Visteon Product Development

Mehrdimensionale NVH-Anwendungen in der

Produktentwicklung in denBereichen Klima, Motorkühlung,

Elektronik, SteeringRichard O’Sullivan, NVH Specialist, Kerpen, Germany

Visteon Product Development

Mehrdimensionale NVH-Anwendungen in der

Produktentwicklung in denBereichen Klima, Motorkühlung,

Elektronik, SteeringRichard O’Sullivan, NVH Specialist, Kerpen, Germany

OutlineOutline• Overview of NVH Facilities and Equipment• What signal types can be recorded?• How parallel acquisition of various parameters with

noise can help identify and solve noise problems– Examples:-

• Steering Hiss vs. Pressure• Compressor Ticking noise vs. Pressures

• Who needs 100kHz sampling?• Some interesting recordings• Questions

Equipment & Facilities –General DescriptionEquipment & Facilities –General Description• Two Semi-Anechoic Rooms

• Transmission-Loss Lab (two reverberant rooms)

• Multi Channel Data acquisition including artificial Head

PicturesPictures

Semi-Anechoic Room 1 Transmission-Loss Lab

Semi-Anechoic Room 2

1. Acoustic Performance• Absorbing cones on walls and ceiling, sound reflecting floor• Interior size (L/W/H [m]): 8.25 / 7.25 / 4• Background noise level <15 dBA• Lowest frequency of free-field condition (Cut-off frequency) 50 Hz• Silent air supply for HVAC unit testing• Rubber spring decoupling avoids structure-borne noise transmission into the room• Silent compressor drive

2. Testing Techniques• Sound pressure level recording (in-vehicle / subsystem / component)• Binaural analysis for psycho-acoustic engineering• Sound intensity determination

3. Benefits• Quantitatively precise determination of main acoustic quantities• Development of acoustically optimized A/C-systems with low sound emission anddefined psycho-acoustic performance• Subjective appraisals of two vehicles in parallel possible

Semi-Anechoic Room 1Semi-Anechoic Room 1

1. Acoustic Performance• Absorbing perforated elements on walls and ceiling, sound reflecting floor• Interior size (L/W/H [m]): 6.1 / 4.1 / 3.4• Background noise level 20 dBA• Lowest frequency of free-field condition (Cut-off frequency) 125 Hz• Rubber spring decoupling avoids structure-borne noise transmission into the room• Silent compressor drive

2. Testing Techniques• Sound pressure level recording (in-vehicle / subsystem / component)• Binaural analysis for psycho-acoustic engineering• Sound intensity determination

3. Benefits• Quantitatively precise determination of main acoustic quantities• Development of acoustically optimized A/C-systems with low sound emission anddefined psycho-acoustic performance

Semi-Anechoic Room 2Semi-Anechoic Room 2

1. Acoustic Performance• Two Reverberation Rooms, coupled by window• Diffuse sound field by multi-reflection of sound waves within the room• Silent air supply for HVAC units and silent compressor drive can be installed• Rubber spring decoupling avoids structure-borne noise transmission into the room• Source Room Volume 65 m³

Cut-off Frequency 174 Hz• Receiver Room Volume 120 m³

Cut-off Frequency 142 Hz

2. Testing Techniques• Sound power level determination (system / subsystem / component)• Transmission-Loss determination

3. Benefits• Reverberation room method for sound power determination is faster and moreprecise than sound intensity technique

• Transmission-Loss testing is standard customer requirement

Transmission-Loss LabTransmission-Loss Lab

• Data Acquisition Hardware•Manufacturer: Head Acoustics

•Model: SQLab2 (4 units)•Max Total Sample rate: 200kHz•Maximum Channel Count: 60

•Model: SQLab3 (2 units)•Max Total Sample rate: 640kHz•Maximum Channel Count: 66

•Model: SQuadriga (1 unit)•Max Total Sample rate: 200kHz•Maximum Channel Count: 4 plus rpm•Small, portable, powered from Notebook (USB)

•Manufacturer: RACAL HEIM•Model: DATAREC A80 (1 unit)

•Max Total Sample rate: 128kHz•Maximum Channel Count: 16

Recording equipment detailsRecording equipment details

Input Signal Capabilities 1Input Signal Capabilities 1

• Voltage (AC or DC), DIC20 or DIC61– Due to high input impedance, can be used to monitor

driving voltages of Fans, pumps, motors etc. with highaccuracy

– Recorded parallel with noise to give “Pump Noise vs.Driving Voltage” for example

