WO2013004940A1

WO2013004940A1 - Module for monitoring at least one physical quantity characteristic of the state of a member for guiding by contact, which is powered by a thermoelectric generator

Info

Publication number: WO2013004940A1
Application number: PCT/FR2012/051432
Authority: WO
Inventors: Jean-Charles CHAILLOUT; Pascal Desbiolles; Sébastien Guillaume
Original assignee: Ntn-Snr Roulements
Priority date: 2011-07-04
Filing date: 2012-06-22
Publication date: 2013-01-10
Also published as: FR2977666A1; FR2977666B1

Abstract

The invention relates to a module (10) for monitoring at least one physical quantity characteristic of the state of a member for guiding by contact, in particular a bearing (80), the monitoring module (10) comprising: at least one state sensor (54, 58) for providing an electric signal for measuring the physical quantity, and an electric circuit (50) comprising a circuit for querying the state sensor, which is connected to the state sensor (54, 58); and a circuit for supplying power to the monitoring module (10). The module further comprises at least one thermoelectric converter (22, 24) built into the power supply circuit, a base plate (28) for channeling a heat flow, moving by means of thermal conduction, from the bearing (80) to the thermoelectric converter (22, 24), a cooling radiator (36) for discharging a heat flow, moving by means of thermal conduction, from the thermoelectric converter (22, 24) toward the outside, and at least one insulating heat seal (46) for insulating the cooling radiator (36) from the base plate (28).

Description

MONITORING MODULE OF AT LEAST ONE PHYSICAL SIZE CHARACTERISTIC OF THE STATE OF A CONTACT GUIDE MEMBER,

POWERED BY A THERMOELECTRIC GENERATOR

TECHNICAL FIELD OF THE INVENTION

The invention relates to an autonomous module for monitoring a physical quantity, including a physical quantity characteristic of the state of a contact guide member. The term "contact guide member" in the context of the present application means any sliding or rolling guide member for linear or rotary guidance. In particular, the smooth or rolling bearing bearings, and in particular the bearings housed in bearing boxes, are particularly concerned. Linear guidance devices are also targeted, in particular of the type comprising a plate running on a linear track by sliding a plate equipped with rollers rolling on a linear track. Also covered are linear bearings, linear bearings and ball screw nuts.

STATE OF THE PRIOR ART

In some applications, particularly in the field of public transport, energy production or industrial, the requirements of reliability and availability of facilities are particularly severe. These requirements result in a need for monitoring the wear elements of these installations, and in particular bearings for guiding rotating members, such as bearings of alternator shafts, or railway axles.

But these bearings have an extremely long potential life before a defect appears, which can for example be several billion revolutions for a rolling bearing, but can be reduced under severe operating conditions. . The malfunction of a rolling bearing may have various origins, including galling, wear, cracks, cage breaks, corrosion or flaking, which is an alteration of the surfaces of the raceways or rolling bodies, due to the fatigue of the material. In such a context, systematic preventive maintenance which consists of dismounting the bearings at regular intervals to check their condition has a high cost of immobilization and a relative efficiency since the vast majority of the bearings thus verified are without defaults. The continuous monitoring of the bearings is therefore a major issue for the operational safety of the facilities, particularly in terms of availability and reliability.

In the document DE 10 20080 46202 is proposed an autonomous module for monitoring the state of a rotating member, taking advantage of the thermal output of the rotating member to supply the electrical circuit of the monitoring module via a converter thermoelectric. According to one embodiment, the thermoelectric converter and its associated radiator are embedded on the rotating member, the rotation of the member ensuring a cooling air flow of the radiator. According to a second embodiment, the thermoelectric converter and its radiator are fixed, the device further comprising a fan associated with the rotating member to generate a forced air stream at the radiator. This device is however not suitable for monitoring a bearing housed in a bearing box, such as an axle box or a gearbox, within which no thermal gradient is observed. sufficient. DE 10 2007 017 461 describes an autonomous power supply module for an electrical circuit, including a thermoelectric generator taking advantage of a heat flux available in the environment of the electric circuit to generate by Seebeck effect. a voltage. The module is further provided with a voltage stabilization circuit at the output of the thermoelectric generator. No provision is made to integrate this module into a housing allowing in situ use. The module is therefore not usable in a severe environment.

DE 10 2007 056 150 describes an autonomous module for measuring a physical quantity present in a medium delimited by a wall having a hole, comprising a sensor for measuring the physical quantity in question, a thermoelectric converter for supplying the sensor, a radiator connected to the thermoelectric converter and a screw intended to penetrate into the hole of the wall so as to allow the measurement of the physical quantity by the sensor, the screw constituting a thermal conductor between the middle and outside via the thermoelectric converter and the radiator. It is also envisaged means of wireless transmission measures. This experimental device proves however little exploitable in a severe industrial environment.

A similar observation can be made concerning the monitoring of the state of linear guide members, and in particular guide devices by rollers or ball bearings.

SUMMARY OF THE INVENTION

The invention aims to remedy all or part of the disadvantages of the state of the art identified above, and in particular to provide means for monitoring a guide member by contact and in particular a bearing housed in a bearing housing or a linear guide device, minimum energy cost, and preferably without external wire connection, and without significantly modifying the bearing housing or the linear guide device.

According to one aspect of the invention, it relates to a bearing housing comprising a bearing box body defining a cavity for housing a bearing for guiding a rotating member, in particular an axle stub axle. , a bearing box cover closing the cavity, and an acoustic emission sensor attached to the outside of the bearing box and having an acoustic coupling face mechanically coupled to an outer face of a wall of the bearing box in such a way that the acoustic emission sensor is able to detect the transient elastic waves resulting from internal local micro-displacements of the bearing and propagating to the wall.

