Experimental/Numerical Analysis of the Timing Belt Drive Behavior of a V6 Engine

The timing belts used for automotive engine are asked to last more and more, and to be less noisy. In this way, it is necessary to simulate the behavior of the engine timing belt drives for optimization, but also to understand it from experimental analysis. The first objective of the work was to analyze experimentally the behavior of a V6 engine timing belt drive in terms of: pulley speeds, belt span tensions, transmission error. The second objective was to compare the measurements with simulations. The engine has four overhead camshafts and 4 valves per cylinder. The timing belt drive is composed of six pulleys, three idlers and an automatic tensioner. The crankshaft and the two first camshaft speeds are measured with optical encoders. Spans tensions are measured by means of strain gauges glued on the idler mounting axes. All the data are simultaneously recorded. Tests have been run from 800 rpm to 6000 rpm. Measured data are first analyzed in the time domain. Some phenomena like, nil span tensions, speeds acyclism and transmission error amplitude, are observed. Then, analyses of the harmonic content of the span tensions, pulley speeds and transmission errors between the crankshaft and the camshafts, are performed versus engine rotation speed. Finally, the tests have been simulated and comparisons are made between numerical and experimental results.