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Transmissions, Gearboxes and Axl e s

RotasPro Noise Analysis. Transmissions, Gearboxes and Axl e s. Discom Industrial Measurement Inc. Cabin noise. Base System. Gearboxes and Components. APAS-II. ROTAS-Mobil. MESAM 4.

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Transmissions, Gearboxes and Axl e s

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  1. RotasPro Noise Analysis Transmissions, Gearboxes and Axles

  2. Discom Industrial Measurement Inc. Cabin noise Base System Gearboxes and Components APAS-II ROTAS-Mobil MESAM 4 The company was founded in 1985. It is situated in Göttingen in the heart of Germany. Since 1989 the main product are measurement system for the acoustical quality analysis. There are 20 employees and more than 500 test systems deployed. Base system are ROTAS and MESAM-4 (a joint development with DaimlerChrysler). Build on top of them are APAS for the cabin noise analysis, ROTAS-GP for the analysis of gearboxes and transmissions, ROTAS-ZP for the gear test, ROTAS-TMO for the test of tapered roller bearings.

  3. Discom: Customers and Applications American Axle, USA Front and Rear Axles, 5 Systems Jatco, Japan CVT Transmissions GM, USA, Opel D and A Gearboxes and Axle Testers, Gear Testers 44 Systems Bentley, UK Cabin Noise Analysis APAS, 2 Systems Borg-Warner, USA,UK Transmissions und Axles 11 Systems Renault, Peugeot Transmissions, Gear Testers 11 Systems DaimlerChrysler D, US Cooperation MESAM4, gearboxes, transmissions and engines. 48 Systems Robert Bosch Starters, injection pumps, production database 6 Systems SKF D, USA, India, Ukraine Tapered Roller Bearings, 35 Systems Eaton, Br Manual transmissions, mobil system SAIC Shanghai Automobile Internatiol Corp. Gearboxes test systems, 5 Systems First Automobile Works, China Gearboxes 2 Systems Skoda, Cz Gearboxes, 7 Systems Fiat, Iveco, Tata, It, Brazil, India Manual Transmissions 20 Systems SFT, Magna Stey Powertrain Axles and gearboxes 28 Systems Ford, D Gear Testers 4 Systems Tongil, Korea Axles, Durability test Stand, 1 System Graziano, ItalyGearboxes and Axles for Audi, Aston Martin, Ferrari, Lamborghini, Maserrati Volkswagen D, ES, SA,AR, China,B,SK,BR Gearboxes, Transmissions, Gear Testers, Cabin Noise Production Database, 178 Systems Getrag, USA Sc, Single Flank Gear Tester for Cummins Engine Gears with Tors. Acceleration Cummins ZF D Gear Testers 4 Systems Hyundai, Korea Gear tester 2 Systems

  4. Rotas NVH Testing • End of line test with vehicle correlation and the ability to find production errors • Separation of noise components from inner wheels of transmissions • Calibrated evaluation for comparison of the production process with car experiences • Simultaneous measurement and evaluation of all transmission order components • Recognition of nicks on gears and bearings • Trainable system in combination with fixed limits • Test results stored in central data base • Intranet evaluation of test results for groups of test benches

  5. ROTAS Test Stand Configuration Parameter- und Limit Database Sensors Test Stand Control Rotas Analysis Program Result Database Archives, SQL-DB Presentation Web Statistics

  6. Rotas Analyzers TAS USB Measurement frontend. 10 analog channels, 4 speed inputs, D/A monitor outputs. Mobile system with USB power for 5 ICP sensors 19”-Industrial PC. TAS Frontend RAID system Dual Core and I7 CPUs Panel with IPC and TAS Frontend. AC and UPS build into panel

  7. BKS03 Accelerometer The BKS03 has a linear frequency range of up to 10 kHz and can be used to pick up the NVH signal also from unfinished surfaces

  8. Analysis of transmission noise RotasPro separates the noise into the different sources inside the transmission like input, intermediate and output shaft. I addition, the the total noise is evaluated. A main noise source is the tooth mesh of the gears. A prominent method is the calculation of the spectral components of the noise. The spectrum shows the characteristic of the noise in form of a curve. For transmissions, spectral components exist for tooth mesh and its harmonics. The spectra are compared with limit curves. If the limit curve is exceeded, a defect can be assumed. In addition, temporal measurement give Crest, Peak and RMS values, which are used for the identification of nicks on the transmission parts. Noise sources