The positioning of the sensor on an outer wall of the axle box allows to consider a non-intrusive mounting on existing models of bearing boxes, which avoids a requalification of the bearing box. For the record, the qualification of a bearing box, particularly in the fields where the safety of the installations is essential, for example for railway or nuclear power applications, requires long and extensive tests on the load bench. The positioning of the sensor also makes it possible to envisage a rise in renovation, on pre-existing bearing boxes. It is the experience that has revealed that against all odds an acoustic emission sensor is able to give a signal representative of the state of the bearing, even if it is disposed at a distance from it on a face of the bearing housing opposite to the cavity where the bearing is housed.

This type of sensor has a low power consumption, and is particularly suitable for the instrumentation of a bearing box without wired electrical connection with the outside. The signal processing from such a sensor can also be simple, thus low energy consumption.

In many applications, we see that the fixed element of the bearing, which is secured to the axle box and will be called in the following generically fixed ring, is not solicited uniformly around the rotation axis of the bearing, but instead the bulk of the load is on a restricted angular sector around the axis of rotation of the bearing, for example on a sector of less than 180 ° and in practice less than 120 °. In general, this observation is made for applications in which the axis of rotation of the bearing is horizontal or more generally inclined with the vertical axis determining the direction of gravity. This will be the case for example for an axle box, the angular sector then being generally open upwards and corresponding to the part of the outer ring of the bearing bearing the bulk of the vehicle weight. This will also be the case for a primary wind turbine shaft bearing, the angular sector can then be turned down and correspond to the zone carrying the bulk of the weight of the rotating crew consisting of the primary shaft and the propeller of the wind turbine. In such circumstances, it will be advantageous to provide that the acoustic coupling wall is located in the same angular sector as the charging zone, if possible in close proximity to the portion of the fixed ring corresponding to the charging zone. According to a preferred embodiment, the acoustic emission sensor comprises a piezoelectric transducer, particularly suitable for minimizing the power consumption, both by the sensor itself and in the subsequent processing of the signal. Indeed, such a sensor has an excellent signal-to-noise ratio, which allows a lower amplification of the signal.

The acoustic emission sensor may be integrated with a monitoring module comprising an electrical circuit for processing an acoustic emission signal emitted by the acoustic emission sensor to compare the acoustic emission signal with a signature. Bearing characteristic and issue a bearing diagnostic signal.

The module may advantageously comprise a sealed protective casing of the acoustic emission sensor and the electrical circuit, comprising at least one mechanical interface for fixing to the bearing box.

This monitoring module may further comprise a temperature sensor and / or a bearing rotational speed sensor (s) connected to the electrical processing circuit, the diagnostic signal of the bearing being a function of the temperature and / or the measured speed (s). In particular, the characteristic signature of the bearing may depend on the temperature measured by the temperature sensor and / or the speed measured by the speed sensor. The monitoring module may further comprise a power supply circuit connected to the processing circuit and the transmission circuit. These circuits are advantageously integrated in the waterproof housing of the monitoring module. According to a preferred embodiment taking advantage of the heat dissipated by the rotation of the bearing, the monitoring module can also comprise: a thermoelectric converter integrated in the electrical supply circuit, a channeling sole of a thermal flow transiting the inside the bearing box to the thermoelectric converter, a cooling radiator positioned so as to protrude outside the bearing box to evacuate a thermally conductive thermal flux from the thermoelectric converter to the outside, at least one thermal insulation seal to isolate the soleplate on the outside. cooling radiator.

Thus, an autonomous power supply of the instrumentation of the bearing box, that is to say without wired power supply connection from the outside.

The soleplate will preferably be in contact with a thermal coupling wall of the bearing box. The acoustic emission sensor can be directly coupled to the soleplate, which in this case has a dual function of mechanical interface coupling between the acoustic emission sensor and the wall of the bearing box, and heat conduction .

According to one embodiment, the instrumentation housing serves to accommodate both the acoustic emission sensor, the processing circuit, the thermoelectric converter, and possibly at least a portion of the transmission circuit. This instrumentation box can at least partially be constituted by the radiator, the sole and the heat seal.

In the case where a thermometric sensor is used, it may advantageously be disposed on the sole. If necessary, it can be provided that the bearing box is provided with a passage so that the sole penetrates inside the housing cavity of the bearing.

The instrumentation housing may further comprise a body forming with the sole and the cooling radiator one or more hermetically sealed cavities housing the thermoelectric converter and the acoustic emission sensor. According to a preferred embodiment, the acoustic emission sensor is coupled to the body of the instrumentation box, which has the acoustic coupling face with the wall of the bearing box, for transmitting to the acoustic emission sensor the waves transient elastics resulting from internal local microdetrations of the bearing. The sole has on its side a wall thermal interface with the bearing box, intended to come into contact with a hot outer face of the cover or the body of the bearing box. This thermal interface wall is preferably perpendicular to the acoustic coupling face of the body of the housing. This arrangement makes it possible to ensure good contact on the one hand between the sole plate and the bearing box for transmitting heat to the thermoelectric converter, and on the other hand between the wall of the bearing box and the acoustic coupling face.

The bearing box cover may advantageously comprise an open housing on the outside in which is housed at least a portion of the housing, the housing having at least two perpendicular faces constituted by the outer face of the thermal coupling wall. and the outer face of the acoustic coupling wall.

The heat insulation seal is preferably disposed between the body and the cooling radiator or between the body and the sole. The body may itself be made of thermally insulating material, so as to form all or part of the insulation seal. By insulating material is meant here a material so the thermal conductivity is at least five times lower, and preferably at least ten times lower than the thermal conductivity of the materials of the sole and the radiator. For example, the material constituting the body of the instrumentation housing may be a stainless steel, having a thermal conductivity of the order of 26 Wm K, the soleplate being made of copper with a conductivity of the order of 390 Wm. K ⁴ and an aluminum radiator, having a thermal conductivity of the order of 230 Wm ^ ⁴ . If one chooses for the soleplate an oxidizable material under the intended conditions of use, for example copper, it will be advantageous for the soleplate to be completely protected from the ambient air or more generally from the external environment. It is thus expected that the body of the instrumentation casing envelops the soleplate on all sides other than that in contact with the wall of the bearing box constituting the hot source, for example the coupling wall. In addition, you can provide a seal, if possible thermal insulation, disposed between the body of the instrumentation housing and the bearing box, to protect the sole of the hostile external environment. The body of the instrumentation box is then preferably stainless, or at least stainless in depth, under the expected ambient operating conditions, especially in air between -40 and + 150 ° C.

