ATEX-type wireless pressure sensor. Wheel and aircraft equipped with such a sensor.

Abstract

A wireless sensor comprising a first printed circuit board (11), a first electronic circuit extending over a first portion (11.1) of the first printed circuit board (11), an antenna (14) electrically connected to the first electronic circuit, and a battery (13) that powers the first electronic circuit. The sensor includes an inner housing (20) that surrounds at least the battery (13) and is at least partially enclosed by the first portion (11.1) of the first printed circuit board (11), the antenna (14) extending out of the inner housing (20), and an outer casing (30) in at least two separate, attached parts, namely a first part (31) extending mainly around the inner housing (20) and the first portion (11.1) of the first printed circuit board (11), and a second part (32) that surrounds the antenna (14). Vehicle and aircraft wheel equipped with such a sensor. ABRIDGED FIGURE: Fig. 1

Description

Title of the invention: Wireless pressure sensor of ATEX type. Wheel and aircraft equipped with such a sensor.

[0001] The present invention relates to the field of measuring physical quantities such as the pressure of a gas, for example in a tire of a vehicle wheel and in particular of an aircraft wheel.

[0002] BACKGROUND OF THE INVENTION

[0003] It is useful to know the pressure of the tires equipping the different wheels of an aircraft's landing gear during different phases of aircraft operation (for example, when parked, during taxiing before takeoff, in flight and especially during the approach prior to landing) or as part of maintenance operations.

[0004] To this end, the aircraft is conventionally equipped with an automatic tire pressure monitoring system. This monitoring system is known as a "TPMS" (Tire Pressure Monitoring System) and includes, for each wheel, a pressure sensor mounted on the rim. The pressure sensor is coupled to an onboard data processing system and allows pilots to have a real-time display in the cockpit of the tire pressure during the various phases of aircraft operation. During maintenance operations, operators can also consult this display to obtain the desired information.

[0005] The pressure sensor is generally attached to one end of a self-sealing inflation valve to allow removal of the pressure sensor without significant loss of tire pressure. The inflation valve is screwed into a bore that communicates through the rim with the internal volume of the tire.

[0006] Wireless pressure sensors are known to include an electronic circuit which is powered by a battery and which includes a pressure measurement module and a radio communication module connected to an antenna.

[0007] Due to the presence of a battery, these pressure sensors are subject to thermal runaway resistance requirements.

[0008] It is recalled that thermal runaway is an uncontrolled reaction that can occur in batteries: beyond a certain threshold, the battery temperature increases uncontrollably. The exothermic chemical reactions occurring in the battery cause a temperature increase, while the production of gas from the chemical reactions, associated with the evaporation of The electrolyte causes an increase in the battery's internal pressure. This can lead to material being ejected from the pressure sensor, a potentially dangerous event for the aircraft.

[0009] Among the preventive safety measures used to mitigate the consequences of thermal runaway, the most common technique is to confine the pressure sensor in a housing robust enough to withstand a battery explosion. For example, explosion-proof housings are used. An explosion-proof housing is designed to withstand an explosion occurring within it and to prevent the ignition of combustible materials surrounding the housing. Explosion-proof housings must therefore ensure an external temperature (skin temperature) lower than that sufficient to ignite the surrounding materials. The effectiveness of explosion-proof housings makes them expensive, heavy, and bulky, which makes them relatively unattractive for use in applications where cost, weight, and / or size are critical factors.

[0010] Furthermore, the radio communication performance of the pressure sensor must be maintained despite these battery containment mechanisms. However, the housings used are generally metallic for reasons of mechanical strength and can interfere with the radio waves emitted or received by the pressure sensor.

[0011] Finally, this mechanical complexity makes recharging or replacing the battery at the end of its lifespan difficult or even impossible. The pressure sensor must then be replaced with a new one, which generates high maintenance costs for the operator and the manufacturer, and contributes to pollution. However, the Applicant takes environmental factors into account in all phases of design and development to obtain aeronautical components and products that are less energy-intensive, more environmentally friendly, and whose integration and use in civil aviation have moderate environmental consequences, with the aim of improving aircraft energy efficiency.

[0012] SUBJECT OF THE INVENTION

[0013] The invention aims in particular to provide a wireless sensor which at least partially overcomes the aforementioned drawbacks. Summary of the invention

[0014] To this end, the invention provides a wireless sensor comprising a first printed circuit board, a first electronic circuit extending over a first portion of the first printed circuit board, and an antenna connected electrically to the first electronic circuit, and a battery that powers the first electronic circuit. The sensor includes an internal housing that surrounds at least the battery, which is closed at least partially by the first portion of the first printed circuit board, the antenna extending out of the internal housing, and an external housing in at least two separate parts, namely a first part extending mainly around the internal housing and the first portion of the first printed circuit board, and a second part that surrounds the antenna.

