G0701-2-4 Observations of Oil Flow into the Piston Skirt Bearing Area

Abstract

Oil film on the piston skirt area has significant effects on friction loss, oil consumption and piston slap noise. Therefore, it is important to form necessary and sufficient oil film on the skirt. In order to clarify the oil supply mechanism to the piston skirt, the oil film behavior was visualized and observed through a sapphire cylinder. The following results were obtained: (1) Oil film on the piston skirt area was affected by adhered oil thickness to the cylinder liner. (2) Blow-by gas-dragging caused oil flow into the skirt bearing area. (3) In some cases, oil flowed from the oil drain holes at the oil ring groove into the skirt bearing area.