The module may further comprise at least one adapting cushion of deformable thermal conductor material disposed between the cooling radiator and the thermoelectric converter or between the thermoelectric converter and the sole, or two cushions on both sides. thermoelectric converter, so that the thermoelectric converter, sandwiched between the radiator and the sole, is pinched with a controlled contact pressure, despite any dimensional tolerances manufacturing or assembly parts.

The presence of such cushions makes it possible, during the design and production of the module, to decouple the dimensioning of the parts of the instrumentation casing to ensure its mechanical strength in a hostile vibratory environment, and that of the parts to ensure a good thermal and / or acoustic conduction.

We will choose for cushion a material preferably having a very low thermal contact impedance. Considering that the sole, the possible cushion between sole and thermoelectric converter, the thermoelectric converter itself, the possible cushion between thermoelectric converter and radiator and the radiator are thermally arranged in series between the hot source constituted by the wall of the bearing box and the cold source constituted by the ambient air, and considering that each of these elements has a thermal impedance, it will be preferred for the adaptation pad or cushions materials whose thermal impedance is lower than that radiator, and preferably lower than that of the sole. In particular, a flexible elastomer sheet loaded with metal particles may be chosen for an adaptation cushion. It will also be possible to choose a thermo-conductive grease loaded with metal particles.

We prefer a cushion capable of deforming elastically and / or plastically compressive to absorb a stroke greater than the maximum positioning tolerance between the radiator and the sole and the relative movements induced by the differential expansion of the materials in case thermal fluctuations. Good results were obtained with a glass fiber filled 0.5 mm to 5 mm polymer sheet having a Young's modulus of 60 to 180 kPa and a Shore 00 hardness of 35 measured according to ASTM standard. D2240-02.

According to one embodiment, the monitoring module further comprises a radio transmission antenna and an electrical transmission circuit connected to the antenna. This antenna can be housed in a cavity of the cooling radiator closed by a cover made of materials transparent to electromagnetic waves at least in a frequency range corresponding to a maximum gain of the antenna. Thus the antenna is protected, especially if the module is in a hostile environment such as a railway vehicle bogie.

According to another aspect of the invention, it relates to a method of monitoring the state of wear of a bearing disposed in a bearing box comprising a box body in which the bearing is housed. and a can lid enclosing the can body, wherein an acoustic emission sensor is coupled to an outer wall of the can to measure transient elastic waves resulting from internal local micro-displacements of the bearing and propagating to the outer wall.

It is advantageous to compare the elastic waves measured at a characteristic signature of the bearing to carry out a diagnosis of the state of the bearing. One can also measure a temperature inside the box, and proceed to the diagnosis of the state of the bearing as a function of the elastic waves and the temperature measured.

It is also possible to measure a rotational speed of the bearing, and to stop diagnosing the state of the bearing when the speed of rotation of the bearing remains below a predetermined threshold for a given time.

According to another aspect of the invention, it aims to provide an autonomous monitoring module using exclusively the energy available in the direct environment of a rotary or linear guide member by contact such as a bearing rolling bearing or a sliding bearing, a linear guide device by rollers or by ball or roller pads, for monitoring the state of the guide member. More specifically, there is provided a module for monitoring at least one physical quantity characteristic of the state of a contact guiding member, comprising: at least one state sensor for providing an electrical signal for measuring the physical quantity, an electrical circuit comprising: a polling circuit of the state sensor connected to the state sensor, a power supply circuit of the monitoring device, a thermoelectric converter integrated into the electrical supply circuit, a channel insulator, a thermal flow transiting from the guide member to the thermoelectric converter; - a cooling radiator for discharging a thermal flux passing through the thermal conduction of the thermoelectric converter outside, at least one thermal insulation seal to isolate the cooling radiator from the soleplate.

Thus, the thermal energy generated by the guide member is used, energy which, transported by the thermal flux channeled by the soleplate, is transformed by the thermoelectric converter which has a cold source thanks to the radiator. cooling.

Preferably, the module comprises an instrumentation housing for housing the electrical circuit at least partially constituted by the radiator, the soleplate and the heat seal, the instrumentation housing comprising at least one mechanical interface for fixing to a connected support. to the guide member. There is thus a unitary subassembly that can be mounted on the support connected to the guide member. This support may for example be a bearing box, for example an axle box, a gearbox, a crankcase or a wind turbine bearing box. The support may also be constituted by a movable plate of a linear guide system, this plate being provided with rollers or a ball circulation circuit rolling on a fixed guide track.

In the case where the support is a housing housing of the bearing, the sole may be provided to come into direct contact with an outer wall of this box, or to get inside the box. The first solution will be preferred in all situations where the bearing box pre-exists and is retrofitted with the module.

According to a preferred embodiment, the instrumentation housing further comprises a body interposed between the soleplate and the radiator and forming with the soleplate and the radiator a housing cavity of the thermoelectric converter. The heat insulation seal (s) can then be placed between the body and the cooling radiator and / or between the body and the soleplate. The material constituting the body may be a thermal insulator, so that the body itself constitutes the thermal insulation seal or a part thereof. By insulating material is meant here, as indicated above, a material so the thermal conductivity is at least five times lower, and preferably at least ten times less than the thermal conductivity of the constituent materials of the soleplate and the radiator.

