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This paper describes a measurement method using laser induced fluorescence we have developed for simple simultaneous measurements of piston ring oil film thickness at plural points for internal combustion engines. The findings obtained by the measurements of oil film thickness on both thrust and anti-thrust sides of the piston for a mono-cylinder compact diesel engine using this new measurement method are also discussed in this paper. One of main findings is that the oil film thickness of each ring on both sides differs markedly in terms of the absolute value and the stroke- to-stroke variation. It is found that this difference in oil film thickness is caused by the difference in the amount of lubricating oil supplied to the oil ring, and the effect is greater than that of engine speed or load.

Exhaust-gas recirculation (EGR) causes the piston rings and cylinder liners of a Diesel engine to suffer abnormal wear on the sliding parts. The present study aimed at making clear such abnormal wear structurally by examining the state of lubrication of the piston with a floating liner method, observing directly a visualized cylinder and experimenting on a Diesel engine for wear. As a result, it was confirmed that soot in EGR gas would change a lot the characteristics of the piston friction force. There are two mechanisms: one directly enters the sliding surfaces, and the other enters the ring rear, applying more load to them. It was also confirmed that the level of wear on the piston ring would vary to a large extent as the state of lubrication changed.

This paper reviews a validation project on CFD commercial codes organized by Society of Automobile Engineers of Japan (JSAE) in 2001. As benchmark problems, four major objects of vehicle flow design are selected for Vehicle aerodynamics, Engine cylinder flow, Air-conditioning and Defroster duct flow. 14 titles of commercial software sold in Japan are applied to these problems. The results of each problem are compared with reference experimental data and evaluated in vi ews of vehicle design and development. Feasibility of auto-meshing techniques and computation cost in recent hardware are also discussed.

We developed a two-degree-of-freedom (2-DOF) control system for a diesel engine airpath system. First, a physical airpath model of the diesel engine was developed, followed by a nonlinear feedforward controller developed based on the inverse characteristics of the developed physical model. The dynamics of turbocharger and manifolds were considered in the feedforward controller to improve the transient response. The feedback controller was designed by H∞ control theory considering plant nonlinearities as uncertainties. The feedforward and feedback controllers were implemented as a 2-DOF freedom control scheme. The effectiveness of the proposed method was evaluated by conducting simulation and experiment.

A study was conducted to understand the effects the specifications of the crank-slider mechanism have on piston friction losses. The information obtained through the study is believed to be useful information for reducing the piston friction. A single-cylinder spark-ignited gasoline engine was designed and constructed to have not only a real-time piston friction measurement system using the floating liner method, but also provisions to facilitate changing the specifications of the crank-slider mechanism. This paper describes the study results obtained under various engine-operating conditions and reports the parametric test results of three crank ratios and five crankshaft-offset amounts tested.

This paper describes measurements of oil film thickness of piston ring packages which have different oil control rings. The oil film thickness measurements were taken at three points, namely, the piston thrust side, front side and rear side, by the Laser Induced Fluorescence Method(LIF). One of the main findings is that the oil film thickness on the thrust side varies greatly from cycle to cycle, while cyclic variations are smaller on the front and rear sides. This difference is due to the smaller inclination of the oil control rings on the front and rear sides, compared with that on the thrust side. It is also found that oil consumption has a good correlation with oil film thickness on the thrust side and that the thrust side oil film thickness becomes thinner as the oil ring becomes narrower.

Offsetting the crankshaft axis with respect to the cylinder axis has been thought to be a method to reduce piston side force[1]. Hence the piston friction is expected to be reduced. An automotive manufacturer has already used the crankshaft offset for a production gasoline engine to improve fuel economy. The authors have conducted research into the effect of crankshaft offset on the piston friction. A single-cylinder engine was modified to have a crankshaft offset. Piston frictional force was measured in real-time by using a floating liner method. In addition, laser-induced fluorescence (LIF) technique was employed to measure oil film thickness on the piston skirt area, and a gap sensor was used to measure piston motion. As a result, the authors concluded that the effect of crankshaft offset on piston friction could not be explained only by its effect on the piston side force. In accordance with the measurement results, crankshaft offset changed piston slap motion.

