The Friction Behavior of Individual Components of a Spark-Ignition Engine During Warm-Up

This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. The research presented herein fills a void in the published literature through investigation of transient friction contributions by individual internal combustion engine components during simulated engine warm-up. Currently, engine manufacturers design internal combustion engines primarily for use at steady-state operating conditions with little design consideration for transient engine warm-up. Using the motoring torque waveform and cycle-averaged data of a spark-ignition internal combustion engine, the present work determined the friction behavior of individual engine component assemblies, including the valve train, pistons and connecting rods, oil pump, and crankshaft of a modern internal combustion engine. A common criticism of the standard motoring method is that the engine does not warm up, so lubricant temperature and viscosity does not model that of a fired engine. In the present study, the lubricant and coolant were warmed from 25 to 85 • C. Observations were presented as to the effect of engine speed and the temperature of the coolant and lubricant on total engine friction. Contributions of individual engine components to total engine losses were examined, as well as their variation with engine temperature. The added knowledge of the transient effects of engine temperature can help future designers to mitigate friction and component wear, thus improving overall maintenance costs, specific fuel consumption, and emissions.