may include at least one capture means disposed, at least partially, in said rim. Thus, the collection device is fixed to the rim. It is therefore possible to change the wheel's tire without having to replace or remove the collection device. According to one embodiment, the characterization device may include at least two capture means separated by any non-zero angle. Advantageously, the characterization device can include at least two capture means, separated by an angle of 90°. This relative angular position ensures better capture of acoustic resonance. Indeed, regardless of the wheel's position, when a resonance is created in the cavity formed by the wheel's tire, the two frequencies f; and fade resonance can be detected when a load is applied to the wheel. Two scenarios are therefore possible: the first induced resonance frequency f, can only be captured by a only one of the two capture methods, therefore the second frequency of induced resonance f, can only be captured by the other means of capture, or Each of the two induced resonance frequencies f, and f' can be captured by each of the two means of capture. Thus, in all cases, it is possible to detect the two resonance frequencies f1 and fs representative of the load applied to the wheel. Advantageously, the characterization device may include at least two means for capturing the device, separated by an angle of 45°, Thus, the relative angular position of 45°, around the axis of rotation of the wheel, between at least these two means of capture is preserved even during the rotation of the wheel. This relative angular positioning ensures better capture of the acoustic resonance. Indeed, regardless of the wheel's position when the resonance is created, this relative angular positioning of the capture devices guarantees that at least one of the two capture devices is capable of capturing each of the two induced resonance frequencies when a load is applied to the wheel. Advantageously, the characterization device may include at least one excitation means disposed in, or opening into, said cavity of the wheel. Thus, the means of excitation does not constitute a hindrance or a limit to the characterization of the load of the wheel during rolling. Preferably, the excitation means located in, or opening into, the cavity formed by the wheel tire can be an acoustic excitation means. This makes it possible to create acoustic resonance by directly exciting the air within the cavity. Consequently, the creation of acoustic resonance is facilitated. Furthermore, such an acoustic excitation means is more reliable because it is less sensitive to external factors such as ambient noise. Alternatively or in addition, at least one means of excitation located, or opening, in the cavity may be mechanical. Advantageously, the characterization device may include at least one excitation means disposed outside said wheel cavity. Thus, such a means of excitation can, for example, be placed on the wheel rim or on any other part of the vehicle. This allows access to the excitation mechanism without having to remove the wheel, and in particular the tire. Therefore, maintenance of the mechanism is simplified. arousal is facilitated. According to another aspect of the invention, a vehicle is proposed comprising at least one characterization device and / or at least one wheel according to the invention. Advantageously, the characterization device may include at least one excitation means disposed on the vehicle opposite a wheel of said vehicle. In particular, the excitation means can be placed at the level of a wheel arch of said wheel. Thus, the vehicle is equipped with an onboard excitation system, which allows the load to be characterized regardless of its location. Furthermore, since the excitation system has a fixed position, it can be designed, calibrated, and optimized to create acoustic resonance as efficiently as possible. Advantageously, the characterization device may include at least one excitation means disposed elsewhere than on the vehicle. In other words, the said means of excitation is not carried on the vehicle. Thus, it is possible to have an excitation device, such as a loudspeaker, external to the vehicle and movable independently. Consequently, such an excitation device offers greater flexibility. Indeed, it can be positioned near a wheel for characterization and then moved, for example, for storage. Advantageously, the vehicle according to the invention may include at least one device according to the invention and, for each wheel of said vehicle, at least one means for capturing a sound signal inside the cavity formed by the tire of said wheel. Thus, it is possible to characterize the total load of the vehicle. Furthermore, it is possible to determine the load distribution of said vehicle and the load centering, that is to say, the position of the vehicle's center of gravity. According to another aspect of the invention, a method for characterizing a load applied to a wheel of a vehicle is proposed, characterized in that it comprises the following steps: excitation, to create an acoustic resonance within a cavity formed by a tire of said wheel, capturing a sound signal inside said cavity, and detection of at