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A truck and bus transportation which support logistics and people, diesel engines are highly expected to have high thermal efficiency and low exhaust emissions over the next few decades. Effective methods to achieve even higher thermal efficiency are to reduce a cooling loss from combustion chamber wall. A multi-hole diesel injector has a significant impact on improving engine thermal efficiency by enhancing a combustion activity and reducing a cooling loss. In this study, two types of diesel injectors - 8-hole and 14-hole - with the same flow rate were tested under heavy-duty diesel engine condition. Heat release rate, energy balance and engine emissions were investigated using the single-cylinder engine with displacement of 1,478 cc. Furthermore, an optical engine was used to observe quantitative spray penetration and flame development from shadowgraph imaging and analyze flame temperature by a two-color method.

Four years have passed since the automated mechanical transmission was first introduced in city buses, and this system is now making steady inroads into the market. The development of this system was a result of the cooperation between Kinki Nippon Railway Co., Ltd., the largest bus and coach transportation company, and Hino Motors Ltd., the largest truck and bus manufacturer in Japan. First an investigation was conducted of the topography and traffic conditions of the bus routes, then trial runs and refinement of the computer control software was carried out using three chosen routes, and finally the actual performance of the system was tested according to the finalized specifications. This paper introduces the development process, provides a background to the city bus service, and describes the benefits brought by this system and the successful results of this cooperation.

In Japan, environmentally-friendly vehicles, such as HV, PHV, EV, and FCV, have been researched and developed as solutions to the energy and environmental problems, but none of these vehicles have been fully satisfactory in all respects, such as environmental performance, vehicle performance, and adaptability to existing infrastructure. Hino Motors, Ltd. launched a hybrid bus in 1992 as a pioneer in hybrid commercial vehicles and has sold more than 10,000 hybrid buses and trucks. An electric-powered minibus designed under the concept of short travel distance and high charging frequency was developed to make use of Hino’s abundant experience in the development of HV and the past market results it has achieved. Since 2012, these buses have operated in three areas as community buses.