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The piston and piston ring are used in a severe contact environment in engine durability tests, which causes severe wear to the piston ring groove, leading to significant development costs for countermeasures. Conventionally, in order to ensure functional feasibility through wear on the piston top ring groove (hereinafter “ring groove”), only functional evaluations through actual engine durability testing were performed, and there was an issue in determining the limit value for the actual amount of wear itself. Because of this, the mechanism that may cause wear on the ring groove was clarified through past research, but this resulted in judgment criteria with some leeway from the perspective of functional assurance. To establish judgment criteria, it was necessary to understand both functional effect from ring groove wear and the mechanism behind it.

Recent automobile engines are equipped with many devices that are driven by oil pressure. Generally, engine oil is used for oil pressure, and in addition to its conventional functions of lubrication and cooling, etc., it also plays an important role in accurately driving such devices. One of the factors that can interfere with the characteristics of engine oil is air contamination. Excessive air contamination can cause issues with driving devices. Although there are various factors that contribute to air contamination, this paper focuses on, and attempts to help predict, the air generated by engine oil falling and colliding with the surface of the oil in the oil pan as it returns from the top to the bottom of the engine. Using the particle method as the prediction method, the coupled Moving Particle Simulation (MPS) and Discrete Element Method (DEM) calculations were used to represent the generation of air.

During engine durability tests (peak power, constant engine speed) conducted in the development process, it has been the case that excessive wear has occurred to the upper surfaces of the piston top ring grooves, despite the fact that contact pressure due to combustion pressure has been low. This has resulted in considerable increases in development man-hours. The research discussed in this paper therefore set out to conduct a factor analysis of wear on the upper surfaces of piston top ring grooves in order to elucidate the wear mechanism in petrol engine for passenger car. This paper will discuss the test method employed in the factor analysis and the mechanism of wear demonstrated by the analysis. First, the form of the wear was analyzed, and rig test methods able to reproduce wear were developed. With regard to the form of wear, both sliding and impact modes were observed. Sensitivity analyses for each form of wear were conducted using rig tests.

The reduction of engine weight is today a widely used and effective approach to increasing automotive fuel efficiency . However, the realization of weight savings in the engine can increase deformation of the crankshaft and cylinder block, resulting in fretting fatigue of the contact surfaces of the bearing caps and the cylinder block. Although researchers have identified the mechanism of fretting fatigue on the cylinder block, as yet there is no effective method of addressing the issue in the development stage. The research discussed in this paper applied quality engineering methods to investigate a variety of factors considered to influence fretting fatigue in unit test equipment. The results of the study indicated a good correlation between unit tests and actual engine tests. The paper will also discuss analytic methods for obtaining basic materials data, and methods of prediction of fretting fatigue at an early design stage.

The independent bearing cap is a cylinder block bearing structure that has high mass reduction effects. In general, this structure has low fastening stiffness compared to the rudder block structure. Furthermore, when using combination of different materials small sliding occurs at the mating surface, and fretting fatigue sometimes occurs at lower area than the material strength limit. Fretting fatigue was previously predicted using CAE, but there were issues with establishing a correlation with the actual engine under complex conditions, and the judgment criteria were not clear, so accurate prediction was a challenge. This paper reports on a new CAE-based prediction method to predict the fretting damage occurring on the bearing cap mating surface in an aluminum material cylinder block. First of all, condition a fretting fatigue test was performed with test pieces, and identification of CAE was performed for the strain and sliding amount.

The properties sought in a multi-layer steel cylinder head gasket include cylinder pressure sealing and fatigue strength in order for there to be no damage while the engine is in operation. Diesel engines, in particular, have high cylinder pressure and a high axial tension by the cylinder head bolt demanding severe environment to the gaskets. As engine performance is enhanced, there are cases when cracks develop in the gasket plate, necessitating countermeasures. The cause of cracking in a flat center plate, in particular, has not yet been explained, and no method for evaluation had previously existed. Three-dimensional non-linear finite element calculation was therefore performed to verify the cause. First, a static pressurization rig test was used and the amount of strain was measured to confirm the validity of the calculations. Then the same method of calculation was used to verify the distribution of strain, with a focus on the plate position.

Piston skirt friction has been considered to be related to cylinder block bore distortion and piston secondary motion, but it has been studied almost exclusively in isolation, and its detailed relationship to the functioning of an actual engine has not been clarified. In an attempt to improve correlation with actual engine behavior this study evaluated piston skirt performance using computer simulation of piston secondary motion that include the effects of cylinder bore distortion, skirt stiffness and skirt form. First, calculation results of cylinder block bore distortion and piston secondary motion was compared with measurement value respectively by amount of deformation and amount of secondary motion, and that validity was confirmed. Next, the technique was applied to the development of an actual engine, and the engine performance was studied along with the establishment of a method to predict friction.

As a result of demands for friction reduction and other performance requirements, there has been a trend towards reductions of bearing width and increases in load. Thus, high performance predictions are required to determine bearing feasibility limits. Measurement of oil film distribution is essential to judging bearing feasibility. Therefore, a thin film sensor was developed to enable highly accurate oil film pressure measurements in small bearings used in passenger vehicles. The sensor has a particularly smooth surface, making measurement possible with little effect on the lubrication conditions of sliding parts. For this research, the sensor was formed on the shaft so that oil film pressure distribution could be measured around the total periphery of the bearings. Three-dimensional oil film distribution measurements were conducted by the detection of multiple points on the sensor.