Abstract
This paper investigated an abnormal noise under idle condition and analyzed the mechanism of the noise based on the results of experiments and dynamics simulations. It is confirmed that knocking inside variable valve timing phaser is the source of the abnormal noise. The results of experiments show that half-order rhythm of the vibration and noise components around 1000 and 2100 Hz are different from the other dominant components, which is possible to involve the abnormal noise. Numerical analyses are conducted to simulate the process of the abnormal noise. It is found that the thickness of the blades of the variable valve timing rotor has significant influence on the abnormal noise. The simulation implies that increasing the thickness of the rotor blades will decrease the abnormal noise. When the thickness increases to 3.0 mm, the acoustic frequencies within 1000–1200 Hz have an average drop of 3.7 dB(A), and the acoustic frequencies within 2000–2200 Hz have an average drop of 12.5 dB(A). The results of verification experiments show that the amplitudes of the abnormal noise have obvious reduction, and the abnormal noise is basically eliminated under subjective evaluation.
Highlights
As in recent years, manufacturers have made great process in controlling civil automobile’s interior sound pressure level; under idle condition, abnormal irritating noise, which used to be sheltered by other noise, has become an increasingly important issue.[1,2] Since human beings are more sensitive to the prominent and rhythmed abnormal noise, reducing or eliminating abnormal noise is essential to improve noise vibration and harshness (NVH) performance and riding comfort.Automotive abnormal noise mainly includes buzz, squeak, and rattle.[3]
Implicit dynamics, and acoustic boundary elements model (BEM) are applied to the calculation of the valve timing (VVT) knock model
The results indicate that the VVT phasers with optimized blades contribute to the reduction of the abnormal noise
Summary
Manufacturers have made great process in controlling civil automobile’s interior sound pressure level; under idle condition, abnormal irritating noise, which used to be sheltered by other noise, has become an increasingly important issue.[1,2] Since human beings are more sensitive to the prominent and rhythmed abnormal noise, reducing or eliminating abnormal noise is essential to improve noise vibration and harshness (NVH) performance and riding comfort. The dynamic bearing force, gearbox vibration, and noise radiation were investigated in different rotational speed and load.[7] Liu et al.[8] developed a nonlinear 3-degree of freedom (3-DOF) torsional model of the clutch system for reducing the abnormal noise during vehicle accelerating. They carefully studied the nonlinear characteristics of the multi-staged clutch damper and the gear backlash and investigated the vibration transmission characteristics of the clutch and the influence of each critical physical parameter on noise generation.[8] Chikatani and Suehiro[9] studied the influence of drag torque applied to the clutch disc on the idling rattle noise. The optimization effects are verified through the validation experiments of vibration and noise
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Journal of Low Frequency Noise, Vibration and Active Control
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
