Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M13/00—Testing of machine parts
  • G01M13/04—Bearings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03D—WIND MOTORS
  • F03D17/00—Monitoring or testing of wind motors, e.g. diagnostics
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
  • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
  • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
  • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
  • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
  • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre

Definitions

• the invention lies in the field of monitoring the aging of parts subjected to a rotational movement. It applies in particular to the monitoring of the rotating elements of a wind turbine. More specifically, the invention relates to a method for monitoring the deformations of a surface of a part able to undergo rotational movement, by means of a measuring device comprising an optical fiber acting as a sensor.
• An object of the invention is in particular to remedy all or part of the aforementioned drawbacks by proposing a method of monitoring deformations of a rotating element which impacts as little as possible the operation and aging of this rotating element, and which is it - not influenced by rotation.
• the invention is based on the property according to which a moving part which initiates a failure such as a crack, propagates in the structure a cyclic anomaly of stress, and therefore of deformation.
• any cracking is preceded by a non-homogeneity of the stresses in the part or by a non-homogeneity of the material. This non-homogeneity goes hand in hand with a non-homogeneity of the deformations of the part.
• this non-homogeneity of the deformations necessarily entails a non-homogeneity of the dynamic stresses generated and diffused over the whole of the part.
• the piece undergoes locally a compression - depression cycle during which the stresses are distributed differently over time.
• the cyclic deformation of the part can be detected in a site of the structure chosen as strategic both for the relative ease of installation of the sensor, and for the capacity of this site to undergo stress variations in case of failure.
• a single sensor disposed on all or part of the periphery of the base of the blade will react to any damage to the blade, both locally and in any other location. the blade.
• the subject of the invention is a method for monitoring deformations that may occur on a surface of a part capable of undergoing rotational movement, the method being characterized in that it comprises:
• ⁇ a step of transmitting a light signal to a first end of an optical fiber whose at least one portion is tensioned between two points on the workpiece surface, ⁇ a step of measuring a characteristic of the received light signal at a second end of the optical fiber, said characteristic changes as a function of a length of the optical fiber intermediate its ends, and
• ⁇ a step of comparing the characteristic of the light signal to a reference signal.
• the section of optical fiber is preferably a convex portion of the surface of the piece, so as to remain in contact with the piece along its entire length.
• the part is for example a rotating element of a wind turbine or a turbine. It may especially be a ring of a mechanical bearing.
• a plurality of optical fibers are used, each optical fiber comprising a stretch stretched between two points of the surface of the part.
• each optical fiber comprising a stretch stretched between two points of the surface of the part.
• ⁇ a light signal is emitted at a first end thereof
• ⁇ the characteristic of the light signal is compared with a reference signal.
• the optical signals are preferably emitted simultaneously in each optical fiber to allow corroboration of the results.
• two optical fibers are used, the stretched portion of a first optical fiber being arranged with respect to the stretched portion of the second optical fiber according to an axial symmetry whose axis of symmetry is an axis of the rotational movement. of the room.
• the surface is a surface of revolution whose axis of revolution coincides with an axis of the rotational movement of the part.
• the stretched sections of the optical fibers can then be angularly distributed along the axis of revolution so as to cover a circumference of the surface of revolution.
• the method may further comprise a step of transmitting, by wireless link means, each measured characteristic, or the result of each comparison between the measured characteristic and the reference signal, or a part of these elements. .
• the transmission step can be performed only in case of anomaly, in particular to limit the power consumption of the wireless link means. Indeed, because of the rotational movement of the workpiece, these means are generally powered by a battery mounted on the workpiece. The limitation of the electrical consumption then makes it possible to prolong the life of the battery. Moreover, it is also possible to provide an electric generator powered by the movement of the room to recharge the battery.
• the transmission, measurement and comparison steps are carried out continuously for a determined period of time so as to allow monitoring of the deformations of the part for at least one complete turn of the part.
• the subject of the invention is also a wind turbine comprising a part capable of undergoing rotational movement, and a device for monitoring deformations of the part.
• the monitoring device comprises:
• a light source adapted to emit a light signal at a first end of the optical fiber
• ⁇ a detector capable of measuring a characteristic of the light signal received at a second end of the optical fiber, said characteristic changes as a function of a length of the optical fiber intermediate its ends, and
• ⁇ a processing module adapted to compare the characteristic of the light signal to a reference signal.
