Analysis of piston assembly friction using the indicated mean effective pressure experimental method to validate mathematical models

Abstract

The piston assembly friction is experimentally measured using the indicated mean effective pressure with detailed accuracy. The experimental results are compared with a relatively less complex piston assembly friction model typical of those used in industry, predicting the individual performance of compression rings, the oil control ring, and the piston skirt. The validation is carried out under fired conditions on a single-cylinder gasoline engine. The experimental results for an SAE 0W20 lubricant without a friction modifier were compared with the predictions. The predicted results correlate very well with the measurements, especially at higher lubricant inlet temperatures. The piston skirt friction was predicted using a simple concentric piston—cylinder model and a more realistic but computationally intensive method incorporating the piston's secondary motion. The results clearly indicate that a relatively less complex model can give realistic results under real engine conditions.