Wireless data collection system

Abstract

The invention relates to an electromagnetic signal-based data collection system, 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 that coincides with the first bandwidth for exchanging signals with the first antenna. The device comprises a thermally protective casing (207; 210) surrounding at least the second antenna (205) while defining a cavity around it, such that the second antenna radiates signals outside the protective casing substantially in the second bandwidth. The invention also relates to an aircraft equipped with such a system.

Description

[0001] WIRELESS DATA COLLECTION SYSTEM

[0002] The present invention relates to the field of data collection, particularly in vehicles, and for example for the collection of data in a hot environment such as the engine compartment of a vehicle.

[0003] BACKGROUND OF THE INVENTION

[0004] 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 houses an engine control station. To control the operation of the engine and / or ensure its maintenance, it is necessary to retrieve a certain amount of information relating to the engine, such as temperature, shock, vibration data as well as configuration information (for example the product number P / N and the serial number S / N).

[0005] Regarding the recovery of data relating to the operation of the engine: a classic solution is to place sensors in the engine compartment and to connect them by electrical cables to the control station which collects the data in question. However, the use of cables increases the weight of the vehicle and therefore its energy consumption, and is quite restrictive in terms of vehicle design.

[0006] For the collection of configuration information, a classic solution is to maintain up-to-date, in an information system outside the vehicle, a list of replaceable components used (commonly referred to as LRU, from the English Line-Replaceable Unit). However, copying the data (P / N and S / N) is a source of work and especially of errors (non-compliance with the life potential of an LRU or implementation of a non-compliant configuration).

[0007] Furthermore, in other areas of everyday life, such as packaging and parcel tracking, it is known to collect data via RFID technology (from the English Radio Frequency Identification or radio-identification). This technology is implemented by means of systems comprising a reader and radio-labels (commonly called RFID tags). The reader comprises a first electronic circuit with an integrated circuit connected to a first antenna having a first bandwidth and each radio-label comprises a second electronic circuit with an integrated 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 the exchange of electromagnetic signals. Radio-labels are relatively fragile and very sensitive to heat.

[0008] SUBJECT OF THE INVENTION

[0009] 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.

[0010] SUMMARY OF THE INVENTION

[0011] To this end, the invention provides a system for collecting data by electromagnetic signals, comprising, on the one hand, a collector provided 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 comprises a thermal protection envelope surrounding at least the second antenna by defining a cavity around it so that the second antenna radiates signals outside the protection envelope substantially in the second bandwidth.

[0012] Thus, it is possible to collect data without using electrical cables while ensuring reliable data transmission. However, to protect the antenna from heat, the antenna is surrounded by a thermal protection envelope. However, this envelope could alter the properties of the antenna. To remedy this, the envelope defines a cavity around the antenna allowing the antenna to radiate in the free space of the cavity. The thickness of the thermal protection envelope around the antenna can be limited so that the envelope can perform its thermal protection function without significantly altering the radiation of the antenna. The invention is suitable for use in the environment of a heat engine with temperatures between 100°C and 250°C or even higher.

[0013] The invention also relates to a vehicle comprising a propulsion engine arranged in an engine compartment and at least one remote device of such a system, the remote device being fixed in the engine compartment. Other characteristics and advantages of the invention will emerge from reading the following description of particular and non-limiting embodiments of the invention.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Reference will be made to the attached drawings, including:

[0016] [Fig. 1] Figure 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;

[0017] [Fig. 2] Figure 2 is a schematic block view of a data collection system according to the invention; [Fig. 3] Figure 3 is a schematic view of a remote device of this system, according to a first embodiment of the invention, in section along a plane parallel to a substrate of an electronic circuit of the remote device;

[0018] [Fig. 4] Figure 4 is a schematic view of this remote device, in section along a plane perpendicular to the substrate of the electronic circuit of the remote device; [Fig. 5] Figure 5 is a view similar to Figure 3 of a remote device according to a second embodiment of the invention.

