Shoichi Iwamoto

Performance Characteristics of Experimental Small Stirling Engine

It is an effective method to increase the mean pressure in a cylinder for the improvement of Stirling engine output. However, for low-pressure type Stirling engines that use air as the working gas, gas leakage and frictional resistances in the shaft seal devices become a serious problem. A newly developed one-way type shaft seal of the low frictional resistance based on the same principle as has been applied to the one-way type piston ring, was set in an experimental engine and operated.As a result, it is confirmed that the power of low pressure type Stirling engines can be remarkably increased by using the one-way type shaft seal because the increase of mean pressure in a cylinder can be easily obtained

A Study for the Characteristics of Torsional Vibration Damping in Diesel Engines

The engine damping ratios obtained by the experiments for both high-speed and low-speed diesel engines have been analyzed by using the non-dimensional damping functions defined in the previous paper. The obtained results are as follows:1) For high-speed diesel engines, friction damping is dominant in engine damping and for low-speed diesel engines, it is comparable to hysteresis damping.2) The non-dimensional function φ1 (cr, D) for high-speed diesel engines is approximately expressed by the following equation.φ1 (cr, D) =0.105R-2.8 (1.5<R<4)where, R ; ratio of inertia moment of flywheel IF to the sum of inertia moments of each cylinder mass IE . The above equation means that the value of φ1 (cr, D) decreases exponentially with increase of natural frequency ωn.3) The value of φ1 (cr, D) for low-speed diesel engines is very small in comparison with that in high-speed diesel engines, and changes only slightly in accordance with the variation of mass ratio R.4) The value of ψ2 (n, p) is almost independent of mass ratio R. As the values of damping ratio due to hysteresis damping, which have been obtained by the experiments for both high-speed and low-speed diesel engines, are approximately 0.002, it can be said that damping ratio due to hysteresis damping ζh is nearly constant. This fact confirms the results of the analysis carried out in the previous paper.