Inertia forces and balancing

Despite its appearance, the MCE-5 does not generate high inertia forces: the operational speed of its different components is not equivalent to that of conventional engines.

As it is shown on the following scheme, the roller-guided piston is the only part that moves on the entire engine stroke (full speed). Other moving parts such as the gear-wheel and the synchronized roller only travel on half a stroke (half speed). Concerning the rod, most of its mass is rotationally balanced (87% in the case of the first MCE-5 prototype):

As can be seen on the following graph, at same speed, second order inertia forces generated by MCE-5 reciprocating parts are lower than those of a Diesel engine and higher than those of a SI engine:

It is important to underline that the power/second-inertia-forces ratio is favorable to MCE-5: max power for the 2.2 L Diesel engine is about 125 kW while that of MCE-5 is 160 kW.

However, MCE-5 distinguishes itself from conventional engines by the inertia momentum generated by its gear-wheels. But this new inertia source has no consequences on the engine vibration level because the torque applied to the engine block by the gear-wheels is 45 degrees out of phase from that applied by acceleration-deceleration of other moving parts.

As a result, engine tilt is slightly shifted few degrees forward, but at same amplitude. This is due to the fact that max torque applied to the engine block by the gear-wheels occurs when minimum torque is generated by other moving parts, and inversely:

Conclusion

	1)	The MCE-5 is a SI engine: it generates low crankshaft torque variations compared to Diesel engines (crankshaft torque variations are particularly penalizing for passengers comfort at low speeds).
	2)	At same speed, the MCE-5 reciprocating parts generate unbalanced second order inertia forces that are lower than those of modern Diesel engines.
	3)	As the MCE-5 kinematics is purely conservative and remains always invariable whatever the Compression Ratio, the MCE-5 second order balancing rules are strictly identical to those of conventional engines. As a result, it is possible but not indispensable to implement second-order balancing shafts on luxury cars.
	4)	Inertia momentum generated by the MCE-5 gear-wheels has no consequences for the engine vibrations level.

(see: VCR engines’ requirements for mass-production: inertia forces and balancing)