Effect of Wet Liner Vibration on Ring-liner Interaction in Heavy-duty Engines

Abstract

<div class="section abstract"><div class="htmlview paragraph">Lubricating oil consumption (LOC) is a direct source of hydrocarbon and particulate emissions from internal combustion engines. LOC also inhibits the lifetime of exhaust aftertreatment system components, preventing their ability to effectively filter out other harmful emissions. Due to its influence on piston ring- bore conformability, bore distortion is arguably the most critical parameter for engine designers to consider in prevention of LOC. Bore distortion also has a significant influence on the contact forces between the piston ring and cylinder wall, which determine the wear rate of the ring and cylinder wall and can cause durability issues. Two drivers of bore distortion: thermal expansion and head bolt stresses, are routinely considered in conformability and contact analyses. Separately, bore distortion/vibration due to piston impact and combustion/cylinder pressures has been previously analyzed in wet liner engines for coolant cavitation and noise considerations. However, the effect of piston impact on bore distortion and ring conformability/contact has not been addressed sufficiently in the literature, even though the magnitude of piston impact driven liner deformation can be as high as the thermal bore distortion. This current research explores the addition of the piston impact effect to existing bore distortion and conformability/contact analysis techniques. A simulation workflow is here presented that incorporates piston secondary motion and oil transport, transient structural finite element analysis of the cylinder, and a curved beam ring-liner conformability/contact model. Sample cases are studied with this new technique, focusing on the contact and conformability at the ring gap location. Significantly higher ring-liner clearance and higher contact are observed. As a result, higher oil leakage, wear, and combustion gas blow-by may become substantial and design adjustments may be warranted. This new simulation workflow can be used in power cylinder unit design to potentially reduce LOC, blow-by, and durability barriers to higher efficiency engines.</div></div>