Sensor system for an element of a vehicle, and vehicle including such sensor system

Description

DESCRIPTION of the industrial invention entitled: “Sensor system for an element of a vehicle, and vehicle including such system sensor”, by: CRF Consortium Company, Italian, Strada Torino 50 - 10043 Orbassano (TO). Designated Inventors: PERES Salvatore, LAMBERTINI Vito Guido Filed on: September 12, 2024 **** DESCRIPTION TEXT Field of invention This invention relates generally to vehicles, and has been developed with reference to the theme of mechanical integrity diagnostics of elements of such vehicles, particularly structural elements. Known technique As is known, vehicles have a load-bearing structure which includes a plurality of structural elements, generally made of metallic material, or alloys metallic, or with composite materials characterised by high characteristics mechanical. Although these elements are characterized by a robustness medium-high mechanical, in normal use of the vehicle they can structural damage or accidental deformations of such structures may occur components. For example, accidental collisions with bumps or steps or other roughness in the vehicle movement, or impacts caused by moving objects (e.g. stones) present on the road surface thrown against the vehicle during its journey), or other incidents may cause significant impacts on elements and components of the vehicle structure, with consequent possible damage or deformations of the themselves, and potential dangers for the entire vehicle and its occupants. Sensor systems have been proposed that are designed to detect any damage to structural elements of vehicles, but such known systems are typically complex and characterized by unsatisfactory detection quality. Purpose and summary of the invention In view of the above, the present invention aims to essentially to increase the safety of a vehicle, in particular providing an improved sensor system for monitoring the integrity of a or more structural elements or components of the vehicle itself, against any deformations or damages of a mechanical nature. An additional purpose of the invention is to indicate such a sensor system of simple, economical construction and compact. The invention also aims to indicate a vehicle equipped with such a sensor system. These and other purposes, which will become clearer in subsequently, they are achieved according to the invention by a sensor system and a vehicle having the characteristics which form the subject of the following claims. Claims form an integral part of the technical teaching here administered in connection with the invention. Brief description of the drawings Further objects, features and advantages of the invention will become clear. from the detailed description that follows, made with reference to attached drawings, provided by way of non-limiting example, in which: - figure 1 is a schematic representation of a generic vehicle; - Figure 2 is a schematic perspective representation of a structural component of the vehicle in figure 1, equipped with a sensor system integrity in accordance with the invention; - Figure 3 is a schematic section of an ultrasonic transducer used in the sensor system of Figure 2; and - figure 4 is a schematic plan representation of a possible implementation variant. Detailed description of the invention Figure 1 shows a schematic representation of a vehicle in accordance with to the invention, indicated in the complex with 1, whose supporting structure includes various structural elements. In the following, for simplicity, reference will be made to a metal floor of the vehicle, indicated with 2 in figure 1, without prejudice to the sensor system according to the invention is also susceptible to application in relation to other structural elements or components of the vehicle, not necessarily made of a metallic material. In figure 2 a structural element 2 of the is schematically represented. vehicle 1, which is here assumed to be a platform 2 of a design known in itself, for example steel format. In accordance with one aspect of the invention, the structural element 2 represented by the floor has associated or integrates a collision sensor system or integrity of the element itself. As we will see, the aforementioned sensor system is configured to monitor the integrity or deformation status of the floor (or other structural element of the vehicle 1), or detect any impacts on it it, evaluating its effects. In the example of Figure 2, the sensor system comprises at least one ultrasonic transducer 12, configured to generate ultrasound (frequencies above 20 kHz). The transducer 12 is associated with the structural element 2, here represented by the vehicle floor 1. In various embodiments, the transducer 12, which operates as an emitter of ultrasound, it is a piezoelectric generator. In preferred embodiments, and as visible in figure 3, the transducer 12 comprises a layer of piezoelectric material 15, on two opposite sides of the which electrode layers 16 and 17 are provided. Electrode layers 16 and 17 can for example, be made using an electrically operated paint or ink conductive placed directly on the two opposite faces of layer 15, or from electrically conductive plates. The transducer 12, including the layers 15-17 is preferably arranged or printed on a relevant matching layer 18. Between the transducer 12 and the structural element 2 there is a layer of metamaterial, indicated by 14 in figure 2, that is, a material created artificially and designed to have peculiar properties. As is known, the metamaterials are typically made from the composition of multiple elements arranged in repetitive patterns, on scales smaller than the wavelengths of the phenomena that you want to influence. The properties of metamaterials are not therefore linked to the properties of the constituent materials, but rather to the their “periodic” nanostructure, in which shapes, geometries, dimensions, orientation and arrangement give properties capable of manipulating waves mechanical, here mechanical sound waves. Metamaterial 14 can be formed from metallic material (e.g. example aluminum), or with a plastic material, or with a composite material. metamaterial 14 can be made with the same constituent material the structural element 2, or be part of such element, or form such element element. The realization of the transducer 12 and the metamaterial 14 can be optimized by 3D printing, but other technologies are not excluded traditional notes. The transducer 12 – i.e. its electrode layers 16 and 17 – is connected via suitable electrical conductors (for example tracks formed with an ink, or a paint, or an electrically conductive paste, or wiring) to a relative PS modular power supply system. In various embodiments, such as the one exemplified in figure 2, the sensor system further comprises at least one ultrasonic receiver 13 associated with the body of the structural element 2, at the side or face opposite to that to which layer 14 and transducer 12 are associated on it. In various preferred embodiments, the receiver 13 is of the following embodiment: similar to emitter 12, with operation based on the piezo-resistive effect. The receiver 13 is arranged in front of the emitter 12 – with the element 2 interposed and layer 14 – and is connected – for example in ways similar to those indicated for the emitter 12 – to a control unit CU, configured to acquire and process signals coming from the receiver 13. In the non-limiting example shown, the CU control unit, in addition to receiving signals from the receiver 13, check the PS power supply system of the transducer 12. In accordance with an important aspect of the invention, the layer of Metamaterial 14 is configured for ultrasonic wave conversion longitudinal, i.e. linearly polarized – typically generated by a piezoelectric transducer such as the one indicated with 12 – in ultrasonic waves circularly polarized. Compared to linearly polarized ultrasonic waves, the waves circularly polarized ultrasound allows for more timely diagnosis and complete with any lesions and deformations of the structural component 2, also in the direction of the wave, which is not the case with linear waves. How the ultrasonic wave-based sensor system works circularly polarized, for example, facilitates the detection of cracks or deformations in element 2 oriented in an arbitrary way, which are instead difficult to be detected using linearly polarized waves. In theory, a crack in the material constituting the structural element 2 could be