Engine valve and seat insert wear depending on speed changes

Abstract

The minimization of valve and seat insert wear is a critical factor for consideration in the pursuit of engine performance improvement. In order to achieve this goal, an innovative simulator was developed with the ability to generate and control high temperatures up to 900°C and various frequencies up to 80 Hz during motion, just as in the case of an actual vehicle engine. This wear simulator is considered to be a valid reproduction of the engine valve and seat insert wear process operating with various speeds during engine activity.

This work focuses on the different degrees of wear at three different test frequencies (10 Hz, 25 Hz, and multi-hertz). In this study, the seat insert's exterior surface temperature was controlled at 350 °C, the number of cycles was 2.1×10⁶and the test load was 1960 N. The wear depth was measured before and after testing using a confocal laser microscope. It was found that higher frequencies caused a greater degree of wear than lower frequencies under identical test conditions (temperature, valve displacement, number of cycles, and test load). It was intended that an actual vehicle engine be used to perform a similar test, in order that the multi-hertz test, using a combination of the 10 and 25 Hz frequencies be applied. In the wear mechanism, adhesive wear, shear strain, abrasive wear, and surface fatigue wear were observed.