Mechanism equipped with a distance measurement sensor and associated measurement method

Abstract

A mechanism comprising at least one first part and a measuring sensor (10), the measuring sensor comprising: a body (11) arranged to be fixed on a first portion of said first part, a rod (13) slidably mounted in the body (11), a return element (19) for the rod (13) towards said first part such that one end of the rod (13) is kept in permanent contact: with a second portion of said first part, the sensor then being arranged to evaluate a distance between the two portions of said first part, or with a second part of the mechanism, the sensor then being arranged to evaluate a distance between said two parts of the mechanism; the sensor (10) comprising an antenna (32) which is arranged to supply the sensor (10) and to acquire and transmit a signal representative of a distance. FIGURE IN ABRIDGED DIAGRAM: Fig. 2

Description

Title of the invention: Mechanism equipped with a distance measurement sensor and associated measurement method

[0001] The invention relates to a mechanism equipped with a distance measurement sensor.

[0002] The invention also relates to a method for measuring a distance between two portions of a part of such a mechanism or between two parts of such a mechanism.

[0003] BACKGROUND OF THE INVENTION

[0004] Modern aircraft wheel brakes comprise a stack of discs (also called a heat sink) including rotor discs that are rotationally linked to the wheel and stator discs that are held stationary in rotation. These discs are pressed against each other by means of pistons or pushrods received or integrated into a fixed part of the brake (also called the ring) to generate, by friction, a braking torque sufficient to slow the wheel. The discs are subject to wear with each braking operation, and it is important to know their state of wear in order to plan their replacement. In this regard, aircraft brakes are generally equipped with at least one wear indicator in the form of a rod passing through an eyelet attached to the ring and connected to a portion of the disc stack opposite the support (called the thrust plate), so that the indicator moves within its eyelet as the discs wear.The position of the indicator relative to the eyelet is therefore indicative of the wear condition of the disc stack. To give a rough idea, the heat sinks are typically changed after 2000 to 4000 landings. Before replacement, the disc stack has generally lost five centimeters in thickness.

[0005] Maintenance operators regularly check the position of the wear indicator (typically daily before the first flight) to verify the wear condition of the discs and replace them with new discs when the wear indicator reaches a maximum wear position. Such a check is reliable, but it does not allow for a precise estimation of the wear of the inspected brake discs and makes any automated monitoring of brake disc wear difficult. In addition, unwanted movement between the brake support and the disc stack can occur. This unwanted movement forces the indicator into the eyelet, which can lead to breakage and loss of the indicator.

[0006] SUBJECT OF THE INVENTION

[0007] The invention aims in particular to simplify, improve and make more reliable the measurement of a displacement between two parts of a mechanism or between two portions of a part within a mechanism. Summary of the invention

[0008] To this end, the invention provides a mechanism comprising at least a first part and a measuring sensor, the measuring sensor comprising:

[0009] - a body arranged to be fixed onto a first portion of said first part,

[0010] - a rod mounted to slide within the body,

[0011] - a rod return element towards said first part so that one end the stem must be kept in constant contact:

[0012] • with a second portion of said first part, the sensor then being arranged to assess the distance between the two portions of said first piece, or

[0013] • with a second part of the mechanism, the sensor then being arranged to evaluate a distance between said two parts of the mechanism.

[0014] The sensor includes an antenna which is arranged so that, under the action of an electromagnetic field external to the sensor:

[0015] • Both power the sensor so that said sensor can generate a signal representative of a position of the rod in the body, representative of the distance separating the two portions of the part or of the distance separating the two parts of the mechanism, and

[0016] • Both retrieve and transmit said signal representing the position of the rod in the body towards the outside of the sensor.

[0017] Thus, the sensor allows the signal, representing the position of the rod, to be transmitted remotely without needing to be connected by wire to another part of the mechanism. Therefore, the sensor can advantageously be installed in areas that are difficult for a maintenance operator to access and / or in areas subject to high stress (for example, those subject to rotational movements).

[0018] Furthermore, no connection is necessary to retrieve the signal representing the position of the rod.

[0019] Furthermore, the antenna advantageously allows the sensor to be powered without the need to integrate a battery into the sensor. This is particularly advantageous in environments with very high temperatures, since installing a battery then becomes difficult or even impossible.

