nvh performance vs weight reduction classical and

NVH PERFORMANCE VS WEIGHT REDUCTION

CLASSICAL AND INNOVATIVE SOLUTIONS

Dr. ZHANG Charles

Road map of CO2 emission reduction in Europe, USA & China

The risk of financial penalty after 2020 if the CAFÉ target is not achieved.

Gasoline Euro5:

~ 23,2 g CO2 /km 1l/100km

CAFÉ : Corporate Average Fuel

Economy

OUTLINE

CO2 emission reduction strategy and impact on NVH performance of PC

Weight reduction – case study

Design optimization with classical solutions (Damping, Sound package

& BIW optimization)

Innovative passive solutions potential – performance and cost

Active Noise and Vibration Control and its contribution to weight reduction

Overview of AVC and ANC technology

Key features of AVC/ANC for automotive applications

Active Sound Design overview

Conclusion

OUTLINE


Weight reduction

design optimization with classical solutions


Active Noise and Vibration Control

Contribution of Active Noise and Vibration Control




Conclusion

Fuel consummation = Vehicle energy need / PWT efficiency

The PWT efficiency increasing with new technologies, down speeding and down

sizing*. (* the trends of down sizing is stopped due to new depollution regulation.)

Weight direct effect

Aerodynamics

Tire

E-Power

Other

Vehicle energy need in customer drive condition

Total

Aerodynamics

Tire rolling resistance

E-Power

Power need at constant speed (w/o air cond.) Energy consummation

Impact on NVH performance – 2 examples : low resistance tire and high efficiency engine

Exp. 2 Old Eng. 1.2L; New Eng. 1.3L

Gap New/Old Eng.

Power +25%

Torque +30%

Fuel consummation -10%

Noise radiation +3dB

85% lost due to local deformation

15% lost due to air resistance

The energy lost of tire is 15% due to air resistance

and 85% due to deformation in the contact area.

The indicator of tire resistance : Kg/t (resistance

force/vehicle load)

Green tire : 6 kg/t and Bad tire > 10kg/t.

Green tire increase 2 to 3 dB road noise

Road Noise

Green tire

Normal tire

Exp. 1 Green tire

Weight evolution of B segment cars in last 15 years in Europe market

The mass reduction should not have a negative impact on acoustic comfort.

1% mass reduction = 0.5% CO2 emission reduction (8 -10 kg = 1g)

Weight gap is small

but NVH poor

Weight gap is big and

NVH perf. gap is big

Weight gap is small

but some car is

more noisy.

OUTLINE




& BIW)


Active Noise and Vibration Control

Contribution of Active Noise and Vibration Control




Conclusion

Case study 1 (1/2) – Damping material or multi-effect of 2 layer insulator

Foam along

w/o HL

Foam along

w/o HL

Foam along has non damping effect

to panel vibration !

2 layer insulator is designed 18 dB/Oct. attenuation (noise radiation) after critical frequency.

But its damping effect is not well known.

In certain conditions, 2 layer insulator may replace damping sheet.

0 Hz 200 Hz 400 Hz 600 Hz

VTF of floor

NTF

A

A Damping ++ Insulation -

A

B

B Damping ++Insulation+

B

C

C Damping + Insulation ++ C

Case study 1 (2/2) - Damping material or multi-effect of 2 layer insulator

In average 3 to 4 kg damping material on the floor C/D segment cars in Europe. But <1 kg

for Renault cars. (Golf 7 : 5 kg and Renault Megane 4 : 1 kg.)

Case study 2 (1/2) – Weight reduction of sound package – enhanced absorption

Enhanced absorption effect

The absorption of porous material

is enhanced in a ‘closed’ space.

NR of 3 layer is 5 to 10 dB higher

in a closed space than in an open

space.

Case study 2 (2/2) – Weight reduction of sound package – enhanced absorption

1600 Hz 4000 Hz6300 Hz

Case study 3 (1/2) – BIW weight reduction – NVH and passive safety

Golf 7i30

Under bay structure is a key area for pedestrian crash and NVH.

Automotive OEMs adopt different strategies to find a compromise NVH & Passive Safety.

Case study 3 (2/2) – BIW weight reduction – NVH and passive safety

1 kg

Mass

Sh

ock

To

we

r stiffn

es

s

Architecture 1

Architecture 2

A cross sectors (NVH, PS, Packaging, BIW, …) workshop to optimize this area :

Inputs : NVH & PS performance criterial, packaging constraint, assembling rules, …

Define several scenarios of architecture in the area

For each scenario, launching a numerical optimization

Parameter of optimization : thickness and topology of pieces.

Each scenario has a different potential to achieve performance target and weight reduction.

Case study 4 (1/3) - Eolab : technology illustration for the car of 2025

Fuel consummation : 1 L/100Km or 22g CO2 emission / km

PHEV with a 3 cylinder ICE; -400 kg and -30% SCx vs Clio 4

A concept car using simultaneously innovative ‘passive’ solutions

and

active solution to ensure acoustic comfort

PHEV 3cyl PWT

SCx -0.200m² Camera instead of side mirror

Positive and negative factors for NVH

- High body sensitivity Low friction tire high road noise

excitation-

Non idle vibration (EV mode) Low air dynamic excitation ANC for low and medium frequency noise +

Composite double wall floor

Casting Alu struc. note Body stiffness +20%

Case study 4 (2/3) -

Case study 4 (3/3) - Weight reduction, cost and NVH performance : Passive solution or Active solution

Over cost

High strength steels ~1€/kg

Aluminum alloys 4 to 8€/kg

Magnesium 8 to 12€/kg

Polymer matrix Composite > 12€/kg

Booming +3 dB but same global modes

and road noise

• Option 1 : eliminate all diesel

engines

• Option 2 : ANC

Simulation : consequence of -10 to 15 kg of BIW

Booming

Road noise

For innovative passive solution, a deep

industrial process change is necessary.

