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Over the last few decades, in-cylinder visualization using optically accessible engines has been an important tool in the detailed analysis of the in-cylinder phenomena of internal combustion engines. However, most current optically accessible engines are recognized as being limited in terms of their speed and load, because of the fragility of certain components such as the elongated pistons and transparent windows. To overcome these speed and load limits, we developed a new generation of optically accessible engines which extends the operating range up to speeds of 6000 rpm for the SI engine version, and up to in-cylinder pressures of 20 MPa for the CI engine version. The main reason for the speed limitation is the vibration caused by the inertia force arising from the heavy elongated piston, which increases with the square of the engine speed.

To avoid knocking phenomena, a special crank mechanism for gasoline engine that allowed the piston to move rapidly near TDC (Top Dead Center) was developed and experimentally demonstrated in the previous study. As a result, knocking was successfully mitigated and indicated thermal efficiency was improved [1],[2],[3],[4]. However, performance of the proposed system was evaluated at only limited operating conditions. In the present study, to investigate the effect of piston movement near TDC on combustion characteristics and indicated thermal efficiency and to clarify the knock mitigation mechanism of the proposed method, experimental studies were carried out using a single cylinder engine with a compression ratio of 13.7 at various engine speeds and loads. The special crank mechanism, which allows piston to move rapidly near TDC developed in the previous study, was applied to the test engine with some modification of tooling accuracy.

A new stratified charge system has been developed for direct injection gasoline engines. The special feature of this system is employment of a thin fan-shaped fuel spray formed by a slit nozzle and a shell-shaped piston cavity. This system, basically classified into the wall-guided mixture preparation concept that leads air/fuel mixture to the spark plug periphery by means of spray penetration and piston cavity configuration without an extra intake air flow controlling system, obtained wide engine operating area with stratified combustion and high output performance. This report presents the characteristics of stratified mixture formation and combustion, especially the important factor for achieving stable stratified combustion in the high-speed region, which have been clarified through analytical studies.

The durability of an automatic transmission is greatly affected by its lubrication properties. However, it is difficult to estimate exactly the flow rate of lubricating oil at each part of the automatic transmission, because of its structural complexity under rotating conditions. This paper presents a simple model which can estimate the flow rate of lubricating oil in the automatic transmission. Using this method, we can obtain various information about the lubricating state at every part of the automatic transmission and can help our judgement of whether lubrication is sufficient. To test this model and its results, we tried some experiments and examined the lubricating state by measuring discharge rate of oil. The estimated data is in good agreement with the experimental data. This study should assist in the optimal design of the lubricating system in the automatic transmission.

The purpose of this study is to analyze con-rod bearing lubrication under reduced oil supply rate conditions. An engine was modified to measure the oil supply rate to a con-rod big-end bearing. Then the effects of the oil supply rate on bearing temperatures and the contact between a journal and a bearing were investigated in order to analyze lubrication characteristics. The bearing temperatures increased in accordance with reduced oil supply rate. On the other hand, the contact frequency hardly changed under almost all conditions, but steeply increased near one-third of the standard oil supply rate at the highest speed of 5000 rpm in the experiments. The results show that the reduced oil supply rate decreases the cooling effect but the hydrodynamic lubrication was sufficiently achieved except the above-mentioned severe condition.

In internal combustion engine, it is well-known that oil infiltrates the combustion chamber through the clearance between the piston ring and the cylinder bore with vertical reciprocating motion of the piston, leading to an increase in oil consumption. The deformation of the cylinder bore is inevitable to some extent in the actual engine because of the tightening of cylinder head bolt and heat load._As to the function of the piston ring, it is desirable that it conforms to such bore deformation. The author et al. made a glass cylinder engine in which closed piston ring gap could be visualized, based on the idea that piston ring conformability to the sliding surface of bore could be evaluated from minute changes of the piston ring gap. This newly-devised visualized engine was an in-line 4-cylinder engine, capable of running up to 6,000 rpm, in which the closed gap of piston ring could be observed minutely during engine operation.

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.

Hybrid vehicles (HVs) are becoming more widely used. Since HVs supplement engine drive with motor power, the lubricant oil temperature remains at a lower level than in a conventional gasoline vehicle. This study analyzed the effect of cylinder bore temperature and lubricant oil temperature on engine friction. The results showed that, although the lubricant oil temperature was not relevant, the bore temperature had significant effect on piston friction. It was found that raising the temperature of the middle section of the cylinder bore was the most effective way of reducing piston friction.

