NVH Optimisation of an Electric Parking Brake · or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc. EPB Noise Optimisation Process •

NVH Optimisation of anElectric Parking Brake

H.-J. Griebel, T. Treyde, T. KasterTRW Koblenz

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

EPB Noise Optimisation Process

• Use of NVH development tools

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

EPB Noise Optimisation Process

• Use of NVH development tools

• Efficient development process

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

EPB Noise Optimisation Process

• Use of NVH development tools

• Efficient development process

• Effective noise reduction

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

Electric Parking Brake (EPB)

• parking the vehicle at 30% hill

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

Electric Parking Brake

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

EPB Noise

... is not a vehicle interior noise issue

... is an exterior noise concern

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

Noise Characteristic

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

Howlingnoise

Wavelet analysis

apply

Speed reduction

Noise Characteristic

1000 Hz

2000 Hz3000 Hz

6040

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

• Apply noise comparable torelease noise, but mirrored

• Noise annoying mainly duringapply „howling sound“

• Structural resonance at 1400Hz in combination with speedreduction

Howlingnoise

Wavelet analysis

apply release

Speed reduction

Noise Characteristic

Structural resonance

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

• Impact hammer test atthe rotor shows nosignificant resonance at1400 Hz

• The cause of thestructural resonance is notthe rotor

Noise Radiation

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

• Impact hammer test at the rotor showsno significant resonance at 1400 Hz

• The cause of the structural resonance isnot the rotor

Noise Radiation

• cause of the noise is not the caliper

• cause seems to be the actuator

Release

Laser holography0

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

release

releaseapply

=> housing cover showes big amplitudes

Laser Holography of Housing

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

=>

Modal Analysis at 1457 Hz

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

=>

Modal Analysis at 1529 Hz

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

Calculated Noise Radiation

DeformedDeformedplotplot

PressurePressure

Displ, XDispl, Xcompcomp

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

Housing Modification

Baseline shell meshBaseline shell meshBaseline solid meshBaseline solid mesh

Modification solid meshModification solid mesh

Improvement not sufficient

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

Actuator Design

drive gear; 15 teath

motor; 5 poles

toothed belt

gear

swash plate

sliding block

cover

housing

Cover removed

connector

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

Detailed Noise Analysisclearance compensation apply

structural resonance

gear meshing noise

5th motor order

rattle noise

harmonic ofgear meshing noise

speed characteristic

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

High-Speed Camera Analysis

=> Belt touches housing=> Discontinuity of rotation = cause of rattle noise

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

EXCITATION IS:

a) Motor and gear orderrelated

b) Rattle noise is non-stationary

SOLUTION STRATEGYCONSEQUENTLY:

1: Optimize belt drive

2: Decoupling of motorand gear againsthousing

3: Increase of housingstiffness

Solution Strategy

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

α

helical gearing

decoupling of motor and gearfrom housing

base

helical gearing

decoupling from housingincrease of stiffness

helical gearingdecoupling from housingincrease of stiffness

EPB Noise Reduction1

2+3

1+2+3

Increase of housingstiffness

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

EXCITATION IS:

� Motor and gear orderrelated

b) Rattle noise is non-stationary

SOLUTION STRATEGYCONSEQUENTLY:

1: Optimize belt drive

2: Decoupling of motor andgear against housing

3: Increase of housing stiffness

Solution Strategy

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

EXCITATION IS:

� Motor and gear orderrelated

b) Rattle noise is non-stationary

SOLUTION STRATEGYCONSEQUENTLY:

1: Optimize belt drive

2: Decoupling of motor andgear against housing

3: Increase of housing stiffness

“DoE”

Solution Strategy

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

Test

Num

ber

Effe

ct 1

Effe

ct 2

Effe

ct 3

1 1 1 12 1 1 23 2 1 24 2 1 1

Rattle Noise Investigation Using DoE

Subjective ratingRating

Not acceptab le Acceptab le

Index 1 2 3 4 5 6 7 8 9 10

Noise annoying accetab le goodvery

goodexce llent

extrem ly

unp leasent

very

unp leasentunp leasent

clearly

noticab lenoticab le

hard ly

noticab le

hard ly

existing

not

existing

Ger

äusc

h N

r.

Test

pers

on 1

Test

pers

on 2

Test

pers

on 3

Test

pers

on 4

Test

pers

on 5

Test

pers

on 6

Test

pers

on 7

Test

pers

on 8

Test

pers

on 9

Test

pers

on 1

0

1 7 7 6 9 6 6 8 6 8 72 5 4 5 3 4 5 5 5 5 23 4 6 4 4 4 5 7 5 8 44 2 3 4 2 4 3 2 3 5 15 9 9 7 10 7 7 9 7 9 86 3 4 5 3 4 4 5 4 6 3

16

Testplan

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

DoE Result

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

Main influences

Main factors:

• torque

• speed

• gear guiding

DoE Result

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

standard motor

stronger motor

Rattle Noise Reduction

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

Comparison Before / After

� Reduced motorand gear orderrelated noise

�Reduced rattle noise

This copyrighted document is the property of TRW and is disclosed in confidence. It may not be copied, disclosed to others,or used for manufacturing, without the prior written consent of TRW. ©2006 TRW Automotive Inc.

Summary

EPB noise reduction by combining

- Multi channel sound quality system

- Laser holography

- Noise simulation

- High speed camera

- DoE philosophy and software