detected by receiving a linearly polarized ultrasonic wave that is reflected by the crack itself. However, it is not possible to detect such a crack using a shear wave. linearly polarized if the polarization direction is parallel to the orientation of the crack: on the other hand, the same crack can be detected using circularly polarized waves. The specific structuring of metamaterial 14 for conversion purposes of ultrasonic waves from linear to circular can be of any known type suitable for the purpose. In preferred embodiments, the metamaterial 14 is consisting of a repetitive composition of substantially nanostructured units parallelepiped, and characterized by the presence of cylindrical holes arranged obliquely. In operation, the transducer 12 is powered to output cyclically high-frequency acoustic pulses (ultrasound), in the form of waves linearly polarized, whose dominant component is therefore longitudinal. metamaterial layer 14 has the effect of increasing the orthogonal component of the acoustic waves, which are thus converted into polarized waves circularly, detectable by the receiver 13. In figure 2 the polarized waves linearly emitted by the transducer 12 and the circularly polarized waves in exit from metamaterial 14 are only schematized for illustrative purposes, indicated by LPW and CPW, respectively. In case element 2 has cracks or irregularities, or even deformations due for example to an impact or to tensile overloads, the waves received by receiver 13 will vary from those typical of the condition of normal integrity of element 2, and the receiver itself will provide in output a signal representative of the structural condition of the element same. In various embodiments the control unit CU is arranged for compare from time to time the signals received by the receiver 13 with values ​​of reference, for example representative of the integrity condition of the element structural 2. Based on this comparison the CU control unit is able to detect any defects, imperfections or deformations in element 2, as well as classify the severity of the structural damage and the consequent actions required to the safety of the vehicle and its occupants (for example the emission of a alarm signal or vehicle stop). The classification and consequent procedures can be carried out for example by the CU unit at exceeding of threshold values ​​by the signal from receiver 13 predetermined. As mentioned, this type of monitoring is extremely effective thanks to the transformation of linearly polarized waves into polarized waves circularly, allowed by the use of metamaterial 14, the polarized waves circularly being more predictive in view of identification complete with structural lesions, for the reasons indicated above. The presence of the receiver 13 can be understood as optional since, in possible implementations, the reception functionalities can be implemented directly in the same transducer 12, which will then operate both from both emitter and receiver. In that case, the transducer 12 will be configured and controlled – according to methods known in the art – to first emit the sound impulse in in the form of linear waves and then detect the returning echo in the form of circular waves. Again, in the event of irregularities occurring in the mechanical structure of the structural element 2, the reflected echo will vary from the normal state integrity, in the event that the same element 2 has been subjected to impacts such as compromise the structure. Naturally in implementations of this type the transducer 12 will be connected to the CU control unit, so that it receives the representative echo signals, compare them with the values ​​of reference, and carry out the necessary processing, for example for the evaluation of the extent of any damages and the resulting actions. In embodiments where the transducer 12 is arranged to operate As both emitter and receiver, the CU control unit is configured to command the transducer itself in transmission mode, for the purpose of emission of ultrasound in a defined period of time, and then switch the operation in a reception mode, for a defined period of time. signal generated by transducer 12 in receive mode is read and processed from the CU unit, particularly comparing any signal variations, such variations being a function of the state of the structure of package 2. As already indicated, in the case of linear waves, the fracture along the direction of the motion of the waves would not provide any signal variation, while the use of circular waves obtained through metamaterial 14 allows to detect a signal variation even in such conditions. Even in this type of implementations signal variations are compared with the case studies stored in the CU unit and, in particular, when thresholds are exceeded predetermined, the consequent procedures will be activated. In various embodiments the control unit CU is arranged for process the signals received from the receiver 13, or from the transducer 12 if it It also works as a receiver, even to identify the position of the defect created in the structural element 2. For example, in the presence of a crack in the element 2 which determines a returning echo, from the timing of the echo itself with respect to at the emission the distance of the crack from the transducer 12 can be estimated. It should be noted that an ultrasonic wave generated by a transducer of the type indicated with 12 has a three-dimensional diffusion, although attenuated as it increases of the distance from the emitter, since the orthogonal components, which are not prevalent, are always present. For this reason it is preferable that 14 the metamaterial is reproduced on the entire end surface of group 11 (here the surface of end of element 2 facing the transducer 12), to ensure the amplification of the normal components, consequently attenuating the longitudinal component. The motion of the wave thus becomes roto-translational, and in This way the identification of anomalies, but also of deformations is guaranteed excessive induced voltage overloads. In this way the sensor system integrity can also work with a single pair of 12-13 transducers, or a single transducer 12 operating in transmission and reception, as described. The integrity sensor system may also include a single metamaterial layer 14 having associated with it a plurality of transducers 12 and 13 (or only 12 transducers operating in transmission and reception), for example in positions spaced laterally from each other, as exemplified in figure 4. In shapes For the implementation of this type, a single system of PS power supply and a single CU control unit associated with the various transducers 12 and 13 (or 13). The use of multiple transducers can be useful, for example, to cover an entire area of ​​interest and / or to allow the CU control unit a more precise and rapid identification of the problem area. From what has been described above it is clear that the invention allows to equip a structural element or component of a vehicle with a system integrity sensor, with simplified assembly, low cost, and effective and precise monitoring performance, even with a minimum number of components and wiring. As indicated, for simplicity's sake, reference has previously been made to a floor, but the sensor system which is the subject of the invention is susceptible to use in combination with other structural elements or components of the vehicle, such as examples other parts of its chassis, or of its drive or transmission system, or of its shock absorber system, its doors, etc. As mentioned, the invention is not limited to the monitoring of components formed from materials metals or metal alloys. It should also be noted that the structural component subject to monitoring it could itself be made with metamaterial 14: in that case, therefore, the same metamaterial will act as a structural element and as an element for the conversion of the acoustic waves emitted by the transducer 12 from linear to circular. In applications of this type, the receiver 13 – when provided – will be also associated with metamaterial 14, on the opposite side to the transducer 12. A structural element of the vehicle may also include a first portion made with conventional shape and a second portion nanostructured to fulfill the function of metamaterial as previously described. Naturally the construction details and the forms of implementation may vary widely from those described and illustrated, without thereby departing from the scope of the present invention.

