Experimental and numerical analysis of automotive gearbox ...€¦ · Idle gear dynamics Experimental and simulated relative velocities rpm) (m/s) (m/s) Ω = 750 rpm et A = 125 rpm

Experimental and numerical analysis of

automotive gearbox rattle noise

Younes KADMIRI

Emmanuel RIGAUD, Joël PERRET-LIAUDET

Journées GDR Visible, 18-19 mai 2011, IFSTTAR, Bron

Introduction

Improving acoustic confort

External noise sources:External noise sources:

- Aerodynamic

- Pneumatic

Introduction Numerical model Idle gear dynamics Housing vibration Conclusion

Introduction

Improving acoustic confort

External noise sources:External noise sources:

- Aerodynamic

- Pneumatic

Internal noise sources:

- Engine

- Gearbox

(gear whine, rattle noise)

Engine GearboxIntroduction Numerical model Idle gear dynamics Housing vibration Conclusion

Kinematic scheme of TL4 gearbox

Introduction

Idle gearsDriving gears and shaftsSynchronizing systemDifferentialHousing


123

564

Introduction

Differential

Configuration : Neutral


123

564

Introduction

DifferentialDifferential

Configuration : 3rd gear ratio engaged


Ve

loci

ty

Introduction

2500

2600

Ve

loci

ty

Four-cylinder four stroke engineTime

2400


Housing vibrationOperating conditions

Rattle noise

Idle gear dynamics

Vibration transfer(shaft, bearings)

Housing vibration- Operating speed

- Drag torque

- Contact stifness/damping

Excitation sourceDesign parameters

- Idle gears inertia

- Backlashes


Numerical model

Excitation sourceVelocity fluctuation

- Idle gears dynamics

- Impacts time history

- Transmitted forces

Housing vibration

- Operating conditions

- Design parameters

Impulse response

Rattle noise

characterization

Housing vibrationImpulse response

Renault criterion


x(t)

y2(t)

Non linear model

Angular displacement Displacement along the action line

mx(t)

F

y1(t)

y2(t)

Free fligth

y2(t)

Permanent contact Impacts

y2(t)

Fxm −=&&F

m x(t)

y2(t)

y1(t)

)()(0 11 tymFtR &&+=<)()(0 22 tymFtR &&+=>

F

mx(t)

y1(t)

)()( −−++ −−=−iiyxryx &&&&

10 ≤≤ r

F

mx(t)

y1(t)


Dimensionless non linear model

6 variables necessary to describe rattle noise

(m, F, r, H, j, ω)(m, F, r, H, j, ω)

Vaschy-Buckingham

theorem

3 dimensionless numbers

F

mH2ω=Λ

H

jj =~

r


Time responses for

yx ~,~yx ~,~

Λ = 1,1

85.0,8~ == rj

Λ = 1,5

yx ~,~yx ~,~

Λ = 1,1 Λ = 1,5

t~

t~

Λ = 2,5 Λ = 3,5


Active flank

Impulses diagram

B: rebounds and contact intermittency

I~ C: chaotic response

Reverse flank

Λ

D: 2T 2 impacts response

E: 1T 2 impacts response


Conclusion

Restitution coefficient

Numerical model

Spectral content of

Λ parameter (m, H, F, ω)

Gear backlash

Spectral content of

velocity fluctuation

Measuring these parameters is necessary


Test bench (BACY)Experiments performed :

• Key parameters measurement (restitution coeff., drag torque, …)

• Idle gear dynamics measurement• Idle gear dynamics measurement

• Housing vibration measurement

• Radiated noise measurement.


Gearbox instrumentation

• Weak dimensions

• Small gear backlash = 0.1 mm

• Idle gear and supporting shaft are indepedant

• Severe operating conditions (high Ω, oil churning, high T, ...)• Severe operating conditions (high Ω, oil churning, high T, ...)

Optical encoder on driving gear

Driving gear

Configuration : 2nd, 3rd and 4th gear ratioConfiguration : 2nd gear ratio

Optical encoder on idle gear

Idle gear


Idle gear dynamics

T

Experimental and simulated relative velocities

rpm

)

(m/s

)

(m/s

)

Ω = 750 rpm et A = 50 rpm

Neutral T

Experimental and simulated Poincaré maps

(rp

m

(m/s

)

(m/s

)Time (s) Time (s)

/s)

Time (s)

Φ : phase (s)

ti : Impact time

T : period

[ ]Ttii

=Φ

Φ (s) Φ (s)

I(k

g.m

/s)

I(k

g.m

/s)


T

Idle gear dynamicsExperimental and simulated relative velocities

Rp

m)

(m/s

)

(m/s

)

Ω = 750 rpm et A = 100 rpm

NeutralExperimental and simulated Poincaré maps

(Rp

m

(m/s

)

(m/s

)Time (s) Time (s)

/s)

Time (s)

Φ : phase (s)

ti : Impact time

T : period

[ ]Ttii

=Φ

Φ (s) Φ (s)

I(k

g.m

/s)

I(k

g.m

/s)


Idle gear dynamicsExperimental and simulated relative velocities

rpm

)

(m/s

)

(m/s

)

Ω = 750 rpm et A = 125 rpm

3rd ratio engagedExperimental and simulated Poincaré maps

(rp

m

(m/s

)

(m/s

)Time (s) Time (s)

/s)

Time (s)

Φ : phase (s)

ti : Impact time

T : period

[ ]Ttii

=Φ

Φ (s) Φ (s)

I(k

g.m

/s)

I(k

g.m

/s)


Model outputs

Housing vibration

Successive impulses

Model outputs

Time response

Housing responseMeasured transfer fonction

Housing response


Exp

eri

me

ntsΩ=750 rpmHousing vibration

A=50 rpm A=75 rpm A=100 rpm

Exp

eri

me

nts

Sim

ula

tio

n(m

/s²)

Time (s) Time (s)Time (s)

Sim

ula

tio

n(m

/s²)


Renault Criterion «5 faces»

Ω=500, 750, 1000 rpm

«5

fa

ces»

(d

B)

Experiments / Simulated

«5

fa

ces»

(d

B)

Cri

teri

on

«5

fa

ces»

(d

B)

A (rpm)

Cri

teri

on

«5

fa

ces»

(d

B)

A (rpm)

A 50 rpm 75 rpm 100 rpm 125 rpm

Experiments 16,4 dB 18,6 dB 19,5 dB 20,9 dB

Simulation 14,9 dB 17,6 dB 18,6 dB 20,6 dB

Error 1,5 dB 1,0 dB 0,9 dB 0,3 dB

A (rpm) A (rpm)


- Experiments performed with BACY allowed non linear numerical model.

- Operational software.

- Rattle noise can be predicted for:

Conclusion

- Rattle noise can be predicted for:

• any gearbox,

• any gear ratio,

• any operating conditions.

- Parametric studies allow gearbox design optimization.

Ω=750 rpm, A=75 rpm Ω=750 rpm, A=125 rpm

Backlash (µm)

«5

fa

ces»

(d

B)

Backlash (µm)

«5

fa

ces»

(d

B)

Documents

Experimental and numerical analysis of automotive gearbox ...€¦ · Idle gear dynamics Experimental and simulated relative velocities rpm) (m/s) (m/s) Ω = 750 rpm et A = 125 rpm