The wear on engine valve and seat insert is one of the most important factors affecting engine performance. The engine valve and seat insert must be able to withstand the severe environment that is created by: high temperature exhaust gases generated while the engine is running, rapid movement of the valve spring, high pressure generated in the explosive process. In order to study such problems, a simulator has been developed to generate and control high temperatures and various speeds during motion. The wear simulator is considered to be a valid simulation of the engine valve and seat insert wear process with various speeds during engine activity.
This work focused on the test of various degrees of wear on four different exhaust valve materials such as HRV 40, HRV40-FNV (face nitrided valve), STL #32, STL #6,. Throughout all tests performed in this study, the outer surface temperature of the seat insert was controlled at 350°C, the cycle number was 4.0 X 106, the test load was 6860 N, the fuel was LPG, the test speed was 20 Hz (2400 RPM) and the seat insert material was HVSI-2.
The mean (standard deviation) maximum roughness of the exhaust valve and seat insert was 25.44 (3.16) (3.16) ㎛ and 27.53 (3.60) ㎛ at the HRV40, 21.88 (2.38) ㎛ and 25.94 (3.07) ㎛ at the HRV40-FNV, 36.73 (8.98) ㎛ and 61.38 (7.84) ㎛ at the STL #32, 73.64 (23.80) ㎛ and 60.80 (13.49) ㎛ at the STL #6, respectively.
It was discovered that the maximum roughness of exhaust valve was lower as the high temperature hardness of the valve material was higher under the same test conditions such as temperature, test speed, cycle number, test load and seat insert material. The set of the HRV40-FNV exhaust valve and the HVSl-2 seat insert showed the best wear resistance.