[0020] Furthermore, in the case where the antenna is an RFID antenna, a unique identification of the sensor would then be natively assigned which would make it possible to avoid certain errors during the operations of evaluating the wear of a part.

[0021] Consequently, the invention simplifies and significantly improves the operations of evaluating the condition of a mechanism (measuring a displacement of one part relative to another, symptomatic of the deformation or wear of at least one of these parts, or between two portions of the same part symptomatic of a deformation of said part).

[0022] The invention proves particularly advantageous in environments with severe environmental constraints (for example, in environments exposed to dust, and for example, carbon dust). In particular, it should be noted that the use of the invention is then much more advantageous than the use of a laser beam to detect the wear of one or more parts. Indeed, the measuring sensor will then maintain its accuracy despite the dust (whereas the laser beam could be obstructed by this same dust).

[0023] According to optional features, used individually or in whole or in combination: - The measuring sensor is configured so that it can only be powered via its antenna. - the sensor is an inductive type sensor, - the measurement sensor includes a passive RFID tag comprising at least one electronic chip and the antenna, - the rod acts in service as a magnetic field emitter, the sensor also including a measuring device for detecting said magnetic field, - The return mechanism is a spring mounted in the body next to the rod to exert a tensile force on it. - the return mechanism is a spring arranged at least partially around the rod to exert a pressing force tending to pull the rod out of the body, - the mechanism is a vehicle wheel brake, the brake comprising a stack of discs, the sensor being fixed to a fixed part of the brake, forming the first part, in such a way that the rod is applied against the front part of the stack of discs, forming the second part, the sensor thus measuring the distance separating the front part of the stack of discs from the fixed part, a distance representative of the wear of the stack of discs, - the invention may also relate to an assembly such as the one mentioned above and a reader equipped with an antenna, the reader and the sensor being arranged to communicate with each other via their antennas, the sensor also being externally powered by the reader via their antennas, - the invention may also relate to a method for measuring the distance between two portions of the same part or between two parts of a mechanism as described above, comprising the steps of: • Bring a reader equipped with an antenna close to the sensor, with the sensor and the first part remaining in place in the mechanism, • Generate an electromagnetic field from the reader towards the sensor antenna, • Retrieve, via the sensor antenna, at the reader level, the signal representing the position of the rod in the body.

[0024] Other features and advantages of the invention will become apparent from the following description of a particular, non-limiting embodiment of the invention. Brief description of the drawings

[0025] Reference will be made to the attached drawings, among which:

[0026] [Fig-1] [Fig. 1] is a perspective view of an aircraft wheel brake equipped with a measuring sensor according to a particular embodiment of the invention;

[0027] [Fig.2] [Fig.2] is a perspective view of the measuring sensor visible in [Fig.1]

[0028] [Fig.3] [Fig.3] is an exploded view of the measuring sensor of [Fig.1];

[0029] [Fig.4] [Fig.4] is a diagram illustrating a method of using the measuring sensor of the [Fig.l];

[0030] [Fig.5] [Fig.5] is a schematic front view of an aircraft equipped with wheels according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] With reference to [Fig. 5], the invention is described herein in application to an aircraft 100 equipped with braked wheels. More specifically, the invention relates to a mechanism comprising a measuring sensor. The mechanism is a brake for a wheel 103 rotatably mounted on an axle 102 carried by a landing gear 101 of the aircraft 100. The wheel 103 comprises a hub rotatably mounted on the axle 102 by means of bearings, and a rim connected to the hub by a disc and arranged to carry a tire.

[0032] With reference to [Fig. 1], a typical aircraft wheel brake 1 comprises a stack of discs (or heat sinks) 2 threaded onto a torsion tube 3. The stack of discs 2 includes stator discs 2A held stationary against rotation (for example, by cooperation with external splines of the torsion tube 3) and rotor discs 2B rotationally bound to the wheel rim. The stack of discs 2 extends between a brake actuator support, here a hydraulic ring 4 (commonly called an actuator-carrying ring) with pistons 5 attached to one end of the torsion tube 3, and a backplate 6 attached to the other end of the torsion tube. The stack of discs 2 includes a thrust plate 7, bearing against the first stator disc 2A and opposite the ring 4, which distributes the thrust exerted by the pistons 5 over the entire front surface of the stack of discs 2. This well-known arrangement will not be described in further detail.

