Search Results

A laboratory test simulator has been developed to analyze the intake-valve deposit formation mechanism. The characteristics of the deposits formed with the simulator were compared with those of the real engine deposits. This comparison verified that the simulator deposits ILLEGIBLE nearly equal to those of engines. The influence of each parameter such as valve temperature, oil or gasoline quality was tested individually using this simulator. The intake valve temperature influenced the location and quantity of the deposits. The deposit formation significant in the temperature range of about 0-350 °C. The high-boiling components of oil ILLEGIBLE increased the deposits. The increase oxidation products and the decrease of antioxidants in used oil caused a significant increase of deposits. The commercial premium gasoline in Japan containing practical detergents ILLEGIBLE down and decreased the deposits. Another premium gasoline affected the oil quality, in increasing the deposits.

Quality control of gasoline constituents and its effect on the Intake Valve Deposits (IVD) has become a recent issue. In this paper, the effects of gasoline and oil quality on intake valve deposits were investigated using an Intake Valve Deposit Test Bench and a Sludge Simulator. The deposit formation from the gasoline maximized at an intake valve temperature of approximately 160 °C, and the deposits formed from the engine oil were maximum at approximately 250 °C. Therefore, the contribution of the gasoline or the engine oil appears to depend on the engine conditions. The gasoline which contains MTBE or ethanol with no detergent additive slightly increases the deposition amount. The gasoline with a superior detergent significantly decreases the deposition amount even when MTBE or ethanol is blended in the gasoline. Appropriate detergent fuel additive retards the oil deterioration.

The purpose of this paper is to study the mechanism of sludge formation by use of a laboratory scale sludge simulator and to propose a new method to evaluate engine oil dispersancy. The simulator consists of a synthetic blow-by gas generator, a reaction vessel and a waste gas disposal device, and this synthetic blow-by gas is bubbled into a sample oil. After a certain hours of bubbling, n-hexane insolubles, defined as “sludge” in this paper, are separated from the oil sample by centrifuge and/or filtration. The following results were obtained. (1) IR spectra of the sludge formed by the simulator is similar to that of the sludge formed in actual engines. (2) The essential components for the sludge formation are thermal decomposition products of fuel, nitrogen monoxide and air. (3) Olefin rich gasoline gives rise to much sludge formation. Adaptability of the simulator for the evaluation of engine oil dispersancy was examined.