Sintered silicon nitride, particularly in structural ceramics, has superior properties such as low weight, heat resistance, wear resistance, etc. It is already being applied to automobile engine parts such as the swirl chamber and the turbine rotor. In recent years, the strength of silicon nitride has shown to be above 1000MPa. This has been achieved through advances in manufacturing technology such as materials powder, forming, sintering and so on. But the silicon nitride is easily damaged during grinding because it has less fracture toughness than metal. Consequently, the inherent strength of the material is not demonstrated in the actual products presently produced. It is assumed that the main cause of strength reduction is microcrack. In ordinary grinding methods, the length of microcrack has been estimated at approximately twenty micrometers by fracture mechanics analysis.

The effect of GTL diesel fuel on organic materials used in fuel delivery systems of vehicles was investigated. Specimens made from 16 kinds of organic materials were immersed in GTL diesel fuels synthesized at Refinery-A and Refinery-B (referred to as GTL-A and GTL-B, respectively) and then subjected to tensile testing. The tensile test results revealed that elongation of the nylon sample immersed in GTL-A was extremely small, about 4% of that of untreated nylon. In the light of this finding, the GTL diesel fuels and nylons before and after immersion test were analyzed in detail using about 20 analysis methods to determine the cause for poor elongation. The following points were found. (1) GTL-A consisted of low molecular-weight paraffins. (2) GTL-A had low molecular-weight i-paraffins. (3) The nylon immersed in GTL-A contained low molecular-weight paraffins. (4) The paraffins in the nylon immersed in GTL-A were richer in i-paraffins than the original GTL-A.

In a previous paper (Part 1 of this series), nylon-66 specimens were immersed in two GTL diesel fuels (GTL-A and GTL-B) and then subjected to tensile testing. The tensile test results revealed that the elongation of the specimen immersed in GTL-A was dramatically reduced. The GTL diesel fuels and nylon specimens before and after immersion were analyzed to determine the cause of the decline in elongation. It was found that the poor elongation was caused by penetration and oxidation of low molecular-weight paraffins and that the ease of penetration and oxidation of paraffin depended on the structure of paraffin. In this paper, the low molecular-weight paraffins detected in GTL-A were mixed to produce model fuels. Then, pieces of nylon cut from the tensile test specimen, were immersed in the model fuels. In addition, partial oxidation products of the paraffin (alcohol, aldehyde or ketone and acid) were used in immersion tests of the nylon pieces.

A direct injection (DI) gasoline engine having a new stratified charge combustion system has been developed. This new combustion process (NCP) was achieved by a fan-shaped fuel spray and a combustion chamber with a shell-shaped cavity in the piston. Compared with the current Toyota D-4 engine, wider engine operating area with stratified combustion and higher output performance were obtained without a swirl control valve (SCV) and a helical port. This report presents the results of combustion analyses to optimize fuel spray characteristics and piston cavity shapes. Two factors were found to be important for achieving stable stratified combustion. The first is to create a ball-shaped uniform mixture cloud in the vicinity of the spark plug. The optimum ball-shaped mixture cloud is produced with a fuel spray having early breakup characteristics and uniform distribution, and a suitable side wall shape in the piston cavity to avoid the dispersion of the mixture.

Recently, single action draw with cushion replaces draw with double action presses. In the single action draw, binding fluctuation problem occurs by its structure. We applied an NC cushion to prevent the problem. We compared the cushion force wave with and without an NC cushion. The NC cushion showed effective damping. We studied the binding force control of a side member outer panel. The panel didn't have the formable range of binding. This means the lowest binding force to avoid wrinkling, still had crack problems. We introduce four patterns of binding force control with the NC cushion. As a result, we found the suitable pattern to suppress the surface distortion. Controlling the binding force shows effectiveness as a means of suppressing surface distortions.

