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Variable Cam Timing (VCT) Knock Root Cause Analysis and Failure Mode Prevention
Technical Paper
2019-01-5003
ISSN: 0148-7191, e-ISSN: 2688-3627
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Sector:
Event:
Automotive Technical Papers
Language:
English
Abstract
Knock in the Camshaft Torque Actuated (CTA) in the Variable Cam Timing (VCT) engine can be a NVH issue and a source of customer complaint. The knock noise usually occurs during hot idle when the VCT phaser is in the locked position and the locking pin is engaged. During a V8 engine development at Ford, the VCT knock noise was observed during hot idle run. In this paper investigation leading to the identification of the root cause through both test and the CAE simulation is presented. The key knock contributors involving torque and its rate of change in addition to the backlash level are discussed. A CAE metric to assess knock occurrence potential for this NVH failure mode is presented. Finally a new design feature in terms of locking pinhole positioning to mitigate or eliminate the knock is discussed.
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Citation
Moetakef, M., Paul, D., and Festag, G., "Variable Cam Timing (VCT) Knock Root Cause Analysis and Failure Mode Prevention," SAE Technical Paper 2019-01-5003, 2019, https://doi.org/10.4271/2019-01-5003.Also In
References
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