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Recently, as one of the effective measures for engine noise reduction, vibration damping steel sheets (VDSS) have been increasingly applied to engine oil sumps. This paper describes the formability of VDSS. Various factors closely related to drawability are considered. This study has been carried out in a production engineering process of manufacturing exceedingly deep, single blank sheet, oil sump for heavy-duty truck diesel engines. Some treatment of the surface of the VDSS was found to be a principal factor influencing deep drawability.

Since in-cylinder flame temperature has a direct effect on an engine's NOx characteristics, this phenomena has been studied in detail in a multi-cylinder DI diesel engine using a new method allowing the in-cylider temperature distribution to be measured by the two color method. An endoscope is installed in the combustion chamber and flame light introduced from the endoscope is divided into two colors by filters. The images of combustion phenomena using the two wavelengths are recorded with a framing streak camera which includes a CCD camera. The flame temperature and KL factor are immediately calculated by a computer using the two color images from the CCD camera. In the case of EGR, the test was conducted under 75% load conditions. The flame temperature was reduced according to an increase of EGR rate.

Hino has developed new J-series medium-duty diesel engines for trucks and buses. The new J-series comprises four, five and six-cylinder engines with the same cylinder bore and stroke and with both naturally aspirated and charge air cooled. Both output and torque have been enhanced along with fuel efficiency in an engine that is lighter and more compact than ever and reaches new heights of durability and reliability. J-series engine features a 4-valve system and OHC valve train design, which achieved an uniform combustion by a centered nozzle and combustion chamber design. This decreases the maximum combustion temperature and hence improved the NOx,smoke and PM emissions. And a reduced pumping loss results in improving the fuel consumption. J-series engines thus meet the Japanese 1994 emission regulations. Another feature is a fully electronically controlled common-rail fuel injection system, which is equipped in a specified engine of naturally aspirated 6 cylinder.

A new concept for diesel combustion was investigated by means of numerical simulation, engine experiment, and combustion observation in order to realize a simultaneous reduction of NOx and particulate emission. This concept (HiMICS: Homogeneous charge intelligent Multiple Injection Combustion System) is based on pre-mixed compression ignition combustion combined with multiple injection. Combustion characteristics of HiMICS concept was investigated by comparing with both a standard single injection and a pilot injection. In HiMICS concept, the pre-mixture is formed by a preliminary injection performed during a period from the early stage of the induction stroke to the middle stage of the compression stroke. Modified KIVA-II code was used to predict engine performances and emissions of each injection method. The simulation results show a capability of considerable improvement in the trade-off relation between NOx emissions and fuel consumption of HiMICS.

We have developed a new test method in which temperature of cavity lip of a piston alone during engine rotation is reproduced, cavity lip strain is measured. As the results of strain measurement using the test method in a condition that simulates of conventional engines, a strain behavior was out-of-phase. And in a condition that simulates of high-load engines in future, strain behavior was clockwise-diamond cycle. It was found from the result of the test method developed that strain increased on the cavity lip. The fatigue life of the cavity lip was evaluated using the strain measured and isothermal fatigue curves which obtained by the strain controlled isothermal fatigue test. The result of engine durability test has revealed that the developed method was valid for thermal fatigue evaluation of the cavity lip.

Japan's new 2005 long-term emissions regulation was implemented in October 2005. Both NOx and PM emissions standards were reduced to 2 g/kWh and 0.027 g/kWh, which were 40 and 85 percent lower than the 2003 new short-term emissions standards, respectively. These emissions standards are as stringent as the Euro5 standards that are scheduled for implementation in 2008. In addition, the transient-cycle test procedure for emissions compliance, labeled JE05, was introduced to replace the D13-mode steady-state test procedure. This paper describes exhaust emissions reduction technologies developed for Hino's 13-liter heavy-duty diesel engine so that it meets the above standards. A production catalyzed wall-flow DPF was employed to reduce PM emissions in both mass and small particles. NOx emissions were reduced by improving combustion with cooled EGR and without use of a NOx aftertreatment device.

