At high engine speeds the inertia loads caused by the high accelerations of the valves as they open and close generate camshaft torques which can excite torsional oscillations of the camshafts. If the valve timing, and for V engines, the V-angle are such that the torques from each camshaft tend to reinforce one another, then these torques can be significant. Any resulting torsional vibrations can cause valve timing errors at certain engine speeds, especially in the cylinders remote from the camshaft drive train. This can result in valve and piston collisions which can result in the destruction of the engine. To damp these vibrations the engine designer needs to ascertain the magnitude of the torques for the engine orders associated with the largest harmonic components. To do this the camshaft torques need to be computed and then analysed. This harmonic analysis can be achieved with a personal computer and the Fast Fourier Transform. This chapter describes the method of computing the cam shaft torques and adding them together and gives examples of the results of the Fourier analysis, which show the effect of valve timing and V-angle on the magnitude of the resulting constituent engine orders for a V8 engine.


Torsional Vibration Exhaust Valve Valve Timing Eighth Order Engine Order 
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Copyright information

© Springer-Verlag London 2013

Authors and Affiliations

  1. 1.Oxendon SoftwareMarket HarboroughUK

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