Extending the Performance of Net Shape Molded Fiber Reinforced Polymer Composite Valves for Use in Internal Combustion Engines

摘要

Fiber Reinforced Composite (FRC) materials offer the possibility of reduced mass and increased performance over metals. Used in internal combustion engines, this may enable increased power and mechanical efficiency. Previous work has both shown structural and thermal limitations. A net-shape resin transfer molded intake valve has been developed, using a single-piece carbon fiber preform and the high temperature polymer PETI-RFI. Performance has been validated through testing. High engine load conditions resulted in thermal failure of FRC valves. Thermal modeling was conducted to simulate the effect of fiber orientation and coating combinations on transient thermal performance of FRCs. One dimensional modeling has predicted FRC valve surface temperatures to be 12O deg. C higher than that of a steel valve. Simply re-orienting conductive fiber along the heat path may reduce the temperature rise to below that of steel. Two dimensional analysis has resulted in a novel method of evaluating thermal performance. Using the unitless ratio of thermal resistance at the coating surface and at the interface boundary, designated Bb, an accurate prediction of the interface temperature can be obtained. Relative temperature gradients in both coating and core materials can also be estimated. Using this methodology a fiber and coating structure is proposed that reduces FRC core temperature by 80%. It has been shown that careful selection of fiber orientation and coating materials can enable a polymer matrix composite material to withstand the structural and thermal environment of an IC engine combustion chamber.