An Assessment of Diesel Engine Poppet Valves

Abstract

The paper reviews an assessment of the factors affecting the reliability and durability of poppet valves of highly rated medium speed diesels burning standard or residual oils. Detailed analysis demonstrated that an undercut (tuliped) profile is preferable. Optimum dimensional proportions are derived. The valve behaviour under operating conditions was such as to suggest that it plays a passive part in the phenomenon of ‘valve sinkage’. The adoption of ‘differentially angled seats’ appears to have little meaning in practice. Cylinder head deflection was a governing feature of seat ‘guttering’. A review of material properties suggested that the often quoted Eichelberg quality factor is inadequate and an alternative parameter for assessing the suitability of materials is derived. All materials suitable for valve manufacture possess poor resistance to corrosion attack. A number of possible palliatives are examined.