NVH Optimisation of an Electric Parking Brake. H.-J. Griebel, T. Treyde, T. Kaster TRW Koblenz

Transcription

1 NVH Optimisation of an Electric Parking Brake H.-J. Griebel, T. Treyde, T. Kaster TRW Koblenz

2 EPB Noise Optimisation Process Use of NVH development tools

3 EPB Noise Optimisation Process Use of NVH development tools Efficient development process

4 EPB Noise Optimisation Process Use of NVH development tools Efficient development process Effective noise reduction

5 Electric Parking Brake (EPB) parking the vehicle at 30% hill

6 Electric Parking Brake

7 EPB Noise... is not a vehicle interior noise issue... is an exterior noise concern

8 Noise Characteristic

9 Noise Characteristic apply Wavelet analysis 3000 Hz 2000 Hz Speed reduction 1000 Hz Howling noise 40 60

10 Noise Characteristic Wavelet analysis apply release Speed reduction Howling noise Structural resonance Apply noise comparable to release noise, but mirrored Noise annoying mainly during apply howling sound Structural resonance at 1400 Hz in combination with speed reduction

11 Noise Radiation Impact hammer test at the rotor shows no significant resonance at 1400 Hz The cause of the structural resonance is not the rotor

12 Noise Radiation Impact hammer test at the rotor shows no significant resonance at 1400 Hz The cause of the structural resonance is not the rotor Release Laser holography 0 cause of the noise is not the caliper cause seems to be the actuator

13 Laser Holography of Housing release apply release => housing cover showes big amplitudes

14 Modal Analysis at 1457 Hz =>

15 Modal Analysis at 1529 Hz =>

16 Calculated Noise Radiation Deformed plot Pressure Displ, X comp

17 Housing Modification Baseline shell mesh Baseline solid mesh Modification solid mesh Improvement not sufficient

18 Actuator Design motor; 5 poles drive gear; 15 teath connector housing Cover removed toothed belt gear swash plate sliding block cover

19 Detailed Noise Analysis clearance compensation apply speed characteristic harmonic of gear meshing noise structural resonance gear meshing noise rattle noise 5th motor order

20 High-Speed Camera Analysis => Belt touches housing => Discontinuity of rotation = cause of rattle noise

21 Solution Strategy EXCITATION IS: a) Motor and gear order related b) Rattle noise is nonstationary SOLUTION STRATEGY CONSEQUENTLY: 1: Optimize belt drive 2: Decoupling of motor and gear against housing 3: Increase of housing stiffness

22 EPB Noise Reduction 1 helical gearing Increase of housing stiffness base 2+3 decoupling from housing increase of stiffness decoupling of motor and gear from housing helical gearing? helical gearing decoupling from housing increase of stiffness 1+2+3

23 Solution Strategy EXCITATION IS: Motor and gear order related SOLUTION STRATEGY CONSEQUENTLY: 1: Optimize belt drive 2: Decoupling of motor and gear against housing 3: Increase of housing stiffness b) Rattle noise is nonstationary

24 Solution Strategy EXCITATION IS: SOLUTION STRATEGY CONSEQUENTLY: Motor and gear order related 1: Optimize belt drive 2: Decoupling of motor and gear against housing 3: Increase of housing stiffness b) Rattle noise is nonstationary DoE

25 Rattle Noise Investigation Using DoE Test Number Effect 1 Effect 2 Effect Testplan Subjective rating Not acceptable R ating Acceptable Index Noise annoying accetable good extrem ly unpleasent very unpleasent Geräusch Nr. Testperson 1 Testperson 2 unpleasent Testperson 3 Testperson 4 clearly noticable Testperson 5 noticable hardly noticable Testperson 6 Testperson 7 Testperson 8 Testperson 9 very good hardly existing Testperson 10 excellent not existing 16

26 DoE Result

27 DoE Result Main factors: torque speed gear guiding Main influences

28 Rattle Noise Reduction stronger motor standard motor

29 Comparison Before / After Reduced motor and gear order related noise Reduced rattle noise

30 Summary EPB noise reduction by combining - Multi channel sound quality system - Laser holography - Noise simulation - High speed camera - DoE philosophy and software