• FIG. 1 shows schematically an example of a wind turbine used as an electrical generator and whose parts can be monitored by the method according to the invention
• FIG. 2 and 3 show an example of a ball bearing on which can be implemented a deformation monitoring device adapted to implement the method according to the invention
• FIG. 7 represents an example of steps of the method of monitoring a rotating element according to the invention.
• FIG. 8 represents, by two graphs, examples of light signals operated by the monitoring device.
• the invention is based on a monitoring device using the properties of propagation of a light signal in an optical fiber integrally attached at least two points to the part to be monitored. It is indeed well known that an elongation of the optical fiber in its longitudinal direction implies a contraction in the transverse direction, which impacts the attenuation effect of the amplitude of the light signal traveling through the optical fiber. Braided or twisted optical fibers are also known, whose variation in length results in local variations in curvature which also have the effect of modifying the amplitude of the signal received after transmission by the optical fiber. Thus, the measurement of the amplitude of the light signal makes it possible, by comparison with a reference amplitude, to determine fairly precisely the variation in length experienced by the monitored part between the two points to which the optical fiber is fixed.
• Patent application EP 0 264 622 A1 describes an example of such a monitoring device.
• the device comprises an optical fiber, and a measuring device adapted to emit a light signal at one end of the optical fiber, and to measure an amplitude of the light signal received at another end of the optical fiber.
• FIG. 1 shows schematically an example of a wind turbine used as an electric generator.
• the wind turbine 10 comprises a nacelle 1 1 supported by a mast 12, a hub 13 in pivot connection with the nacelle 1 1 along an axis X, substantially horizontal, and blades 14 supported by the hub 13.
• the nacelle 1 1 is in pivot connection with the mast 12 along a Y axis, substantially vertical, to allow the orientation of the X axis in a direction parallel to the wind direction.
• each blade 14 is in connection pivot with the hub 13 along an axis Zi, Z 2 or Z 3 , to allow the orientation of each blade according to the wind speed.
• the axes Z 1 , Z 2 and Z 3 are perpendicular to the X axis, and concurrent at a point of the X axis. Preferably, they are distributed uniformly around the X axis, that is to say with an angle of 120 degrees between them.
• the nacelle January 1 contains an alternator, not shown, a shaft is rotated, directly or indirectly, by the hub 13.
• the nacelle January 1 may also contain drive means, not shown, suitable for causing the blades 14 to rotate relative to the hub 13 along their respective axes Z 1 , Z 2 or Z 3 .
• Figures 2 and 3 show an example of a ball bearing on which can be implemented a deformation monitoring device.
• Figure 2 shows the ball bearing in a cross-sectional view
• Figure 3 shows this bearing in a partial cross-sectional view.
• the ball bearing 20 provides the pivot connection between the hub 13 and one of the blades 14.
• the bearing 20 comprises an outer ring 21, a first row of balls 22, a second row of balls 23, and an inner ring 24.
• the outer diameter of the bearing 20 is for example of the order of two meters in diameter.
• the hub 13 is secured integrally to the inner ring 24, and the blade 14 is fixedly secured to the outer ring 21.
• the fixing of the hub 13 to the inner ring 24 is carried out, in this example, by a set of fasteners uniformly distributed around the periphery of the inner ring 24.
• Each fastening element comprises for example a stud and two nuts.
• the inner ring 24 then comprises a set of bores 241 made parallel to the axis Zi; the hub 13 likewise comprises a set of bores each capable of coming opposite one of the bores 241.
• Each stud passes through a bore 241 of the inner ring 24 and a bore of the hub 13.
• a nut is screwed to each end of the studs so as to make the hub 13 integral with the inner ring 24.
• the fixing of a 14 to the outer ring 21 can be achieved by studs and nuts.
• the outer ring 21 may then comprise bores 21 1, for example parallel to the axis Zi.
• any other suitable fastening means could be used to make integral the blade 14 to the outer ring 21 and the hub 13 to the inner ring 24.
• the bearing 20 is for example to oblique contact, in order to withstand an axial force along the axis Zi due in particular to the force of gravity and the centrifugal force experienced by the blade 14.
• the bearing 20 shown in Figures 2 and 3 further comprises a ring gear 212 formed on a peripheral surface 213 of the outer ring 21.
• the ring gear 212 can mesh with a pinion, not shown, which is actuated to orient the blade 14, for example depending on the wind speed.
