Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
  • G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D3/00—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive
  • F16D3/50—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive with the coupling parts connected by one or more intermediate members
  • F16D3/78—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive with the coupling parts connected by one or more intermediate members shaped as an elastic disc or flat ring, arranged perpendicular to the axis of the coupling parts, different sets of spots of the disc or ring being attached to each coupling part, e.g. Hardy couplings
  • F16D3/79—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive with the coupling parts connected by one or more intermediate members shaped as an elastic disc or flat ring, arranged perpendicular to the axis of the coupling parts, different sets of spots of the disc or ring being attached to each coupling part, e.g. Hardy couplings the disc or ring being metallic
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
  • G01H3/00—Measuring characteristics of vibrations by using a detector in a fluid
  • G01H3/04—Frequency
  • G01H3/08—Analysing frequencies present in complex vibrations, e.g. comparing harmonics present
• • 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
  • G01M13/02—Gearings; Transmission mechanisms
  • G01M13/028—Acoustic or vibration analysis
• • 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
  • G01M13/045—Acoustic or vibration analysis
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D2300/00—Special features for couplings or clutches
  • F16D2300/18—Sensors; Details or arrangements thereof

Definitions

• the present invention relates to an apparatus for detecting coupling defects of power transmission couplings during dynamic operation of rotating equipment or machinery.
• the invention relates to the detecting of defects in power transmission couplings including a flexible assembly comprising one or more flexible elements.
• non-intrusive monitoring systems are commonly used in applications where real time monitoring of the rotating and reciprocating equipment on process plants is impeded by long distances or difficulty of access. Efficient operation and maintenance of rotating and reciprocating equipment is essential to maximise production and minimise downtime. Non-intrusive monitoring systems are used to detect or predict equipment defects before catastrophic failure of the equipment occurs, which would result in loss of production capacity and possible injury of personnel.
• Power transmission couplings are components that transmit torque at a speed ratio of 1 :1 between the shaft ends of a driving and driven machine. They are incorporated in the drive train to compensate small
• a hub 102 or adapter is provided on the end of a shaft on both driven and driver equipment and a transmission unit 104 connects the hubs 102 together to transmit drive and torque from the driver equipment to the driven equipment.
• a flexible assembly 106 is provided as interface between each hub 102 and transmission unit 104 to absorb angular, radial and axial misalignment between the driven and driver equipment.
• An example of a flexible assembly 106 is the flexible membranes found in John Crane ® T SeriesTM and M SeriesTM couplings, in which the flexible assembly 106 comprises a series of flexible elements 108 as illustrated in figure 2.
• the flexible elements 108 are stacked together on juxtaposed engagement, the flexible assembly 106 being secured alternately to a hub 102 and the transmission unit 104 by an even number of bolts 110, 1 12, which pass through holes 14 spaced angularly about the flexible elements108.
• the flexible assembly (106) and individual flexible elements (108) are exposed to torsional stresses due to the drive torque and bending stresses due to shaft misalignment.
• the flexible elements When operating a coupling within the specified design limits, the flexible elements achieve a theoretical infinite service life of more than 10 6 load cycles, However, if conditions exceed the specified limit, operation beyond the misalignment limit and/ or torque transmission beyond the design limit, the coupling will eventually fail due to fatigue stress cracks in the flexible elements 108 of the flexible assembly 106.
• each flexible assembly 106 comprises a series of individual flexible elements 108, it is difficult to detect failure of an individual flexible element 108 of flexible assembly 106.
• Each flexible element 108 during operation emits a different acoustic trace or signal.
• An object of the present invention is to provide a non-intrusive component failure detection system using an acoustic method that is able to detect failure of a flexible assembly 106 of a power transmission coupling.
• said apparatus comprises;
• At least one sensor mounted in proximity to said assembly, the sensor providing an analogue signal corresponding to an airborne acoustic signal emitted by the assembly;
• filter means to reduce background noise from the analogue signal; an analogue to digital converter for converting the analogue signals to a digital signal;
• a method of detecting fatigue induced failure of an assembly having a single flexible element or a series of flexible elements arranged in juxtaposed engagement, for transmitting power from one component to another, the assembly having a cyclic operating speed frequency said method comprises;
• said sensor or sensors converting airborne acoustic signals emitted by the assembly into analogue signals
• the or each acoustic sensor is placed from 1 to 200 cm from the assembly, with an unobstructed path to the assembly.