[0015] Thus, the inner casing and the outer housing form a double enclosure that limits the risk of material being expelled from the battery. The printed circuit board contributes to the containment of the battery itself, and the positioning of the antenna outside the inner casing prevents the latter from significantly interfering with the radio waves emitted or received by the antenna. The separate outer housing can be configured to provide mechanical strength without hindering radio communications.

[0016] According to optional features, used individually or in whole or in combination: - the antenna is attached to a second portion of the first printed circuit board extending parallel to a central axis of the external housing; - the first part of the external casing is made of metal and the second part of the external casing is made of plastic; - the internal casing is made of metal; - the internal casing has a tubular shape with a blind first end and a second end closed by a closure plate pierced with an opening for the connection of the first electronic circuit to the antenna; - the antenna is supported by a second portion of the first printed circuit board passing through the opening of the closing plate; - the sensor comprising a second electrical circuit extending over a second printed circuit board fixed to the outside of the internal housing and received in the external housing, the second electronic circuit being electrically connected to the first electronic circuit by pins passing through at least one wall of the internal housing; - the second electronic circuit is arranged to measure gas pressure and the first part of the external housing forms a valve body for connection to a pressurized circuit.

[0017] The invention also relates to a vehicle wheel and an aircraft equipped with such a sensor.

[0018] The vehicle wheel comprises a rim, a tire surrounding the rim and defining with it a sensor according to the invention mounted on an inflation valve fixed to the rim and in communication with the internal volume, the sensor comprising a second electrical circuit extending on a second printed circuit board fixed to the outside of the internal casing and received in the external housing, the second electronic circuit being electrically connected to the first electronic circuit by pins passing through at least one wall of the internal casing, the second electronic circuit being arranged to measure a gaseous pressure and the first part of the external housing forms a valve body for connection to a pressurized circuit.

[0019] The aircraft comprising at least one landing gear equipped with such a wheel.

[0020] 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

[0021] Reference will be made to the attached drawings, among which:

[0022] [Fig-1] [Fig.1] is a simplified representation of an aircraft comprising main landing gear having wheels equipped with the pressure measurement sensor according to the invention;

[0023] [Fig.2] [Fig.2] is an axial cross-sectional view of one of the wheels of the aircraft illustrated in [Fig.1];

[0024] [Fig.3] [Fig.3] is a side view of an electronic circuit and a battery of the sensor according to the invention;

[0025] [Fig.4] [Fig.4] is a front view of the electronic circuit and battery of the sensor according to the invention;

[0026] [Fig.5] [Fig.5] is a side view of an internal housing in place on the electronic circuit and battery;

[0027] [Fig.6] [Fig.6] is a front view of this internal casing;

[0028] [Fig.7] [Fig.7] is an end view of this internal casing;

[0029] [Fig.8] [Fig.8] is a side view of this internal housing in place on the circuit electronics and the battery, positioned in a first part of the external casing;

[0030] [Fig.9] [Fig.9] is a side view of the external housing, the two parts of which have been closed onto the internal casing in place on the electronic circuit and the battery. DETAILED DESCRIPTION OF THE INVENTION

[0031] With reference to [Fig. 1], the invention is herein described in application to an aircraft A comprising main landing gear P, each comprising a leg J ​​having a first end articulated to a structure of the aircraft A and a second end provided with an axle E. Each axle E is provided with a wheel R comprising, as shown in [Fig. 2], an annular rim 1 on which a tire is mounted 2. As is known, the tire 2, together with the rim 1, defines a volume V in which a gas is trapped. The rim 1 is connected by a disc 3 to a hub 4 mounted to rotate around an axis X on a free end of the axle E. A self-sealing inflation valve 5 is screwed into a bore 6 in the rim 1, connecting the internal volume V to the outside. All of this is known in itself and will not be detailed further here.

[0032] A pressure sensor, generally designated as 10, is mounted on the inflation valve 5. This type of mounting is conventional, unlike the structure of the pressure sensor 10 itself.

[0033] With reference to figures 3 to 9, the pressure sensor 10 here comprises a first printed circuit board 11 and a second printed circuit board 12. Printed circuit boards, commonly called PCBs, have a structure known in itself.

[0034] The first printed circuit board 11 includes a first portion 11.1 carrying a first electronic circuit comprising a control module and a radio communication module electrically connected to each other. A battery 13 is also attached to the first portion 11.1 and is electrically connected to the control module of the first electronic circuit to power the first electronic circuit. The first printed circuit board 11 includes a second portion 11.2 carrying an antenna 14 electrically connected to the radio communication module. The antenna 14 may be etched onto the second portion 11.2 and / or comprise a component soldered onto this second portion 11.2.

[0035] The first electronic circuit performs the following functions: - power supply for all components of the first and second electronic circuits; - radio communication (for this purpose it includes the controller and the impedance matching network).