The superior fuel economy of diesel engines compared to gasoline engines is favorable in reducing carbon dioxide (CO2) emissions. On the other hand, the reductions in nitrogen oxides (NOx) and particulate matter (PM) emissions are technically difficult, thus the improvement in the emission reduction technologies is important. Although the cooled exhaust gas recirculation (cooled-EGR) is the effective method to reduce NOx emissions, it is known to have durability and reliability problems, especially of the increased wear of piston rings and cylinder liners. Therefore, the degree of cooling and amount of EGR are both limited. To apply the cooled-EGR more effectively, the wear reduction technology for such components are indispensable. In this study, the negative effects of cooled-EGR on the wear are quantified by using a heavy-duty diesel engine, and its wear mechanism is identified.

Decrease of engine lubricating oil consumption is necessary to reduce environmental impact. Usually oil consumption is estimated experimentally at the engine development stage, and it is expensive in terms of both time and cost. Therefore it is essential to develop its calculation method. The purposes of this study are clarifying the mechanism of engine lubricating oil consumption and developing the calculation method for the estimation of oil consumption. In this report, oil film on the piston skirt, which affected on oil volume supplied to the oil ring, was observed. Furthermore the effect of piston skirt design on oil consumption was investigated. Findings showed that the splashed oil on the cylinder liner had much effect on the oil film on the piston skirt hence oil consumption. It was suggested that the splashed oil on the cylinder liner affected on supply oil volume and it should be considered in the calculation of oil consumption.

In a diesel engine, the mixing of the fuel spray and in-cylinder air controls rate of beat release during combustion, namely it will determine the thermal efficiency, maximum output and gas or noise emission, etc. Therefore, it is important to measure the droplet size and its volume density distribution in diesel fuel sprays. The optical measuring method, which includes a light scattering and holographic technique, seems the only feasible method for analysing these unsteady characteristics of fuel sprays. The light scattering technique described herein was based upon Mie scattering theory, and the droplet size and volume density distribution of fuel sprays were calculated from the combination of the light extinction and the forward-to-backscattering ratio of Mie scattering intensity. The volume density and droplet size distribution of fuel sprays were obtained from the light intensity distribution on a photograph of fuel sprays.

This paper presents technical solutions and a development process to accomplish not only superior fuel economy but also excellent driveability with a turbocharged diesel engine for heavy duty trucks. For better fuel economy, one of the basic considerations is how to decrease the friction losses of the engine itself while keeping the required horsepower and torque characteristics. A high boost turbocharged small engine offers this possibility, but it has serious disadvantages such as inferior low speed torque, poorer accelerating response, insufficient engine braking performance, and finally not always so good fuel consumption in the engine operating range away from the matching point between engine and turbocharger. These are not acceptable in complicated traffic conditions like those in Japan - a mixture of mountainous and hilly roads, city road with numerous traffic signals, and freeways.

A historical review of Japanese turbocharged diesel engines for heavy duty vehicles is described, and newly developed turbocharged diesel engines of HINO are introduced. The design features of these engines include new turbocharging technologies such as highly backward curved impeller for compressor blade, variable controlled inertia charging and waste gate. Laboratory and field test results demonstrated better fuel economy and improved low speed and transient torque characteristics than the predecessors. Several operational experiences, technical analysis and reliability problems are discussed.

Fuel injection timing retardation for reducing exhaust emission of direct injection diesel engines prolongs the period to complete cold starting. Engine speed at this period varies through some accelerating and faltering stages. The speed variation and relating combustion characteristics was investigated through the measurement of cylinder pressure for each cylinder as well as the dynamic fuel injection timing and instantaneous engine speed. An improvement of cold start was shown by application of afterheat of a sheathed type glow plug and an electronic fuel injection timing control device.

A new combustion system for a light duty D.I. diesel engine was developed, and a 3.5 ton payload truck (6.5 ton G.V.W.) equipped with this D.I. diesel engine and this combustion system realized good fuel economy and lower exhaust gas emission. Generally, light duty vehicles have to operate over a wide engine speed range. Therefore application of a D.I. diesel engine to light duty vehicles is difficult because of combustion tuning requirements over a wide engine speed range. Up to now, most of the diesel engines for light vehicles have been of the I.D.I. type. But the D.I. diesel engine has an evident advantage of lower fuel consumption. In these circumstances the authors developed a new combustion chamber shape for a small D.I. diesel engine with turbulence induced intake port and optimum fuel injection equipment. Various combustion chamber geometries were tested and evaluated.