In this study, the cause of backfire concerning an external mixture formation type hydrogen engine was clarified. It has been known that the maximum output power of the external mixture formation type hydrogen engine should be kept significantly low, because of backfire. Generally, the backfire of this type of hydrogen engine is caused by pre-ignition. In this type of hydrogen engine, pre-ignition occurred for a range of lean mixture. Under this study, therefore, the relationship between the occurrence of backfire and the temperature at the tip of the spark plug electrode, and the detection of the luminescence spectrum of the flame near the spark plug were examined and studied in relation to the spark plug ignition theory which appeared to be promising. Then the pre-ignition timing and location were studied by detecting the flame luminescence spectrum.

A comprehensive formulation is presented for the dynamics of a rotating flexible crankshaft coupled with the dynamics of an engine block through a finite difference elastohydrodynamic main bearing lubrication algorithm. The coupling is based on detailed equilibrium conditions at the bearings. The component mode synthesis is employed for modeling the crankshaft and block dynamic behavior. A specialized algorithm for coupling the rigid and flexible body dynamics of the crankshaft within the framework of the component mode synthesis has been developed. A finite difference lubrication algorithm is used for computing the oil film elastohydrodynamic characteristics. A computationally accurate and efficient mapping algorithm has been developed for transferring information between a high - density computational grid for the elastohydrodynamic bearing solver and a low - density structural grid utilized in computing the crankshaft and block structural dynamic response.

CRT looks promising in achieving clean Diesel emission particularly PM, however, it presents two limits in exhaust gas temperature levels, i.e., at idling to low power region requiring emission temperature 260°C minimum, and at high power region 450°C maximum. These problems can only be solved by the proposed method under the currently available known technologies. At the lower power side, 260°C minimum, can be materialized by the use of “Exhaust Secondary Cam (ESC)”, throttling intake air and exhaust gas lines together with other means like reduction of number of cylinders in operation. At the high power side, 450°C maximum, will easily be cleared by “Hyperbrid supercharging system” invented by the author.

The interest in using combustion pressure in engine control systems has initiated development activities to integrate pressure sensors into existing engine components. Since cylinder head gasket contacts the combustion chamber of multiple cylinders, the ability to add pressure-sensing capability is of unique interest. Two viable multi-layer steel cylinder head gasket design approaches have been developed to fulfill this interest. These designs offer the full sealing performance of traditional multi-layer steel designs, but also include accurate pressure sensors packaged in a total gasket thickness realistic to modern engines.

Hybrid electric vehicle with internal combustion engine fueled with hydrogen can be a competitor to the fuel cell electric vehicle that is thought to be the ultimately clean and efficient vehicle. The objective in this research is to pursue higher thermal efficiency and lower exhaust emissions in a hydrogen-fueled engine for the series type hybrid vehicle system. Influences of compression ratio, surface / volume ratio of combustion chamber, and boost pressure on thermal efficiency and exhaust emissions were analyzed. Results showed that reduction of the surface / volume ratio by increased cylinder bore was effective to improve indicated thermal efficiency, and it was possible to achieve 44% of indicated thermal efficiency. However, brake thermal efficiency resulted in 35.5%. It is considered that an improved mechanical efficiency by an optimized engine design could increase the brake thermal efficiency largely.

Historically Diesel engines with turbocharger (TC) suffer so called “Turbo-Lag”, which presents deficiency in intake air-supply during the low engine speed stage. This insufficient air-supply causes emissions much higher than their normal operating conditions. For this a “Hybrid” supercharge-engine has been proposed [1], where a mechanically driven supercharger (SC) is used during the low engine speed zone. This paper proposes a new EGR (Exhaust Gas Return) system concept applicable to Diesel engines, which will achieve the compatibility to the stringent emission standard of USA in the year 2004, which is more stringent than EURO-3. S.P.Edwards et al [2] discussed some measures to clear EURO-3 values are discussed, but those, “D” and “E” in the Figure 1 are not possibly achievable in the near future. Therefore only EGR among those discussed in the paper is realistic.

