Response of centrifugal pendulum vibration absorber considering gravity at low engine speed

This study examined the performance of the centrifugal pendulum vibration absorber’s (CPVA) under the influence of centrifugal force and gravity fields. The focus was on identifying the factor that influenced noise, vibration, and harshness (NVH) problems that originate owing to the centrifugal pendulum absorber being at low engine speed such as engine start-stop or idle. Consequently, mathematical models were established employing Lagrange equation of the second kind, analytical solutions were obtained using the method of multiple scales, and several simple elementary mathematical equations describing the movement of the absorber were derived. Further, the analytical solutions were compared with the numerical simulation results of the complete non-linear equation of motion, which indicated that the former were suitable for studying the performance of CPVA. The theoretical analysis of the application with four absorbers and two absorbers under gravity field was conducted. The absorbers were found to be not always synchronized in the gravity field in certain special conditions such as lower engine speed range or small viscous damping. It was concluded that larger viscous damping coefficient can result in an improvement in the synchronization or reduce the range of nonlinear jumps caused by changes in excitation torque. Further, super-harmonic resonance of CPVA under the gravity field was determined and exact response was calculated, wherein the term “2nd order response gravity impact factor” was defined. In addition, the effects of CPVA installation angle relative to engine ignition angle were analyzed, and a set of tautochronic epicycloid CPVA was tested to verify the findings. The analytical solutions were consistent with the test results, thereby proving the applicability of the research method and results in a vehicle.