experimental and numerical analysis of automotive gearbox ...€¦ · idle gear dynamics...
TRANSCRIPT
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
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
123
564
Introduction
Differential
Configuration : Neutral
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
123
564
Introduction
DifferentialDifferential
Configuration : 3rd gear ratio engaged
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
Ve
loci
ty
Introduction
2500
2600
Ve
loci
ty
Four-cylinder four stroke engineTime
2400
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
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
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
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
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
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)
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
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
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
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
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
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
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
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
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
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.
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
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
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
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)
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
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)
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
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)
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
Model outputs
Housing vibration
Successive impulses
Model outputs
Time response
Housing responseMeasured transfer fonction
Housing response
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
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)
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
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)
Introduction Numerical model Idle gear dynamics Housing vibration Conclusion
- 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)