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This paper presents the analytical method of piston secondary motion with an experimental verification for a small gasoline engine. To analyze the vibration, a modeling of the piston secondary motion is carried out and numerical simulation is performed. In this method, both dynamic characteristics of the part of piston skirt and cylinder liner are taken into consideration. As compared the simulated results with the experimental results, the validity of presented model has been confirmed and this numerical model is effective to comprehend the piston slap secondary motion.

In this paper, the modeling technique of the dynamic characteristics of the monocoque-type tractor frame, and the reduction technique of the noise and vibration of the tractor by the design modification of the frame are proposed. First, the vibration characteristics on each part of the tractor, and the noise characteristic in the cabin are measured. Secondly, the full-structure of the frame is separated into the sub-structures of cases and joint parts, and each one is modeled. Then, the model accuracy is improved by using the model tuning method with the sensitivity analysis. Finally, the design change of the frame is carried out with the object of increasing stiffness while reducing weight. As the result of this modification, the cabin noise level can be effectively suppressed about 4 [dB].

The purpose of this paper is to establish a method of predicting the noise and vibration of tractor cabins in the engine-idling state by using Statistical Energy Analysis (SEA). At first, an analytical model of a tractor cabin is constructed, and power flow equations are formulated for the tractor cabin. To solve these equations, SEA parameters are estimated experimentally and analytically. These parameters are the modal density, loss factor, coupling loss factor, and input power. With these parameters, the noise and vibration responses of the tractor cabin are calculated. Good agreements are found between the analytical and experimental data.

To observe the effect of engine applications on small engine design, bending and torsional stresses of a crankshaft were measured dynamically under various load conditions. A dynamometer and a generator were selected as the load sources, because these two devices can provide different load patterns respectively. As the results, the peak bending stresses at the crankshaft pin fillets of a dynamometer set engine were about 40∼60% larger than those of a generator set engine. Conversely, the peak torsional stress at a crankshaft journal of the dynamometer set engine was about 25% smaller than that of the generator set engine. To investigate the reasons of these differences. additional measurements and FEM calculations were carried out. Finally we found that the stiffness of the crankshaft support had a great influence on the value of the peak bending stress and the torsional stress was affected by the installation angle between the engine TDC and the rotor of the generator.