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This paper introduces the details of a low noise design realized by fully utilizing the theoretical methods for the prediction of noise and vibration, applied to Hino's new “H07D” engine. In the development of this engine, the reduction of the vehicle interior noise was one of the highest priority aims. For this purpose, the influence of the engine noise on the vehicle noise was firstly investigated to identify the major noise sources. Then, making best use of noise prediction techniques (FEM, etc.), the noise radiation mechanisms were clarified and the components identified as major noise sources were re-designed. In these improvements, the theoretical techniques also predicted carefully the effect of design changes on the related components, including their installation in an engine as required. These procedures achieved a remarkable noise reduction of the engine by cost effective methods.

In diesel engine trucks, the sound quality improvement as well as the noise level reduction is demanded because of their annoying exterior noise. The semantic differential method was applied to evaluate the sound quality of trucks. In order to improve the analytical accuracy, subjects who can evaluate the characteristics of sound quality were statistically selected among all the subjects. Comfortability and powerfulness were extracted as the principal components by using the data of the selected subjects. It has been clarified that the comfortability strongly relates to high frequency element ratio, high frequency level, etc. The powerfulness strongly relates to the Zwicker loudness.

In Biodiesel Fuel Research Working Group(WG) of Japan Auto-Oil Program(JATOP), some impacts of high biodiesel blends have been investigated from the viewpoints of fuel properties, stability, emissions, exhaust aftertreatment systems, cold driveability, mixing in engine oils, durability/reliability and so on. This report is designed to determine how high biodiesel blends affect oil quality through testing on 2005 regulations engines with DPFs. When blends of 10-20% rapeseed methyl ester (RME) with diesel fuel are employed with 10W-30 engine oil, the oil change interval is reduced to about a half due to a drop in oil pressure. The oil pressure drop occurs because of the reduced kinematic viscosity of engine oil, which resulting from dilution of poorly evaporated RME with engine oil and its accumulation, however, leading to increased wear of piston top rings and cylinder liners.

A large-size truck is equipped with a variety of audible warning devices. These warning devices are grouped into three categories by their usage, i.e., malfunction type, proximity type and attention type. The sound characteristics of warning sound that are investigated for each type are signal envelope, fundamental frequency and the number of harmonics. Many sounds are synthesized with nine fundamental frequencies, ten or fewer harmonics and two signal envelopes. With volume fixed, these sounds are evaluated using an unpleasantness rating scale, and the functional impression of these sound is also chosen. From the results, the range of fundamental frequencies, the number of harmonics and the shapes of signal envelopes for preferable sound quality are determined.

In a tractor-trailer, ride comfort affected by horizontal human body motions, so called “wavy” and “shaky” feelings, is at issue. Insight about “wavy” and “shaky” feelings which is important for efficient vehicle development is not enough. Experiments using 6-axis motion generator and motion capture and inverse-analysis using multi-body human model indicated the characteristics of each feeling. Motion observation and transfer function indicated that while a bad subjective score of “wavy” feeling corresponds to same-phase roll motion of chest and pelvis up to 0.7Hz, “shaky” correlates to an antiphase of them around 2Hz. By multiple regression, dominant vibration components of the human body and the vehicle to subjective evaluation of the feelings above were identified. Explanatory variables for the “wavy” feeling are roll rate and lateral jerk and those for the “shaky” are lateral acceleration and longitudinal acceleration.

An on board burner that enables DPF regeneration even when an engine is at standstill has been researched. By employing pre evaporative combustion with a wick burner, miniaturization of the burner system was successfully accomplished as well as stable ignition and combustion. Total heat necessary for DPF regeneration was reduced in comparison to the active DPF regeneration by means of engine control and an oxidation catalyst. Uneven temperature distribution in DPF and excessive temperature rise, which had been recognized as issues in the regeneration of a DPF while engine is at standstill, were solved by increase of combustion air amount and multi-step control of regeneration temperature and reliable regeneration was accomplished.