[0033] A measuring sensor 10 is carried by the stack of disks 2, the measuring sensor 10 being arranged in the present case to determine the distance separating two parts of brake 1, characteristic distance of the wear of said stack of discs. The measuring sensor 10 is therefore here a wear measuring sensor 10.

[0034] Preferably, the sensor 10 is an inductive type sensor.

[0035] This allows for a sensor that consumes relatively little energy when in operation.

[0036] The measuring sensor 10 comprises a body 11. The body 11 extends longitudinally along a first axis X. The body 11 has an elongated, substantially cylindrical shape.

[0037] The body also includes a first extension 12. The first extension 12 extends along a second axis Y and has a parallelepiped shape. The second axis Y is orthogonal to the first axis X. The first extension 12 is therefore a continuation of the body 11. Here, the body 11 and the first extension 12 form a single piece.

[0038] The first extension 12 is hollow and closed by a cover 12.1. The cover 12.1 is shaped here into a plate. For example, the cover 12.1 is rectangular. Here, the cover 12.1 is screwed onto the first extension 12, for example here by means of four fixing screws.

[0039] Inside the first extension 12 is housed a base 12.2. The base 12.2 extends, for example, perpendicularly to the cover 12.1 when the base 12.2 and the cover 12.1 are in place on the first extension 12. The base 12.2 is here shaped as a platform. For example, the base 12.2 is rectangular.

[0040] An electronic card 12.3 is supported by said base 12.2. In the present case, the electronic card 12.3 is arranged in the first extension 12 of the body 11. Preferably, the electronic card 12.3 is fixed to the base 12.2. Here, the electronic card 12.3 is screwed onto the base 12.2, for example, by means of two fixing screws. The electronic card 12.3 includes, for example, at least one controller.

[0041] The body 11 also includes a second extension 16. The second extension 16 extends along a third axis Z. The third axis Z is, for example, orthogonal to the first axis X. The second extension 16 has a cubic shape. Here, the second extension 16 has a smaller volume than the first extension 12. Similarly, the second extension 16 is a continuation of the body 11. Here, the body 11 and the second extension 16 form a single piece.

[0042] The body 11 comprises an upper face and a lower face.

[0043] The body 11 is closed at its upper face by an upper cover 15. The upper cover 15 is fixedly mounted on the body 11. Here, the upper cover 15 is screwed onto the body 11, for example here by means of two fixing screws.

[0044] The body 11 is closed at its lower face by a plug 20.

[0045] The measuring sensor 10 also includes a rod 13. More specifically, the sensor 10 has a rod 13, slidably mounted in the body 11. The rod 13 extends along the first axis X. The rod 13 has an upper end 17 and a lower end 14. The upper end 17 has an opening 17.1. Said opening 17.1 houses at least part of the upper cover 15. Preferably, said opening 17.1 houses at least part of a lower extension 15.1 of the upper cover 15.

[0046] The lower end 14 of the stem 13 extends beyond the body 11. Preferably, the lower end 14 extends through the body 11 and the cap 20.

[0047] Therefore, the rod 13 is coaxial with the body 11. The rod 13 thus acts as a probe. In this respect, its lower end 14 has a spherical tip to ensure near-point contact with the push plate 7. To maintain point contact between the lower end 14 of the rod 13 and the push plate 7, the sensor 10 also includes a return element. Here, the return element is a spring 19. The spring 19 is arranged in the body 11 of the sensor 10. Preferably, the spring 19 extends along the first axis X. Preferably, the spring 19 surrounds the upper end 17 of the rod 13. Therefore, the spring 19 is fixed at one end to the upper cover 15. On the other hand, the spring 19 is fixed at a second end against a rim 17.2 of the upper end 17 of the rod 13. Here, the spring 19 is a helical spring.The spring 19 is thus advantageously arranged to exert a pressing force tending to push the rod 13 out of the body 11 and thus keep its lower end 14 in contact with the push plate 7. Thus, thanks to the return exerted by the spring 19, the rod 13 is kept permanently in contact with the push plate 7 and moves in the body 11 as the stack of discs 2 wears down.

[0048] The position of the rod 13 in the body 11 is therefore representative of the wear of the stack of discs 2.

