In situ torque transmissibility frequency response function measurements of a centrifugal pendulum vibration absorber in a torque converter clutch damper

Abstract

This investigation details torsional testing and characterization of torque converter clutch (TCC) damper variants containing centrifugal pendulum absorbers (CPAs) utilized in light duty production vehicles. Data collected on a torque converter dynamometer test stand was used to correlate a nonlinear model of the combination TCC damper and CPA when locked with zero relative slip speed. The range of test torques and speeds are related to when driveline, chassis and body noise and vibration concerns are high and the damper-CPA combination are required to provide maximum isolation. To facilitate model correlation efforts, modified configurations of the same torque converter design were procured, enabling separation of damping effects from the CPA and damper springs. Under load, the locked TCC was torsionally excited to acquire torque transmissibility frequency response functions (TTFRFs). The anti-resonance of the CPA was measured, and the viscous damping coefficient estimated. A manual tuning and modified half-power bandwidth method were used to estimate the equivalent viscous damping of the CPA. Additional test cases included torsional excitation amplitude and oil temperature to ascertain differences in CPA response and tuning order. The objective of the investigation is to demonstrate the influence of damper spring and CPA integration, extraction of CPA damping from actual hardware and the utility of including representative damping in model-based design of future damper-CPA assemblies.