An Analytical Evaluation Method for Lubrication Oil Consumption

Abstract

A study of engine oil consumption (OC) was conducted both theoretically and experimentally. It was found that oil blowing into the combustion chamber through the top ring gap (termed ‘reversed oil’) and oil returning to the crankcase through the oil ring gap (termed ‘blowby oil’) are important factors affecting OC. It was also observed that depending on the ring gap clearance, enlarged because of ring wear (for example the radial ring wear of 50 μ corresponds to a gap enlargement of roughly 0.31 mm) or non-optimal ring gap clearance and inter-ring volume, the 2nd land pressure can exceed cylinder pressure—leading to increasing reversed oil and consequently higher OC. The deterioration of OC with increasing operation has been traced to lowered oil-scraping capability with ring wear. This is true. However, the above-mentioned phenomenon can be considered as another reason for such OC. This paper describes the relationship between reversed oil/blowby oil ratio and OC, and presents a procedure for optimizing ring gap clearance and interring volume for acceptable OC. This study, however, neglected oil supplied to the ring pack via the valve set.