[0049] The electronic card 12.3 carries or is connected to a measuring device, such as a magnetic Hall effect detection circuit, adapted to emit a signal (here electrical) representative of the position of the rod 13 in the body 11. For example, a magnetic rod 13 and a measuring device similar to those described in document FR-A-3124856 may be used.

[0050] For example, the magnetic rod 13 is movable relative to the measuring device. The rod 13 is, for example, movable in translation relative to the measuring device along a first direction. The rod 13 is capable of emitting a magnetic field detected by the measuring device. The rod 13 is preferably arranged so that an orientation of the magnetic field considered in a first plane orthogonal to the first direction evolves as a function of a distance separating the first plan of one end of the rod, the measuring device being configured to produce a signal representative of the orientation of the magnetic field and therefore of the position of the rod 13 in the body 11 and therefore representative of the wear of the stack of discs 2.

[0051] More specifically here, the electronic card 12.3 thus makes it possible to generate a signal representative of the position of the rod 13 in the body 11 and therefore representative of the wear of the stack of discs 2.

[0052] Preferably, the spring 19 is chosen so that the force applied by the rod 13 on the thrust plate 7 is greater than and sufficient to prevent it from moving within the body 11 under the effect of vibrations during operation. The force of the spring 19 depends in particular on the mass of the rod and must be sufficient to prevent the rod from becoming stuck due to any dust that may infiltrate between the rod and the body 11.

[0053] The measuring sensor 10 also includes, in this case, an RFID housing 80 incorporating a passive RFID tag 30. "Passive" means that the RFID tag does not have an energy source powering said RFID tag. The passive RFID tag 30 can optionally be associated with a low-capacity energy storage means to facilitate the commissioning of the passive RFID tag 30. For example, the energy storage means is a capacitor, for example, a capacitor of approximately 100 pF.

[0054] Therefore, the sensor 10 is itself passive. In particular, the sensor 10 does not have any power source. In particular, the sensor 10 does not have a battery or cell.

[0055] The housing 80 has a base 18 closed by a cover 23. The housing 80 is made of electrically insulating material.

[0056] The housing 80 is, for example, arranged on the second extension 16. Optionally, the housing 80 is attached to the second extension 16, for example, by screwing (for example, here, by means of four fixing screws). Here, the housing 80 is attached to the second portion 16 via its base 18.

[0057] The base 18 is for example shaped so as to present a portion of attachment to the body 11 extended by a support for the cover 23.

[0058] In this case, the base 18 is attached to the body 11 at its attachment portion. In particular, the base 18 is attached to the body 11 at a face of the attachment portion opposite the face forming the support. Preferably, an area of ​​said face is the same size and / or shape as the second extension 16. For example, said area is centered on said face of the attachment portion. The dimensions of the base 18 are, however, larger than the dimensions of the second extension 16. Preferably, the base 18 is made of plastic.

[0059] As already mentioned, the cover 23 covers the base 18 so as to form the closed housing 80. The cover 23 comprises a flat surface 23.1 and a peripheral edge 23.2. The peripheral edge 23.2 is, for example, orthogonal to said flat surface 23.1. Furthermore, the cover 23 rests on the base 18, and in particular on the support of the base 18, by means of its peripheral edge 23.2. Preferably, the cover 23 is made of plastic. The base 18 and the cover 23 thus jointly define an internal cavity. Here, the base 18 and the cover 23 are fixed to each other, for example, by screwing. The RFID housing 80 optionally includes sealing means arranged between the cover 23 and the base 18 such as a seal 90. Said seal 90 extends for example over the entire peripheral edge 23.2 at the junction between said edge 23.2 and the base 18.

[0060] The RFID tag 30 is integrated into the housing 80 and, in particular, is housed in the internal cavity. The RFID tag 30 is thus protected from the external environment by the housing 80.

[0061] In the present case, the RFID tag 30 includes at least one electronic chip 31. The electronic chip 31 includes, for example, at least one controller such as, for example, a microcontroller 40.

[0062] Furthermore, the RFID tag 30 includes at least one antenna 32.

[0063] It is therefore understood that the antenna 32 and the electronic chip 31 are both arranged inside the housing 80, and in particular inside its internal cavity. For example, the antenna 32 is supported by the electronic chip 31 and / or a circuit board supports both the antenna 32 and the electronic chip 31.