The correlation between newly approved EN 15751 and the internal diesel injector deposits (IDID) due to fuel oxidative deterioration has not been made clear. In the present research, the Rancimat method was slightly modified to research the relationship between fuel oxidative deterioration and the deterioration products generated from the fuel. After heating fuel at 120 to 150°C for a set period, insoluble deterioration products (IDID-like substances) were generated and their weights were measured. At the same time, the shifts of the conductivity in trap water were analyzed from a new perspective, and its relationship with the deterioration products was investigated. At 120°C and 130°C, conductivity rising rates after the inflection point (this set of data represents the rate of organic acid generation in the fuel, and we named “Oxidation rate”) exhibited a strong correlation with the quantity of deterioration products.

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.

The noise-generating mechanism of a reciprocating air compressor for heavy duty vehicles during idling was investigated. It was elucidated that the gear rattling noise of the air compressor drive gear train caused by the negative value of the air compressor drive torque was a major noise source. To completely suppress the gear rattling phenomenon, a new loading device with an air cylinder that cancels the negative value of the air compressor drive torque was fabricated. When the loading device was worked, the impulsive sound level was reduced to 10 dB(A). It was found that the impulsive sound level during gear rattling is closely related to the difference in gear teeth velocity between the crankshaft gear and the air compressor drive gear, as one of the characteristics that are needed to obtain a guide for carrying out estimations in the calculation simulation.

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.

The separation of combustion noise and mechanical noise from the total noise of a four-cylinder in-line diesel engine at idling was carried out with high accuracy by changing the fuel injection timing. The mechanical noise, which accounts for the major share at 93%, was then separated into noises from the typical mechanical causes, and the valve train was found to be the major noise source. From analysis of the noise generating mechanism for the valve train, it was clarified that the noise was caused mainly by the gear rattling owing to the variation in the camshaft drive torque.

Reducing friction between the piston ring and cylinder is an effective way of meeting the demand for lower fuel consumption in vehicle engines. To that effect, the authors have proposed a new and efficient friction reduction treatment for the cylinder. At first glance, this treatment seems similar to typical microtexture treatments, but it is built on a different approach. Through a rig tester, it was confirmed that optimizing the shape of the dimples and the treatment area for the cylinder improves FMEP between the piston ring and the cylinder liner by 17%. This report presents an analysis of the test results to explain the mechanism by which this effect is achieved. Fuel consumption was measured in an actual engine, and a maximum fuel consumption improvement of 3.2% was confirmed after conversion to the Japanese heavy duty vehicle fuel economy standards (Category T2). Lubricating oil consumption, blow-by and durability were also examined.

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.

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.

Technical impacts on engine oil performance by the use of waste cooking oil as bio-diesel fuel (BDF) are not well understood while the industry has made significant progress in studies on quality specifications and infrastructure. The authors, who consist of a consortium organized by Japan Lubricating Oil Society (JALOS), examined technical effects of waste cooking oil as BDF on engine oil performance such as wear and high temperature corrosion using vehicle fleets and bench tests to identify technical issues of engine oil meeting the use of BDF. The study brings fundamental information about technical impacts of BDF on engine oils.

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.

Hino Motors developed J-series 4.7-liter inline-four cylinder and 7.7-liter inline-six cylinder engines for complying with the 2004 U.S. exhaust emissions regulations. Several technologies were incorporated in the development process to accomplish simultaneous reductions in both exhaust emissions and fuel consumption while the engine performance, reliability, and durability were maintained at the levels acceptable for truck application. Newly developed technologies include a cooled EGR system, a common-rail fuel injection system, a VNT system, and an engine control system for harmonized control of EGR valve and VNT. This paper reports the development approaches and results.

Tooth contact marking of gears is an important quality characteristic that affects tooth strength and gear noise. Tooth contact marking measurement is generally done by painting the tooth surfaces of two meshed gears, rotating the gears and visually observing contact marks. Since it requires much working hours and experience to judge such a measurement, a method of measuring contact tooth markers by image processing has been developed. In this measurement method, the tooth surfaces of rotating gears are continuously observed by a TV camera, and the images are stored in an image memory device. Such quantities as the tooth surface size and tooth surface brightness level are set as initial settings, and the set values are compared with the observed images by a microcomputer to give the results of the measurement.

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.

The coupling behavior of the torsional, bending, and longitudinal vibrations in the crankshaft is described. The incidental excitation forces under crankshaft torsional vibration due to reciprocating and rotating masses are derived theoretically. Experiments on the coupling behavior of the crankshaft vibrations and the excitation behavior in the engine structure were performed in a four-cylinder automotive engine; their results are discussed.