If one chooses for the soleplate an oxidizable material under the intended conditions of use, for example copper, it will be advantageous for the soleplate to be completely protected from the ambient air or, more generally, from the external medium. It is thus expected that the body of the instrumentation box of the monitoring module envelops the soleplate on all sides other than that in contact with the wall of the bearing box constituting the hot source, for example the coupling wall. In addition, there may be provided a seal, if possible thermal insulation, disposed between the body of the instrumentation box and the bearing box and surrounding the sole, to protect the sole of the hostile external environment.

The thermoelectric converter is sandwiched between the soleplate and the radiator. In order to ensure a good contact pressure between these elements and to facilitate mounting of the module, the latter may advantageously be provided with at least one adapter pad made of deformable thermal conductor material, arranged between the cooling radiator and the thermoelectric converter and / or between the thermoelectric converter and the soleplate.

According to a preferred embodiment, the electric circuit further comprises a radio transmission antenna connected to an electrical transmission circuit. To protect it in a hostile environment, the antenna can in particular be housed in a cavity of the cooling radiator closed by a cover of material transparent to electromagnetic waves at least in a frequency range corresponding to a maximum gain of the antenna.

Advantageously, the electrical circuit may comprise a power saving circuit connected to a displacement sensor of the guide member and able to put the interrogation circuit out of standby when a signal of the rotation sensor of the bearing exceeds a predetermined threshold for a given time. This displacement or motion sensor can measure a speed of displacement of the guide member or any other physical quantity representative of the movement of the guide member, for example a vibration measured by a accelerometer, an acoustic emission measured by a high-frequency piezoelectric sensor, a temperature. In any case, the electrical energy of the signal emitted by the rotation sensor will be used to supply power to the energy saving circuit and to cause the power supply circuit to be awakened. According to one embodiment, the thermoelectric converter has a hot face facing the sole and a cold face opposite the hot face and facing the cooling radiator. The thermal transfer between the soleplate and the radiator is thus ensured by conduction through the thermoelectric converter. In the case where several thermoelectric converters are necessary, they can be arranged thermally in series or in parallel with each other, between the sole and the radiator.

The cooling radiator is preferably made of a metallic material, for example an aluminum alloy. The soleplate is also preferably made of a metallic material, for example a copper alloy. The body can be made of stainless steel.

According to a preferred embodiment, the power supply circuit comprises an electrochemical accumulator, recharged by the thermoelectric converter. The electrochemical accumulator is preferably placed in abutment on the cooling radiator or on a matching cushion of flexible material and good thermal conductor, the objective here being to cool as much as possible the electrochemical accumulator, the performance of which can be alter in case of too high temperature.

The physical quantity (s) includes at least the acoustic emission of the bearing, the temperature of the bearing or the vibration of the bearing. Preferably, the temperature is used in combination with one of the other two quantities to determine the state of the bearing.

According to another aspect of the invention, it relates to a bearing box comprising: a box body defining a cavity for housing a bearing for guiding a rotating member, and a box lid closing the cavity, a monitoring module as described above, for monitoring at least one physical parameter characteristic of the state of the bearing, the sole of the monitoring module being in contact and bearing against a wall of the box body or the box lid, or through an opening of such a wall.

According to a particular application, the bearing box is an axle box housing an axle stub, the cooling radiator having flat fins parallel to a horizontal axis perpendicular to the axis of rotation of the bearing.

According to another application, the bearing box is a wind turbine bearing housing housing a wind turbine propeller axis, the cooling radiator preferably comprising flat fins arranged parallel to the direction of the air flow. .

The bearing may in particular be a rolling bearing or a plain bearing.

It can advantageously be provided that the box body or the box cover has a cavity open towards the outside of the box and constituting a housing for the monitoring module, the radiator protruding out of the cavity to the outside. . Preferably, this cavity has a side wall perpendicular to an axis of rotation of the bearing and constituting the thermal coupling wall. This coupling wall is preferably in the load zone of the bearing, which also corresponds to the maximum heat dissipation zone.

According to another aspect of the invention, it relates to a power supply method of a monitoring module of at least one physical parameter characteristic of the state of a bearing housed in a box bearing, according to which: transferring heat by thermal conduction from the inside of the bearing box to a hot face of a thermoelectric converter located outside the bearing box; transferring heat by thermal conduction from a cold side of the thermoelectric converter to a heat sink radiator thermally insulated from the bearing box and located in a forced ambient air flow; an electrochemical accumulator is charged with the thermoelectric converter, - an interrogation circuit of a sensor for measuring the physical quantity is supplied with the thermoelectric converter and / or the electrochemical accumulator.

A voltage adapter may be interposed between the thermoelectric converter and the accumulator. Preferably, a transmission circuit connected to a radio-electric antenna is supplied with the thermoelectric converter and / or the electrochemical accumulator.

To limit the consumption, it can be provided to stop supplying at least the interrogation circuit when the speed of rotation of the bearing is less than a predetermined threshold for a predetermined time.

According to another aspect of the invention is provided a monitoring module of at least one physical parameter characteristic of the state of a contact guiding member, comprising: at least one state sensor to provide a electrical signal for measuring the physical quantity, an electric circuit comprising: a polling circuit of the state sensor connected to the state sensor, a power supply circuit of the monitoring device, and - a power saving circuit connected to a displacement sensor of the guide member by contact and able to put the interrogation circuit out of standby when a physical quantity characteristic of the movement of the contact guiding member measured by the displacement sensor of the contact guiding member is greater than a predetermined threshold during a predetermined time.

The energy saving circuit makes it possible to define an optimal power supply strategy for the interrogation circuit of the state sensor, minimizing the energy required by the module, which makes it possible, if necessary, to make the module autonomous, in the sense that it does not require external power supply.

