Investigations on Valve Recession of a Commercial Vehicle Engine

Investigations on valve recession of a commercial vehicle engine inlet valve are done. Failure analysis of inlet valve of a six cylinder commercial vehicle engine developing power of 155 BHP is carried out using the software tools IDEAS and TYCON. Failed engine valves are investigated and concluded that the mode of failure of most of them is valve recession, the possible factors responsible for the valve failure are analyzed including the metallurgical properties of the valve. Combustion force, impact force during closure of the valve are the major factors responsible for valve recession. The valve seat angle is considered in the analysis to find if the change in this angle is helpful in increasing the life of the valve. The prevailing wear mechanism has been shown related to the critical operating conditions such as valve closing velocity, combustion load, valve misalignment relative to the seat insert and seat insert material choice. Besides this, the wear volume of the valve face was found to change with valve material, engine operation conditions, geometries, and dynamics changed. Besides adhesion, abrasion, and corrosion associated wear mechanisms, shear strain was found to be additional major wear mechanism. After detailed analysis, it has been noticed the change in valve seat angle, valve material and plasma coatings on the valve improve the life of the valve.