  9. Order Analysis Exact order analysis is accomplished by generating of the same amount of samples per revolution of a part, independent of its revolutionary speed. Digital resampling allows for the processing of 3 to 5 shafts of a transmission. From this resampled time domain signal, spectra evaluation produces order components. These are the amplitudes of sine components, which are cyclic with the revolution of the part Input One rev Input One rev Input One rev Constant number of samples per revolution

  10. Revolution Synchronous Transmission Analysis The transmission noise is the sum of the noise originating from the individual mechanical components. For the gear noise components, the individual sources can be isolated by the transmission ratio. Input Shaft Interm. Shaft Output Shaft Synchronous order analysis: The signals are acquired synchronous to the inner shafts. Acoustical Stroboscope Input Shaft Interm. Shaft Output Shaft

  11. Synchronous Averaging I Signal For every shaft, averaging is performed synchronous to its revolution. Signal components of the synchronousshaft are enhanced, other noise components are attenuated. One shaft is shown. Rotas can do the processing for 3 to 5 shafts simultaneously. Usually, only one sensor is needed. The synchronization can be done for inner shafts, for which only the transmission ration is known. + Background + Signal + Background + Signal + Background Summe * 1/n = Average: Signal enhanced

  12. Synchronous Averaging II Nicks are shown in the synchronous channel that is synched with the offending shaft. The nick detection is based on the Crest value Crest = Peak value/RMS value AG4 V4.0 Typ 39 Unit 67 04.Jun'2000,17:10:16 ------------------------------------------------------------------- Code Description Gear Is Lim Av Unit Kx 448 NICK 3.-Gear / Up 3-Z 16.8/ 12.0/ 9.5 Crest ZwAn --------------------------------------------------------------------

  13. Time Domain Measurements Peak: The maximum amplitude in a time domain signal. In the example to the right the Peak value is about 15 g RMS: The average energy in a time domain signal. In the example to the right the RMS value is about 0.9 g. The exact formula is Sqrt(Sum((xi)2) for all measurement values xi Crest: The ratio of the peak value divided by the RMS value: Crest = Peak value/RMS value In the example to the right the Crest value is about 16.8. It has no unit The Crest value is a good indication of the ‘Peakiness’ in a signal. Good gears have a Crest value of 3-8, bad gears have a Crest value from 10 to 30. Tickeval: The Tickeval value indicates the maximum difference of short-time spectra taken over the revolution from the average short-time spectrum for the revolution. Good gears have values of 6, bad gears have values above 12. Peak RMS AG4 V4.0 Typ 39 Unit 67 04.Jun'2000,17:10:16 ------------------------------------------------------------------- Code Description Gear Is Lim Av Unit Kx 448 NICK 3.-Gear / Up 3-Z 16.8/ 12.0/ 9.5 Crest ZwAn --------------------------------------------------------------------

  14. Separation of Gear Errors • The acoustical signal holds the components of both gears. • Knowing the transmission ratio, the periodicity of each gear can be found. Gear mesh components only depend on the pairing of the gears. • Eccentricities and surface errors can be separated because they have a cycle that corresponds to the originating gear. The following errors can contributed individually: • Eccentricities, • Deviation from circular shape • Tooth spacing • Surface waves (Ghost Orders) • Nicks 16 20 The gear mesh component depends on the pairing 16 20 Eccentricities and surface errors can be contributed individually.

  15. Time Domain Versus Order Domain I Gear with 5 teeth, 4 revolutions Sine smooth gear contact Triang harsher gear mesh Sawtooth harsh gear mesh Fourier transform: Order spectrum Order at number of teeht: 5 Base order H1 Harmonics at odd multiples of nr of teeth (5) H1, H3, H5, .. Strong harmonics of number of teeth (5) H1, H2, H3, ..

