Wireless data collection system

Abstract

A data collection system using electromagnetic signals, comprising, on the one hand, a collector (100) equipped with a first antenna (105) having a predetermined bandwidth, and, on the other hand, at least one remote electronic device (200) comprising a second antenna (205) having a second bandwidth coinciding with the first bandwidth for exchanging signals with the first antenna. The device includes a thermal protection enclosure (207; 210) surrounding at least the second antenna (205) by defining a cavity around it such that the second antenna radiates signals outside the protective enclosure substantially in the second bandwidth. Aircraft equipped with such a system. FIGURE IN ABRIDGED DIAGRAM: Fig. 1

Description

Title of the invention: Wireless data collection system

[0001] The present invention relates to the field of data collection, particularly in vehicles, and for example for data collection in a hot environment such as the engine compartment of a vehicle.

[0002] BACKGROUND OF THE INVENTION

[0003] Motor vehicles have an engine housed in an engine compartment that is more or less insulated, particularly thermally and acoustically, from the rest of the vehicle, which also houses an engine control unit. To control the engine's operation and / or perform its maintenance, it is necessary to retrieve certain information relating to the engine, such as temperature, shock, and vibration data, as well as configuration information (for example, the product number P / N and the serial number S / N).

[0004] Regarding the retrieval of data relating to engine operation: a conventional solution is to place sensors in the engine compartment and connect them via electrical cables to the control unit, which collects the data in question. However, the use of cables increases the vehicle's weight and therefore its energy consumption, and proves quite restrictive in terms of vehicle design.

[0005] A common solution for collecting configuration information is to maintain an up-to-date list of the replaceable components used (commonly referred to as LRUs, or Line-Replaceable Units) in an information system outside the vehicle. However, copying the data (P / N and S / N) is labor-intensive and, more importantly, prone to errors (failure to respect the lifespan of an LRU or implementation of a non-compliant configuration).

[0006] Furthermore, in other areas of everyday life, such as packaging and parcel tracking, it is known to collect data using RFID (Radio Frequency Identification) technology. This technology is implemented using systems comprising a reader and radio tags (commonly called RFID tags). The reader includes a first integrated circuit electronic circuit connected to a first antenna having a first bandwidth, and each radio tag includes a second integrated circuit electronic circuit connected to a second antenna having a second bandwidth substantially identical to the first bandwidth. The first electronic circuit of the reader can thus communicate with the second electronic circuit by exchanging electromagnetic signals. Radio tags are relatively fragile and very sensitive to heat.

[0007] SUBJECT OF THE INVENTION

[0008] The invention aims in particular to enable the collection of data, such as identifiers, in a relatively hot environment by limiting the weight of the equipment required for the collection. Summary of the invention

[0009] To this end, the invention provides a data collection system using electromagnetic signals, comprising, on the one hand, a collector equipped with a first antenna having a predetermined bandwidth, and, on the other hand, at least one remote electronic device comprising a second antenna having a second bandwidth coinciding with the first bandwidth for exchanging signals with the first antenna. The device includes a thermal protection enclosure surrounding at least the second antenna by defining a cavity around it such that the second antenna radiates signals outside the protective enclosure substantially in the second bandwidth.

[0010] Thus, it is possible to collect data without using electrical cables while ensuring reliable data transmission. However, to protect the antenna from heat, it is surrounded by a thermal protection sheath. This sheath could alter the antenna's properties. To remedy this, the sheath defines a cavity around the antenna, allowing it to radiate within the cavity's free space. The thickness of the thermal protection sheath around the antenna can be limited so that the sheath can perform its thermal protection function without significantly altering the antenna's radiation. The invention is suitable for use in the environment of an internal combustion engine with temperatures ranging from 100°C to 250°C or even higher.

[0011] The invention also relates to a vehicle comprising a propulsion engine disposed in an engine compartment and at least one remote device of such a system, the remote device being fixed in the engine compartment.