The active solution can be applied on

the current cars.

OUTLINE




& BIW)


Active Noise and Vibration Control and its contribution to weight reduction




Conclusion

Active Vibration Cancellation overview – Active Control Mount

ACM is applied by many automotive OEMs.

Feedforward control with or without adaptive filter.

The recent trend : sensor-less ACM for cost reduction.

Engine LH/RH mounts for idle and driving

vibration & booming

Torque bar for low engine speed

vibration & booming

5 dB

Vib. At mount point

Active force Eng. Input

Residue vib.

Active Vibration Cancellation overview – Active Dynamic Damper

Moving mass of ADD generate an inertial force out of phase with engine excitation

Implemented close to a main input force or on transfer path.

Example : ADD applied below RH Eng. mount in X/Z direction

ADD presents 2 advantages and 1 inconvenient vs Passive Dynamic Damper :

Less mass, since a bigger displacement, 𝐹 = 𝑀 ∗ 𝑑 ∗ 𝜔2

Cover a larger frequency band and follow engine rpm

More expensive than PDD

ANC overview – Booming noise reduction

A control algorithm integrated in the audio unit to generate a sound out of the phase with

engine noise (2nd order) at driver/passengers’ ears.

Frequency range : 60 to 180 Hz without sub-woofer down to 30 Hz with sub-woofer

Bloc diagram of MEFX-LMS type

control algorithm

Reference signal

Robustness

FRF accuracy (from speaker to micro) used in controller

design.

On/Off detector to avoid the instability of ANC.

SPL road noise with and without control [18]Frequency response of decomposed

common error SAN feedback controller [18]

ANC overview – feedback based controller for Road noise reduction [18]

Honda [18] present narrow-frequency bands road noise cancellation

Single-frequency Adaptive Notch (SAN) filter : reduce the sound level (not only road noise) in the

selected frequency range.

Compatible with booming control algorithm.

t=tn

ANC overview – full feedback noise cancellation in narrow-frequency bands [16]

Narrow band ‘notch’ at selected frequency or following engine speed.

Based on Bode-Freudenberg-Looze theorem,

Positive area (noise increasing) = Negative area (noise decreasing)

Road noise SPL peaks related to body or chassis resonance at known frequency.

Rear axle modes Tire mode

This algorithm may reduce simultaneously booming noise and

road noise at selected narrow-frequency bands

Limitation of AVC & ANC and Expected evolution in the future

Cost and packaging in engine bay

Active torque bar for high torque engine

AVC

ANC

Simultaneous Booming and Low frequency Road noise (at specific frequency-bands) ANC

Self learning and auto adaptive system model during life cycle of vehicle

Plat-form right sizing : ANC associated with high excitation engine (diesel and high torque

gasoline engine)

Cost reduction

Idea for cost reduction

Sharing maximum components with audio unit by choosing the right ANC

implementation strategy.

Stand alone ANC Integrated ANC

+ Independent of audio unit

+ Short delay for development & implementation

- Cost

+ Cost

- Audio unit dependent

- Complicates project management :

Multi-Media, PWT & Vehicle

Integration ANC in platform development for light weight design

BIW stiffness is a fundamental not only for NVH (Idle N/V) but also for S&R and vehicle dynamic

feeling / comfort.

ANC must be associated with all high excitation PWT to right sizing of platform.

In M/H frequency, new materials, good design + new assembly processes to get performant

door and BIW sealing.

50 Hz 250 Hz

BIW design +

new materials

BIW stiffness

ANC

Booming, MF Engine Noise

And LF Road noise Wind noise, M/HF engine and

Accessory noise

Enhanced absorption sound package

+ good door and BIW sealing

Engine Sound Enhancement of Sports cars

Sports cars ≠ Normal passenger cars with sportive option

The engine sound quality is an important emotional criterial.

This population of clients does not accept electronically generated sound.

ASD has been adopted by major automotive OEM. Some times combined with mechanical

solutions.

Whatever ASD, the sound must never give an artificial feeling.

4 Cyl. Turb.

Nature eng.

sound

4 Cyl. Turb.

Sound pipe

& Elec. ESE

Alpine A110 - 1962 New Alpine - 2017

Multi-senses

A combination of on-board ambiance with vehicle chassis and power train behavior.

The driver may personalize his driving experience

Quality you can see, touch and hear.

Who should be the responsible of ASD, NVH, design or perception quality ?

ASD & ADAS (Active Driving Assistance System) : Alert sound

With ADAS, more and more alert sound, which may create some confusion.

Example : passing a continuous line

Door open ? Safety belt ?

Tire pressure ? …

Hesitation = Danger

The alert sound must make a clear sense for quick driver reaction.

Conclusion

In Europe, the classical passive solutions achieve its limited for the weight reduction after

decennaries efforts of automotive OEMs. In the future, the innovative material and active

solutions will take more important place.

AVC & ANC : ‘Massive’ application and integration in new plat-form development for a global

optimization with passive solutions for acoustic comfort, mass and cost reduction.

ASD : more quality, more emotion and more pleasant on-board ambiance

Thank you

nvh performance vs weight reduction classical and

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