  16. Time Domain Versus Order Domain II, Modulations Gear with 5 teeth, 4 revolutions Sine with modulating sine Smooth gear mesh with eccentricity Triang with modulating sine harsher gear mesh with eccentricity Triang with modulating triang harsher gear mesh with several eccentricities Fouriertransformation: Ordnungsspektrum Order at nr of teeth H1 withside bands +/- 1 order Harmonics H1, .. with side bands +/- n.Order Harmonics H1, .. with side bands +/- 1 order

  17. dBV 80 Mix 70 Antrieb 60 50 40 50 60 70 80 90 100 110 120 130 Ord Synchronous Averaging III Revolution synchronous averaging gives periodic (cyclic) signals. This corresponds to the cyclic nature of the gear sets. These signals can be transformed into the spectral domain without any time domain leakage windows. This allows for high spectral resolution. Eccentricities can be easily distinguished from the gear mesh orders. The noise components can be attributed to their origins. Blue: Conventional order spectrum with Kaiser Bessel Window Green: Revolution synchronous order spectrum without window function GM 2 *GM Ghost Orders Ecc..

  18. Input H1 Input H2 Input VZ1 H1 VZ5 H1 VZ1 H2 VZ5 H2 VGW 5. Gg H1 OW 5. Gg 5. Gg H2 HW -12 dB -10 dB Mix Order spectra of a lay shaft transmission Limits: red O-Spectra: black Input: 26 Z VZ1: 35 Z VZ 4: 43 Z 5. Gear 27 Z i = 1.1764

  19. dBg VGW 105 VGW-lim 90 75 60 45 10 20 30 40 50 60 70 80 90 Ord Evaluation of Order Spectra The order spectra of the synchronous channels and of the mix channel are compared with a limit curve. Every order of the limit curve has an underlying error code. This error code is generated from transmission ratios in a semiautomatic fashion. If the limit curve is exceeded, the error code gives rise to an error message in plain text. The limit curves consist of portions, which are generated by a learning process and of portions which are set to fixed values. The learn rnode is used for those spectral portions, where there are results from driving experiments available yet. Generally this holds true for tooth spacing problems, ghost orders and bearing noise (in the mix channel). Fixed limits are adopted from driving experiments, usually for the gear mesh and for the side bands.

  20. Measurement Report A protocol is generated for every unit. It holds information about unit type, serial number, time of measurement and defect report. There are three kinds of report: Short:: serial numbers only for good units, defect report for failing units. Normal: Report line for every unit Long: All measurement values in tabular form. Around 300 measurement results are stored in a protocol database for statistical evaluation. 5000 units use about 20 Mbyte of disk space. The test stand control system can request several protocol variants for own recording purposes.

  21. Spectral Limits Hats for gear mesh orders and their side bands Limit curve from Average + Offset + n times standard deviation. Overridden by minimum and maximum polygons and by the fixed hats.

  22. Learning What is learned Learning methods For all measurements, the following statistical properties are computed: Average (AV) und Standard deviation (STD) From these numbers, a limit L is generated according to L = AV + Offset + n* STD. The offset and the multiplier of the standard deviation is selectable. For spectral measures, an offset of 5 dB and a std-factor of 3 is normally used. Maximum and minimum values set upper and lower bounds for the limit L. A new learn consist of a base learn (usually 5 units), where all units are accepted that are below maximum polygons and below hats. The base learn is followed by an additional learning (usually 100 units). Here every unit is evaluated against the already established limit curves. Only error free units will be added to the learning sample. Another available choice consists of a indefinite learn process with a selectable time constant. During the whole learning process, the fixed limits apply. This assures, that all known data (like limits from car experiments) will be used as a guidance during the process.

  23. Cabin noise components Noise sources There are many different transfer paths for the sound and the vibration from the gearset to the drivers ear. Each path has its own frequency dependent transfer function Noise from the motor, wind and tires may mask certain frequency bands from the gears. These effects induce the speed, torque and vehicle dependent noise perception of the gear sets. Transfer paths

  24. Speed Accel M2 M4 M1 M3 Order Resamp FFT Average + Spectro- gramm Order- tracks Averaging over microphone postions To compensate for the cabin resonance's, four microphones are positioned within the cabin: Front left, middle and right position, one in the rear. The energy of the microphone signals is averaged in the spectral order domain. One sensor is mounted on the transmission to allow for the simultaneous analysis of the gearbox vibration data.

