Toshihiro Ozasa

Theoretical analysis of bearing performance of microgrooved bearing

Abstract To meet todays requirements for higher performance engine bearings, microgrooved bearings, that is plain bearings with shallow circumferential grooves, were developed. Recently, the performance of microgrooved bearings, obtained experimentally, were reported [1] , [2] . The authors calculated the bearing performance of the microgrooved bearings by elastohydrodynamic lubrication theory. In this paper, the authors describe theoretically the calculation method and the performance of the microgrooved bearings.

Development of transparent cylinder engines for schlieren observation

A square piston engine and a side-view collimating (SVC) cylinder engine are developed for side-view schlieren visualization of in-cylinder processes. The square piston engine has a square cylinder with two flat quartz windows permitting optical access to the entire cylinder volume. Compression sealing is provided by three polyimide ring assemblies which maintain the windows clean during the actual observational. In contrast with the square piston engine, the SVC cylinder engine permits to take schlieren photographs in practical engine geometries. This is made possible by designing the SVC cylinder so that it does not disperse parallel light rays.

Elastohydrodynamic Lubrication Model of Connecting Rod Big-End Bearings: Application to Real Engines

This study presents an elastohydrodynamic (EHD) lubrication model of connecting rod big-end bearings developed taking into consideration the effects of inertia and oil holes. In this model, the effect of inertia, namely the body force, on load and deformation is practically and rationally expressed based on engine dynamics and a structural model ofa connecting rod. A method of defining the deformation of bearings has been proposed to simplify numerical analysis. The effect of oil holes, namely an oil feed hole in a journal and an oil jet hole in a bearing, is considered as a boundary condition in the EHD lubrication theory. Calculations of oil flow rate and potter loss are also included.

Schlieren Observation of Spark-Ignited Premixed Charge Combustion Phenomena Using a Transparent Collimating Cylinder Engine

The schlieren photographs of in-cylinder processes in a spark-ignited premixed charge gasoline engine were observed via a transparent collimating cylinder and were presented in comparison with a pressure analysis. The schlieren photographs of the spark, the initial flame and the unburned gas ejection from the piston crevice, which is unable to be observed by direct photography, were clearly taken. It shows that the small difference in the initial combustion process among cycles is intensified by the movement of the piston during the expansion stroke. Finally, this difference appears as the cycle by cycle variation in the pressure and the rate of heat release. The observed flame size increased faster and was larger than the burned gas estimated from the pressure. The difference between them is large enough and can not be explained without considering the mixing of burned and unburned gases inside the flame front.

Analysis of noise occurrence by cavitation in the main bearing of diesel engine

Abstract This paper presents an analysis of noise occurrence at the 7th main bearing of an inline six cylinder diesel engine. From experimental results of the engine, it seems that cavitation in the bearing oil film is a major factor for this noise, and the noise occurs with a combination of the following conditions; (1) cavitation exists in oil film at the main bearing, (2) main journal is unstable and (3) excitation force acts at this moment. This assumption is analyzed using engine vibration analysis, EHL analysis and stability analysis. The results agree with the condition of the noise occurrence.

Study on Analysis Support of Lubrication Phenomenon by Three-Dimensional CAD Development of Auxiliary Analysis Tool for CAD

Three-dimensional CAD (Computer Aided Design) software can be used to analyze phenomena related to movement such as vibration and friction. But this requires knowledge for handling material properties and uses special three-dimensional CAD functionality. For these reasons, analysis based on three-dimensional CAD of phenomena is greatly influenced by skill level in model design and enormous time if required due to processing of analysis. Therefore, it is difficult to treat as an auxiliary tool for analysis. Also, various software exist as three-dimensional CAD, but each software varies in method of use. In addition, automatically obtained finite element mesh data in analysis differs depending on software. Therefore, even with the same model, it is difficult to analyze under the same conditions and to obtain the same result [14]. In this paper, we will study the method for analyzing the lubrication phenomena. From this study we will propose a method easy even for beginners, and show that the analysis method is simple and quick and reduces the burden on the designer.

Simplified estimation method of bearing friction for engines

Many journal bearings exist in an engine. Therefore, the effects of operation and design parameters of a journal bearing on power loss are the important information. In this study, simplified estimation method of bearing friction is proposed by means of a regression equation. Dimensional analysis on friction of a journal bearing is performed for the operation and design parameters using hydrodynamic lubrication under steady load. Based on the dimensional analysis, the effect of the parameters is evaluated and the regression equation is proposed. The regression equation is fitted for two cases; one is based on calculated frictions with hydrodynamic lubrication under steady load and the other is based on experimental frictions obtained using a bearing test apparatus. In the bearing test apparatus, a rotor is supported by a pair of test journal bearings and friction torque of the test journal bearings is measured based on angular deceleration of the rotor. Power loss of journal bearing is numerically calculated with hydrodynamic lubrication under dynamic load of an engine and it is compared with the power losses estimated with the regression equations. Finally, the suitability for the simplified estimation method is discussed.