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The synchronous belt employed in the valve train of automotive engines is operated under fluctuating load. Two types of the belt vibration are observed. One is the well-known lateral vibration. The other is the vibration in the belt running direction which may cause the resonant vibration of the camshaft rotation and may affect the belt life. The purpose of this paper is to describe an analysis of the latter vibration. This vibration was analyzed using the model composed of the inertia moment of the camshaft system and the nonlinear elasticity of the belt in the running direction. The predicted resonant frequency and amplitude were in good agreement with the measured ones. The influence of each factor of the model on the vibration was also investigated. The stiffness in the belt running direction that is determined by the tooth distortion When the belt engages with the pUlley should be increased to reduce the amplitudes of the resonant Vibration.

The main factors influencing the development of engine oils for the future are environmental protection, resource utilization and customer satisfaction. Improving engine oil no longer means just providing adequate durability but also maximizing fuel efficiency, minimizing detrimental effects on emission systems and maximizing useful life. Opportunities for improvements in these areas, discussed in detail in this paper, will be considered by ILSAC (International Lubricant Standardization and Approval Committee formed by the American Automobile Manufacturers Association, AAMA, and Japan Automobile Manufacturers Association, JAMA) in developing the ILSAC GF-3 standard to be introduced around the year 2000.

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.

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 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.

Lubrication of a connecting rod bearing is analyzed by the theory of elastohydrodynamic lubrication (EHL). The hydrodynamic of a connecting rod bearing was calculated in consideration of not only the effects of bearing elastic deformation but also those of bearing shapes. Journal center loci were measured to confirm the accuracy of calculated results. The governing equations of EHL are the Reynolds equation, the clearance gap equaution and the load equation. The effects of the shapes of a connecting rod bearing were included in the clearance gap equaution. The calculated results agree well with the measured results. Results of this study show that lubrication of a connecting rod journal bearing is significantly influenced by bearing elastic deformation and shapes of a connecting rod bearing.

Fifty percent distillation temperature (T50) can be used as a warm-up driveability indicator for a hydrocarbon-type gasoline. MTBE-blended gasoline, however, provides poorer driveability than a hydrocarbon-type gasoline with the same T50. The purposes of this paper are to examine the reason for poor engine driveability caused by MTBE-blended gasolines, and to propose a new driveability indicator for gasolines including MTBE-blended gasolines. The static and dynamic evaporation characteristics of MTBE-blended gasolines such as the evaporation rate and the behavior of each component during evaporation were analyzed mainly by using Gas Chromatography/Mass Spectrometry. The results of the analysis show that the MTBE concentration in the vapor, evaporated at ambient temperature (e.g. 24°C), is higher than that in the original gasoline. Accordingly, the fuel vapor with enriched MTBE flows into the combustion chamber of an engine just after the throttle valve is opened.

It has been reported that the middle range of gasoline distillation temperatures strongly affects vehicle driveability and exhaust hydrocarbon (HC) emissions, and that MTBE(CH3-O-C4H9)- blended gasoline causes poor driveability during warm-up. The present paper is concerned with the results of subsequent detailed research on gasoline characteristics, exhaust emissions and driveability. In this paper, first it is demonstrated by using four models of passenger cars having different types of exhaust gas treatment system that decreased 50% distillation temperature (T50) reduces exhaust HC emission. This result indicates lowering T50 in the market will contribute to improving air quality. Secondly gasoline behavior in the intake manifold is investigated by using an engine on the dynamometer in order to clarify the mechanisms of HC emission increase and poor engine response which are caused by high T50.

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.

An investigation of throttle response of engines during warm-up was conducted using various gasolines. Test data were obtained from an engine on a test bench at intermediate temperature around 20∼ 30 °C. By using the engine test bench data, correlation coefficients between engine response time and gasoline characteristics were calculated. The result shows that the middle range of distillation temperature is an important factor in gasoline characteristics for warm-up driveability of fuel injected engines. It also shows that 50% distillation temperature can be used as one indication of warm-up driveability. This indication is effective only for hydrocarbon type gasolines. In the case of MTBE blended gasoline, the distillation temperature becomes low when MTBE is blended to gasoline, but throttle response was not improved. It is also found that the effect of gasoline distillation on throttle response is enhanced by intake valve deposits.

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.

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.

Computer Aided Engineering System for crankshaft damper pulley design was developed. This system enables a designer to develop a high performance crankshaft damper pulley in a short time. This system consists of computer simulation for torsional vibration of crankshaft with a damper pulley and parametric damper pulley design program. High accuracy and easy operation are required for the simulation. New procedure of FE analysis which can accurately and easily predict stiffness of crankshaft in less than 4 hours was developed. And the database for damper rubber property which was measured under the condition of wide range enough to cover actual engine operation was created. It was shown that the calculated results agree well with the experimental results. Parametric damper pulley design program were developed. This program is composed of the design standards and stores of know-how in Toyota.

The oil consumption phenomena during transient engine operating condition is analyzed. The investigation of the oil consumption by means of the real-time oil consumption meter shows that higher intake manifold vacuum during engine-brake condition causes a larger amount of transient oil consumption. The reverse blowby gas flow into the combustion chamber from the crankcase is generated by the high vacuum under engine-brake condition. It is found that this reverse gas flow carries the oil into the chamber from the third land of the piston through the ring end gap of the compression rings. The oil on the piston skirt leaks into the third land through the clearance between the oil ring and the cylinder bore. The weakened bore-to-ring contact pressure by the piston slap motion increases the amount of the leakage oil. New ring sets and pistons are developed based on the results of this study.

The reduction of engine oil consumption rate is one of the important concerns for automotive engineers. However, it has been difficult to solve this subject, since the oil consumption mechanism has not yet been elucidated. In this study, to clarify the oil loss mechanism via the piston rings, a transparent glass cylinder engine was used to observe oil behavior between cylinder wall and piston surface. For photographic observation, a high speed camera, a still camera. and a TV camera were used. Since the new photographic system by using TV camera with a synchro - flash and a synchro-memory was applied, it was also possible to observe the oil behavior in detail. Moreover, a new visual method by which colored oil was injected from the various points on the piston surface and traced was developed for easy analysis of oil movement around the piston ring.

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.

Oil consumption mechanism was analyzed by measuring the radial movement of the upper side rail in a three piece type oil ring, together with the piston movement. Ultra-miniature inductive displacement sensors were designed to measure the oil ring movement and fitted on the upper side rail with a part of the 3rd land cut out. The clearance between the side rail and the cylinder wall was measured under various operating conditions. The results showed that the radial movement of the oil ring was affected by the piston movement, which results in the possibility of degrading the oil control ability for the cylinder wall because the oil ring temporarily moves with the piston. Accordingly, the designs to improve the piston movement or to be less affected by the movement proved to be an important factor for the reduction of the oil consumption.

Computer Aided Engineering system for automotive piston design was developed which can predict total piston performance in a short time at the planning stage of piston design. Many previous studies attempted to calculate piston performance accurately with experimental data and their main purpose was not to create a tool for piston design. The purpose of this CAE system is to provide a tool for a designer to predict total piston performance easily and rapidly without experimental data. This system has following two characteristics. Firstly, new finite element methods were developed which can predict temperature distribution without experimental data, thermal skirt expansion for a strutted piston and skirt-to-bore contact pressure under engine operating conditions. The predicted result are accurate enough to predict piston performance at the planning stage of piston design.