Evolution of heavy duty engine valves - Materials and design

Engine poppet valves control gas flow in internal combustion engines. The combustion event and the flow of the gases formed past the valve during the intake or exhaust portion of the combustion cycle, expose heavy duty diesel valves to high temperatures, oxidizing or corroding atmospheres and high stresses from firing and seating. This paper is a review of heavy duty diesel engine valve material and design evolution over the last fifty years in North America. The primary driving forces behind the evolution have historically been the need for improved durability and more cost effective designs. However, in recent years engine emission regulatory requirements have become an equally important influence on valve material selection and design. The paper also endeavors to predict how heavy duty diesel engine valve materials and designs may change in response to these driving forces in the foreseeable future.