[0064] Furthermore, the electronic chip 31 / antenna 32 assembly is arranged on the base 18 and, in particular, on its support. Preferably, the base 18 has dimensions larger than those of the electronic chip 31 / antenna 32 assembly so that the electronic chip 31 / antenna 32 assembly can rest on the base 18 without protruding from it.

[0065] In addition, the electronic chip 31 / antenna 32 assembly is covered by the cache 23 so as not to protrude from the cache 23.

[0066] It is therefore understood that the electronic chip 31 / antenna 32 assembly is entirely arranged in the housing 80.

[0067] In the present case, the electronic chip 31 / antenna 32 assembly is fixed in the housing 80. For example, the electronic chip 31 / antenna 32 assembly is fixed to the base 18 and / or the cover 23. In the present case, the electronic chip 31 / antenna 32 assembly is screwed to the base 18 by the same screws as the cover 23. The electronic chip 31 / antenna 32 assembly is thus sandwiched between the base 18 and the cover 23.

[0068] Depending on the performance envisaged, the dimensions of the antenna 32 may vary from one application to another.

[0069] In all cases, the antenna 32 is arranged so as to present an emission field directed outwards from the stack of discs and more particularly outwards from the lander. The orientation of the antenna 32 is such that the antenna 32 can communicate remotely with an RFID reader without it being necessary to remove the wheel. This orientation can, for example, be ensured by a specific positioning of the antenna 32 in its housing 80 and / or by a specific position of the housing 80 relative to the body 11 (via, for example, the second extension 16). In the present case, it is the specific orientation of the second extension 16 that gives the antenna 32 a particular orientation.

[0070] It is noted that the housing 80 extends coaxially to the Z axis and / or to the second extension 16. It is also noted that the antenna 32 and / or the electronic chip 31 and / or the cover 23 and / or the base 18 extend coaxially to the Z axis.

[0071] Furthermore, at least one cable 33 is arranged in the sensor 10 to connect the electronic chip 31 / antenna 32 assembly to the electronic board 12.3.

[0072] The measuring sensor 10 is fixedly mounted on the actuator-carrying ring 4. More precisely, the measuring sensor 10 is fixedly mounted on the existing ring 4, without modification thereof. The ring 4 has an eyelet (i.e., a hole having an axis parallel to the central axis of the stack of discs 2). A lower threaded portion 11' of the body 11 (and for example of the cap 20), coaxial with the rod 13, is arranged to be engaged in the eyelet from the face of the ring 4 opposite the push plate 7 and to protrude from the eyelet towards the push plate 7. A nut 21' is engaged on said threaded portion 11' and allows the measuring sensor 10 to be fixed to the ring 4. Preferably, an anti-rotation washer 22' is interposed between the nut 21' and the ring 4 to block the rotation of the nut 21' after it has been tightened.

[0073] It should be noted that, in general, the measuring sensor 10 is applicable to a mechanism comprising at least one first part. The spring 19 thus allows the rod 13 to remain in contact: - With a different portion of the first part than that carrying the body 11 of the measuring sensor 10, the measuring sensor 10 then being arranged to evaluate a distance between the two portions (the other portion and the body 11) of said first part, or - With a second part of the mechanism, the rod 13 being fixed on another part of the mechanism than that to which the body 11 of the measuring sensor 10 is fixed, the measuring sensor 10 then being arranged to evaluate a distance between said two parts.

[0074] Thus, evaluating the distance between two portions of a first part makes it possible to evaluate a deformation of said part (potentially including the appearance and propagation of a crack).

[0075] Conversely, evaluating the distance between two parts of the same mechanism makes it possible, for example, to assess the wear of one of these two parts or the deformation of one or both of said parts. The method for checking brake wear will now be described. Here, brake wear is considered to be manifested by an increase in the distance between two parts of the brake. The measuring sensor 10 is fixed to a fixed part of the brake, forming the first part, such that the rod 13 is applied against the front part of the stack of discs, forming the second part. The measuring sensor 10 thus measures the distance separating the front part of the stack of discs from the fixed part, a distance representative of the wear of the stack of discs.

[0076] In a first step (step 1), as shown in [Fig. 4], an operator brings an RFID reader 50 close to the measuring sensor 10. This can take place during a maintenance operation to inspect the condition of the brake. It is therefore clear why the antenna 32 is oriented outwards from the lander so that the operator can bring the RFID reader 50 close without having to dismantle the brake and / or the wheel of the lander.