[0019] DETAILED DESCRIPTION OF THE INVENTION

[0020] With reference to Figure 1, the invention is described here in application to an aircraft A comprising two engines M placed in the same engine compartment C. The engine compartment C comprises a front partition Cav, a rear partition Car, two side partitions Cl and a firewall Cpf separating the two engines M from each other. The engine compartment C comprises an upper opening closed by an upper cover Cs.

[0021] With reference to Figure 2, the system according to the invention comprises a data collector (or reader) generally designated 100 and here a plurality of remote electronic devices 200.

[0022] The collector 100 comprises an electronic circuit 101 which comprises a printed circuit board 102 carrying an integrated circuit 103 and a transmitter / receiver 104 connected by a connecting cable to an antenna 105 (or first antenna) which is separate from the electronic circuit 101. The integrated circuit 103 comprises a processor and a memory containing a program executable by the processor and data. The printed circuit board 102 further comprises at least one connector 106 making it possible to connect 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) forming part of the frequency bands used for RFID devices. The collector 100 is here embedded in the aircraft: the electronic circuit 101 is arranged outside the engine compartment C; the antenna 105 is arranged in the engine compartment.

[0023] Each remote device 200 comprises an electronic circuit 201 which includes a printed circuit board 202 carrying an integrated circuit 203 and a transmitter / receiver 204 connected to an antenna 205 tuned to a second frequency band (or second bandwidth) to be able to communicate with the collector 100 as will be seen. The antenna 205 thus has a second bandwidth coinciding with the first bandwidth. By "coincide", we mean that each of these two bandwidths overlaps the other over at least a third, or even half of this bandwidth, or more depending on the desired transmission reliability. The bandwidth extends here between -3dB and +3dB around the frequency corresponding to the maximum power of the transmitted signals.

[0024] 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 of storing an identification of the component on which it is fixed; - a function of storing a parameter setting or a configuration of the component on which it is fixed;

[0025] - a function for measuring and storing an environmental parameter of the component on which it is attached...

[0026] 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).

[0027] The remote device 200 is a passive type RFID device in the sense that it does not have a battery and is powered by the energy of the signals that it receives via the antenna 205. This type of power supply for RFID devices is conventional.

[0028] The remote device 200 comprises a thermal protection envelope in which at least the antenna 205 is housed, but here also the entire electronic circuit 201. The remote device 200 also comprises a means for compensating for an influence of the thermal protection envelope 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.

[0029] Thus, the collector 100 can retrieve the stored data by interrogating the remote device 200. The collection is initiated by the collector 100 which sends a request signal containing a data request (for example identification), 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 on which it is fixed before sending:

[0030] - a data signal containing the other data contained in its memory.

[0031] - an identification signal containing a TID (Transponder ID).

[0032] 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 recovered by the collector 100 is then transmitted to a predictive maintenance system, for example either via the avionics network R or by an RFID link initiated with a reader of a maintenance operator. The data recovered by the collector 100 can be stored in the memory of the collector 100 or in a memory connected to the avionics network R.

[0033] It will 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:

[0034] - the identifier of the component with which the remote device 200 is associated,

[0035] - a configuration or setting of the component with which the remote device 200 is associated,

[0036] - the value of an alert threshold,

[0037] - the value of a threshold for controlling the storage or transmission of the parameter measured by the remote device 200... For example, in the latter case applied to a remote device 200 measuring the temperature, the temperature is not stored or is not transmitted as long as it is lower than the threshold value. Furthermore, the temperature can be used to extend the life of the remote device 200. Indeed, if a remote device 200 is interrogated at too high a temperature, there is a risk of premature aging. It is therefore preferable for a remote device 200 not to respond to an RFID request if its internal temperature is too high.

[0038] The device comprises a thermal protection envelope surrounding at least the antenna 205 by defining a cavity around it. This makes it possible to reduce, or even cancel, an offset in the bandwidth of the antenna caused by the presence of the protective envelope. The thermal protection envelope has a thickness around the antenna 205 which can be adjusted, if necessary, so as to further reduce this frequency offset. In any event, the antenna radiates signals, outside the protective envelope, substantially in the second bandwidth.