– Temperature via intermediate conditioning (eg.Greisinger)

– Displacement from Laser Transducer (e.g. Waycon)

Input Signal Capabilities 2Input Signal Capabilities 2

• ICP type Transducers, DIC20, DIC61– Microphones, Accelerometers, Force Gauges– AC coupled only– High signal quality due to amplifiers in transducer– Transducers not so robust due to amps inside– Sensitive to electro-magnetic or inductive interference– Temperature range not so large– Shock resistance less due to amplifier overloading– But modern transducers much more robust

Input Signal Capabilities 3Input Signal Capabilities 3

• Strain Gauge or Bridge PoweredTransducers, SGC20– Force Transducers (e.g. HBM)– Strain Gauges– Some pressure transducers (usually having

diaphragm with strain gauge)• These usually have good dynamic limits

– Can also be used as stable transducer powersupply (up to 10v 80mA)

Input Signal Capabilities 4Input Signal Capabilities 4

• Charge amplifiers, CHG20– Accelerometers without built-in conditioning

• Wider temperature range, better shock resistance– Dynamic pressure transducers, e.g. Kistler

• Measure only “AC” component, not constant component• Have excellent dynamic response often >100KHz• Large dynamic range, limited only by charge amp range• Applications include pressure cycle monitoring in combustion

engines, pumps, compressors etc.– Show detailed pressure levels even during high speed running

(assuming suitable acquisition rates)

Input Signal Capabilities 5Input Signal Capabilities 5

• Artificial Head, EBU20– Digital signal transmission, so no cable noise– High dynamic range and low noise microphones

give high signal detail

Input Signal Capabilities 6Input Signal Capabilities 6

• CAN Bus Information, CAN10– Permits parallel recording of all parameters

available on CAN Bus– Saves installation of extra transducers for

monitoring various parameters (Temperatures,speeds, rpm, steering angle, etc)

– Data update speed is relatively slow (typically100Hz)

• Rpm update too slow for use with runups

Example 1 – Hiss Noise duringsteeringExample 1 – Hiss Noise duringsteering• Steering hiss noise is clearly dependant upon hydraulic boost pressures• Typical rig test involves clamping the steering rack, and turning the input

shaft in both directions slowly to get the full range of boost in bothdirections, with hysteresis

• By recording Boost pressure parallel to noise, the level of steering hisscould be clearly compared for various parts

• Hiss noise related to boost pressure clearly correlates with subjectiveratings

In vehicle Hiss Noise vs. PressureIn vehicle Hiss Noise vs. PressureGear Hiss Noise vs. Pressure

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-100 -80 -60 -40 -20 0 20 40 60 80 100Pump high pressure (Left -ve)

10cm

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z H

P fil

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BA)

C01 Baseline as received VR5

C02 Measured gear fitted VR6

C03 Original gear re-fitted VR5.5

Example 2 – Compressor Ticking vs PressuresExample 2 – Compressor Ticking vs Pressures

• Climate compressor changes displacementaccording to required load– Inlet pressure maintained almost constant– Outlet pressure increases with load

• Ticking noise only occurred at certain loadconditions (= displacements)

• Parallel recording of noise and pressure clearlyshowed pressure region where ticking occurred

Compressor Tickingnoise(vibration) vs PressuresCompressor Tickingnoise(vibration) vs Pressures

Example 3 –100kHz parallel samplingExample 3 –100kHz parallel sampling• “Ticking” or “Rattling” noise audible in vehicle during

light steering over small bumps• Needed to localise ticking source• Accelerometers recorded in parallel at high sampling

rates used to indicate ticking source– Speed of sound in steel=5000m/s, Alu=3000m/s– Spatial resolution possible in steel=5cm, Alu=3cm

• Ticking effectively localised to upper part of steeringgear tower

Steering Tick Measurement LocationsSteering Tick Measurement Locations

Steering Tick PlotsSteering Tick Plots

Sum upSum up

• More to NVH than noise and vibration– Recording other parameters in parallel can often

help understand root cause• Take it to the limit!

– High speed acquisition helps keep up withsounds in steel

Questions ?Questions ?

Some sound bitesSome sound bites

• 1 – How close was that?• 2 – Fred the head misses nothing!• (switch to ArtemiS playback)