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This study utilizes an eddy current proximity probe to approximate the acceleration of a valve in a SOHC valve train. Several techniques are discussed for extrapolating acceleration data from displacement data through numerical differentiation. The data were compared to acceleration data as measured by an accelerometer mounted on the valve face. It was found that valve train acceleration behavior can be reasonably approximated using displacement data as measured by a proximity probe when differentiated using a three-point, Lagrangian interpolation. But the frequency response of the proximity probe is severely restricted by the limitations of the measurement and data collection instrumentation, the limitations of the differentiation method and the continuity of the base measured data.

This study analyzes the vibration characteristics of the valve train of a 2.0L SOHC Chrysler Corp. Neon engine over a range of operating speeds to investigate and demonstrate the advantages and limitations of various dynamic measurements such as displacement, velocity, and acceleration in this application. The valve train was tested in a motoring fixture at speeds of 500 to 3500 camshaft rpm. The advantages of analyzing both time and frequency domain measurements are described. Both frequency and order analysis were done on the data. The theoretical order spectra of cam displacement and acceleration were computed and compared to the experimental data. Deconvolution was used to uncover characteristic frequencies of vibration in the system. The theoretical cam acceleration spectrum was deconvolved from measured acceleration spectra to reveal the frequency response function of the follower system.

Testing of an OHC valve train with hydraulic lash adjuster in which the valve displacements, velocities and accelerations were measured and analyzed in both time and frequency domains, coupled with analysis of the frequency content of the valve acceleration function and its ramps, show that traditional designs of the opening and closing ramps used on some IC engine valve cams can exacerbate vibration in the follower system causing higher levels of spring surge and noise. Suggestions are made for improvement to the design of the beginning and ending transitions of valve motion which can potentially reduce dynamic oscillation and vibration in the follower train.

Microcellular urethane jounce bumpers are used in many automotive suspension systems. This study experimentally determined the dynamic force, acceleration, displacement, dynamic stiffness, and natural frequencies of constant-cross-section bumper samples made with microcellular urethane materials of three different densities. Four impact energy levels were used. Dynamic responses were analyzed in both time and frequency domains. The dynamic displacement, acceleration, and force responses are nonlinear and the dynamic stiffness exhibits a hysteresis loop. A mathematical model for dynamic stiffness and damping is developed. Average dynamic stiffness proved to be approximately twice that of the static stiffness for the same materials as independently measured over the same range of deflection by the bumper manufacturer. Natural frequencies of the sample bumpers were measured by two methods with close correlation of the results which ranged from 320 to 420 Hz for the samples tested.