Dynamic model of a crankshaft assembly with two degrees of freedom

Nowadays, growing attention is directed towards energy efficiency and issues related to respecting energy. An extremely vital role at improving energy efficiency plays the cogeneration technologies. In the 2012/27/UE Directive [1], the gas turbines [2] in combination with heat recovery, combustion engines [3, 4], steam engines [4], fuel cells [5-7], microturbines [8], Rankine organic cycle [9, 10], Stirling engines [11-15], and others, were included among cogeneration technologies, in which electric energy is produced from waste heat in the combined process. In this work, the distributed generation sources have also been addressed. From the perspective of the article herein, the sources equipped with the crankshaft assembly have been particularly emphasised. This mechanism converts chemical energy of, among others, fuel or working element into mechanical energy (the piston reciprocating motion is converted into rotary motion of a crankshaft). In this work, the physical model of the crankshaft assembly has been shown, with two degrees of freedom. On the basis of analysis of the physical model (with the static mass reduction), a single-piston simulation model has been developed of the crankshaft assembly, using the Matlab&Simulink software. On the basis of the analysis of the system, the motion equations have been derived, which served the purpose of building the simulation model. Because of the conducted simulations, the curves of displacement, velocity, and piston acceleration have been presented, and, respectively, the angular displacement, angular velocity, and angular acceleration of the crankshaft. The constructed model should be seen as a part of a multi-piston working mechanism in a, for example, Stirling engine