• the analogue signal is filtered using an envelope demodulator which averages the peak analogue signals over a time frame and replaces them with mean value analogue signals.
• the senor for airborne acoustic emission may be connected to means for processing the acoustic signal via a node and gateway, the node being connected to the gateway wirelessly.
• Each node preferably comprises at least one sensor operable to measure the acoustic emission of the flexible assembly, a W
• each gateway comprises a signal processor for processing data from each node and a combined wireless transmitter and receiver interface; and a computer 5 connected to the gateway, characterised in that data from each node is transmitted to the gateway via radio frequency and said command station sends a configuration message from the gateway to each node to specify one or more analysis function to perform.
• FIG. 1 illustrates a cross section of a typical membrane coupling
• FIG. 2 illustrates a typical flexible element of the membrane coupling
• Figure 3 illustrates an acoustic emissions detection system for determining fatigue induced failure of an assembly according to the present invention
• Figure 4 illustrates enveloping of acoustic signals according to the present invention
• Figure 5 illustrates absolute digitised acoustic signals of an intact coupling according to the present invention
• Figure 6 illustrates Fast Fourier Transformation Spectrum of an intact coupling according to the present invention
• Figure 7 illustrates acoustic signals of a coupling with one fractured0 flexible element according to the present invention
• Figure 8 illustrates Fast Fourier Transformation Spectrum of a coupling with one fractured flexible element according to the present invention
• Figure 9 illustrates acoustic signals of a coupling with two fractured flexible elements according to the present invention.
• Figure 10 illustrates Fast Fourier Transformation Spectrum of a coupling with two fractured flexible elements according to the present invention
• Figure 1 1 illustrates acoustic signals of a coupling with three fractured flexible elements according to the present invention
• Figure 12 illustrates Fast Fourier Transformation Spectrum of a coupling with three fractured flexible elements according to the present invention
• Figure 3 illustrates the digital acoustic signals derived from a high order statistical sampling process
• Figure 14 illustrates the digital acoustic signals derived from combining the Fast Fourier Transformation Spectrum and the high order statistical sampling process
• FIG. 15 illustrates RMS values of the digital acoustic signals.
• a schematic of an acoustic emissions detection system 200 for determining fatigue induced failure of the flexible assemblies 106 of a power transmission coupling 100 according the present invention is shown.
• the acoustic emissions detection system 200 comprises an acoustic emission transducer 202 for detecting variations in acoustic signals or stress waves emitted from a stack of flexible elements 108 forming the flexible assemblies 106 of the power transmission coupling 100 shown in figures 1 and 2.
• Such acoustic signals or stress waves are commonly generated as a result of flexing, bending, stretching and frictional stress caused by the flexible elements 08 under operation. More importantly, characteristic signals are emitted by the flexible elements 108 when a crack initiates and propagates.
• the frequency bandwidth of the acoustic emission transducer 202 is selected to reduce picking up background whilst being sensitive to be able to pick up acoustic signals generated by the flexible assembly 106, by detecting the airborne acoustic signals
• the acoustic emission transducer 202 is a piezo-electric transducer designed to convert acoustic signals into an analogue signals. For detecting airborne acoustic signals, the acoustic emission transducer 202 operates in a frequency range between 25 to 90 kHz.
• the analogue signals are then sent to a control module 204.
• the control module 204 comprises an amplifier 206 for amplifying the analogue signal and an envelope modulator 208 where the peak analogue signals are averaged over a time frame and replaced by mean values.
• Figure 4 illustrates the peak signals being averaged over a time frame and replaced by mean values for filtering the background noise.
• the analogue signals are converted into digital signal by an analogue to digital converter, where the digital signals are then sent to a data acquisition module 210.
• the data acquisition module 210 samples the signal in discrete data sets, whereby the sampling time covers a minimum of 2 shaft revolutions. Afterwards each data set is split, whereby one set of digital signals is sent to a signal processor 212.
• the signal processor 212 uses a Fast Fourier Transform to calculate the frequency components of the signal -frequency domain-. The remaining signal set is left as acquired in the time domain.
• Both, time domain and frequency domain of the signal are then sent to a diagnostic module 214 to determine the occurrence and frequency of signal characteristics with respect to the rotational speed of the coupling 100.
• Figures 5 to 12 illustrate typical signals processed by the diagnostic module 214.