The monitoring module is particularly suitable for monitoring a bearing. The physical quantity characteristic of the rotation of the bearing can be the rotational speed of the bearing conventionally measured by a speed sensor, the temperature in the bearing box or on an outer wall of the bearing box, measured by a sensor of temperature, a vibration of the bearing housing or the bearing, measured by a sensitive accelerometric sensor, in particular in a frequency range of less than 20 kHz and preferably less than 100 Hz or acoustic emission. Similarly, in the case of the monitoring of a linear guiding member, the physical quantity characteristic of the linear movement may be the speed of a plate of the linear guiding system, measured in a conventional manner by a speed sensor, the temperature of the plate or of a guide rail on which the plate moves, measured by a temperature sensor, a vibration of the plate, measured by a sensitive accelerometric sensor, especially in a frequency range of less than 20 kHz and preferably less than 100 Hz or an acoustic emission. One can choose an immediate awakening of the interrogation circuit when the threshold is exceeded, in which case, the waiting time is zero.

The standby of the circuit can take place automatically at the end of a measurement cycle, or when the physical quantity characteristic of the state of the guiding member measured by the state sensor passes below a predetermined threshold, or even when the characteristic magnitude of the movement of the guide member, measured by the movement sensor of the guide member, passes below a predetermined threshold for a predetermined time.

According to a preferred embodiment, the power supply circuit comprises an electrochemical accumulator.

The power supply circuit may comprise at least one transducer adapted to convert into electrical energy a kinetic energy and / or thermal emitted by the guide member. The transducer or transducers may in particular include a thermoelectric converter as described above in connection with other aspects of the invention, and for example a thermoelectric converter having a hot face connected by thermal conduction to a base of the module in contact with a wall of the guide member or through a wall of a housing of the guide member and a cold face connected by thermal conduction to a cooling radiator, preferably positioned in a flow of air.

According to a preferred embodiment, the contact guiding member is a bearing housed in a bearing housing. The at least one transducer includes at least one thermoelectric converter having, on the one hand, a hot face thermally conductive to a sole of the monitoring module in contact with a wall of the bearing box or through a wall of the bearing and diving box. inside the bearing box and on the other hand a cold face connected by thermal conduction to a cooling radiator.

It can also be envisaged that the movement sensor of the guide member is connected to the supply circuit in such a way that when the guiding rotates, the movement sensor of the guide member generates a signal that supplies power to the supply circuit. This provides a source of energy that can be used as a main or auxiliary source, for example in addition to a thermoelectric converter. This will be possible in particular with a polarized passive electromagnetic velocity sensor of the coil and phonic wheel or magnetic encoder type.

The monitoring module may further comprise a radio transmission antenna and a transmission circuit connected to the antenna. Still in a concern for energy control, it can be provided that the transmission circuit is able to be fed by the antenna when it is placed in an electromagnetic field of a remote transceiver device. In such a configuration, the transmission circuit can limit its use of the power supply circuit during the transmission phases, which is particularly advantageous, especially if the transmission phases take place at a standstill, for example in a maintenance phase, where the landing does not emit heat and does not turn.

Moreover, always in a concern of minimizing the energy requirements and maximizing the autonomy of the monitoring module, it is possible for the state sensor to be an acoustic emission sensor able to detect the transient elastic waves. resulting from local micro-displacements internal to the guide member. Indeed, such a sensor is low energy consumption and does not require sophisticated signal processing, themselves energy consumers. Other state sensors may however be envisaged, for example a temperature sensor or an accelerometric sensor.

According to another aspect of the invention, it relates to a bearing box, in particular an axle box, comprising: a bearing box body defining a cavity for housing a bearing for guiding an organ rotating, in particular an axle journal, and a bearing box cover closing the cavity, a monitoring module as described above, for monitoring at least one physical parameter characteristic of the state of the bearing.

The state sensor is preferably disposed outside the bearing box, preferably in a dedicated housing fixed to the bearing box. The rotation sensor of the bearing can be arranged outside the bearing box (for example if it is a thermometric or accelerometric sensor). It can also penetrate inside the cavity through an opening in a wall of the bearing box body or the bearing box cover. According to another aspect of the invention, it relates to a bearing box cover, in particular an axle box, comprising: means for fixing to a body of the bearing box, and a module for monitoring as described above, for monitoring at least one physical parameter characteristic of the state of the bearing, the sole of the monitoring module being in contact and bearing against a thermal and / or acoustic coupling wall of the box lid bearing, or through an opening in a wall of the bearing box cover.

This solution is particularly suitable for an existing hardware renovation context, the only existing part of the bearing box to be modified being the lid, which does not require requalification of the entire box.

According to another aspect of the invention, it relates to a method for managing the power supply of a monitoring module of at least one physical parameter characteristic of the state of a housed landing. in a bearing box, according to which: an electrochemical accumulator is charged with at least one thermoelectric generator, an interrogation circuit of a state sensor is supplied to measure the physical quantity when the rotational speed of the bearing is greater than a first predetermined threshold; stopping supplying at least the interrogation circuit when the rotational speed of the bearing is less than a second predetermined threshold for a given time.

As explained above, this energy saving measure allows greater autonomy of the monitoring module.

BRIEF DESCRIPTION OF THE FIGURES

Other characteristics and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures, which illustrate: FIG. 1, a block diagram of a monitoring module according to a mode of embodiment of the invention; - Figure 2, a sectional view of a monitoring module according to one embodiment of the invention; Figure 3, a sectional view of the monitoring module of Figure 2 along a sectional plane parallel to that of Figure 2; Figure 4 is an exploded view of the monitoring module of Figure 2; - Figure 5, a sectional view of a bearing box, here an axle box, incorporating the monitoring module of Figure 2; Figure 6 is a sectional view of a module according to an alternative embodiment.

For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED DESCRIPTION OF AN EMBODIMENT

In Figure 1 is schematically illustrated a monitoring module 10 of a rotary bearing, consisting of several technological bricks, namely a brick 12 of energy recovery from the environment, a brick management and storage of this energy 14, a measurement brick 16 composed of one or more sensors for measuring one or more physical quantities characteristic of the state of the bearing, a signal processing brick 18 and a transmission brick 20 a diagnosis of the state of the bearing. In the following, it will be assumed by way of illustration that the bearing in question is a rolling bearing housed in a railway axle box, but this particular application is not necessarily of a limiting nature.