[0077] In a second step (step 2), the RFID reader 50 generates an electromagnetic field directed towards the first antenna 32 of the RFID tag 30, thereby powering the RFID tag 30 remotely. More specifically, the energy from the electromagnetic field generated by the RFID reader 50 is stored in the storage means of the passive RFID tag 30. When sufficient energy has been stored, it powers the electronic board 12.3 of the passive RFID tag 30. In this case, the sensor 10 is therefore configured to be powered only via the antenna 32 of the passive RFID tag 30. Simultaneously, the RFID reader 50 also remotely interrogates the RFID tag 30. Indeed, the RFID reader 50 uses an antenna which provides energy to the RFID tag 30 and communicates with said RFID tag 30 via antenna 32.In other words, the electromagnetic field generated by the RFID reader 50 allows, on the one hand, for the sensor 10 to be powered via its antenna 32 so that said sensor can generate a signal representing the distance separating the two parts. On the other hand, the electromagnetic field generated by the RFID reader 50 allows for the retrieval and transmission of this signal representing said distance.

[0078] During a third step (step 3), the RFID tag 30 supplies power and communicates in turn with the electronic board 12.3 via the cable 33. From then on, the microcontroller 40 communicates with the electronic board 12.3 and asks it to transmit the position of the rod 13 in the body 11 representative of the brake wear. From then on, the electronic card 12.3 transmits the signal representing the position of the rod 13 in the body 11 to the microcontroller 40 of the electronic chip 31.

[0079] Next, the antenna 32 transmits the position of the rod to the RFID reader 50. The RFID reader 50 thus retrieves, via its antenna, the position of the rod 13 in the body 11, which is representative of brake wear.

[0080] Optionally, in a fourth step, the data retrieved by the RFID reader 50 is transmitted and / or stored on at least one computer 60 located remotely from both the sensor 10 and the RFID reader 50. This computer 60 may or may not be integrated into the aircraft. The position of the rod 13 thus constitutes data that can be stored in a database. Therefore, storing this data on a computer 60 facilitates automatic data analysis.

[0081] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention.

[0082] In particular, although here the brake actuator support is a hydraulic ring carrying pistons, the invention is also applicable to an electromechanical brake in which the ring 4 is replaced by a support carrying electromagnetic actuators having pushers to exert a thrust on the push plate 7.

[0083] The sensor can be fixed to any fixed part of the brake relative to which the front part of the stack of discs moves axially during braking. The fixed part can be the body of an actuator or a lever attached to the torsion tube. It can be fixed to it by any means (screwing, bolting, crimping, gluing, clamping, etc.).

[0084] Although here the return element is an elastic element of the mechanical spring type, other return elements such as magnetic means may be used.

[0085] In particular, although here the spring is arranged at least partially around the rod to exert a pressing force tending to draw the rod out of the body, the spring can be mounted in the body next to the rod to exert a tensile force on the latter. Thus, according to a particular embodiment of the invention, the rod is integral with a bracket to which one end of a helical spring is attached, the other end of which is attached to the body to exert a tensile force on the bracket, and therefore on the rod, tending to draw the rod out of the body and thus maintain its end in contact with the thrust plate.

[0086] Although here the rod 13 is cylindrical, it can also be conical in combination in particular with an inductive measuring device.

[0087] The lower end 14 of the rod is preferably arranged to offer the smallest possible contact area with the thrust plate 7 with the lowest possible coefficient of friction. The lower end 14 may have a spherical cap shape allowing quasi-point contact with the thrust plate 7 and It must be made of stainless steel. Alternatively, it can be coated with an anti-friction coating, for example based on bronze or graphite.

[0088] Although here the lower end of the rod comes to rest against a push plate interposed between the brake actuators and the discs, the rod may come to rest against the first stator disc of the stack of discs if the latter is not equipped with a push plate.

[0089] The invention can be used to estimate deformation, crack propagation, etc.

[0090] Although the invention here requires a passive RFID tag, another passive receiver may be considered, the passive receiver also comprising an antenna. The passive receiver may, for example, include a diode rectifier arranged to rectify the signal into a DC voltage (the voltage being stored in an energy storage medium such as a capacitor). The passive receiver may also include non-volatile memory, and preferably, electrically-erasable and programmable read-only memory (EEPROM). Furthermore, the passive receiver may include a processing unit (for example, a microprocessor) arranged to manage the exchange of data between the reader and the measurement sensor.

