Abstract
In this paper, taking a certain type of high-power diesel engine exhaust valve abnormal wear phenomenon as an example, we conduct research on the exhaust valve surface micromorphology characteristics, contact surface accumulation products, additive transition layer, and combustion test. These passed diesel sulfur content comparative test, diesel additive composition analysis, and high-sulfur-content and low-sulfur-content diesel and diesel oil additive action test. At present, there is no authoritative research on the influence of sulfur content in diesel on valve seat wear of high-power diesel engines, and the protection mechanism of diesel additives on the valve seat is not clear. The sulfur in diesel, like the lead in gasoline, has long been known to resist wear in the valve seats of high-power diesel engines; just as gasoline additives compensate for the loss of lead, diesel oil additives seem to compensate for the loss of sulfur. Tests show that a uniform carbon deposition layer is formed on the contact surface after the diesel is burned, and the carbon deposition layer is more densely and uniformly adsorbed on the contact surface under the action of diesel additives to form an antiwear layer. Tests also show that the sulfur in diesel has no effect on the wear resistance of the valve seat.
Highlights
In the field of ship propulsion power, a certain type of highpower diesel engine has experienced frequent large-scale exhaust valve abnormal wear phenomenon since 2019
We studied the micromorphological characteristics of the exhaust valve seat surface, the accumulation product of the contact surface, the additive transition layer, and the combustion test. rough the test, we have clarified that the sulfur content in diesel has no effect on valve seat wear
Analysis on Micromorphology of Wear Surface of Valve Seat. e cylinder head material of a high-power diesel engine is grey iron. ere have been many, since the early scholars of the internal combustion engine valve seat wear made a lot of theoretical research
Summary
In the field of ship propulsion power, a certain type of highpower diesel engine has experienced frequent large-scale exhaust valve abnormal wear phenomenon since 2019. Fuel will induce the wear of the exhaust seat hole of the cylinder head, which originally occurred in the gasoline lead-free improvement of the vehicle engine. Ese lead oxides and salts have a low hardness and play a role of solid lubrication in the sealing interface and avoid oxidation of the cylinder head seat hole in contact with high temperature gas. Regarding the antiwear mechanism of the additives, Pyle and Smrca [11] found that the products after combustion of lubricating oil additives in gasoline engines have wear inhibition effect on exhaust valve seat holes, but the inhibition efficiency is much lower than that of gasoline; that is, there is a certain time lag. We learned that the antiwear mechanism of diesel additives on valve seats is mainly to adsorb carbon deposits, making the carbon deposits more uniform and dense, and forming an antiwear protective layer
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