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This paper introduces the Japanese standards and regulations of automobiles with brakes as the central subject and clarifies the difference from those of Europe and USA by comparison. Further, this paper describes not only the application status of the standards and regulations in Japan but also the features of structure and performance of Japanese trucks that are designed and produced under such standards and regulations. It can be said that the Japanese trucks are comparatively simple in structure but are in a level equal to or higher than European and USA automobiles in respect of performance. Also in respect of the international harmonization, the internationalization of standards is being conducted in Japan on the basis of ISO and the internationalization for regulations is considered to be under preparation.

The running direction of a vehicle can be controlled by not only wheel steer but also torque steer. This paper introduces the tractive torque steer effect produced by a newly developed electropneumatic control system, the limited-slip differential for large-sized vehicles. This system enhances the vehicle's running stability and controllability by controlling the tractive force of the drive axle. The tractive force maintains a stable running course against disturbances such as road roughness and wind gusts, thereby enhancing the steering response and providing a better feeling of handling to the driver. The system also improves mobility. especially on low-μ roads. It is expected that a single axle equipped with this system will exhibit good performance comparable to that of tandem axle.

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.

A driving simulator system for developing steering road feel has been developed. A new steering gear box or an electronic steering system is installed on the simulator and its road feel and control algorithm are developed according to the characteristics of any vehicle which has been programed into the engineering work-station. The vehicle model programed into the engineering work station runs according to the driver's operations, which are fed through the new steering system to be tested. The steer-restoring torque of the vehicle programed into the engineering work-station is produced by an actuator, and gives the impression through the new system of having been fed back from an actual road.

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.

Ultra-low energy consumption and ultra-low emission vehicle technologies have been developed by combining petroleum-alternative clean energy with a hybrid electric vehicle (HEV) system. Their component technologies cover a wide range of vehicle types, such as passenger cars, delivery trucks, and city buses, adsorbed natural gas (ANG), compressed natural gas (CNG), and dimethyl ether (DME) as fuels, series (S-HEV) and series/parallel (SP-HEV) for hybrid types, and as energy storage systems (ESSs), flywheel batteries (FWBs), capacitors, and lithium-ion (Li-ion) batteries. Evaluation tests confirmed that the energy consumption of the developed vehicles is 1/2 of that of conventional diesel vehicles, and the exhaust emission levels are comparable to Japan's ultra-low emission vehicle (J-ULEV) level.

Hino Motors is about to launch a new truck model FA as a family product of the model FB class 5 category trucks which have been sold since 1986, Model FA, a class 3 category cab-over-engine truck has a GVW of 13,500 Lbs. and is powered by a 3.8 liter direct injection turbocharged diesel engine which produces 125 HP in conformity with federal exhaust gas emission regulations for 50 states. The new truck was designed and developed to satisfy several principal design objectives such as excellent maneuverability, driving comfort, superior fuel economy as well as sufficient reliability and durability within the simplest possible structure. This paper describes its design objectives, features focusing on cab and engine and technologies devoted to the development.

To reduce the vehicle fuel consumption at high speed, it is very effective to minimize the aerodynamic resistance of the vehicle, which forms most of the vehicle running resistance at high speed. This paper presents a reduction of the aerodynamic resistance of van type truck through the wind tunnel tests using 1/5 scaled model. Firstly, the aerodynamically desirable cab shape for cargo type truck is investigated by changing main cab shape factors such as corner curvatures. Secondly, several effective attachments for Van type truck are investigated, and lastly, the effect of these aerodynamic improvements on the fuel consumption are clearified by vehicle running test.

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.

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.

Hino Motors had developed an electronically controlled mechanical automatic transmission and employed it for the ′85 models of large size buses, and also ′86 models of heavy/ medium duty trucks. This system gives minimum fuel consumption and even smoother/easier driving than an automatic transmission with torque converter, by controlling an engine also with a transmission and employing an oil spray clutch. The trade name of this system is EE-Drive which means easy and economy drive.

