Model Verification of CAE with NVH-test Acting on Downsized Car Engines
Today’s trend of downsized internal combustion engine development for cars is characterized with; high torque, low engine speed, low weight, high degree of cyclic irregularity, low excitation frequency due to fewer cylinders active e.g. 4-cylinder or less. Torque output 100 Nm at low engine speed 1000 rpm has become normal. This implies in respect of vibrations that it is important to control engine suspension rigid body modes e.g. roll yaw and pith ones. The rigid body modes frequencies should be low so they cannot be reached and induced by the low exciting harmonics of cylinder pressure and mass forces for low engine speeds or idling. Crucial is the rigid body modes in relation to the excitation forces. It is also important to control the overall flexible vibration modes.