[0012] Other features and advantages of the invention will become apparent from the following description of particular, non-limiting embodiments of the invention. Brief description of the drawings

[0013] Reference will be made to the attached drawings, among which:

[0014] [Fig. 1] [Fig. 1] is a partial schematic perspective view of an aircraft equipped with a system according to the invention, showing more particularly an engine compartment of this aircraft;

[0015] [Fig.2] [Fig.2] is a schematic block view of a collection system data according to the invention;

[0016] [Fig.3] [Fig.3] is a schematic view of a remote device of this system, according to a first embodiment of the invention, in cross-section along a plane parallel to a substrate of an electronic circuit of the remote device;

[0017] [Fig.4] [Fig.4] is a schematic view of this remote device, in cross-section along a plane perpendicular to the substrate of the electronic circuit of the remote device;

[0018] [Fig. 5] [Fig. 5] is a view analogous to [Fig. 3] of a device offset according to a second embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] With reference to [Fig. 1], the invention is described herein in application to an aircraft A comprising two engines M located in the same engine compartment C. The engine compartment C includes a forward bulkhead Cav, a rear bulkhead Car, two side bulkheads Cl, and a firewall Cpf separating the two engines M from each other. The engine compartment C has a top opening closed by a top cowling Cs.

[0020] With reference to [Fig.2], the system according to the invention comprises a data collector (or reader) generally designated as 100 and here a plurality of remote electronic devices 200.

[0021] The collector 100 includes an electronic circuit 101 comprising a printed circuit board 102 carrying an integrated circuit 103 and a transceiver 104 connected by a link cable to an antenna 105 (or first antenna) which is separate from the electronic circuit 101. The integrated circuit 103 includes a processor and memory containing a program executable by the processor and data. The printed circuit board 102 further includes at least one connector 106 for connecting the electronic circuit 101 to an avionics network R of the aircraft A. The antenna 105 is tuned to a frequency band (or first bandwidth) that is part of the frequency bands used for RFID devices. The collector 100 is here integrated into the aircraft: the electronic circuit 101 is located outside the engine compartment C; the antenna 105 is located inside the engine compartment.

[0022] Each remote device 200 comprises an electronic circuit 201 which includes a printed circuit board 202 carrying an integrated circuit 203 and a transceiver 204 connected to an antenna 205 tuned to a second frequency band (or second bandwidth) in order to communicate with the collector 100, as will be seen. The antenna 205 thus has a second bandwidth coinciding with the first bandwidth. By "coinciding," it is meant that each of these two bandwidths overlaps the other by at least one-third, or even half, of this bandwidth, or more depending on the desired transmission reliability. The bandwidth here extends between -3dB and +3dB around the frequency corresponding to the Maximum power of transmitted signals.

[0023] The integrated circuit 203 comprises a processor and a memory containing a computer program, executable by the processor, and data. The remote device 200 can be arranged to perform at least one of the following functions: a function for memorizing the identification of the component on which it is fixed; a function for memorizing a setting or configuration of the component on which it is attached; a function for measuring and storing an environmental parameter of the component to which it is attached...

[0024] To this end, the electronic circuit 201 of the remote device 200 is connected to a sensor 206 (for example, temperature, shock or vibration or pressure sensor).

[0025] The remote device 200 is a passive RFID device in the sense that it does not have a battery and is powered by the energy of the signals it receives via the antenna 205. This type of power supply for RFID devices is classic.

[0026] The remote device 200 includes a thermal protection enclosure in which at least the antenna 205 is housed, but also the entire electronic circuit 201. The remote device 200 also includes a means for compensating for the influence of the thermal protection enclosure on the electromagnetic signals exchanged between the two antennas 105, 205. The compensation means is arranged so that the electromagnetic signals transmitted in the first bandwidth by the antenna 105 are received in the second bandwidth by the antenna 205 and vice versa.