The energy recovery can take advantage of different energy sources present in the direct environment of the sensor, including the rotation of the shaft guided by the bearing or the temperature in the direct vicinity of the bearing. Other available sources of energy, such as the deformation of one of the bearing rings or solar energy, would in theory be conceivable. The chosen choice must take into account the chosen mechanical integration and the system integrating the bearing to be instrumented.

In the embodiment illustrated more specifically in Figures 2 to 5, the energy recovery brick implements at least one, and here in this case two thermoelectric converters 22, 24 placed in parallel in a stream As shown schematically in FIG. 2, these thermoelectric converters 22, 24 each comprise, in known manner, a hot face and a cold face, which should be placed in a heat flow to obtain the desired thermoelectric effect. Insofar as these thermoelectric converters must also be mechanically protected from their potentially hostile environment, they are inserted into an instrumentation box 26 allowing this heat flow. The housing comprises a metal soleplate 28, for example made of copper or a copper-based alloy, having a lateral external thermal coupling face 30 exposed to a heat source and an inner face 32 in contact and in abutment with a piece of metal. adaptation 34 also copper, this part being directly in contact with the hot face of the thermoelectric converter. Preferably, the adapter piece 34 is fixed to the soleplate 28 by screws 35. The housing also comprises a finned cooling radiator 36 of aluminum alloy, intended to be placed in a cold air flow, or at least relatively cold compared to the hot source. A thermal path is made between the cold face of the thermoelectric converters 22, 24 and the cooling radiator 36 via a copper adapter piece 38 and an adaptation cushion 40.

The radiator 36 and the sole 28 do not come into direct contact with each other, but are instead separated by a body 41 of the housing, forming with the sole 28 and the radiator 36 a housing cavity 42 thermoelectric converters 22, 24, closed on one side by the radiator 36 and on the other by the soleplate 28. Preferably, the body 41 is made of a thermally insulating material and constitutes a heat seal insulating the radiator of the sole. It may also be a thermally conductive material, in which case a specific heat seal must be provided between the body 41 and the radiator 36, and / or between the body 41 and the soleplate 28.

The sole 28 is fixed to the body 41 preferably by fixing screws 47, visible in Figure 4. The radiator 36 is preferably mounted on the body with the fixing screws 48. In the example embodiment, and to take into account the significant mechanical constraints of the application envisaged to equip a railway axle box, there is provided a stainless steel body, the sole being made of copper and the aluminum radiator. Seals 43, 44 are provided on the one hand between the sole 28 and the body 41, and on the other hand between the body 41 and the radiator 36. A rigid plate of thermally insulating material 46 is also provided between the body and the radiator to form a heat seal. To avoid any oxidation of the sole 28, the stainless steel body 41 envelops and completely covers the sole 28 on all sides other than the thermal coupling face. During assembly of the instrumentation housing 26, the thermoelectric converters are sandwiched between the adaptation parts 34, 38 and, ultimately, between the sole plate 28 and the radiator 36. adaptation 40 disposed between the radiator 36 and the adaptation piece 38 is deformable and allows to perfectly control the contact pressure at the interfaces between the thermoelectric converter and the adaptation parts. In the example illustrated in the figures, this adaptation cushion 40 is disposed between the radiator and the adapter 38 on the cold face side of the thermoelectric converters 22, 24 and the radiator 36, but could alternatively be positioned, following a variant, between the adapter 34 on the hot face side of the thermoelectric converters and the sole 28. It is also possible to provide two adapter cushions on either side of the thermoelectric converters 22, 24, to protect both the face The cushions are of deformable, good thermal conductor material, and have surface properties adapted to the parts between which they interpose, in order to maximize the contact surface and to minimize the thermal resistance of the thermocouple. contact at each interface.

The instrumentation box 26 accommodates not only the thermoelectric converters 22, 24, but also an electrical circuit of the monitoring module 10, embodied by one or more printed circuit boards 50 fixed to the body by screws 51 and incorporating the energy management and storage 14, measurement 16, signal processing 18 and transmission 20 management and storage bricks.

The electrical circuit comprises in particular a power supply management circuit, connected firstly to the thermoelectric converters 22, 24 and secondly to an electrochemical accumulator 52. The electrochemical accumulator 52 can advantageously be thermally insulated. of the soleplate and thermally connected to the radiator, to ensure that the accumulator operates in a sufficiently low temperature range. The power supply management circuit can advantageously include a circuit for determining the state of charge of the electrochemical accumulator. The electrical circuit further comprises a polling circuit of the state of the bearing, connected to one or more sensors of physical quantities characteristic of the state of the bearing, in this case an acoustic emission sensor 54, a temperature sensor and, where appropriate, a speed sensor 58, or even other sensors, such as those envisaged in the document FR 2 944 875, the description of which is here incorporated by reference.

The acoustic emission results from an energy release in the form of transient elastic waves in a material having irreversible degradation. The acoustic emission of a plain bearing or rolling bearing part during the rotation makes it possible to determine the degradations such as cracks or spalling at the workpiece or, in the case of a plain bearing, state of lubrication or possible tearing of material. It is possible to determine, by experience, specific signatures of these impairments. The acoustic emission sensor 54 is constituted by a piezoelectric transducer having a coupling face to the part to be monitored, and sensitive to vibrations in the ultrasonic field, and particularly in a vibratory range beyond 20 kHz. This acoustic emission sensor 54 is disposed in the instrumentation box 26 of the monitoring module 10 and mechanically coupled directly to the sole plate 28 or to the body 41 of the instrumentation box. In the embodiment illustrated in the figures, the acoustic emission sensor 54 is more specifically fixed and coupled to the body 41 of the housing, plated on a thin wall 60 intended to come into direct contact with a wall of the box. bearing. An electromagnetic shielding cover 62 is provided to isolate the acoustic emission sensor 54 from possible disturbances. The thermometric sensor is positioned in contact with the hot face of the sole, directly near the hot face of the thermoelectric converter.

