## 4 Results
Figure 12: Comparison of the angular velocities of the first output, second output, and switchboard—results from Simpack. The velocity of the pistons obtained from the Simpack software is illustrated in Figure 10, and the velocity obtained from MATLAB is shown in Figure 11. The results of velocity are shown for both the \(x\) and \(z\) axes. As can be seen, this motion is harmonic in both directions. Comparing the results, the amplitudes and frequencies of the investigated movements are similar in both the Simpack (Figure 10) and MATLAB (Figure 11) outputs. Lastly, Figures 12 and 13 show the time dependence of the angular velocities of the first and second outputs and the switchboard under constant rotations. These values are constant because, for the outputs, the position of the center of gravity is constant. Further, the angular velocity of the switchboard oscillates according to the harmonic function. When compared in more detail, the amplitudes and frequency are very similar to the waveforms of the angular velocity of the functional block. The angular velocities of the first and second outputs are constant, and these values are the same as those of the angular velocity of the functional block. velocity of the second output is 20.00 rad/s for the MATLAB and of 20.15 rad/s for the Simpack. From this, the difference of angular velocities of the first output is 0.11 rad/s and for the second output is 0.15 rad/s. As the last compared kinematic quantity, the angular velocity of the switchboard was chosen. In contrast to other angular velocities shown in Figures 12 and 13, the angular velocity of the switchboard has the sinusoidal waveforms for both the MATLAB and Simpack software. The mean value is the same for both software, namely 19.60 rad/s. However, the amplitude obtained by the MATLAB is 0.40 rad/s and by Simpack is 0.45 rad/s. From this, the difference of the amplitudes is 0.05 rad/s. Based on these results, we conclude that both models were set up properly and could be used for further research. In addition, the results of complex simulations performed by the multibody program Simpack did not show the presence of a singularity in the constructed mechanism. From the compiled analytical and numerical model, it is, therefore, possible to proceed to the construction of a real prototype (Figure 14) without the danger of a malfunction resulting from the selected geometry. Up to  
The waveforms of the individual kinematic quantities show output characteristics similar to those of the waveforms of the output quantities on the crankshaft of a conventional combustion engine. Therefore, a flywheel should be applied to smooth the run of the resulting torque. This flywheel will ensure that the torque is regular and that the transmission of this torque will not cause excessive vibrations of other related elements [1; 2; 9; 12]. Finally, here are assessed the potential frictional losses of this non-conventional engine mechanism design. The designed model is symmetrical with six kinematic couples as following: two pistons in cylinders--two translational couplings; stones in a plate--two general couplings; bearings lengths--two rolling couplings. For this time, the manufactured prototype is determined for pedagogical purposes; therefore, cylinders are made of transparent plastic material PMMA (polymethyl methacrylate), and pistons are made of PTFE (polytetrafluoroethylene). The friction coefficient is of \(f_{Ap}\) = 0.40 [46]. Further, copper stones are guided in a technical plastic PA6G (cast nylon), and their friction coefficient is of \(f_{Bp}\) = 0.80 [46]. Rolling coefficients of two rolling bearings are assumed of \(f_{C}\) = 0.02 [46]. Efficiency coefficients are inverse values. As a result, the total efficiency of the designed engine with transparent plastic cylinders is very small. Therefore, it is necessary to take into account the use of other more suitable materials for the real application of the designed engine. The plastic components would be surely made of metal material.