[0036] The second printed circuit board 12 includes a second electronic circuit forming a pressure measurement module and having contact areas for its connection to the control module of the first printed circuit board.

[0037] The electronic circuits (control module, radio communication module and pressure measurement module) have a structure known in itself which will not be described in more detail here.

[0038] The pressure sensor according to the invention is characterized in that it comprises an internal housing 20 and an external housing 30 which form a double enclosure.

[0039] The internal housing 20 comprises a tubular body 21 having a first blind end 21.1, provided with an external thread, and a second open end 21.2 between which extends a lateral opening 21.3 delimited by edges 21.4 extending in a plane parallel to a central axis of the tubular body 21. When the inner casing 20 is fully assembled, it surrounds the battery 13, the first portion 11.1 of the first printed circuit board 11 being pressed against the edges 21.4 of the lateral opening 21.3 to close it. Screws 22 passing through the first portion 11.1 are screwed into these edges 21.4 to press the first portion 11.1 against said edges 21.4. The second portion 11.2 of the first printed circuit board 11 extends projecting from the tubular body 21 by its second end 21.2. A closing plate 23, having an opening for the passage of the second portion 11.2, closes the second end 21.2. The closing plate 23 is fixed to the second end 21.2 via screws 24 screwed into the second end 21.2 through the closing plate 23. An optional screw 25 passes through the second portion 11.2 is advantageously screwed into a part of the closing plate 23 to press the second portion 11.2 against said part.

[0040] The inner housing 20 also includes electrically conductive pins 26 passing through the wall 21.5 closing the first end 21.1 of the tubular body 21. The pins 26 have first ends projecting inside the inner housing 20 and electrically connected to contact areas of the first electronic circuit (for example, via soldered wires) and second ends projecting outside the inner housing 20, to which electrically conductive tracks of the second printed circuit board 12 are soldered. The pins 26, which here all extend parallel to the central axis of the tubular body 21, have two functions: an electrical connection function from the second electronic circuit to the first electronic circuit and a support function for the second printed circuit board 12 and a mechanical connection function of the latter to the housing 20. The pins 26 pass through the wall 21.5 closing the first end 21.1 of the tubular body 21 via glass beads 27 to ensure a seal between the pins 26 and said wall 21.5. The glass can be replaced by any other electrically insulating material which also guarantees pressure resistance / sealing resistance.

[0041] The tubular body 21 and the closing plate 23 are both made of metal, so that the inner casing 20 defines a metallic enclosure forming a first level of containment. By closing the lateral opening 21.3, the first portion 11.1 of the first printed circuit board 11 forms part of this enclosure. Since the antenna 14 is located outside the inner casing 20, the latter does not interfere with the transmission of radio signals to or from the antenna 14.

[0042] The external housing 30 comprises a first part forming a valve body 31 and a second part forming a cover 32 for the protection of the antenna 14.

[0043] The valve body 31 has a hollow, revolution-shaped form, with a first tubular and threaded end 31.1, for cooperating with the threaded end of the valve. The inflation valve 5 and a second open end 31.2 having a flat front surface to support the cover 32. The valve body 31 has sufficient internal volume to fully accommodate the internal housing 20. The second printed circuit board 12 carrying the second electronic circuit is then arranged on the side of the first threaded end 31.1. The valve body 31 is internally provided with a threaded hole fitted with a sealing gasket to cooperate hermetically with the thread of the first end 21.1 of the tubular body 21 and to define a hermetically sealed chamber, in which the second electronic circuit is located, in communication with the internal volume V of the tire via the inflation valve 5.

[0044] When the tubular body 21 (and its contents) and the second printed circuit board 12 carrying the second electronic circuit is in place in the valve body 31, the second portion 11.2 carrying the antenna 14 extends outward from the valve body 31 by the second end 31.2.

[0045] The cover 32 is tubular in shape with a first open end 32.1 and a second closed end 32.2 arranged to cover the protruding part of the subassembly. The cover 32 is secured by screws engaged in the valve body 31 through the cover 32.

[0046] The valve body 31 is preferably made of metal while the cover 32 is made of thermoplastic material, for example polyetheretherketone (PEEK), or any other material compatible with radio wave transmission.

[0047] We thus obtain a pressure sensor 10 provided with: - a first level of containment provided by the internal casing 20; - a second level of containment provided by the external box 30.

[0048] This limits: - the risk of sparks in the vicinity of the sensor; - the risks associated with the consequences of a thermal runaway of the battery 13, in particular an increase in external temperature on the surface of the sensor 10; - the risks of material projection in the event of an explosion of battery 13.

[0049] The proposed arrangement also allows for a relatively compact double enclosure and is relatively simple to manufacture due to the independence of the inner casing 20 and the outer casing 30. The fixing of the inner casing 20 directly into the valve body 31 of the outer casing 30, i.e. between two elements having high mechanical resistance, is also advantageous because it is simpler to produce.

