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AMESim FSO-2106 Transmission Rattle and Clunk Modeling

CAViDS Consortium. AMESim FSO-2106 Transmission Rattle and Clunk Modeling. A CAViDS Consortium Project. Summary Report September 13, 2012. CAViDS Consortium. AMESim Rattle and Clunk Model Initial Approach. Break the system into relevant parts for analysis of each mechanism.

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AMESim FSO-2106 Transmission Rattle and Clunk Modeling

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  1. CAViDS Consortium AMESim FSO-2106 Transmission Rattle and Clunk Modeling A CAViDS Consortium Project Summary Report September 13, 2012

  2. CAViDS Consortium AMESim Rattle and Clunk ModelInitial Approach • Break the system into relevant parts for analysis of each mechanism. • Simulate the critical inputs for each mechanism • Predict the system response to the inputs • Evaluate the response by relevant criteria • Study the effect of critical parameters governing the response

  3. CAViDS Consortium Idle Rattle Model

  4. CAViDS Consortium Idle Rattle Inputs Measured Simulated Key components Engine instability 18 rpm p-p at 6.5 Hz (38.5 rad/sec^2 peak) Firing 2 rpm p-p at 25 Hz (16.5 rad/sec^2 peak)

  5. CAViDS Consortium Idle Rattle Prediction and Evaluation No separation Inertia loads to not exceed drag Acceptance Criteria No separation (inertia tooth load does not exceed drag tooth load) Inertia torque = gear angular acceleration times inertia of gear assembly

  6. CAViDS Consortium Idle Rattle Results Engine instability 38.5 rad/sec^2 Firing 16.5 rad/sec^2

  7. CAViDS Consortium Idle Rattle Conclusions • Idle torsional input to transmission dominated by 6.5 Hz oscillation (engine speed instability?) • Reverse idler through sixth gear robust against rattle for inputs measured • Reverse main shaft gear on threshold of rattle for 6.5 Hz input but OK for firing frequency • Did not observe rattle per se on Milford vehicle which is consistent with analysis • Did observe roll noise modulated by 6.5 Hz oscillation on Milford vehicle which is consistent with analysis • Brazil had no rattle issues

  8. CAViDS Consortium Idle Rattle Recommendations • Determine the cause of 6.5 Hz engine oscillation at idle • Understand GM’s evaluation of idle rattle • Evaluate idle rattle with 6.5 Hz oscillation corrected • Get time files of actual idle speed and input to model

  9. CAViDS Consortium System Clunk Model This represents 3rd gear

  10. CAViDS Consortium System Clunk Input Simulated Key components Constant -100 Nm torque Transition to 100 Nm torque over 1 second (tip in) Constant 100 Nm torque Transition to -100 Nm torque over 1 second (tip out)

  11. CAViDS Consortium System Clunk Evaluation Evaluation: Amplitude of first impact at zero crossing on tip-in and tip-out Frequency is first driveline mode

  12. CAViDS Consortium System Clunk Results

  13. CAViDS Consortium System Clunk Conclusions • Total system backlash influences system clunk

  14. CAViDS Consortium Declutch Clunk Models Split System to simulate clutch disengagement

  15. CAViDS Consortium Declutch Clunk Input and Evaluation Simulated Key components Ramp up torque over 5 seconds Constant torque Release Torque to zero over 50 msec Evaluation Peak dynamic torque at transition

  16. CAViDS Consortium Declutch Clunk Conclusions • Backlash does not influence clutch disengagement clunk • There is no significant difference between the peak dynamic torque predicted at the flywheel or at the transmission during the clutch disengagement process

  17. CAViDS Consortium Clunk Recommendations • Understand design role of DMF free play • Experimentally determine effects of reducing or eliminating DMF free play in tip-in/tip-out and clutch /declutch clunk • Obtain precise spring-mass parametric input for DMF, clutch, drive shaft and axle • Work with GM on AMESim model development • Predict effects of tip-in and clutch engagement rate

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