• a deformation monitoring device 30 may be implemented therein. It should be noted that the monitoring device 30 of course makes it possible to detect deformations due to damage to the outer ring 21 itself, but also to any part connected with it.
• the monitoring device 30 comprises an optical fiber 31, a light source 32 adapted to emit a light signal at a first end of the optical fiber 31, and a detector 33 capable of measuring a characteristic of the light signal received at a second end of the light. optical fiber 31.
• the measured characteristic changes as a function of the length of the optical fiber 31 between its ends. This is for example the amplitude of the light signal, or the travel time of the light signal between the two ends of the optical fiber 31.
• the light source 32 and the detector 33 can be combined in the same module.
• one of the physical ends of the optical fiber 31 may be coupled to a reflector capable of reflecting the light signal.
• the second physical end of the optical fiber 31 is then used both for transmitting and receiving the light signal.
• the optical fiber 31 In order to make it possible to monitor the deformations of the peripheral surface 213, the optical fiber 31 must comprise at least one stretch stretched between two points of the peripheral surface 213. In a usual manner, the section matches the peripheral surface 213. According to a preferred form of realization, the optical fiber 31 is installed so that the section undergoes a prestressing tension.
• the section undergoes a variation in length, in this case a contraction, even in the case where the deformation of the peripheral surface 213 involves a rimpedement of the two points to which the optical fiber 31 is fixed.
• the optical fiber 31 is prestressed over its entire length, that is to say between the end connected to the light source 32 and that connected to the detector 33.
• FIG. 4 shows a first example of implementation of the deformation monitoring device 30 on the bearing 20.
• the light source 32 and the detector 33 are contained in a single module, and the optical fiber 31 runs over the entire perimeter of the peripheral surface 213.
• the optical fiber 31 is prestressed along its entire length.
• FIG. 5 represents a second exemplary implementation of a deformation monitoring device 50 on the bearing 20.
• the device 50 comprises two light sources 32A and 32B, two detectors 33A and 33B, and two optical fibers 31. A and 31 B.
• the optical fiber 31 A runs on a first half of the perimeter of the peripheral surface 213, between the light source 32A and the detector 33A
• the optical fiber 31 B runs on a second half of the perimeter of the peripheral surface 213, between the light source 32B and the detector 33B.
• Each optical fiber 31 A, 31 B, 31 C is preferably prestressed along its entire length.
• FIG. 6 represents a third example of implementation of a deformation monitoring device 60 on the bearing 20.
• the device 60 comprises three light sources 32A, 32B and 32C, three detectors 33A, 33B and 33C, and three optical fibers 31A, 31B and 31C.
• the optical fiber 31A runs between the light source 32A and the detector 33A; the optical fiber 31 B short between the light source 32B and the detector 33B; and the optical fiber 31 C runs between the light source 32C and the detector 33C.
• each optical fiber covers substantially one third of the perimeter of the peripheral surface 213.
• Each optical fiber 31 A, 31 B, 31 C may be centered with respect to a blade 14.
• the deformation monitoring device may comprise any number of sets each comprising an optical fiber, a light source and a detector. The advantage of having several sets is to allow more localized monitoring of deformations. Moreover, the optical fibers may overlap at least partially on the periphery of the surface to be monitored.
• FIG. 7 represents an example of steps of the deformation monitoring method according to the invention.
• the light source 32 emits a light signal, for example a pulse, at a first end of the fiber optical 31.
• the detector 33 receives the light signal at the other end of the optical fiber 31 and measures a characteristic of this light signal.
• the characteristic may be an amplitude of the light signal, or a transmission time of the light signal between the light source 32 and the detector 33.
• the light signal may be single frequency, spread over a frequency band, or be composed of several single-frequency signals.
• the optical fiber 31 may be a single-mode or multimode fiber. Thus, the characteristic measured by the detector 33 may actually result from a combination of characteristics.
• the characteristic of the light signal is compared with a reference signal.
• the comparison is performed by a processing module, integrated or not with the detector 33.
• the reference signal may be an amplitude value, for example an amplitude value of the light signal measured during an initialization phase, when the part to be monitored is considered as having no defects, and / or during a rest phase, when the part is not rotated.
• the reference signal may also be a reference period, for example measured during the initialization phase and / or rest.
• the light signal emitted by the light source 32 is not necessarily a pulse, but can be a continuous signal, in which case the reference signal can also be continuous.
• the duration of the light signal is for example determined so that the part to monitor a complete revolution revolution during this time.