The interrogation circuit interrogates the thermometric sensor and the acoustic emission sensor 54, and transmits the data to a signal processing circuit. It is deliberately unsophisticated given the balance sheet system energy. Indeed, a simplification of this treatment is preferred to allow a higher measurement frequency. The processing circuit also includes storing the data. Depending on the level of acoustic emission measured, the operating state of the bearing is represented by an indicator that can take three states:

Green: the bearing is healthy

Orange: a start of flaking is detected. It is necessary to program a maintenance operation to replace it. This can be done at the same time as the next scheduled maintenance deadline.

Red: The chipping condition is advanced. It is urgent to change the bearing concerned to avoid a risk of overheating, and possible breakage.

Depending on the state of the indicator, it is possible to make a record of the measurements recorded on demand for a more in-depth analysis. Finally, the electrical circuit comprises a low-power radiofrequency transmission circuit connected to a transmission antenna 64. The antenna 64 is housed in a cavity 66 formed in the radiator. This cavity is turned towards the outside and closed by a protective cover 68 made of material transparent to electromagnetic waves. Because of the metal mass constituted by the radiator 36, the design of the antenna 64 is specific and takes into account the electromagnetic characteristics of the material. A conductive metal plate 70 is interposed between the antenna and the radiator to form a ground plane for increasing the performance of the antenna.

The monitoring module 10 thus defined can equip a bearing box, for example a rail vehicle axle box 72 as illustrated in Figure 5, consisting of a box body 74 closed by a cover of box 76, delimiting a sealed cavity 78 housing a bearing 80 for guiding an axle stub 82. In the present case, and without this having a limiting character, the bearing 80 is a rolling bearing, consisting of of a fixed outer ring 84 with two paths of oblique bearing, two inner rings 86 with oblique raceways and rolling bodies 88, in this case conical rollers, held in cages 90. The fixed outer ring 84 is integral with the body 74 of the axle box, while the inner rings 86 are fitted on the axle stub 82 and held in position by a rocket cap 92.

As illustrated in the figure, the monitoring module 10 is positioned in a recess 94 of the cover 76, the side wall 30 of thermal coupling of the soleplate being pressed against a side wall 96 directly in the load zone of the bearing 80 94 to maximize heat transfer through this wall 96 which constitutes a thermal coupling wall. The body 41 of the instrumentation box 26 of the monitoring module 10 is fixed to the recess 94 of the cover by four screws 98 (FIG. 4), so as to achieve a good contact pressure between the body 41 of the instrumentation box and the cover 76 of the axle box 72 at the recess 94, which also constitutes an acoustic coupling wall. A seal 100 is provided between the body 41 of the instrumentation box and the bearing box 72, surrounding the soleplate 28, to protect the soleplate 28. Remarkably, the acoustic coupling wall of the recess 94 and the wall thermal coupling 96 are perpendicular to each other, so that the chains of dimensions can be respected on the one hand between the body 41 and the acoustic coupling wall 94 and on the other hand between the sole and the wall of thermal coupling 96, despite possible mounting tolerances between the body 41 and the sole 28.

The speed sensor 58 passes through the recess wall through an orifice, to penetrate inside the axle box 78, facing and at a distance from the air gap of an encoder 104 secured to the rotating crew. , for example rocket cap 92, or one of the rotating inner rings 86 of the bearing. The encoder 104 in question is a so-called "top tower" type encoder, which makes it possible to detect one or two changes of state at each turn. This information is sufficient because the speed sensor 58 is mainly used to manage the energy of the electrical circuit so as to minimize the energy consumption and for the diagnosis of the state of the bearing, which does not require a very precise knowledge of the speed. As long as the speed of the axle is less than a speed threshold off standby, corresponding for example in the railway application considered at a speed of about 80 km / hour for the railway vehicle in question , the electrical circuit remains in deep sleep, the power consumption is very low or zero. When the speed of the axle 82 exceeds a given threshold, the voltage across the speed sensor 58 causes the electrical circuit to come out of its standby state, so that a monitoring cycle can begin.

Conversely, when the speed of the axle 82 decreases under a second predetermined threshold, possibly equal to the first threshold, and remains there for a duration greater than a predetermined time, the electric circuit enters the deep sleep state.

Of course, various variants are conceivable.

[00101] In Figure 6 is shown a variant without speed sensor. One can then consider different strategies for minimizing the energy consumed by the module: it is possible to provide for interrogations spaced apart in time, for example once a day; if other sensors are present in the module, it is also possible to provide a wake-up circuit according to a sufficiently energetic signal delivered by one of these sensors and characteristic of the rotation of the bearing, for example a signal of temperature or a measured vibration RMS value.

The monitoring module 10 is adaptable not only to axle boxes but also to other types of rolling bearing or plain bearings, particularly for wind turbines or industrial machines, in applications where the there is sufficient heating of the bearing and a significant temperature difference between the inside of the bearing box and the external environment. The housing can be formed without body, the radiator then being attached to the sole, with the interposition of a heat seal.

The speed sensor 58 can be used as a source of auxiliary or main electrical power of the monitoring module 10. To do this, the speed sensor 58 must be associated with a multipole encoder ring having a large number of poles, for example 32 poles per revolution, for generating an alternating current for supplying the electric circuit and the accumulator 52.

[00105] The adaptation pieces 34, 38, or at least one of them, may be omitted. The number of thermal converters and their thermally arranged in series and / or in parallel, and electrically in series and / or in parallel, can be determined differently for each application, depending in particular on the volume constraints, the differential thermal source available in hot source and cold source and / or the voltage range to be generated to be compatible with the electrochemical accumulator.

The transmission circuit can be purely passive, so that the antenna 64 also serves to capture the electromagnetic energy emitted by a reading antenna arranged at a distance, this energy serving the transmission circuit for transmitting information on the status of the monitored landing. The above description is also transposed to a linear guide system.

