What is a Automatic Transmission Torque Converter Damper?

Sean Biggs 2012 MSC UK USER CONFERENCE Slide 1

Using MSC Adams to understand Automatic Transmission Torque Converter Damper

Performance

Sean BiggsPowertrain CAE Technical Specialist

JLR

MSC UK USER CONFERENCE 2012


• What is a Automatic Transmission Torque Converter Damper?

• Why is a Torque Converter Damper needed?

• Adams Model Details

• Damper Configuration Study

• A Performance Analysis of 3 Damper Configurations

• Conclusions

Agenda


Lock Up Clutch

Gearbox Input via

Splined ShaftEngine Output

Fluid Coupling Elements

TC Damper

Lock up clutch open: Relative slip across Fluid Coupling provides decoupling

Lock up clutch closed: TC Damper spring elements provides decoupling

What is a Torque Converter Damper?


Simple TC Damper

Effective Gearbox and Driveline Stiffness

Dyno Inertia and Brake

Measured Cylinder Pressure applied to Pistons

Pre

ssu

re

Why is a Torque Converter Damper needed? Forcing Levels

Wide Open Throttle (WOT) cylinder pressures

collected from Vehicle or Driveline Rig Test


Crank Angle (deg)

An

gu

lar

Velo

cit

y

CRANK VELOCITY

CRANK TORQUE

Crank RPM

To

rqu

e

At peak torque levels the Crankshaft Velocity

fluctuations can be in excess of 200 rpm peak to peak

Why is a Torque Converter Damper needed? Forcing Levels


Vehicle System Model

Adams Full Vehicle Model (221 DOF)

PT mounted with Elastomers in full Suspension model with front and rear flexible Subframes from Adams/Flex

PT torsional system uses WOT torque data (detailed in previous slide) to force full gearbox and driveline

torsional system via detailed model of the TC

Damper


Total of 16 Springs

8 Outer with 8 Travel limiting inner Springs nested in Outer

Detailed Damper Model: Configuration 1

DAMPER RATE

AngleTo

rqu

e

Inner Spring Contact Point

Inner Spring simplified stiffness function used but mass effects on outer spring

included. See next slide for outer spring modelling method


12.5 Active Coils

Total of 8 Springs modelled in two batches of 4

ELEM 1

Force Elements:

• Coil to Coil Contact

• Coil Stiffness

• Coil Friction (Contact with Housing)


Friction force per spring coil depends on:

Centrifugal Force

Installed pre-load

Wedge effect *

* As the springs are installed on an Arc a component of the compressive force resulting from torque

application forces the coil into the housing



Damper Attenuation

Engine Out Compared With Gearbox Input

Crank RPM

Cyc

lic V

elo

cit

y

Propshaft

Resonance

Damper

Resonance



Overall Damper Travel

Crank RPM

An

gle

Acro

ss D

am

per

Damper

Resonance


Why is a Torque Converter Damper needed? Vehicle Sensitivity

TC Damper Natural Frequency


Why is a Torque Converter Damper needed? Vehicle Sensitivity

Propshaft Natural Frequency

Note: Engine and Rear Subframe Assy also have Natural Frequencies



DAMPER RATE

AngleTo

rqu

eSecond set of Springs applied in series allows Damper rate to be halved and maintain the overall torque capacity of the damper


12.5 Active Coils


STAGE 1 ELEM 1

Force Elements:

• Coil to Coil Contact

• Coil Stiffness

• Coil Friction

STAGE 2 ELEM 1

7.5 Active Coils





Overall Damper Travel

Crank RPMAn

gle

Acro

ss D

am

per

Damper

Resonance



Damper Attenuation


Crank RPM

Cyc

lic V

elo

cit

y

Propshaft

ResonanceDamper

Resonance


Spring 4 Elem 8

Spring 4 Elem 1 Spring 1 Elem 1

Spring 1 Elem 13

Detailed Damper Model: Configuration 2: Influence of Friction






1g 2 g 3 g



Proceedings of the Institution of Mechanical Engineers

1940

Note that Pendulum Frequency is proportional to angular velocity




Damper Attenuation


Crank RPM

Cyc

lic V

elo

cit

y

Propshaft

Resonance


• Forcing levels for driveline systems are increasing

• Traditional methods of decoupling the forcing are not now available

• The Mechanical system response is highly non-linear and complex

• TC Damper designs are becoming increasingly sophisticated

• MSC Adams allows a detailed understanding of the complete system to be obtained

Conclusions


The Author would like to acknowledge the contributions of the JLR CAE and NVH Test team that made the presentation of this

paper possible

The Tyre model used for the analysis was provided by Dr Matthew Bartram of Loughborough University

Acknowledgements

Documents

What is a Automatic Transmission Torque Converter Damper?