Driveline Torque Intervention for Clunk Mitigation
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Solution Overview
Problem
Manual transmission vehicles, particularly performance-oriented rear-wheel drive configurations, experience objectionable clunk noise due to rapid release of potential energy during abrupt clutch disengagement, causing driveline components to oscillate and impact, leading to vibration and noise.
Innovation Solution
Implementing a method that reduces driveline torque to a neutral state before clutch disengagement through torque intervention at the prime mover, using sensors to determine clutch and accelerator pedal positions and speeds to minimize stored potential energy, allowing the driveline to unwind while the clutch is still constrained, thereby preventing the generation of clunk noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the driver opens the clutch abruptly to rapidly release potential energy, then the vehicle can respond quickly to driver input, but this causes objectionable clunk noise due to driveline components oscillating and impacting
Solution Approach 1:
The system performs preliminary action by detecting the clutch disengagement event and rapidly reducing torque to a neutral state before the clutch fully opens. This preemptive torque reduction allows the driveline to unwind while still constrained, eliminating the potential energy that would otherwise cause clunk noise during abrupt clutch release
Solution Approach 2:
The system uses feedback from clutch position sensors and accelerator pedal position sensors to detect when a clutch disengagement event is occurring. Based on this feedback, the controller dynamically adjusts the torque request to minimize stored potential energy at the critical moment of clutch opening, thereby preventing clunk noise while maintaining responsive vehicle operation
2Force
If torque is maintained at high levels during clutch disengagement, then the vehicle maintains propulsion force, but this prevents the driveline from unwinding and generates clunk noise
Solution Approach 1:
The system applies periodic or pulsed torque reduction during the clutch disengagement event. Rather than maintaining constant high torque, the controller rapidly modulates torque to a neutral state during the critical unwinding phase, then restores torque afterward. This periodic action eliminates clunk noise while preserving overall propulsion force
Solution Approach 2:
The system dynamically changes the torque parameter during clutch disengagement by rapidly reducing it to a neutral state. This parameter change allows the driveline to unwind without generating clunk noise, while the torque is subsequently restored to maintain propulsion force for vehicle operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively reduces objectionable noise generation by minimizing stored potential energy in the driveline during declutch events, ensuring that no potential energy is present when the clutch opens, thus eliminating the clunk noise.
Implementation Method 1
Manual transmission vehicles, particularly performance oriented rear wheel drive configurations, have the capability to rapidly release potential energy stored in the driveline components as torsional 'windup' via the driver opening the clutch abruptly
Implementation Method 2
This reduction in stored potential energy mitigates change in angular momentum when a clutch opens, resulting in reduced levels of objectionable noise generation
Implementation Method 3
the now unconstrained clutch assembly torsionally oscillates and impacts against the limits of the various gear lashes in the driveline
Implementation Method 4
The term 'clunk' means a noise (caused by vibration) that occurs when potential energy stored in the driveline components is rapidly realeased
Data Source
AI summary
A method for mitigating clunk in a driveline of a vehicle system during a declutch event includes determining a current torque request of a prime mover based on an accelerator pedal position of an accelerator pedal of the vehicle system. The method includes determining a clutch pedal position and determining, via a controller, a clutch pedal speed based on a change of the clutch pedal position over time. The method further includes modifying, via the controller, the current torque request to obtain a modified torque request based on the clutch pedal position and the clutch pedal speed such that a stored potential energy in the driveline is minimized by a time that the clutch pedal of the vehicle system is disengaged during the declutch event.