An engine cylinder deactivation device based on waste gas return scheme was designed for a 1.5 L natural aspiration engine. The device can make the intake system switch freely between fresh mixture and high temperature exhaust gas. Simultaneously the electronic control unit(ECU) can shut off fuel supply system and stop the ignition of the deactivated cylinder

so as to make the cylinder stop operation. With the cylinder deactivation device

engine fuel consumption and torsional vibration at low and medium speeds with different loads were experimentally investigated. The test results indicate that the cylinder deactivation technology can obviously save fuel at low and medium speeds with partial load

with fuel saving by up to 15%. However

cylinder deactivation can cause a significant increase in crankshaft torsional vibration with low order rolling vibration in dominance. And the torsional vibration at the flywheel end is remarkable

with the amplitudes of some orders being greater than those at the free end. Therefore

the torsional vibration of the flywheel end should be considered when applying the engine cylinder deactivation technology.