Search Results

According to the principle of pH measurement, an on-board type engine oil deterioration sensor has been developed. The developed sensor is composed of a Pb and oxidized stainless steel electrodes. The sensor signal shows a good linear relationship to the quasi-pH value of the oil. Especially in the region where the oil deterioration proceeds, the remaining basic additives in the oil is easily estimated from the sensor signal.

The effect of phosphorus concentration in gasoline engine oils on the valve train wear was experimentally investigated by using the JASO M328-91 3A valve train wear (3A-VTW) test method. The phosphorus concentration is determined proportionally to the amount of zinc dithiophosphate (ZDDP), which is formulated as both antiwear agent and antioxidant. Lower concentrations of ZDDP generally bring about larger wear in the valve train. However, it was found from the experiments that valve train wear remained low despite a decrease of phosphorus concentration when secondary ZDDPs with short alkyl chain together with appropriate ashless dispersants were selected. Since adsorptivity of secondary ZDDPs with short alkyl chain lengths onto rubbing metal surfaces is higher than that of primary types, the secondary types give excellent antiwear characteristics.

A laboratory scale simulation test method was developed to evaluate deterioration of radial lip seals of fluoroelastomer (FKM) compounds for engine crankshafts. The investigation of the collected radial lip seals of FKM compounds from the field with service up to 450,000km indicated that the only symptom of deterioration is a decrease of lip interference. This deterioration was not duplicated under conventional test conditions using an oil seal test machine because sludge build up at the seal lip caused oil leakage. However, revised test conditions make it possible to duplicate the deterioration experienced in the field. An immersion test using a radial lip seal assembled with the mating shaft was newly developed. This test method was found to be useful to evaluate deterioration of radial lip seals using FKM compounds. Oil additives affect the deterioration of lip seal materials significantly. Therefore, immersion tests of four different oils were conducted to evaluate this effect.

This paper introduces a new simulation test method by using IR analysis which is capable of evaluating the rate of deterioration of VMQ (Silicone) rubber material applied in engine crankshaft seal applications. IR analysis is used to measure the rate of change of the Si-C/Si-0 ratio which indicates the level of deterioration of VMQ material from the hydrolysis of the siloxane bond. Applying the new analysis method, laboratory test conditions could be improved to more closely simulate field conditions.

The purposes of this series of studies are to examine the characteristics of intake-valve deposits and to clarify their formation mechanism. This paper discusses the chemical compositions and physical states of the deposits on the basis of the results obtained by chemical analyses. The results indicate that the deposits mainly originate from engine oil, and suggest that the main reaction route of the deposit formation is the carbonization of oxidized engine oil. Namely, low boiling point (light) fractions in the engine oil easily evaporate from the valve surface. On the other hand, the remaining heavy fractions are subjected to deposit forming reactions. These final states are amorphous and carbonaceous aggregates. The deposit has a tendency to form in the temperature range of about 230 to 350 °C. The location of accumulating deposit depends on the valve surface temperature.