[0091] Although here the mechanism is a brake, the mechanism may be all or part of (or may be associated with) another part of a vehicle or another machine. The invention is applicable to any type of vehicle, aerial, terrestrial, or amphibious, and not only to aircraft.

[0092] The invention is applicable to applications other than a vehicle and for example to any industrial or personal equipment requiring braking or generally to any machine.

[0093] Although here the sensor includes both control means related to the stem (the electronic board) and control means related to the tag (the electronic chip), the sensor may include only one control means, for example, arranged either in the body or in the housing. For example, the sensor may include only one electronic board arranged in the body of the sensor and communicating with the antenna either wired or wirelessly.

[0094] Although here the control means linked to the rod (the electronic board) communicate with the control means linked to the label (the electronic chip) by wire, the communication may be wireless.

[0095] The invention may do without a housing containing the label, for example in cases where measurements are carried out in a low-stress environment.

[0096] Whatever the intended application, the label will preferably be arranged so that its emission field is turned towards the outside of the part associated with the invention. Whatever the intended application, the label will preferably be arranged so that its emission field can be captured by a reader without an operator needing to approach the part and / or dismantle one or more elements to access said emission field.

Claims

Demands

1. Mechanism comprising at least a first part and a measuring sensor (10), the measuring sensor comprising: - a body (11) arranged to be fixed on a first portion of said first part, - a rod (13) mounted to slide in the body (11), - a return member (19) of the rod (13) towards said first part so that one end of the rod (13) is kept permanently in contact: • with a second portion of said first part, the sensor then being arranged to evaluate a distance between the two portions of said first part, or • with a second part of the mechanism, the sensor then being arranged to evaluate a distance between said two parts of the mechanism;the sensor (10) comprising an antenna (32) which is arranged to, under the action of an electromagnetic field external to the sensor (10): • Both supply the sensor (10) so that said sensor can generate a signal representative of a position of the rod (13) in the body (11) representative of the distance separating the two portions of the part or of the distance separating the two parts of the mechanism, and • Both retrieve and transmit said signal representative of the position of the rod (13) in the body (11) to the outside of the sensor (10).

2. Mechanism according to claim 1, wherein the measuring sensor (10) is configured so that it can only be powered via its antenna (32).

3. Mechanism according to any one of the preceding claims, wherein the sensor (10) is an inductive type sensor.

4. Mechanism according to any one of the preceding claims, wherein the measuring sensor (10) comprises a passive RFID tag (30) having at least one electronic chip (31) and the antenna (32).

5. Mechanism according to any one of the preceding claims, wherein the rod (13) plays in service the role of a magnetic field emitting element, the sensor further comprising a measuring device for detecting said magnetic field.

6. Mechanism according to any one of the preceding claims, wherein the return member (19) is a spring mounted in the body (11) next to the rod (13) to exert a tensile force on the latter.

7. Mechanism according to any one of claims 1 to 5, wherein the return member (19) is a spring arranged at least partly around the rod (13) to exert a pressing force tending to push the rod (13) out of the body (11).

8. Mechanism according to any one of the preceding claims, wherein the mechanism is a brake (1) of a vehicle wheel, the brake (1) comprising a stack of discs (2), the sensor (10) being fixed to a fixed part of the brake (1), forming the first part, such that the rod (13) is applied against the front part of the stack of discs (2), forming the second part, the sensor thus measuring the distance separating the front part of the stack of discs from the fixed part, a distance representative of the wear of the stack of discs.

9. Assembly of a mechanism according to any one of the preceding claims and a reader equipped with an antenna (50), the reader and the sensor (10) being arranged to communicate with each other via their antennas, the sensor also being externally powered by the reader via their antennas.

10. A method for measuring the distance between two portions of the same part or between two parts of a mechanism according to any one of claims 1 to 8, comprising the steps of: - Bringing a reader equipped with an antenna close to the sensor, the sensor and the first part remaining in place in the mechanism, - Generating an electromagnetic field by the reader in the direction of the sensor's antenna, - Retrieving by the sensor's antenna, at the reader, the signal representing the position of the rod in the body.

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