2.1.3 Measurement Bearing Position in Engine
Figure 3 shows the installed position of measurement main bearing. Main bearing is numbered from 1 to 9 toward the ait end of engine. The measurement bearings were installed in No. 1, No.2, No.4 and No.8 bearing. The reasons why these are selected are as follows. The feature of the No.4 bearing is influenced by the sequential combustion, so the loading for the bearing is severe. On the other bearings installed fore and aft end of the engine, bearing failure has occurred more frequent than other bearings.
2.1.4 Uneven Alignment Condition
Figure 4 shows the 3 types of alignment condition. The numerical value is relative thickness of bearing for standard thickness. By exchanging the lower part of No.1 bearing, uneven alignment between two adjacent bearings can be made artificially. These conditions are based on the actual adjustment procedure for uneven alignment. The influence of the uneven alignment on journal movement behavior has been measured.
2.2 Measurement Results
Figure 5 shows the journal center locus in each measurement main bearing on full load operation and without uneven alignment. The figures are view from aft end of engine. The rotational direction of journal is clockwise in the figures. The plotted values are crank angle assuming that the top dead center of No. 1 cylinder is 0 deg.
As shown in figure 5, eccentricity is larger than the bearing clearance. It is presumed that the effect of the deformation of bearing housing appeared sensitively owing to fluctuating load. Accordingly the actual locus is smaller than measured result. Nevertheless the relation of eccentricity versus crank angle can be made sure with these figures. Each feature of journal movement behavior is discussed as follows.