The cause of the exhaust smoke and its reduction methods in a small DI Diesel engine with a small-orifice-diameter nozzle and common rail F.I.E. were investigated under high-speed and high-load condition, using both in-cylinder observations and Three-dimensional numerical analyses. The following points were clarified during this study. At these conditions, fuel sprays are easily pushed away by a strong swirl, and immediately flow out to the squish area by a strong reverse squish. Therefore, the air in the cavity is not effectively used. Suppressing the airflow in a piston cavity, using such ideas as enlarging the piston cavity diameter or reducing the port swirl ratio, decreases the excessive outflow of the fuel-air mixture into the squish area, and allows the full use of air in the whole cavity. Hence, exhaust smoke is reduced.

A study of diesel fuel as a lubricant for diesel engines was conducted with the aim of dramatically reducing engine friction and eliminating the need to change the lubricating oil. A prototype single-cylinder engine modified for diesel fuel lubrication was made, and it was confirmed that firing operation is possible. Piston friction during the firing operation was reduced by modifying the shape of the cylinder liner surface to improve the retention of the lubricating oil. The study produced valid findings concerning engine lubrication, not only with diesel fuel, but also with ultra-low viscosity oil.

Piston ring moving zone in the cylinder is one of the most critical lubrication regimes in diesel engines. This area is susceptible to combustion substances. In particular, abnormal wear is occasionally detected due to Exhaust Gas Recirculation (EGR) system equipment. In Japan, NOx emission requirements for passenger car diesels have become more stringent effective October 1, 1986. OEMs tend to apply EGR systems to reduce NOx in exhaust gas. In order to identify the phenomenon of abnormal cylinder wear of EGR equipped engine, engine bench tests were conducted under varied conditions in EGR equipment, cooling water temperature and fuel sulfur content. The test results suggest that wear caused at low temperature is mainly corrosive wear attributable to sulfuric acid formed by reaction with fuel sulfur and condensed water.

Slip-controlled lock-up clutch systems are very efficient and greatly improve fuel economy. On the other hand, these systems can cause unstable vibrations including those known as “shudder vibrations”. In this study, the authors made a theoretical analysis of these unstable vibrations to clarify the fundamental frictional properties of automatic transmission fluids (ATFs) required for slip-controlled lock-up clutch systems. Based on this analysis, we established lubricant technology having a sufficient anti-shudder property and high torque capacity. Further, we developed a new test apparatus to evaluate the anti-shudder durability for lubricant development.

Effects of spray characteristics for stratified combustion of direct injection gasoline engine have been researched. The highly functional piezoelectric (PZT) injector was selected for this research. A hole and swirl nozzle were examined in a wide range of fuel pressure. The hole nozzle aims to make stratified mixture formation by vaporizing fuel on the piston, and the swirl nozzle aims to do so in the air above the piston by utilizing the spray characteristic of lower penetration and higher dispersibility. Both sprays could realize stable stratified combustion. The stability mainly depends on the combination of spray characteristic and piston cavity shape, and the swirl air motion which strength changes corresponding to engine operating conditions. The hole nozzle requires high, and the swirl nozzle less fuel pressure. Even by a large amount of EGR, stratified combustion has the advantage of combustion stability, and is useful to reduce exhaust emissions, especially NOx emissions.

The new intelligent VVT (Variable Valve Timing) -i, is one of the systems developed to improve engine performance. The pulley unit is one of the most important mechanical components of the system. We developed a suitable process for the four main parts of the VVT-i pulley in order to achieve the target performance at a minimal cost. The requirements for the mechanical component, the pulley unit, include light weight and compact design as well as a quick response time. To satisfy these requirements, we developed three helical gears having unique profiles and high accuracy, and a timing pulley which must prevent pressurized oil from leaking. The inner gear is a helical gear with external teeth,and a key way on its inside diameter. The piston gear is a helical gear of which the inside and outside teeth have opposite helix angles. We developed a unique powder compacting technology for these two gears. The timing pulley is also made of sintered metal alloy.

A high strength and high toughness new bainitic steel has been developed which shows comparable mechanical properties, fatigue property, and machinability to those of quenched and tempered SAE 5140. The heat treatment of the bainitic steel is aging after hot forging in order to improve ratio of 0.2% proof stress and tensile strength (i.e. yield ratio) and to avoid warpage associated with quenching. The new bainitic steel has been applied to the slender and lightweight lower arms for automotive suspension. As a result, the total production costs in the lower arms have been reduced by nearly 15 percent.