[0039] As shown in Figures 3 and 4, and according to the first embodiment of the thermal protection envelope, the thermal protection envelope, referenced 207, comprises a block of polymer resin defining a cavity 208 in which the antenna 205 extends and which allows the antenna 205 to resonate in the air of the cavity 208. The cavity 208 then forms a compensation means making it possible to limit the influence of the thermal protection envelope on the bandwidth of the antenna 205. The volume of this cavity 208 can be determined according to the compensation to be carried out. The thickness of the protective envelope is determined according to a thermal conductivity of the thermal protection envelope (207; 210) and an estimated surrounding temperature during operation. More precisely, the thickness of the block of polymer resin forming the thermal protection envelope 207 around the cavity 208 is determined according to:

[0040] - the thermal conductivity of the polymer resin,

[0041] - the maximum temperature that the electronic circuit 201 and more particularly the antenna 205 can withstand,

[0042] - the maximum outside temperature, and possibly

[0043] - a safety coefficient.

[0044] The thickness also depends on the mechanical resistance capabilities required for the resin to provide a mechanical protection function adapted to the environmental conditions of the remote device 200.

[0045] The polymer resin chosen here is a room temperature vulcanizable 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 metal particles, these metal fillers being opaque to electromagnetic radiation. For this type of material, outside the area where the cavity is located, the thickness of the protective envelope can then be between 0.5 and 5 cm, for example. Here, the thickness of the protective envelope at the cavity is lower than on the rest of the card.

[0046] It can be expected that the thickness of the envelope at the cavity, in a direction perpendicular to the card, is less than the thickness of the cavity itself in this direction, or even less than half the thickness of the cavity.

[0047] The thickness of the cavity is for example between 0.3 and 2 cm.

[0048] The thermal protection envelope 207 is formed by molding by placing the electronic circuit 201 in a mold comprising rods supporting the electronic circuit 201 at a distance from the walls of the mold, by placing on the antenna 205 a cover delimiting the cavity 208 (the cover can be manufactured by additive manufacturing) and by pouring the polymer resin in liquid form into the mold so that it encapsulates the entire electronic circuit 201, the cover forming a lost part of the mold. The mold is then positioned on a planetary mixer to promote the release of any air bubbles trapped in the liquid resin before being placed in a low-temperature oven (50-60°C) to help the polymer resin harden. After hardening, the remote device 200 is removed from the mold, the holes left by the rods as well as the volume linked to the shrinkage of the resin during drying are filled with resin which is then left to harden.Deburring, surfacing and engraving operations are then possibly carried out. To facilitate the evacuation of air bubbles, it is also possible to place the mold in a vacuum chamber instead of or in addition to the use of a planetary gear. In addition, if the polymer resin has sufficient hardness, screw passage tubes can be mounted in the mold before pouring the resin so as to allow the remote device 200 to be fixed on a plate 250 by inserting screws into the tubes to screw them into tapped holes in the plate.

[0049] According to an alternative manufacturing method, it is possible to use successive pre-molded layers, at least one of which has a reserve to form the enclosure 207 and which are stacked on top of each other until the electronic circuit 201 is completely encapsulated. The layers can be fixed together for example by gluing or by fixing the stack on a plate using through screws tightening the stack on the plate and the layers against each other.

[0050] As shown in Figure 5, and according to a second embodiment of the thermal protection envelope, the thermal protection envelope, referenced 210, is made of ceramic and more particularly here of silicon nitride. As previously, a cavity 211 is delimited by the thermal protection envelope 208 around the antenna 205 but here also around the entire electronic circuit 1. The thermal protection envelope 210 can cause reflection losses linked to the relative permittivity of the protective envelope 210 and dissipation losses in the ceramic due to the loss tangent. Its shape, its thickness and the ceramic chosen 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 in the directivity of the antenna 205 (increase in the side lobes for example), mismatch of the antenna (increase in the voltage standing wave ratio), antenna pointing error, depolarization, etc. The compensation means 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).