least one resonance frequency in said cavity, represented sensitive to the load, by analyzing said sound signal when a resonance acoustics are created within said cavity. Description of the figures and methods of implementation Other advantages and features will become apparent upon examination of the detailed description of a non-limiting embodiment, and the accompanying drawings on which: Figure [1] is a partial schematic representation of an example of a real- non-limiting description of a characterization device according to the invention; Figure 2 is a partial schematic representation of another example of non-limiting implementation of a characterization device according to the invention; Figure 3 is a partial schematic representation of another example of non-limiting implementation of a characterization device according to the invention; Figure 4 is a partial schematic representation of another example of non-limiting implementation of a characterization device according to the invention; Figure 5 is a partial schematic representation of another example of non-limiting implementation of a characterization device according to the invention; Figure 6 is a partial schematic representation of another example of non-limiting implementation of a characterization device according to the invention; Figure 7 is a representation of examples of possible capture when a Acoustic resonance is created within the cavity depending on the position of the means of capture; Figures 8a and 8b are schematic and partial representations in cutting two wheels, respectively without and with an applied load, and Figure 9 is a partial and highly schematic representation of an example of non-limiting realization of a vehicle according to the invention. It is understood that the embodiments described below are by no means exhaustive. In particular, variants of the invention may be conceived comprising only a selection of the features described below, isolated from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art. This selection includes at least one preferably functional feature without structural details, or with only a portion of the structural details if this portion is sufficient solely to confer a technical advantage or to differentiate the invention from the prior art. In the figures, elements common to several figures retain the same reference. Fig. 1 is a partial schematic representation of a non-limiting example embodiment of a characterization device according to the invention. Figure [Fig.1] illustrates, by a schematic and partial cross-sectional view, a device 100 for characterizing a load applied to a wheel 102 of a vehicle. The wheel 102 includes a rim 104 on which a tire 106 is mounted. A cavity 108 is thus formed by the tire 106. A load (not shown) applied to wheel 102 deforms tire 106 at the level of contact between the wheel 102 and a ground 110. This load is at least partially due to the weight of the vehicle. In the example shown, the vehicle is partially represented by a wheel arch 112 of said vehicle. However, it is important to note that the device 100 according to the invention can also be implemented on a vehicle not including a wheel arch 112. The charge characterization device 100 includes a means 114 for capturing a sound signal inside the cavity 108. Typically, the means of capture can be a microphone or a piezoelectric sensor. In the example shown, the rim 104 is designed to accommodate at least part of said collection means 114 so that it opens into said cavity 108. Alternatively, the collection means 114 may be disposed elsewhere in the cavity 108, for example fixed to a wall of the rim 114 or an inner wall of the tire 106. According to another alternative, the collection means 114 may be disposed outside the cavity 108 of the wheel 102, for example on a lateral part of the rim 104 or on the vehicle at the wheel arch 112. The device 100 further includes a means for analyzing a sound signal captured by the capture means 114. The analysis means 116 is schematically represented at the wheel arch 112. However, the position of the analysis means 116 in [Fig.1] is a positioning by way of example and is in no way limiting. The analysis means 116 is intended to determine at least one, preferably two resonance frequencies in the cavity 108, representative of the load, when an acoustic resonance is created within the cavity 108. This acoustic resonance is created, for example, within cavity 108 when the vehicle is moving. Indeed, when the vehicle is moving, the interaction between the tire 102 and the road surface can create a resonance. Alternatively, when the vehicle is stationary, an acoustic resonance within said cavity 108 can be created by manual excitation, for example by impacting the tire with a hammer-type tool or similar. According to yet another alternative, the recording means 114 can be a reversible acoustic means that can selectively be used as an excitation means and as a recording means, such as, for example, a piezoelectric or electroacoustic transducer. Thus, the reversible acoustic means can first be used in emission mode to generate an acoustic resonance in the cavity 108, and then in recording mode to capture the sound signal. Figure [Fig. 2] is a partial schematic representation of another non-limiting example of an embodiment of a characterization device according to the invention. The example in [Fig.2] includes all the elements described in relation to [Fig.1]. Device 200 of [Fig.2] differs from device 100 of [Fig.1] in that it includes three acoustic excitation means 202, 204 and 206. In the illustrated example, each of the three excitation means is arranged differently in or around wheel 102. A first acoustic excitation means 202 is embedded in the wheel well 112. This first acoustic excitation means 202 is arranged opposite the wheel 102 so as to create an acoustic resonance in the cavity 108 by emitting a sound wave. This first excitation means is therefore completely decoupled from the wheel 102. A second acoustic excitation means 204 is placed on the ground 110 opposite the wheel 102. This second acoustic excitation means 204 is movable and manually positioned so as to be opposite the wheel 102 and allows the generation of an acoustic resonance in the cavity 108 by emission of a sound wave. This second excitation means is therefore completely independent of the wheel and the vehicle. A third acoustic excitation means 206 is embedded in the rim 104. One end of the acoustic excitation means 206 opens into the cavity 108, thus enabling the creation of an acoustic resonance directly within the cavity 108 by the emission of a sound wave. This acoustic excitation means 206 is therefore rotationally fixed with the wheel 102. The relative angular position of this acoustic excitation means 206 with the sound-harnessing means 114 is thus fixed. In the illustrated example, the acoustic excitation means 206 and the sound-harnessing means 114 are positioned at an angle of 90°. Alternatively, this position may be different. The example of device 200 according to the invention as illustrated thus comprises three different means of acoustic excitation 202, 204 and 206. Other embodiments comprising one or more of these three means of excitation are possible, possibly combined with any other embodiment. Figure 3 is a partial schematic representation of another non-limiting example of an embodiment of a characterization device according to the invention. The example in [Fig.3] includes all the elements described in relation to [Fig.1]. Device 300 of [Fig.3] differs from device 100 of [Fig.1] in that it includes a mechanical excitation means 302. In the illustrated example, the mechanical excitation means 302 is located in the wheel arch 112 and comprises an extendable rod 304, the end of which can be brought into contact with the surface of the tire 106 and allows the mechanical creation of a acoustic resonance within cavity 108. Such a mechanical excitation means 302 is thus preferably used to create acoustic resonance in cavity 108 when the vehicle is stationary. According to one embodiment, the mechanical excitation means 302 can be included in the wheel 102, for example included in the cavity 108 or opening into the cavity 108. Figure 4 is a partial schematic representation of another non-limiting example of an embodiment of a characterization device according to the invention. The example in [Fig.4] includes all the elements described in relation to [Fig.3]. Device 400 of [Fig.4] differs from device 300 of [Fig.3] in that it includes a second capture means 402. Similar to the first pickup means 114, the second pickup means 402 is embedded in the rim 104 and opens into the cavity 108. Each pickup means is thus rotationally fixed to the wheel 102. The relative angular position between the two pickup means 114 and 402 is 90°. This relative angular position of 90° ensures the pickup of each of the two resonance frequencies induced by the combination of the two pickup means 114 and 402. Alternatively, other variants of realizations having a different relative angular position between the two capture means 114 and 402 will appear obvious to the person skilled in the art. The advantages of different variants of relative positions between the capture means are described in more detail below in relation to [Fig.7]. Figure 5 is a partial schematic representation of another non-limiting example of an embodiment of a characterization device according to the invention. The example in [Fig.5] includes all the elements described in relation to [Fig.4]. Device 500 of [Fig.5] differs from device 400 of [Fig.4] in that it includes a third capture means 502. Similar to the other two pickup means 114 and 402, the third pickup means 502 is embedded in the rim 104 and opens into the cavity 108. Each pickup means is thus rotationally fixed with the wheel 102. The third pickup means 502 is positioned between pickup means 114 and 402 such that the relative angular position between the third pickup means 502 and each of the other two pickup means 114 and 402 is 45°. A relative angular position of 45° between any two pickup means 114 and 502 or 502 and 402 ensures that at least one pickup means can capture each of the two induced resonant frequencies. Figure 6 is a partial schematic representation of another non-limiting example of an embodiment of a characterization device according to the invention. The