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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.

Valvetrain ticking noise is one of the key failure modes in noise vibration harshness (NVH) evaluation at idle. It affects customer satisfaction inversely. In this paper, the root cause of the valvetrain ticking noise and key parameters that impact ticking noise will be presented. A physics based math model has been developed and integrated into a parameterized multi-body dynamic model. The analytical prediction has been correlated with testing data. Valvetrain ticking noise control is discussed.

In the recent times, the reduction of process variability has become very important for delivering cost-effective product. As per Taguchi's Loss Function, higher variability means higher cost also. The quantification of variability is a tremendous challenge to NVH engineers. To understand the NVH characteristics of an engine, measurements at various locations are needed. Moreover, each measurement is also a function of engine speed. In order to capture the process variability, multiple engines need to be measured. Thus, the final data is a function of engine, location, and speed. The objective of this paper is to define the various types of variability associated with the NVH data and to develop a procedure to estimate them. This paper contains the examples from the test data.

A novel digital signal processing method is presented for isolating the vibrational resonances of rotor components from engine tachometer signals. Speed Clock resampling removes spectral leakage and spreading. Sideband manipulation removes AM signal components. Spectral addition removes translational FM components. Sideband multiplying and averaging removes random noise. The result is a spectrum of high resolution and dynamic range comprised of isolated engine rotor resonances, which can be used to track health and performance in engines and other turbomachines.