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Comparison of Wears in the Engine Valve and Seat Insert Depending on Valve Materials
Technical Paper
2005-03-0065
Sector:
Language:
English
Abstract
Engine valve and seat insert wear 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, and cylinder head
distortion due to the non-uniform cooling system. In order to
overcome 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 focuses on the various degrees of wear of four
different test valve materials (STR 35, STL #6, STL #32, FNV (face
nitrided valve)). Throughout all tests performed in this study, the
outer surface temperature of the seat insert was controlled at
350°C, the test load was 1960N, and the seat insert material was
HVS1-2.
The mean (± Standard Deviation) wear depth of the valve and
seat insert at STR 35 was 31.8 (±1.3)μm and 44.3 (±3.3)μm,
respectively. The mean (± Standard Deviation) wear depth of FNV
(face nitrided valve) and seat insert was 14.0 (±2.2)μm and
56.0 (±2.1)μm, respectively. The mean (± Standard Deviation)
wear depth of the valve and seat insert at STL #6 was 25.8
(±4.7)μm and 46.7 (±3.0)μm, respectively. The mean (±
Standard Deviation) wear depth of the valve and seat insert at STL
#32 was 8.5 (±2.0)μm and 54.7 (±1.9)μm, respectively. It
was discovered that under ideal test conditions (temperature, valve
displacement, cycle number, test load, seat insert material), the
valve with a FNV or STL deposited face had a greater degree of wear
resistance than the general type valve (STR 35 type).
It was also found that among the STL deposited valve faces, the
STL #32 has a higher hardness, and higher wear resistance than STL
#6.
However, the higher the valve surface hardness, the greater the
seat insert wear. For this reason, the valve material must be
developed in accompaniment with the seat insert as counter
material.
Adhesive wear, shear strain and abrasive wear could all be
observed in the wear mechanisms of valves.