example in [Fig.6] includes all the elements described in relation to [Fig.5]. Device 600 of [Fig.6] differs from device 500 of [Fig.5] in that it includes five additional capture means 602 for a total of eight capture means 114, 402, 502 and 602. The additional sensing means 602 are also embedded in the rim 104 and open into the cavity 108. Each sensing means is thus rotationally fixed with the wheel 102. The sensing means 114, 402, 502 and 602 are arranged in the rim so that each of the two successive sensing means has a relative angular position equal to 45°. Fig. 7 is a representation of examples of possible capture when an acoustic resonance is created within the cavity depending on the position of the capture means. Figure 7 illustrates frequency spectra obtained by recording devices when an acoustic resonance is created within the cavity with the vehicle stationary. The recording devices are arranged in the wheel at regular 45° intervals, similar to the arrangement described previously in relation to Figure 6. The recording devices are thus positioned at 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°, with 0° corresponding to the recording device positioned closest to the ground. It is thus possible to see that the frequency spectra obtained by the capture means at 90° and 270°, located in the horizontal axis passing through the center of the wheel in the direction of orientation of the figure, and those obtained by the capture means at 0° and 180°, located in the vertical axis passing through the center of the wheel, each allow the identification of a single peak, corresponding to a single one of the induced resonance frequencies. Thus, the 90° and 270° capture methods only allow the identification of the first induced resonance frequency, equal to 225 Hz in this example. Furthermore, the capture methods at 0° and 180° only allow the identification of the second induced resonance frequency, equal to 235 Hz in this example. It is also possible to see that the frequency spectra obtained by the other means of capture, arranged at 45°, 135°, 225° and 315°, each allow us to identify each of the two induced resonance frequencies, equal to 225 Hz and 235 Hz in this example. The positions of the sensing devices as illustrated are theoretical positions achieved on a test bench. During characterization performed under real-world conditions between two runs, the wheel orientation may differ. In this case, each capture methods may be capable of determining each of the two induced resonant frequencies. Figure 7 illustrates the importance of the relative angular position between the different recording devices. A 90° interval between two recording devices ensures that each of the two resonance frequencies induced by their combination can be identified. Furthermore, a 45° relative angular position guarantees that at least one recording device can capture each of the two induced resonance frequencies. Other embodiment variants having other relative angular positions between the capture means will appear obvious to a person skilled in the art. It is therefore possible to consider non-exhaustive examples of implementation including capture methods spaced at irregular intervals such as 30°, 45° and 90°, Alternatively, it is also possible to consider examples of non-limiting implementations including means of capture spaced at other regular intervals, such as for example 30°. [Fig.8a] and [Fig.8b] are schematic and partial cross-sectional representations of the same wheel, respectively without and with an applied load. Figures [Fig. 8a] and [Fig. 8b] illustrate, by means of cross-sections, the same wheel 802 in contact with the ground 804. The wheel 802 comprises: an 806 rim; an 808 tire; a cavity 810, formed by the tire 808 on the rim 806; and a capture means 812, disposed on the rim 806 and opening into the cavity 810. Fig. 8b differs from Fig. 8a in that a force, Fz, is applied to wheel 802. This force is illustrated in Fig. 8b by an arrow applied to wheel 802 at its axis of rotation 814. Figure 8b shows a deformation of the tire 808 caused by the load Fz. Furthermore, it can be seen that the center of rotation 814 of the wheel 802 is slightly lower than that of the wheel 800. Figure 9 is a partial and very schematic representation of a non-limiting example of a vehicle according to the invention. Figure 9 illustrates, by a top view and in section, a vehicle 900 equipped with four wheels 102. The vehicle 900 includes a load characterization device 902 applied to each of the wheels 102. The characterization device 902 includes, for each of the wheels 102, at least one means for capturing (not illustrated in [Fig.9]) a sound signal within a cavity formed by a tire of said wheel. The characterization device 902 further includes an analysis means 116. Thus, it is possible to characterize the load applied to each of the wheels 102 individually. Consequently, it is possible to characterize the total load of the vehicle. Furthermore, it is possible to determine the load distribution of said vehicle and the load centering, that is to say, the position of the center of gravity 604 of said vehicle. Of course, the invention is not limited to the detailed examples above.

