Umdrehungssynchrone Abtastung I

1
RotasPro Noise Analysis
Transmissions, Gearboxes and Axles
2
Discom Industrial Measurement Inc.
Base System
Gearboxes and Components
Cabin noise
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
Jatco, Japan CVT Transmissions
American Axle, USA Front and Rear Axles, 5
Systems
GM, USA, Opel D and A Gearboxes 14 Systems and
Axle Testers 25 Systems
Bentley, UK Cabin Noise Analysis APAS, 2 Systems
Borg-Warner, USA,UK Transmissions und Axles 8
Systems
Renault, Peugeot Transmissions, 5 Systems
DaimlerChrysler D, US Cooperation MESAM4,
gearboxes, transmissions and engines. 36 Systems
Robert Bosch Starters, injection pumps,
production database 6 Systems
SKF D, USA, India, Ukraine Tapered Roller
Bearings, 26 Systems
First Automobile Works, China Gearboxes 1 System
SAIC Shanghai Automobile Internatiol
Corp. Gearboxes test systems, 4 Systems
Fiat, Iveco, Tata Manual Transmissions 7 Systems
Skoda, Cz Gearboxes, 7 Systems
Ford, D Gear Testers 4 Systems
SFT, Magna Stey Powertrain Axles and gearboxes 28
Systems
Gearbox, SP gearboxes, gear testers 12 Systems
Tongil, Korea Axles, Durability test Stand, 1
System
Graziano, Italy Gearboxes and Axles for Audi,
Aston Martin, Ferrari, Lamborghini, Maserrati
Volkswagen D,SA,AR, China,B,SK,BR Gearboxes,
Transmissions, Gear Testers, Cabin Noise
Production Database, 165 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
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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
Rotas Analysis Program
Test Stand Control
Result Database Archives, SQL-DB
Web Statistics
Presentation
6
Rotas Analyzers
BlackBox, 3 DSPs Frontend, Speed Card, Monitor
output
19-Industrial PC. 3 DSPs, Speed Card, Monitor
output 2.6 GHz P4
Rotas Mobile, 12 Volt Car Supply 3 DSPs, Monitor
output, Laptop
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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
8
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
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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
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Synchronous Averaging I
Signal
For every shaft, averaging is performed
synchronous to its revolution. Signal components
of the synchronous shaft 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
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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'2000,171016 ---
--------------------------------------------------
-------------- Code Description
Gear Is Lim Av Unit Kx 448 NICK 3.-Gear
/ Up 3-Z 16.8/ 12.0/ 9.5 Crest
ZwAn ---------------------------------------------
-----------------------
12
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.
13
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, ..
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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 with side bands /- 1
order
Harmonics H1, .. with side bands /- n.Order
Harmonics H1, .. with side bands /- 1 order
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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..
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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
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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.
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Measurement Protocol
R2528 Typ R25 Seriennr. 1480889
29.May'2000,061210 Getriebe n.i.O.
--------------------------------------------------
------------------------------ Code Fehlertext
Gang Ist Grenz Mw
E O/Tp Kx 6 Rücklaufrad laut
R-Z 98.5/ 93.0/ 88.4 dBg 29.00 RLR
13 Rundlauffehler VZ I 2-Z
102.3/ 97.0/ 91.9 dBg 72.00 VGW
--------------------------------------------------
------------------------------ R2528 Typ R25
Seriennr. 1480984 29.May'2000,062705 Getriebe
n.i.O. --------------------------------------
------------------------------------------ Code
Fehlertext Gang Ist
Grenz Mw E O/Tp Kx 3 VZ I laut
1-S 108.2/106.0/101.2 dBg
70.00 VGW 2 Antriebswellenrad laut
1-S 109.0/106.0/101.2 dBg 52.00 AW
--------------------------------------------------
------------------------------ R2528 Typ R25
Seriennr. 1480992 29.May'2000,063735
Getriebe i.O. ---------------------------------
-----------------------------------------------
R2528 Typ R25 Seriennr. 1480986
29.May'2000,065604 Getriebe n.i.O.
--------------------------------------------------
------------------------------ Code Fehlertext
Gang Ist Grenz Mw
E O/Tp Kx 12 Rundlauffehler Rad AW
1-S 105.2/101.0/ 91.6 dBg 55.00 AW
--------------------------------------------------
------------------------------ R2528 Typ R25
Seriennr. 1480985 29.May'2000,070758
Getriebe i.O. ---------------------------------
-----------------------------------------------
R2528 Typ R25 Seriennr. 1480990
29.May'2000,071856 Getriebe i.O.
--------------------------------------------------
------------------------------ R2528 Typ R25
Seriennr. 1480987 29.May'2000,074306
Getriebe i.O. ---------------------------------
-----------------------------------------------
R2528 Typ R25 Seriennr. 1480988
29.May'2000,075345 Getriebe i.O.
--------------------------------------------------
------------------------------ R2528 Typ R25
Seriennr. 1480991 29.May'2000,080402
Getriebe i.O. ---------------------------------
-----------------------------------------------
R2528 Typ R25 Seriennr. 1480991
29.May'2000,080500 Getriebe i.O.
--------------------------------------------------
----------------------------- R2528 Typ R25
Seriennr. 1480650 29.May'2000,082650
Getriebe i.O. ---------------------------------
-----------------------------------------------
R2528 Typ R25 Seriennr. 1481405
29.May'2000,111724 Getriebe i.O.
--------------------------------------------------
------------------------------
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 reesults 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.
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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.
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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.
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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
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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.
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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
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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
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Vibration and Cabin Noise, Order Cuts
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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 1 Curve 2 H1 Max Bd1 79.1
dB 75.5 dB H1 Aver Bd1 76.2 dB 71.9 dB
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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
A
B
C
D
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Evaluation of Shifting Effort

• Evaluation of shifting effort versus lever
  displacement.
• The synchronization is evaluated via the work
  that is needed (Fs). 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.
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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.
30
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
Server or Test Stand
Work Group PC
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Measurement Transfer over Network
Parameter Database
Measurement Database SQL Server 2000
Server
Measurement System
32
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

33
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.
34
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.
35
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
36
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.
37
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.
38
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.
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Reject Analysis, Top n and Type Specific
The results are shown both in tabular and in
graphical form