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The purpose of this research was to predict the amount of wear on exhaust valve seats in durability testing of gasoline engines. Through the rig wear test, a prediction formula was constructed with multiple factors as variables. In the rig test, the wear rate was measured in some cases where a number of factors of valve seat wear were within a certain range. Through these tests, sensitivity for each factor was determined from the measured wear data, and then a prediction formula for calculating the amount of wear was constructed with high sensitivity factors. Combining the wear amount calculation formula with the operation mode of the actual engine, the wear amount in that mode can be calculated. The calculated wear amount showed a high correlation with the wear amount measured in bench tests and the wear amount measured in vehicle tests.

When CNG, LPG, and other gas fuels were used for combustion in vehicles' engines, a large degree of valve seat wear was observed and it was difficult to provide the same wear resistance as for gasoline engines. Therefore, the mechanism of valve seat wear in gas fuel engines was analyzed and an alloy valve seat was developed. In addition to converting the matrix to an alloy, Co-Mo-Cr was used for the self-lubricating effect present in its hard particles. Also, in order to improve machinability, which is inversely related to wear resistance, a sintered alloy valve seat containing MnS was developed. As a result, wear resistance equal to that for gasoline engines was achieved.