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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.

A multi-tube EGR cooler was developed to have high heat exchanger efficiency with high reliability for heavy-duty diesel engine application. Using three-dimensional numerical analyses as well as several laboratory experiments on both a test rig and a diesel engine, the authors determined the most critical factors for developing such an EGR cooler with low production costs. Technology development focused on achieving a high heat transfer coefficient on the gas side in a tube for increased heat exchanger efficiency and uniform coolant flow distribution in the shell for effective cooling of all tubes in the shell. The tube's inside wall was designed with a spiral configuration both for improved gas flow and heat transfer characteristics. Both the layout of the coolant inlet and outlet on the shell and the arrangement of tubes in the shell were optimized for the best results.

Hino Motors has developed the new K13C, a 12.9 liter six cylinder in-line, heavy duty diesel engine that provides superior fuel consumption, extra low noise and excellent driveability together with a lower exhaust emissions. The initial K13C engine, whose production began in 1986 and about 30,000 units have been produced, is recognized all over the world for its good reliability and fuel economy. The new K13C is using the basic design and manufacturing/assembly processes of the previous one but includes a common-rail type fuel injection system with enhanced electronic controls to meet future regulation and customer requirements. Major design changes consist of a new cylinder head, a new front gear train, a new air intake system, a new turbocharger, a new compression brake system and electronic control module. The optimization of the intake system includes a new intake port and an electronically controlled inertia charging system.

A recent increase in detergent additives to gasoline has resulted in an increase in the accumulation of deposits inside the engine's combustion chamber (this type of deposit will be hereinafter referred to as “CCD”;Combustion Chamber Deposit). Along with this tendency, authors have observed an engine noise generated during warm up, which may be attributable to the CCD accumulation. It was reported that the engine noise was identified as carbon knocking caused when the piston and cylinder head physically come in contact because of these CCDs(1X2) This paper deals with another noise generated by the CCD trapped between the piston ring and piston ring groove.

To obtain low friction engine through piston ring design, a set of two piston rings (two-ring set), one compression ring and one oil ring, has been recently developed. To reduce the number of compression rings from two to one, double angle step joint was employed for the shape of top ring gap, and taper face was introduced to O.D. surface shape. Major subjects of two-ring set were to reduce the oil consumption, to increase the durability, and to get the reliability of double angle step joint. The authors obtained the two piston ring design and the reliability of double angle step joint by rig tests and engine tests.

This paper describes the experimental studies of turbocharged and intercooled diesel engines with particular emphasis on combustion characteristics following increase of boost pressure. Through these studies, it has become possible to determine the optimum air quantity for minimizing fuel consumption at each engine speed range under the restrictive conditions of NOx emission, exhaust smoke and maximum cylinder pressure. Discussed also is the lack of air quantity in the low engine speed range of high-boost turbocharged diesel engines. Various turbocharging systems to improve air quantity in this speed range are introduced herein. Practically the engine performance of conventional turbocharging, waste gate control turbocharging and variable geometry turbocharging are discussed from the viewpoint of torque recovery in the low engine speed range.