• a phenomenon of fatigue resulting in asymmetry of the part to be monitored can thus be observed due to a discontinuity of the light signal received by the detector 33.
• the light signal can be transmitted and received at a predetermined frequency or at the request of 'an operator.
• the monitoring frequency can in particular depend on the criticality of the part to be monitored, and / or previous measurements made on the part to be monitored or on other parts mechanically linked to the part to be monitored.
• the different light signals can be issued independently of each other, or in a synchronized manner.
• the synchronization of the signals has the advantage of being able to correlate the measurement results.
• the monitoring method according to the invention may also comprise a step 74 of transmitting the result of each comparison between a light signal and a reference signal to an external device, for example a control station.
• the data transmitted during step 74 could be the light signals received by the detector (s) 33, the comparison being made by the external device.
• the wind turbine comprises a central housing collecting, preferably by a wireless link, the data from the detector 33, or the processing module performing the comparison.
• this central box collects the data from all the detectors and / or all the processing modules of the wind turbine in question.
• a control station common to the whole of a wind farm can then collect all the data collected by the various central boxes, by a wired or wireless link.
• the monitoring device 30 is preferably powered by a battery, for example a lithium battery.
• data transmission is preferably performed by wireless link means.
• the data transmission can be carried out with a relatively low frequency, for example once a day. This frequency can be lower than the measurement frequency, that is to say the frequency with which a light signal is emitted.
• the data are transmitted only when a failure is found.
• the monitoring device 30 takes advantage of the movement of the monitored part to increase its autonomy.
• the monitoring device 30 may include an electrical generator actuated by the movement of the room and to recharge the battery.
• FIG. 8 represents, by two graphs, examples of light signals exploited by the monitoring device 30.
• a first Figure 81 shows an example of a reference light signal
• the second graph 82 represents an example of a light signal received by the detector 33 in the event of a failure of a part of the wind turbine.
• the amplitude A of the signals is plotted as a function of time, over a period corresponding substantially to two revolution revolutions of the hub 13 of the wind turbine 10.
• the amplitude of the reference signal is substantially constant in time. In the absence of failure, the light signal received by the detector 33 would be identical or similar.
• the measurement signal reveals no discontinuity during a complete rotation of the blades.
• the graph 82 shows a ripple of the amplitude of the light signal, sign of an irregular variation, normally cyclic, of a stress undergone by the part, and thus of a beginning of failure of the part being monitored or of one of the pieces in connection with it.
• the monitoring of stress variation is to monitor first-order effects of room aging, as opposed to monitoring cracks, which are third-order effects. The monitoring of the constraints thus makes it possible to rationally manage the maintenance of the wind turbine, making it possible to anticipate the maintenance operations.
• the monitoring method according to the invention has been described with reference to a bearing between a hub and a wind turbine blade. It could of course be applied to other bearings of a wind turbine, for example a bearing between the hub and a frame of the nacelle of a wind turbine, and other parts undergoing a rotational movement, for example a wheel of a turbine or wheel Pelton. More generally, the method applies to any rotating element having a surface which one wishes to monitor the deformations. This surface may be a peripheral surface. In this case, it may be a surface of revolution whose axis of revolution coincides with an axis of the rotational movement of the rotating element. Preferably, the section of optical fiber stretched between two points of the rotating element conforms to a convex portion of its surface.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Sustainable Energy (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Wind Motors (AREA)
• Rolling Contact Bearings (AREA)
• Length Measuring Devices By Optical Means (AREA)
• Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)

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• 2013
  • 2013-03-21 US US14/775,473 patent/US10151667B2/en not_active Expired - Fee Related
  • 2013-03-21 EP EP13716342.4A patent/EP2976615A1/fr not_active Withdrawn
  • 2013-03-21 WO PCT/FR2013/050607 patent/WO2014147301A1/fr active Application Filing
  • 2013-03-21 CA CA2907602A patent/CA2907602A1/fr not_active Abandoned
  • 2013-03-21 JP JP2016503695A patent/JP2016516204A/ja active Pending
  • 2013-03-21 CN CN201380074854.8A patent/CN105102954A/zh active Pending
  • 2013-03-21 BR BR112015023997A patent/BR112015023997A2/pt not_active Application Discontinuation
  • 2013-03-21 KR KR1020157025477A patent/KR20160016752A/ko not_active Application Discontinuation
• 2016
  • 2016-07-25 HK HK16108849.8A patent/HK1220757A1/zh unknown

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