[0027] Thus, the collector 100 can retrieve the stored data by querying the remote device 200. The collection is initiated by the collector 100, which sends a request signal containing a data request (for example, an identification request). The electronic circuit 201 of the remote device 200, powered by the energy of the request signal, transmits an identification signal containing the identifier of the component to which it is attached before sending: a data signal containing the other data contained in its memory. an identification signal containing a TID (Transponder ID).

[0028] The electronic circuit 101 of the collector 100 is programmed to collect data automatically before each flight, during the flight, or after the flight. The electronic circuit 101 of the collector 100 can be programmed to collect data periodically or all at once. The data retrieved by the collector 100 is then transmitted to a predictive maintenance system, for example, either via the avionics network R or via an RFID link initiated with a reader of a maintenance operator. The data retrieved by the collector 100 can be stored in the memory of the collector 100 or in a memory connected to the avionics network R.

[0029] It should be noted that the collector 100 can also be programmed to update data stored in the electronic circuit 201 of the remote device 200, such as: - the identifier of the component to which the remote device 200 is associated, - a configuration or parameter setting of the component to which the remote device 200 is associated, - the value of an alert threshold, - the value of a threshold for controlling the storage or transmission of the parameter measured by the remote device 200... For example, in this latter case applied to a remote device 200 measuring temperature, the temperature is not stored or transmitted as long as it is below the threshold value. Furthermore, temperature can be used to extend the lifespan of the remote device 200. Indeed, if a remote device 200 is queried at too high a temperature, it risks premature aging. It is therefore preferable that a remote device 200 not respond to an RFID request if its internal temperature is too high.

[0030] The device includes a thermal protection enclosure surrounding at least the antenna 205, defining a cavity around it. This reduces, or even eliminates, any frequency shift in the antenna's bandwidth caused by the presence of the protective enclosure. The thickness of the thermal protection enclosure around the antenna 205 can be adjusted, if necessary, to further reduce this frequency shift. In any case, the antenna radiates signals, outside the protective enclosure, substantially in the second bandwidth.

[0031] As shown in Figures 3 and 4, and according to the first embodiment of the thermal protection enclosure, the thermal protection enclosure, referenced 207, comprises a polymer resin block defining a cavity 208 in which the antenna 205 extends, allowing the antenna 205 to resonate in the air of the cavity 208. The cavity 208 thus forms a compensation means for limiting the influence of the thermal protection enclosure on the bandwidth of the antenna 205. The volume of this cavity 208 can be determined according to the compensation to be achieved. The thickness of the protection enclosure is determined based on a thermal conductivity of the thermal protection enclosure (207; 210) and an estimated ambient temperature during operation. More specifically, the thickness of the polymer resin block forming the thermal protection envelope 207 around the cavity 208 is determined as a function of: - the thermal conductivity of the polymer resin, - the maximum temperature that the electronic circuit 201, and more specifically the antenna 205, can withstand, - the maximum outside temperature, and possibly - a safety factor.

[0032] The thickness also depends on the mechanical resistance capabilities that are desired so that the resin provides a mechanical protection function adapted to the environmental conditions of the remote device 200.

[0033] The polymer resin chosen here is a room-temperature curable silicone resin (RTV). The following RTV polymer resins can be used: RTV 160, RTV 162, RTV 167, RTV 511, RTV 560, RTV 577. It should be noted that the polymer resin chosen here is free of metallic particles, as these metallic fillers are opaque to electromagnetic radiation. For this type of material, outside the cavity area, the thickness of the protective casing can then be between 0.5 and 5 cm, for example. Here, the thickness of the protective casing at the cavity is less than on the rest of the board.

[0034] It can be predicted that the thickness of the envelope at the level of the cavity, along a direction perpendicular to the card, is less than the thickness of the cavity itself along this direction, or even less than half the thickness of the cavity.

[0035] The thickness of the cavity is, for example, between 0.3 and 2 cm.

