Nvh Performance Vs Weight Reduction Classical and Innovative Solutions

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.

CAFÉ : Corporate Average Fuel Economy

Gasoline Euro5:

~ 23,2 g CO2 /km  1l/100km 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

. CO2 emission reduction strategy and impact on NVH performance of PC

. Weight reduction . design optimization with classical solutions . Innovative passive solutions potential – performance and cost

. Active Noise and Vibration Control . Contribution of Active Noise and Vibration Control . Overview of AVC and ANC technology . Key features of AVC/ANC for automotive applications . Active Sound Design overview

. Conclusion Fuel consummation = Vehicle energy need / PWT efficiency

Vehicle energy need in customer drive condition Energy consummation Power need at constant speed (w/o air cond.) Other Total

E-Power Aerodynamics Aerodynamics Tire rolling resistance Tire

E-Power

Weight direct effect

. The PWT efficiency increasing with new technologies, down speeding and down sizing*. (* the trends of down sizing is stopped due to new depollution regulation.) Impact on NVH performance – 2 examples : low resistance tire and high efficiency engine

Exp. 1 Green tire Exp. 2 Old Eng. 1.2L; New Eng. 1.3L . 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 Gap New/Old Eng.

Green tire 15% lost due to air resistance Power +25% Torque +30% Normal tire Fuel consummation -10% Noise radiation +3dB

85% lost due to local deformation Weight evolution of B segment cars in last 15 years in Europe market

Weight gap is small Weight gap is small Weight gap is big and but some car is but NVH poor NVH perf. gap is big more noisy.

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

. 1% mass reduction = 0.5% CO2 emission reduction (8 -10 kg = 1g) 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) . Innovative passive solutions potential – performance and cost

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

Foam along has non damping effect to panel vibration !

Foam along w/oFoam HL along w/o HL

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

VTF of floor A Damping ++ Insulation -

B Damping ++Insulation+ A

C Damping + Insulation ++ B C

NTF C

A B 0 Hz 200 Hz 400 Hz 600 Hz

. 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 Hz 6300 Hz Case study 3 (1/2) – BIW weight reduction – NVH and passive safety

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

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

Golf 7 i30 Case study 3 (2/2) – BIW weight reduction – NVH and passive safety

. 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. Shock Shock Tower stiffness Architecture 1

Architecture 2

Mass

1 kg 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 Case study 4 (2/3) - A concept car using simultaneously innovative ‘passive’ solutions and active solution to ensure acoustic comfort

PHEV 3cyl PWT Positive and negative factors for NVH

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

 High body sensitivity  Low friction- tire  high road noise - excitation

SCx -0.200m² Camera instead of side mirror

Casting Alu struc. note Body stiffness +20%

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

Over cost Simulation : consequence of -10 to 15 kg of BIW

. High strength steels ~1€/kg Booming +3 dB but same global modes and road noise . Aluminum alloys 4 to 8€/kg • Option 1 : eliminate all diesel engines . Magnesium 8 to 12€/kg • Option 2 : ANC . Polymer matrix Composite > 12€/kg

Road noise . For innovative passive solution, a deep industrial process change is necessary. Booming . The active solution can be applied on the current cars. 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) . 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 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.

Torque bar for low engine speed Engine LH/RH mounts for idle and driving Active force Eng. Input vibration & booming vibration & booming

5 dB

Residue vib. Vib. At mount point 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, 퐹 = 푀 ∗ 푑 ∗ 휔2 . 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

Robustness  FRF accuracy (from speaker to micro) used in controller design.  On/Off detector to avoid the instability of ANC.

Reference signal

Bloc diagram of MEFX-LMS type control algorithm 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.

Frequency response of decomposed SPL road noise with and without control [18] common error SAN feedback controller [18] 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.

This algorithm may reduce simultaneously booming noise and road noise at selected narrow-frequency bands

Rear axle modes Tire mode

t=tn Limitation of AVC & ANC and Expected evolution in the future

AVC

. Cost and packaging in engine bay . Active torque bar for high torque engine 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

+ Cost + Independent of audio unit - Audio unit dependent + Short delay for development & implementation - Complicates project management : - Cost Multi-Media, PWT & Vehicle Integration ANC in platform development for light weight design

BIW design + ANC Enhanced absorption sound package new materials + good door and BIW sealing

50 Hz 250 Hz BIW stiffness Booming, MF Engine Noise Wind noise, M/HF engine and And LF Road noise Accessory noise

. 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. Engine Sound Enhancement of Sports cars

Alpine A110 - 1962 New Alpine - 2017 4 Cyl. Turb. 4 Cyl. Turb. Sound pipe Nature eng. & Elec. ESE sound

. 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. 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