Claims

Module (10) for monitoring at least one physical parameter characteristic of the state of a contact guiding member (80), the monitoring module (10) comprising:

at least one state sensor (54, 58) for providing an electrical signal for measuring the physical quantity,

an electrical circuit (50) comprising:

an interrogation circuit of the state sensor connected to the state sensor (54, 58),

a power supply circuit of the monitoring module (10),

characterized in that the module further comprises:

at least one thermoelectric converter (22, 24) integrated in the power supply circuit,

a sole (28) for channeling a heat flux passing from the guide member (80) to the thermoelectric converter (22, 24), a cooling radiator (36) for discharging a thermally conductive thermal flow of the thermoelectric converter. (22, 24) outside, and

at least one thermal insulation seal (46) for insulating the cooling radiator (36) from the sole (28).

Monitoring module (10) according to claim 1, characterized in that it comprises a housing (26) housing the electrical circuit (50), the housing (26) being at least partially formed by the cooling radiator (36) , the sole (28) and the heat seal (46), the housing (26) having at least one mechanical interface (98) for attachment to a support (72) connected to the guide member.

3. Monitoring module (10) according to claim 2, characterized in that the housing (26) further comprises a body (41) interposed between the sole (28) and the radiator (36) and forming with the sole (28). ) and the radiator (36) a housing cavity (42) of the thermoelectric converter (22, 24).

4. Monitoring module (10) according to claim 3, characterized in that the sole (28) is copper or copper-based alloy, the body (41) is stainless steel and the radiator (36) is aluminum .

5. Monitoring module (10) according to claim 3 or claim 4, characterized in that the body (41) constitutes an envelope in which is housed the sole (28).

6. Monitoring module (10) according to any one of claims 3 to 5, characterized in that the heat insulation seal (s) (46) are arranged between the body (41) and the cooling radiator (36). and / or between the body (41) and the sole (28).

7. Monitoring module (10) according to any one of the preceding claims, characterized in that the monitoring module (10) further comprises at least one adapter pad (40) of deformable thermal conductive material, disposed between the cooling radiator (36) and the thermoelectric converter and / or between the thermoelectric converter and the soleplate.

8. Monitoring module (10) according to any one of the preceding claims, characterized in that the electrical circuit (50) further comprises a radio transmission antenna (64) connected to an electrical transmission circuit.

9. Monitoring module (10) according to claim 8, characterized in that the antenna (64) is housed in a cavity (66) of the cooling radiator. (36) closed by a cover (68) of material transparent to electromagnetic waves at least in a frequency range corresponding to a maximum gain of the antenna. 10. Monitoring module (10) according to any one of the preceding claims, characterized in that the electrical circuit (50) comprises a power saving circuit connected to a displacement sensor (58) of the body of guiding and able to put the interrogation circuit out of standby when a signal of the displacement sensor exceeds a predetermined threshold for a predetermined time.

11. Monitoring module (10) according to any one of the preceding claims, characterized in that the thermoelectric converter (22, 24) has a hot face facing the sole (28) and a cold face opposite the hot face and turned towards the cooling radiator (36).

12. Monitoring module (10) according to any one of the preceding claims, characterized in that the cooling radiator (36) is made of a metallic material.

13. Monitoring module (10) according to any one of the preceding claims, characterized in that the power supply circuit comprises an electrochemical accumulator (52), recharged by the thermoelectric converter (22, 24).

14. Monitoring module (10) according to claim 13, characterized in that the electrochemical accumulator (52) is arranged in abutment on the cooling radiator (36). 15. Monitoring module (10) according to any one of the preceding claims, characterized in that the physical quantity (s) include at least one at least one of the following physical quantities: an acoustic emission of the guide member, a temperature of the guide member, a vibration.

A bearing box (72) comprising: a box body (74) defining a cavity (78) for housing a bearing (80) for guiding a rotating member (82), and a box lid (76) closing the cavity (78), characterized in that the bearing box (72) is equipped with a monitoring module (10) according to any one of the preceding claims, for monitoring at least one physical parameter characteristic of the state of the bearing (80), the sole (28) of the monitoring module being in abutment against a thermal coupling wall (96) of the can body (74) or the can lid (76) or passing through an opening of a wall of the box body or box lid.

Bearing box (72) according to claim 16, characterized in that the bearing box (72) is an axle box housing an axle stub (82), the cooling radiator (36) having parallel plane wings to a horizontal axis perpendicular to the axis of rotation of the bearing (80).

Bearing box according to claim 16, characterized in that the bearing box is a wind turbine bearing housing housing a wind turbine propeller shaft.

Bearing box according to one of Claims 16 to 18, characterized in that the box body (74) or the box cover (76) has a cavity open towards the outside of the box (72) and constituting a housing for the monitoring module, the cavity having a side wall (96) perpendicular to an axis of rotation of the bearing and constituting the thermal coupling wall, the radiator (36) projecting out of the cavity to the outside. 20. Bearing box according to claim 19, characterized in that the cavity is formed in the cover (76) of bearing box. Method for powering a monitoring module of at least one physical parameter characteristic of the state of a bearing (80) housed in a bearing box (72), characterized in that:

heat is transferred from the inside (78) of the bearing box (72) to a hot face of a thermoelectric converter (22, 24) located outside the bearing box (72). );

transferring heat by thermal conduction from a cold side of the thermoelectric converter to a heat sink (36) thermally insulated from the bearing box (72) and located in a forced ambient air flow;

an electrochemical accumulator (52) is charged with the thermoelectric converter (22, 24),

a interrogation circuit of a state sensor (54, 58) for measuring the physical quantity is supplied with the thermoelectric converter (22, 24) and / or the electrochemical accumulator (52).

Monitoring method according to claim 21, characterized in that a transmission circuit connected to a radio-electric antenna (64) is supplied with the thermoelectric converter (22, 24) and / or the electrochemical accumulator (52).