[0036] The thermal protection casing 207 is formed by molding. The electronic circuit 201 is placed in a mold with rods supporting the electronic circuit 201 at a distance from the mold walls. A cover delimiting the cavity 208 is then placed on the antenna 205 (the cover can be manufactured by additive manufacturing). The polymer resin is poured into the mold in liquid form so that it encapsulates the entire electronic circuit 201, the cover forming a disposable mold portion. The mold is then positioned on a planetary mixer to facilitate the release of any air bubbles trapped in the liquid resin before being placed in a low-temperature oven (50-60°C) to aid the curing of the polymer resin. After curing, the remote device 200 is removed from the mold. The holes left by the rods, as well as the volume resulting from resin shrinkage during drying, are filled with resin, which is then allowed to cure.Deburring, surfacing, and engraving operations are then possibly carried out. To facilitate the removal of air bubbles, the mold can also be placed in a vacuum chamber instead of, or in addition to, the use of a planetary system. Furthermore, if the polymer resin has sufficient hardness, screw passages can be installed in the mold before the resin is poured to allow for... to fix the remote device 200 onto a plate 250 by inserting screws into the tubes to screw them into tapped holes in the plate.

[0037] According to an alternative manufacturing method, successive pre-molded layers can be used, at least one of which has a reserve to form the enclosure 207 and which are stacked one on top of the other until the electronic circuit 201 is completely encapsulated. The fixing of the layers to each other can be ensured, for example, by gluing or by fixing the stack on a plate by means of through screws clamping the stack on the plate and the layers against each other.

[0038] As shown in [Fig. 5], and according to a second embodiment of the thermal protection enclosure, the thermal protection enclosure, referenced 210, is made of ceramic, and more specifically here of silicon nitride. As before, a cavity 211 is delimited by the thermal protection enclosure 208 around the antenna 205, but here also around the entire electronic circuit 1. The thermal protection enclosure 210 can cause reflection losses related to the relative permittivity of the enclosure 210 and dissipation losses in the ceramic due to the loss tangent. Its shape, thickness, and the ceramic material used will be determined so as to limit this influence while providing the desired thermal protection.More precise compensation can be achieved by taking into account other possible influences, such as an alteration of the directivity of the antenna 205 (increase in side lobes for example), antenna mismatch (increase in the voltage standing wave ratio), antenna pointing error, depolarization... The compensation method is therefore not limited to correcting a frequency shift and can be arranged to compensate for other defects if necessary (compensation for manufacturing defects in the circuit forming the antenna).

[0039] In the preferred embodiment of the invention, the system comprises several remote devices 200 distributed in the engine compartment C, namely: - at least one on the front bulkhead Cav, - at least one on the rear bulkhead, because - at least one on the upper hood Cs, - at least one on the Cpf firewall partition.

[0040] To improve signal transmission, wave-reflecting metasurfaces can be provided, fixed to the partitions Cav, Car, Cs and / or Cpf and / or the cover Cs, to reflect waves from the antennas 205 to the collector 100 and vice versa. Metasurfaces are surfaces that reflect waves at a given frequency, in this case, that of the RFID signals. They can optionally be designed to reflect these waves in a directed manner. At least one of the metasurfaces can be encapsulated / embedded in a thermal protection material, similar to that used for antenna 205.

[0041] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0042] In particular, the remote device may have a different structure from that described.

[0043] The thermal protection block / enclosure can be arranged around the antenna only, the antenna being connected by a cable or connector to the rest of the electronic circuit.

[0044] Other polymer resins can be chosen to form the thermal protection casing, for example, an epoxy resin or a PG 231 or PG 355 resin. The operating temperature range will preferably be from -40°C (or even -60°C) to +150°C, or even higher and above 250°C, and the thermal conductivity will be less than 1 W / (mK). Furthermore, the hardest possible resin, with a Shore D hardness of at least 30, will preferably be chosen to ensure mechanical protection of the antenna and the electronic circuit.