[0051] In the preferred embodiment of the invention, the system comprises several remote devices 200 distributed in the engine compartment C, namely:

[0052] - at least one on the front Cav bulkhead,

[0053] - at least one on the rear partition Car,

[0054] - at least one on the top cover Cs,

[0055] - at least one on the Cpf firewall.

[0056] To improve the transmission of the signals, it is possible to provide wave-returning metasurfaces fixed on the partitions Cav, Car, Cs and / or Cpf and / or the cover Cs to return the waves coming from the antennas 205 to the collector 100 and vice versa. The metasurfaces are surfaces reflecting the waves at a given frequency, here that of the RFID signals. They can possibly be designed to reflect these waves in a directed manner. It is possible to provide for encapsulating / embedding at least one of the metasurfaces in a thermal protection material like the antenna 205.

[0057] 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.

[0058] In particular, the remote device may have a structure different from that described.

[0059] The thermal protection block / envelope may be arranged around the antenna only, the antenna being connected by a cable or connector to the rest of the electronic circuit.

[0060] Other polymer resins may be chosen to form the thermal protection envelope, for example an epoxy resin or a PG 231 or PG 355 resin. The temperature range of use will preferably be from -40°C (or even -60°C) to +150°C, or even higher and beyond 250°C, and the thermal conductivity less than 1 W / (mK). In addition, the hardest possible resin will preferably be chosen, with a Shore D hardness of at least 30 to ensure mechanical protection of the antenna and the electronic circuit.

[0061] Other ceramics can be chosen to form the thermal protection envelope, for example a glass ceramic.

[0062] The material of the thermal protection block / envelope will preferably be chosen according to its performance in terms of radio wave transmission. The invention is also applicable to active type RFID devices, i.e. comprising a battery for powering the electronic circuit for applications at temperatures preferably below 200°C.

[0063] The remote device 200 can be arranged to perform functions other than those indicated and for example one or more functions making it possible to estimate the lifespan of the component with which it is associated, such as:

[0064] - increment a counter at each reading of the remote device 200 by the collector 100 based on the assumption that a reading is carried out after each operating cycle;

[0065] - increment a counter on a specific RFID command used at each engine start to count the number of cycles during which the engine is in operation;

[0066] - measure a temperature by means of an integrated temperature sensor to count the number of cycles or 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 permanently subjected to radioelectric radiation, or because the remote device 200 incorporates a battery);

[0067] - measure an acceleration by means of an integrated accelerometer to count the number of cycles or 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 radioelectric radiation, or because the remote device 200 incorporates a battery).

[0068] The remote device may have a much more basic structure than described and include only passive components.

[0069] The antenna may have a different structure than described and be made from any electrically conductive element such as a printed circuit board, a cable, a bar or a metasurface.

[0070] There are two ways to identify the component with which a remote device 200 is associated:

[0071] - either the S / N and P / N data are stored in the memory of the remote device 200 as described above;

[0072] - 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 which makes the correspondence between the TID and the P / N and S / N.

[0073] The first solution is simpler for recovering the P / N and S / N. The second solution is less energy-intensive, the TID being more directly accessible (this is important when the remote device 200 is at the limit of the RFID antenna range and therefore has little energy).

[0074] The collector can be carried on board the aircraft or be independent of the aircraft for use on the ground by a maintenance operator.

[0075] The invention is applicable to vehicles of all types, such as land, water or air vehicles, whether or not they carry a crew. Regarding 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. System according to claim 1, wherein a thickness of the protective envelope is determined as a function of a thermal conductivity of the thermal protective envelope (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. System according to claim 3 or 4, in which the polymer resin is a silicone resin or an epoxy resin.

6. System according to claim 1, in which the thermal protection envelope (210) is made of 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. Vehicle according to claim 8, the vehicle being an aircraft.

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

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