Masahiko Nakada

Trends in engine technology and tribology

Abstract Fuel economy is one of the most important factors for both customer satisfaction and environmental protection. In order to improve fuel economy great efforts are being made to reduce mechanical losses by reducing friction loss and the weight of engine components, and trigology plays an important role in reducing friction. Some of the tribological problems that automotive engineers are now facing are described in this paper (for example, the problems of piston rings, pistons, bearings, engine oils, etc.). To promote effective environmental protection, automotive engineers, material engineers and tribologists need to cooperate with each other to solve the difficult aspects of engine tribology.

ANALYSIS OF OIL CONSUMPTION BY OBSERVING OIL BEHAVIOR AROUND PISTON RING USING A GLASS CYLINDER ENGINE

In this study, to clarify the oil loss mechanism via piston rings, a transparent glass cylinder engine was used. For photographic observation, a high speed camera, a still camera, and a new system by using TV camera with a synchro-flash and a synchro-memory was applied. Moreover, a unique trace method was developed.Results obtained for this visualization indicated that oil was mainly drawn into the combustion chamber through the gap areas in compression ring joints by high vacuum at engine braking condition and the oil passing over the peripheral surface of the oil control ring was more apparent when the piston rotational movements were greater.

Simulation test method for deterioration of engine crankshaft oil seals

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-O 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.

Development of computer aided engineering for piston design

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. 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 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. Secondly, the automatic mesh generating software was developed which creates three-dimensional piston modeling in less than 30 minutes.

Effects of gasoline composition on exhaust emissions and driveability

A study of the effects of changes in gasoline composition is one area to explore in our effort to reduce tailpipe emissions from vehicles. However, affects on vehicle performances should also be considered from the perspective of practical useage. In this paper, the influence of gasoline composition (aromatics), volatility, and MTBE blending on engine outlet and tailpipe emissions are discussed in particular, focusing on distillation properties which have a close relationship to driveability. Under stable driving conditions and without a catalitic converter, the effects of gasoline volatility is small, while aromatics in gasoline affect exhaust HC and NO{sub x} emissions. MTBE has a leaning effect on the engine intake air/fuel mixture. During a transient driving cycle, a high gasoline 50% distillation temperature causes poor driveability, as a result, HC emissions increase.