3.Results and Discussion
The outcomes from the dynamic analysis show that at the
engine speed of 5000 rpm, the resisting torque oscillations
induced in the camshaft exhibit strong harmonics of 42, 84
and 126 Hz at section 1 – 2 and 3 – 4 whereas 42 and 126 Hz
at section 2 – 3. Also the oscillations experienced at the belt
exhibit harmonics at 167 and 334 Hz, their amplitudes
although are far less than those seen at the sections.
There can be adverse impact of such high frequency
vibrations on valve train components, such as valve spring.
The surge frequency and the natural frequency of the valve
spring is 83.5 Hz and 250 Hz respectively. From the results
of the above analysis, it can be seen that for the engine speed
of 5000 rpm, second harmonic of the torque oscillations at
section 1 – 2 and 3 – 4 is very close to the valve spring surge
frequency whereas the corresponding frequency is missing in
section 2 – 3. This clearly suggests that at some point the
cam torque oscillations are contributing to the surge of the
spring and since this frequency appears at sections 1 – 2 and
3 – 4, locations close to them would be greatly affected.