  25. Order spectrograms Order spectrograms are recorded for the gearbox vibration signal and for the cabin sound field. From these order tracks for arbitrary orders and order spectra for arbitrary speeds can be generated: 2) Order spectrum at 2241 RPM Order track for the 65. order 1) Ordnungs-Spektrogramm 4. Gang Zug

  26. Vibration and Cabin Noise, Spectral Cuts 12 dB Spectral Cut Cabin Noise: 12 db higher than background at 2640 RPM/110 Km/h Spectral Cut Vibration: 50th order of 100 dBg at 2700 RPM

  27. Vibration and Cabin Noise, Order Cuts

  28. Order Tracking • The critical noise sources in a car are usually the gear mesh orders and their sidebands. • These noise sources are highly speed dependent. Detailed speed dependent evaluation uses the track of mesh orders and sidebands over speed. • The gear mesh H1 base order and its harmonics are tracked over speed and compared with speed dependet limit curves. • The track form depends on torque, drive/coast and on the resonances within the gearbox and the test stand. • Within speed bands, average and maximum amplitudes can be evaluated and compared to limits. The single values are ideal for statistical analysis over time. Speed band Tracked Value Curve 1Curve 2 H1 Max Bd1 79.1 dB75.5 dB H1 Aver Bd1 76.2 dB71.9 dB

  29. B B A A A A B B C C C C A B C Shift force evaluation • Shown are measurements with the GSW shift roboter, which measures forces and displacement directly at the transmission shift mechanism. • Shifting effort is shown versus displacement • Positive forces: Shift into a gear • Negative forces: Shifting out of gear • A: Synchronisation work when shifting into a gear. Good repeatability • B: Shifting through after synchronisation. Varying force. • C: Shifting out. Small forces for good transmissions • D: Synchron ring missing D B A C D

  30. Evaluation of Shifting Effort • Evaluation of shifting effort versus lever displacement. • The synchronization is evaluated via the work that is needed (F*s). Therefore, the area of the curve above a window A is computed (work = force * displacement) . D: a transmission without a synchron ring. • The maximum force during shifting into a gear are limited with the polygon B • The maximum forces when shifting out are limited with a polygon C. • End position: a settable end position must be reached when shifting is finished. B A D C Schaltkraft über Weg für 150 Seriengetriebe. Bewertungsfenster erkennen fehlende Synchronringe und Schwergängigkeiten.

  31. Server Management of Multiple Test Benches Test Benches Parameter Setting and Statistical Evaluation Data Parameter PC with Internet Explorer Intranet Central archive of test results Parameter setting and statistical evaluation from every PC with intranet access.

  32. Rotas Data Flow Work Group PC has presentation software installed Can use Intranet statistcis via Internet Explorer Rotas Analyzer Test Stand Measurement Archives Rotas Presentation Measurement Database Intranet Statistics Work Group PC Server or Test Stand

  33. ROTAS Analyzer Local Copy \outbox: \inbox: Collector Service Archive Files: One Test Run Archive Files: One Test Run Archive Files: One Test Run Measurement Transfer over Network Parameter Database Measurement Database SQL Server 2000 Server Measurement System

  34. Order Spectra • Spectra are stored for the individual rotors in the transmission • An additonial Mix spectrum represents the order amplitudes of all parts combined • The spectra are either peak hold amplitudes or averaged amplitudes over a ramp • Limits can be self learned or manually set. The amplitude of gear mesh orders can be set individually by a database

  35. Spectral Statistics Order spectra of production units can be displayed in Campbell or in 3-D graphs. Cuts in the order or in the unit direction show order amplitude versus units or the spectrum of one unit. The pictures show the order spectra of 300 production units. A ghost order of 118 is present in the first 40 units tested.

  36. Order Tracks During the ramps, spectral components are evaluated over the speed. Usually, the main gear mesh orders and their harmonics are tracked. In addition, energy in order bands may be tracked as well. Track limits (shown in red) can be self learned or set manually.

  37. Complete Data Report of a single Unit Macro controlled display of archived data. The database is used for searching of serial numbers, test results etc. Then the presentation software displays a full measurement report Sensor Group 1

  38. Intranet Statistics The information of the SQL measurement database can be retrieved via the intranet. The production results and the measurements can be seen online. An arbitrary time interval can be selected for the analysis.

  39. Statistical Evaulation for Types and Benches Test results The evaluation can be done over gearbox types or over test benches. Any time interval can be specified.

  40. Measurement Statistics and Bench Comparison Over 300 individual measurement results can be evaluated. The comparison of test benches makes it easy to administer large production facilities.

  41. Reject Analysis, Top n and Type Specific The results are shown both in tabular and in graphical form

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