The purpose of the investigation presented here was to develop a high quality SAE 10W-30 engine lubricating oil to meet the heavy duty operating conditions of trucks. The operation of their engines is predicted to become more severe in future because of the trend toward higher power output, nore severe regulation of exhaust emissions and noise as well as the increasing demand for better fuel economy. To meet these demands, an improvement of the wear resistance of engine lubricating oil was considered to be the most important aspect for the development of high performance diesel engines in the future. The engine test developed was able to evaluate various experimental oils by observing wear resistance of the valve train which is considered to be one of the most severe tri-bological conditions. The best oils were determined by optimum selection of the amount and type of detergent, ashless dispersant and zinc dithiophosphate.

A new combustion system for a light duty D. I. diesel engine was developed and introduced (1)*. The combustion chamber, which was used in the combustion system, has 4 concaves on the periphery of the inner wall and was calld HMMS-III. This combustion chamber realized better fuel consumption and lower smoke level over a wide speed range. However, the effects of HMMS-III combustion chamber on in-cylinder air motion and combustion characteristics were not yet clarified in the previous paper. In this study, in order to clarify the effects of HMMS-III combustion chamber on in-cylinder air motion and characteristics, analysis of flow direction and streak line via oil film method was carried out in comparison with flat dish and re-entrant type combustion chambers. Further, measurement of in-cylinder air motion by L.D.V. and observation of mixture formation and burning process via high speed schlieren photography were carried out.

It is preferable that power steering permits “static park” and has a good “road Feel” when running. In order to permit “static park”, a large bore actuation cylinder with high flow pump is required. Such a method, however, has two defects, a loss power for driving a large volume pump and a poor “road feel”. Resolving these problems and achieving the above matters. Hino has developed a load sensing power steering system. This system, which employes two actuation cylinders controlled by means of a unique load sensing valve arrangement, is designed to permit use of only one cylinder for highway speeds and both cylinders during a static park maneuver. When the system is combined with the preceding speed sensing power steering, “static park” is further facilitated and a tasty “road feel” is available in accordance with vehicle speed.

In this paper, the flow patterns and velocity distributions of coolant flow around cylinder liners of diesel engine are studied by numerical calculation and experimental observation. The experiment is carried out by oil film method and direct observation with a transparent acrylic cylinder liner. The calculation is performed with the 3-dimensional model by FEM for fluid flow. The motion of coolant flow by calculation corresponds with the result by oil film method and direct observation with transparent cylinder liner. The visualization of the 3-dimensional calculation gives a good understanding about motion of coolant flow and pressure distribution in water chamber. This method is applied to improve the coolant flow with the stagnation around cylinder liner. The effect of improved design is confirmed by experiment. That is, there are no stagnations in the flow around cylinder liners.

Characteristics of diesel combustion with high pressure fuel injection were investigated, using a supercharged and charge air cooled single cylinder engine. Observation and analysis of combustion was performed using high speed schlieren photography at a definite low level NOx emission, while varying the parameters of both injection pressure and swirl ratio. Engine performance at a high injection pressure was evaluated in combination with shallow dish type combustion chamber and 8 hole nozzle. Two different intake ports (higher and lower swirl ratio) were used for the evaluation. Conventional injection system in combination with toroidal cavity and 4 hole nozzle was compared as a base line. It is generally said that quiescent combustion system is suitable for higher injection pressure configuration. According to the observed result of combustion photographs, however, higher swirl ratio shows better mixing than a lower swirl ratio, which was also confirmed by the performance test.

Noise reduction of diesel engines installed in heavy duty vehicles is one of the highest priorities from the viewpoints of meeting the regulations for urban traffic noise abatement and noise reduction in the cabin for lightening fatigue with comfortable long driving. It is necessary that noise reduction measures then be applied to those causes. Noise reduction measures for the diesel engine can be classified into five categories on the noise radiation block-diagram. These are, reduction of combustion and mechanical forces, deformation and vibration control of cylinder block, vibration control of fastened components, prevention of standing wave and close fitting shields. All noise reduction measures for the diesel engine researched for the purpose of practical use are fully described in this paper.

Hino H-Series engines have been developed from the original which was designed as an indirect injection diesel in 1969. This paper describes the changes resulting in the latest direct injection version of it which develops much more power and economy than the original while maintaining the same box volume. The recent features of its wider application are also described.