• Figures 5, 7, 9 and 11 illustrate the absolute digital acoustic signals acquired from the data acquisition module 210, whereby specific signal patterns are used to determine failure of each flexible element 108 as the coupling 100 rotates.
• Figures 6, 8, 10 and 12 illustrate the digital signals derived from using the Fast Fourier Transformation sampling process, whereby signals are analysed in a spectrum with respect to the frequency of the coupling shaft.
• Figures 5 and 6 illustrate a fully functional coupling without defect, wherein figure 5 only displays background noise. Frequency related to the coupling shaft is absent from figure 6.
• Figures 7 and 8 illustrate a fracture of one flexible element 108 of the coupling 100.
• Figure 7 displays the time domain of the sampled signal set with one dominant signal spike A and figure 8 displays the frequency domain of the sampled signal set that shows an increase in amplitude of the principle and harmonic frequencies related to the coupling speed.
• Figures 9 and 10 illustrate two flexible elements 108 being fractured on the coupling 100.
• Figure 9 displays two signal spikes A and B, and figure 10 displays a further increase in the amplitude of the coupling 100 shaft frequency and a further increase in amplitude of harmonic frequencies in the frequency domain of the sampled signal set.
• Figures 1 1 and 12 illustrate three flexible elements108 being fractured on the coupling 100.
• Figure 1 displays three signal spikes A, B and C, and figure 12 displays a further increase in the amplitude of the coupling 100 shaft frequency and a further increase in amplitude of harmonic
• the signal processor 212 calculates high order statistical values namely Skewness and Kurtosis from the sampled signal set acquired by the data acquisition module 210 and sends the values to the diagnostic module 2 4 to identify coupling and non-coupling related signals and specific faults related to the flexible element 108 in a given time frame.
• Figure 13 illustrates the signals produced by the diagnostic module 214 using the high order statistical sampling process, whereby the results from the Skewness statistical analysis is plotted against the results from the Kurtosis statistical analysis.
• the high order statistical sampling process has the ability to determine whether the flexible assembly 106 is in good working order or if individual flexible elements 108 have been fractured. Referring to figure 13, the Skewness-Kurtosis threshold provides an indication on the performance of the coupling 100.
• the signal processor 212 analyses the digital signals using the Fast Fourier Transformation process combined with the high order statistical sampling process of the second embodiment to provide an indication on the health of the flexible assembly106. Using the following equation, the health of flexible assembly106 can be determined:
• n is an integer and n ⁇ Z
• the combined Fast Fourier Transformation and high order statistical sampling method allows to determine the condition of the coupling for any operational speeds of the coupling 00. Therefore, such method may be applied to couplings 100 that operate on variable or fixed speeds.
• the condition of the coupling 100 is illustrated in graphical format together with the threshold of the coupling health by the diagnostic module 214 for highlight potential problems.
• coupling condition boundaries are set to determine the health of the coupling 100. Values between 0.1 and 1 indicate that the flexible assembly106 is in good working order, values between 1 and 10 indicate that the flexible assembly 106 has a potential problem, e.g. fretting between individual flexible elements 108, and values above 10 indicate that the coupling has failed or cracks are present in the flexible elements 108.
• the signal processor 212 samples the digital signals by calculating the RMS values of the digital signals over one shaft revolution.
• the diagnostic module 214 displays the RMS values of the signals on a graph. Although there is little to
• threshold points may be set by the user such that the diagnostic module 214 would give an indication of a potential total coupling failure.
• sampling processes may sample the signals continuously or intermittently over a specified time frame without depart from the scope of the invention.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Health & Medical Sciences (AREA)
• Signal Processing (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
• Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
• Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
• Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)

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• 2010
  • 2010-12-02 GB GBGB1020381.8A patent/GB201020381D0/en not_active Ceased
• 2011
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  • 2011-12-02 WO PCT/GB2011/001672 patent/WO2012072984A2/en not_active Ceased
  • 2011-12-02 US US13/990,482 patent/US9476860B2/en active Active
  • 2011-12-02 RU RU2013125237/28A patent/RU2573705C2/ru active
  • 2011-12-02 CN CN201180058036.XA patent/CN103348226B/zh active Active
  • 2011-12-02 BR BR112013013164A patent/BR112013013164A2/pt not_active IP Right Cessation
  • 2011-12-02 EP EP11801805.0A patent/EP2646783B1/en active Active

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