Hydrogen can be readily used in spark-ignition engines as a clean alternative to fossil fuels. However, a larger burning velocity and a shorter quenching distance for hydrogen as compared with hydrocarbons bring a larger cooling loss from burning gas to the combustion-chamber wall. Because of the large cooling loss, the thermal efficiency of a hydrogen-fueled engine is sometimes lower than that of a conventionally fueled engine. Therefore, the reduction of the cooling loss is very important for improving the thermal efficiency in hydrogen-combustion engines. On the other hand, the direct-injection stratified charge can suppress knocking in spark-ignition engines at near stoichiometric overall mixture conditions. Because this is attributed to a leaner end gas, the stratification can lead to a lowered temperature of burning gas around the wall and a reduced cooling loss.

This paper presents the development of surrogate models (metamodels) for evaluating the bearing performance in an internal combustion engine. The metamodels are employed for performing probabilistic analyses for the engine bearings. The metamodels are developed based on results from a simulation solver computed at a limited number of sample points, which sample the design space. An integrated system-level engine simulation model, consisting of a flexible crankshaft dynamics model and a flexible engine block model connected by a detailed hydrodynamic lubrication model, is employed in this paper for generating information necessary to construct the metamodels. An optimal symmetric latin hypercube algorithm is utilized for identifying the sampling points based on the number and the range of the variables that are considered to vary in the design space.

Diesel engines make a shrill noise called “idle knock” under low temperature idling operation. This causes a serious noise pollution problem in automobile diesel engines. It was clarified by this study that one important source of this noise was piston slap impulse. Piston slap motion was measured under usual operating conditions and a condition with additional oil supplied into the piston clearance. The piston slap motion was calculated taking into account the frictional resistances of the crank mechanism and squeeze action of oil film. It was concluded that only a negligible amount of oil existed in the piston clearance for the squeeze action.

An analytical method is presented in this paper for simulating piston secondary dynamics and piston-bore contact for an asymmetric half piston model including elastohydrodynamic (EHD) lubrication at the bore-skirt interface. A piston EHD analysis is used based on a finite-difference formulation. The oil film is discretized using a two-dimensional mesh. For improved computational efficiency without loss of accuracy, the Reynolds’ equation is solved using a perturbation approach which utilizes an “influence zone” concept, and a successive over-relaxation solver. The analysis includes several important physical attributes such as bore distortion effects due to mechanical and thermal deformation, inertia loading and piston barrelity and ovality. A Newmark-Beta time integration scheme combined with a Newton-Raphson linearization, calculates the piston secondary motion.

This paper deals with the friction performance results for various new concept piston skirt profiles. The program was conducted under the assumption that friction performance varies by the total amount of oil available at each crank angle in each stroke and the instantaneous distribution of the oil film over the piston skirt area. In previous papers [1,2] it was that lower friction designs would be expected to show higher skirt slap noise. This paper discusses the correlation between friction and skirt slap for each new concept profile design. Finally, this paper explains the friction reduction mechanism for the test samples for each stroke of the engine cycle by observing the skirt movement and oil lubrication pattern using a visualization engine.

Due to increasing economic and environmental performance requirements of internal combustion engines, piston manufacturers now focus more on lower friction designs. One factor strongly influencing the friction behavior of pistons is the dynamic interaction between lubricating oil, cylinder bore and piston. Therefore, the dynamic effect of the oil film in the gap between the liner and piston has been studied, using a single cylinder engine equipped with a sapphire window. This single cylinder engine was also equipped with a floating liner, enabling real-time friction measurement, and directly linking the oil film behavior to friction performance of pistons.

The objective was to rank piston friction and noise for three piston architectures at three cold clearance conditions. Piston secondary motion was measured using four gap sensors mounted on each piston skirt to better understand the friction and noise results. One noticeable difference in friction performance from conventional designs was as engine speed increased the friction force during the expansion stroke decreased. This was accompanied by relatively small increases in friction force during the other strokes so Friction Mean Effective Pressure (FMEP) for the whole cycle was reduced. Taguchi's Design of Experiment method was used to analyze the variances in friction and noise.