Claims

CLAIMS 1. An integrity sensor system of a structural element (2) of a vehicle (1), wherein the integrity sensor system comprises at least one metamaterial (14) and at least one ultrasonic transducer (12) associated with the at least one metamaterial (14), the at least one metamaterial (14) being configured to convert linearly polarized ultrasonic waves emitted by the at least one ultrasonic transducer (12) into circularly polarized ultrasonic waves.

2. The integrity sensor system according to claim 1, wherein at least one ultrasonic transducer (12) and at least one metamaterial (14) are associated with the structural element (2), with at least one metamaterial (14) configured as a layer disposed between at least one ultrasonic transducer (12) and the structural element (2).

3. The integrity sensor system according to claim 1, wherein the structural element (2) is at least partly formed from the at least one metamaterial (14).

4. The integrity sensor system according to any of claims 1-3, further comprising at least one ultrasonic receiver (13) disposed in front of the at least one ultrasonic transducer (12), with the at least one metamaterial (14) interposed, the at least one ultrasonic receiver (13) being configured to detect circularly polarized ultrasonic waves and consequently generate a signal representative of a structural condition of the structural element (2).

5. The integrity sensor system according to claim 4, wherein the structural element (2) is interposed between the at least one metamaterial (14) and the at least one ultrasonic receiver (13).

6. The integrity sensor system according to any of claims 1-3, wherein the at least one ultrasonic transducer (12) is configured to both emit the ultrasonic waves, and to detect the ultrasonic waves as a returning echo and accordingly generate a signal representative of a structural condition of the structural member (2).

7. The integrity sensor system according to any of claims 1-6, wherein the at least one ultrasonic transducer (12) is a piezoelectric transducer.

8. The integrity sensor system according to claim 4, wherein the at least one ultrasonic receiver (12) is a piezo-resistive receiver.

9. The integrity sensor system according to claim 4 or claim 6, comprising a control unit (CU) arranged to compare the signal representative of the structural condition of the structural element (2) with at least one respective reference value, in particular representative of an integrity condition of the structural element (2).

10. A vehicle having at least one structural element (2) and an integrity sensor system according to one or more of claims 1-9.