Measurement of the oil film thickness between the cylinder liner and the piston rings in a heavy duty directly injected diesel engine

摘要

An electrical capacitance measuring method has been used to obtain the cylinder liner oil film thicknesses for various speeds and loads in a heavy duty directly injected diesel engine. Interesting facts have been observed: 1. Increased oil film thickness for the top ring distance to wall during idling. 2. A gas pocket appearing between top ring and liner at increasing speeds and loads. 3. Sideways movement of the piston in the liner when combustion sets in, the motion is not parallel. 4. Oil temperature seems to have little effect on the oil film thickness. A computer model of the top ring showed good conformance with the measurements over the speed and load range, but the calculated oil film thickness is about 3 to 6 times higher.