Electronically controlled systems, originally developed for passenger cars, have been applied to trucks and buses since the early 1980's. With the increase of the objects for those applications their contents have become more and more sophisticated with rapid expansion and growth. This paper has summarized the results of observations on the background situations behind the applications of electronic control systems to trucks and buses in Japan. The status of the electronic applications, in particular to the powertrain, are explained and specific examples are provided. Future trends are also discussed.

Vehicle responsiveness to the driver's steering maneuvers and external turbulences caused by irregularities in the road surface and wind gusts are two opposing factors to be studied for better stability and controllability of vehicles. The cruising speeds of vehicles on freeways have been becoming higher, and wider physiological differences in the driving ability of drivers are appearing with the increase in elderly drivers. Therefore, to meet the requirements of higher cruising speeds and the expanding physiological differences between drivers, an electro-hydraulic feedforward control power steering system has been developed for trucks and buses. This is a parallel operating system consisting of a mechanical route and an electronic route, and improves vehicle responsiveness so as to absorb the physiological differences of drivers.

This paper investigates the effects of Fischer-Tropsch Diesel (FTD) (a completely a paraffinic fuel) on the fuel supply system in automotive applications. In particular, the effects of Gas to Liquid (GTL) (an FTD synthesized from natural gas) on the elastomer components has been investigated by laboratory scale tests and field trials. In the field trials, GTL was supplied to a commercial vehicle operator and the effect of real running conditions was observed. Also, the laboratory scale testing to simulate the actual condition of usage of a commercial vehicle was conducted under stringent conditions, and a correlation with the field trials was investigated. As a result, no negative effects related to GTL were found.

In the '97 Dakar Rally, Hino FT model, 8,000cc engine truck, won 1st, 2nd and 3rd places by defeating upper class trucks having engine of 19,000cc. The average speed of the '97 Hino model was increased more than 15 km/h over the '96 model by improving the riding comfort and handling stability. Larger diameter tires, and softer parabolic leaf springs with long and inclined axle-locus for reducing road impact, gas charged dampers, suspension rods which control compliance-steer-motion and wind-up motion of unsprung masses were adopted for the '97 model.

The Advanced Safety Vehicle (ASV) project phase 2 was organized by the Japanese ministry of lands, infrastructures and transport in 1996 as a five year project. Hino Motors participated in the project and developed an intelligent truck “HINO ASV-2”. HINO ASV-2 was equipped with safety systems for accident prevention and accident avoidance, which were most effective in reducing accidents in freight transport. These intelligent systems aimed to reduce driving fatigue, minimize the chance of driver’s mistake, and prevent the occurrence of accidents. Human-machine interface, and front underrun protection device were also studied. Through the development of the ASV systems, the feasibility and basic functions of these systems were studied. Further development is necessary to implement the ASV systems in production vehicles.

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.

For the purpose of reducing fuel consumption, a hybrid heavy duty truck was considered. Generally, HV (Hybrid Vehicle)'s energy is regenerated from deceleration energy in urban area. Hybrid heavy duty truck's energy is regenerated from potential energy on highway. Under this circumstance, some portion of energy may not be accumulated, because capacity of HV battery is limited. In order to maximize accumulating energy in the next descent, HV battery's energy shall be adequately reduced beforehand. This can be achieved by optimizing motor assist torque considering road's altitude and gradient. In this paper, performance of the algorithm is discussed.

Hino Motors, Ltd. (Hino) launched the world's first hybrid city bus in 1991. Since then, the same hybrid technology has been refined and applied to a range of commercial vehicles, from city and tour buses to light and medium duty trucks, expanding the commercial hybrid vehicle line up. After 20 years of refining this technology, in 2011 Hino launched an all new light duty hybrid truck in Japan. An alternate version of the truck was developed to meet the particular needs of the North American market, differing from the Japanese model in several important features. The Japanese model's automated manual transmission was replaced with a fully automatic transmission, and the motor and inverter specifications were altered. This paper outlines the development process and introduces various characteristics of the technologies employed in the North American hybrid model.