抄録
The Measurement of the indicator diagrams is indispensable in the combustion analysis of internal combustion engines. However, it is exceedingly difficult to obtain accurate indicator diagrams, even today and in spite of the considerable advance and improvement of various precision instruments and analytical techniques. For example, a pass from the interior to the outside of the combustion chamber must be made for measuring the indicator diagrams. And likewise it is difficult to make a pass and attach a pick-up sensor to measure the cylinder pressure especially in engines available on the market.
The stresses of various parts of the engine were measured in order to estimate the cylinder pressure without making an actual pass and application of the sensors. As a result of running a comparison among all of the stresses, an apparent relationship was found especially between the actual cylinder pressure and the stresses of the cylinder head bolts. In this case, the correlation between clyinder pressure and the movement of the cylinder head could be explained mathematically by the differential equations of the cylinder head vibration system. And the constants in these equations could be deduced by the experimental measurements.
Thus, a factual indicator diagram could be estimated by means of adding the vibrational correction to the stress variations of the head bolts. Using this method, it was shown that indicator diagrams could be estimated precisely and accurately.
Moreover, the vibration behavior of the cylinder head can be also calculated in a reverse fashion from the indicator diagrams by this method. In addition, this method can be applied for the measurement of actual indicator diagrams, also may contribute to a better understanding of the noises emitted from the engine surface during operation.
