Abstract
The patented Libralato rotary engine represents a new concept of engine geometry and thermodynamic cycle. The engine mechanism has three principal moving bodies. In the Libralato cycle, all engine phases take place in one revolution. The current paper aims at presenting the behaviour of engine mechanism under inertial loads. Multi-body simulation is necessary for analysing the loads in engine bearings, for engine balancing and for obtaining general information about engine dynamic behaviour.
Multi-body models have been developed in MSC ADAMS software, using the volumes imported from engine CAD. Joints have been defined between main engine components. This study has been performed for main engine parts with material densities corresponding to two sets of materials: I) aluminium alloy, and II) cast iron. The research investigates the implication of inertial loads on the bearing forces and torque. The study was performed for the entire rotating mechanism. The angular velocity of the leading rotor is assumed to be constant. For the models corresponding to the two sets of materials, the following parameters were investigated vs. power rotor angle: forces on three rotational bearings, forces and torque on sliding bearing, and angular speed variations for rotational bearings. The angular velocities of following rotor and link bearing have periodical variations vs. power rotor angle, considering constant angular velocity of power rotor. All loads have large variations vs. rotation angle, indicating a great unbalance of rotating parts.
The results show that the mass of rotating engine mechanism has major influence on the bearing loads, which are significantly reduced in the case of main engine parts manufactured of aluminium alloy. A major problem concerns the large variable torque developed on the sliding link bearing, which could block this bearing. The results obtained from these multi-body analyses have been used for refining the design of the engine prototype.
KEYWORDS – Libralato rotary engine, multi-body analyses, inertial loads, bearings, materials