[0050] Electronic circuits have a simple structure, with printed circuit boards whose shapes are relatively simple.

[0051] It is understood that both the external housing 30 and the internal casing 20 can be easily disassembled to access the battery 13 in order to facilitate its replacement when it is at the end of its life, or its recharging.

[0052] Finally, it should be noted that the radio communication performance of the pressure sensor 10 is improved by: - the choice of a hood 32 made of a material having a permittivity allowing a limited influence on the transmission of radio waves; - a positioning of the first printed circuit board 11 parallel to the central axis of the external housing 30 and the inflation valve 5 so that the antenna 14 has favorable radio wave transmission performance.

[0053] 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.

[0054] In particular, the sensor according to the invention may have a different structure from that described.

[0055] By battery, we mean a rechargeable or non-rechargeable battery, and more generally any energy accumulator supplying energy in electrical form.

[0056] By electronic circuit, we mean any electrical circuit comprising electronic or semiconductor components.

[0057] The battery may not be fixed on the printed circuit board but for example on the tubular body 21, the electrical connection between the battery and the printed circuit then being made with electrically conductive wires for example.

[0058] The antenna can be offset from the printed circuit board and connected to the electronic circuit by one or more electrically conductive wires or cables. Another variant is to have an antenna component that is connected by a connector to the electronic circuit of the printed circuit board.

[0059] It is possible to offset the antenna from the central axis of the external housing 30, in order to have a different radiation pattern.

[0060] The internal housing 20 may comprise more than two parts, for example three (a central tubular body and two closing plates to close the two ends of the central tubular body). The internal housing 20 may alternatively be made entirely or partly of plastic or composite material.

[0061] The external housing 30 may comprise more than two parts, for example three (a central tubular body and two covers to close the two ends of the central tubular body).

[0062] The sensor may comprise more than two separate electronic circuits or, on the contrary, a single electronic circuit.

[0063] Although the invention has been described in relation to a pressure measuring sensor, the invention is applicable to any type of battery-powered sensor and, for example, a temperature sensor, a speed sensor, a mechanical stress sensor...

[0064] Although the invention has been described in relation to a pressure measurement sensor mounted on an aircraft wheel, the invention is applicable to the wheels of any type of vehicle, and in particular to land vehicles. More generally, the sensor of the invention can be used on any type of vehicle, as well as in fixed installations.

Claims

Demands

1. Wireless sensor, comprising a first printed circuit board (11), a first electronic circuit extending over a first portion (11.1) of the first printed circuit board (11), an antenna (14) electrically connected to the first electronic circuit, and a battery (13) that powers the first electronic circuit, characterized in that the sensor comprises an inner housing (20) that surrounds at least the battery (13) which is closed at least partially by the first portion (11.1) of the first printed circuit board (11), the antenna (14) extending out of the inner housing (20), and an outer housing (30) in at least two attached parts separable from each other, namely a first part (31) extending mainly around the inner housing (20) and the first portion (11.1) of the first printed circuit board (11) and a second part (32) that surrounds the antenna (14).

2. Sensor according to claim 1, wherein the antenna is integral with a second portion (11.2) of the first printed circuit board (11) extending parallel to a central axis of the external housing (30).

3. Sensor according to claim 1 or 2, wherein the first part (31) of the outer housing (30) is made of metal and the second part (32) of the outer housing (30) is made of plastic.

4. Sensor according to any one of the preceding claims, wherein the internal housing (20) is made of metal.

5. Sensor according to claim 1, wherein the internal housing (20) has a tubular shape with a first end (21.1) blind and a second end (21.2) closed by a closing plate (22) pierced with an opening for the connection of the first electronic circuit to the antenna (14).

6. Sensor according to claim 5, wherein the antenna (14) is carried by a second portion (11.2) of the first printed circuit board (11) passing through the opening of the closure plate (22).

7. A sensor according to any one of the preceding claims, comprising a second electrical circuit extending over a second printed circuit board (12) fixed to the outside of the inner housing (20) and received in the outer housing (30), the second circuit electronic being electrically connected to the first electronic circuit by pins passing through at least one wall of the internal casing (20).

8. Sensor according to claim 7, wherein the second electronic circuit is arranged to measure a gas pressure and the first part (31) of the external housing (30) forms a valve body for connection to a pressurized circuit.

9. Vehicle wheel (R) comprising a rim (1), a tire (2) surrounding the rim (1) and defining with it a closed volume (V), and a sensor (10) according to claim 8 mounted on an inflation valve (5) fixed to the rim (1) and in communication with the internal volume (V).

10. Aircraft (A) comprising at least one landing gear (J) equipped with a wheel (R) according to claim 9.

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