[0045] Other ceramics can be chosen to form the thermal protection envelope and for example a glass ceramic.

[0046] The material of the thermal protection block / envelope will preferably be chosen according to its performance in terms of radio wave transmission.

[0047] The invention is also applicable to active type RFID devices, i.e. including a power supply battery for the electronic circuit for applications at temperatures preferably below 200°C.

[0048] The remote device 200 can be arranged to perform functions other than those indicated, and for example one or more functions for estimating the lifespan of the component to which it is associated, such as: - increment a counter at each reading of the remote device 200 by the collector 100 based on the assumption that a reading is made after each operating cycle; - increment a counter on a specific RFID control used at each engine start to count the number of cycles during which the engine is running; - measure a temperature using an integrated temperature sensor to count the number of cycles see the operating time of the LRU (which assumes that the remote device 200 is permanently powered to measure and process temperature information: either because the antenna 205 is constantly subjected to radioelectric radiation, or because the remote device 200 incorporates a battery); - measure an acceleration using an integrated accelerometer to count the number of cycles see the operating time of the LRU (which assumes that the remote device 200 is permanently powered to measure and process acceleration information: either because the antenna 205 is permanently subjected to radio radiation, or because the remote device 200 incorporates a battery).

[0049] The remote device may have a much more basic structure than that described and comprise only passive components.

[0050] The antenna may have a different structure from that described and be made from any electrically conductive element such as a printed circuit track, a cable, a bar or a metasurface.

[0051] There are two ways to identify the component to which a remote device 200 is associated: - either the S / N and P / N data are stored in the memory of the remote device 200 as described above; - either the collector 100 retrieves the identifier of the remote device 200 (this identifier is often called TID and is specific to each RFID device) and it is the information system that makes the correspondence between the TID and the P / N and S / N.

[0052] The first solution is simpler for retrieving the P / N and S / N. The second solution is less energy-intensive, as the TID is more directly accessible (this is important when the remote device 200 is at the limit of the RFID antenna ranges and therefore has little energy available).

[0053] The collector can be carried on board the aircraft or be independent of the aircraft for use on the ground by a maintenance operator.

[0054] The invention is applicable to vehicles of all types, such as land, water, or air vehicles, whether crewed or uncrewed. With regard to air vehicles, the invention is applicable to fixed-wing or rotary-wing aircraft, regardless of the number of engines they have.

Claims

Claims

1. System for collecting data by electromagnetic signals, comprising, on the one hand, a collector (100) provided with a first antenna (105) having a predetermined bandwidth, and, on the other hand, at least one remote electronic device (200) comprising a second antenna (205) having a second bandwidth coinciding with the first bandwidth for exchanging signals with the first antenna, characterized in that the device comprises a thermal protection envelope (207; 210) surrounding at least the second antenna (205) by defining a cavity around it so that the second antenna radiates signals outside the protection envelope substantially in the second bandwidth.

2. The system of claim 1, wherein a thickness of the protective jacket is determined based on a thermal conductivity of the thermal protective jacket (207; 210) and an estimated surrounding temperature during operation.

3. System according to claim 1 or 2, in which the thermal protection envelope (207) is made of a polymer resin.

4. The system of claim 3, wherein the polymer resin has a thermal conductivity of less than 1W / (mK).

5. The system of claim 3 or 4, wherein the polymer resin is a silicone resin or an epoxy resin.

6. The system of claim 1, wherein the thermal protection jacket (210) is ceramic.

7. The system of claim 6, wherein the ceramic is silicon nitride or a glass ceramic.

8. Vehicle (A) comprising a propulsion engine (M) arranged in an engine compartment (C), and at least one remote device (200) of a system according to any one of the preceding claims, the remote device (200) being fixed in the engine compartment (C).

9.

10. Vehicle according to claim 8, the vehicle being an aircraft. Vehicle according to claim 9, the aircraft being of the helicopter type.

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