Claims

Claims

1. Device (100; 200; 300; 400; 500; 600) for characterizing a load applied to a wheel (102; 802) of a vehicle, characterized in that said device (100; 200; 300; 400; 500; 600) comprises: - at least one means (114; 402; 502; 602; 812) for capturing a sound signal inside a cavity (108; 810) formed by a tire (106; 808) of said wheel (102; 802), - at least one means (116) for analyzing said sound signal to determine at least one resonance frequency in said cavity (108; 810), representative of said load, when an acoustic resonance is created within said cavity (108; 810), and - at least one means of excitation (202,204,206;302) for creating an acoustic resonance within said cavity (108;810); wherein at least one excitation means (202,204,206) is acoustic and is arranged to create an acoustic resonance in the cavity (108) by emitting a sound wave, without requiring contact with the tire of the wheel.

2. Device (300;400;500;600) according to the preceding claim, characterized in that it further comprises at least one mechanical excitation means (302) arranged to create an acoustic resonance in the cavity (108) by mechanical contact with the tire (106).

3. Device (100;200;300;400;500;600) according to any one of the preceding claims, characterized in that at least one capture means (114;402;502;602;812) is a microphone, or a piezoelectric sensor.

4. Device (100;200;300;400;500;600) according to any one of the preceding claims, characterized in that it comprises an acoustic means which is used selectively as an excitation means and as a capture means (114;402;502;602;812).

5. Device (100;200;300;400;500;600) according to any one of the preceding claims, characterized in that the signal analysis means (106) is configured to determine two resonance frequencies representative of the load.

6. Vehicle wheel (102,802) comprising: - a rim (104;806); - a tire (106;808) forming a cavity (108;810); characterized in that said wheel (102;802) is equipped with a characterization device (100;200;300;400;500;600) according to any one of the preceding claims.

7. Wheel (102,802) according to the preceding claim, characterized in that the characterization device (100;200;300;400;500;600) comprises at least one capture means (114;402;502;602;812) arranged inside said cavity (108;810), or opening into said cavity (108;810) of said wheel (102;802).

8. Wheel (102;802) according to any one of claims 6 or 7, characterized in that the characterization device (100;200;300;400;500;600) comprises at least one capture means (114;402;502;602;812) arranged, at least partially, in said rim (104;806).

9. Wheel (102) according to any one of claims 6 to 8, characterized in that the characterization device (500; 600) comprises at least two capture means (114, 402), separated by an angle of 90°.

10. Wheel (102) according to any one of claims 6 to 9, characterized in that the characterization device (500; 600) comprises at least two capture means (114, 402, 502) separated by an angle of 45°.

11. Wheel (102) according to any one of claims 6 to 10, characterized in that the characterization device (200) comprises at least one excitation means (206) arranged in said cavity (108), or opening into said cavity (108), of said wheel (102).

12. Wheel (102) according to any one of claims 6 to 11, characterized in that the characterization device (200; 300; 400; 500; 600) comprises at least one excitation means (202, 204; 302) arranged outside said cavity (108) of said wheel (102).

13. Vehicle comprising: - at least one characterization device according to any one of claims 1 to 5; and / or - at least one wheel according to any one of claims 6 to 12.

14. Vehicle according to the preceding claim, characterized in that the characterization device (200; 300) comprises at least one excitation means (202; 302) arranged on the vehicle opposite a wheel (102) of said vehicle.

15. Vehicle according to any one of claims 13 or 14, characterized in that the characterization device (200) comprises at least one excitation means (204) arranged elsewhere than on the vehicle.

16. Method for characterizing a load applied to a wheel of a vehicle, characterized in that it comprises the following steps: - excitation, to create an acoustic resonance within a cavity formed by a tire of said wheel, by an acoustic excitation means arranged to create an acoustic resonance in the cavity by emitting a sound wave, without requiring contact with the tire of the wheel; - capturing a sound signal inside said cavity; and - detecting at least one resonance frequency in said cavity, representative of the load, by analyzing said sound signal when an acoustic resonance is created within said cavity.

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