3.3 Influence of engine speed
Fig.13 shows the spreadability at the engine speed of 140 rpm (at 0.02 cc/ome feed in oil feed quantity). More cycles are required than those at 70 rpm. With the wave cut as an example, 109 cycles are required for 100% spread at 70 rpm while 150 cycles are required at 140 rpm, and it is concluded that the spreadability of the cylinder oil per cycle is worse when the engine speed is higher and the running speed is higher.
Fig.14 shows that the spreadability in the stroke direction is more excellent at 140 rpm while the spreadability in the circumferential direction is more excellent at 70 rpm, and the spreadability in the circumferential direction is worse when the running speed is increased.
3.4 Influence of shape of ring running surface
Fig.15 shows the comparison between the barrel-shaped ring running surface and the plain-shaped ring running surface. With the barrel, 109 cycles are required before the cylinder oil is spread 100%, while 163 cycles are required with the plain, demonstrating the more excellent result in spreadability with the barrel.
4. Consideration
Fig.16 shows the summary of the cycles before the cylinder oil is spread by 100% over the liner running surface at the engine speed of 70 rpm, which shows the influence of the oil feed quantity and the effectiveness of the wave cut and the increase in the number of oil-feed holes.
4.1 Effect of wave cut
It is proven from the test result that the wave cut of the liner running surface is more effective to the promotion of the spread of the cylinder oil than the honing. Table 4 shows the comparison between the two, demonstrating that cylinder oil is spread over the liner running surface with the wave cut in a shorter time of 58-70% of that with the honing. In this test, no oil is evaporated; however, in the actual engines, the oil film on the liner surface is lost due to the evaporation, and the excellency in spreadability leads to the recovery speed of the oil film, and thus, the wave cut is effective in maintaining the excellent lubrication of the ring and liner running surface in this aspect.
